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  • 1.
    Andersson, Åsa
    et al.
    Halmstad University, School of Business, Innovation and Sustainability.
    Haglund, Emma
    Halmstad University, School of Business, Innovation and Sustainability. FoU Spenshult Spenshult Research and Development Centre, Spenshult Research and Development Centre, Halmstad, Sweden; Lund University, Dept. of Clinical Sciences, Section of Rheumatology, Lund, Sweden.
    Berthold, Emma
    Halmstad University, School of Business, Innovation and Sustainability.
    Mogard, Elisabeth
    Lund University, Lund, Sweden.
    Torell, Anna
    Ängelholm Hospital, Ängelholm, Sweden.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Innovation and Sustainability.
    Serum Protein Response To A Single High-Intensity Interval Training Bout – Comparison Between Individuals With Spondyloarthritis And Healthy Controls2022In: Annals of the Rheumatic Diseases, ISSN 0003-4967, E-ISSN 1468-2060, Vol. 81, no Suppl 1, p. 780-781Article in journal (Refereed)
  • 2.
    Andersson, Åsa
    et al.
    Halmstad University, School of Business, Innovation and Sustainability.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Innovation and Sustainability.
    Torell, Anna
    Halmstad University, School of Business, Innovation and Sustainability. Ängelholm hospital, Dept. of Rehabilitation.
    Mogard, Elisabeth
    Rheumatology, Dept. of Clinical Sciences, Lund University, Skåne University Hospital.
    Haglund, Emma
    Halmstad University, School of Business, Innovation and Sustainability. Spenshult Research and Development Centre, Halmstad.
    Effects on serum protein levels from one bout of high intensity interval training in individuals with axial spondyloarthritis and controlsManuscript (preprint) (Other academic)
    Abstract [en]

    Background: Axial spondyloarthritis (axSpA) is a chronic inflammatory disease primarily affecting the axial skeleton causing pain, inflammation, and stiffness. Individuals with axSpA are at greater risk of developing cardiovascular disease, which can be counteracted by physical activity. High-intensity interval training (HIIT) has been shown to improve cardiovascular health, but the effect on disease activity and the level of inflammation in axSpA has been less studied. With the aim of investigating how levels of inflammatory cytokines, myokines, and protein markers for bone metabolism are acutely affected by one bout of HIIT, we studied serum from individuals with axSpA and healthy controls (HC). Methods: Ten participants with axSpA and 11 age- and sex-matched HC performed a single HIIT bout on a cycle ergometer: 4x4 minutes intervals with three minutes active rest in between. Blood samples were taken before and one hour after the HIIT bout. Serum proteins (IL-6, IL-17, IL-18, TNFa, CXCL-10, VEGF-A, BDNF, DKK-1, osteoprotegerin, osteocalcin, osteopontin, BMP-7, CRP) were analyzed with a Luminex system or ELISA. Descriptive data are presented as mean with standard deviation. A two-way ANOVA was used for comparisons. Results: A main effect from baseline to one hour post HIIT showed that both groups had a significant increase in serum levels (pg/ml) of IL-6: axSpA 2.2 (3.0) to 3.2 (1.8) and HC 0.4 (0.4) to 1.9 (2.0), p=0.03. VEGF-A (pg/ml) was significantly lower in the axSpA group: 159 (138) vs. HC 326 (184), p=0.03, but was not affected by the HIIT bout. BMP-7 (ng/ml) increased in both groups after the HIIT: axSpA 61.6 (13.1) to 75.2 (20.0) and HC 64.6 (20.8 to 75.0 (17.8), p<0.001. For the other proteins analyzed, there were no significant differences in serum concentrations between individuals with axSpA and HC, or within the two groups before and after one bout of HIIT. Conclusions: One acute bout of HIIT significantly increases the serum concentrations of IL-6 and BMP-7 after 1 hour in both individuals with axSpA and HC. 

  • 3.
    Arakelyan, Arsen
    et al.
    Institute of Molecular Biology, National Academy of Sciences of the Republic of Armenia (NAS RA), Yerevan, Armenia.
    Zakharyan, Roksana
    Institute of Molecular Biology, National Academy of Sciences of the Republic of Armenia (NAS RA), Yerevan, Armenia.
    Hambardzumyan, Marina
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Petrkova, Jana
    Laboratory of Immunogenomics and Immunoproteomics, Institute of Molecular and Translational Medicine, Medical Faculty of Palacky University, Olomouc, Czech Republic.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Biomechanics and Biomedicine.
    Petrek, Martin
    Laboratory of Immunogenomics and Immunoproteomics, Institute of Molecular and Translational Medicine, Medical Faculty of Palacky University, Olomouc, Czech Republic.
    Boyajyan, Anna
    Institute of Molecular Biology, National Academy of Sciences of the Republic of Armenia (NAS RA), Yerevan, Armenia.
    Functional Genetic Polymorphisms of Monocyte Chemoattractant Protein 1 and C-C Chemokine Receptor Type 2 in Ischemic Stroke2014In: Journal of Interferon and Cytokine Research, ISSN 1079-9907, E-ISSN 1557-7465, Vol. 34, no 2, p. 100-105Article in journal (Refereed)
    Abstract [en]

    Recent findings indicated that monocyte chemoattractant protein 1 (MCP1) and its C-C chemokine receptor type 2 (CCR2) play a key role in ischemic stroke (IS) progression. This study was aimed at evaluating the potential association of the MCP1 gene (MCP1) rs1024611 (-2518 A>G) and CCR2 gene (CCR2) rs1799864 (V64I; 190 G>A) functional single nucleotide polymorphisms (SNPs) with IS in the Armenian population. For the purpose of this study, genomic DNA samples of 100 patients with the first-episode IS and 115 healthy subjects (controls) were genotyped for the selected SNPs using a polymerase chain reaction with sequence-specific primers. The results obtained demonstrated that while the CCR2 rs1799864 SNP genotypes were equally distributed among patients and controls, the frequency and carriage rate of the of the MCP1 rs1024611*G minor allele were higher in patients. While a potential association between IS and CCR2 rs1799864 SNP was evaluated for the first time, the latest finding was in agreement with the earlier data reported for some other populations. In summary, this study revealed no association of CCR2 rs1799864 SNP with IS, and a positive association between G minor allele of MCP1 rs1024611 SNP and IS in the Armenian population. Based on the present and earlier reported data, we concluded that the minor G allele of the MCP1 rs1024611 SNP might be considered a risk factor for IS.

  • 4.
    Brorsson, Sofia
    et al.
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS), Biomechanics and Biomedicine.
    Lundgren, Lina
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS).
    Olsson, Charlotte
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS).
    Ett fysiologiskt perspektiv på fysisk aktivitet och hälsa2010In: Hälsa & Livsstil: forskning och praktiska tillämpningar / [ed] Lillemor R-M Hallberg, Lund: Studentlitteratur, 2010, 1, p. 87-112Chapter in book (Other academic)
  • 5.
    Brorsson, Sofia
    et al.
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS), Biomechanics and Biomedicine.
    Olsson, M Charlotte
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS), Biomechanics and Biomedicine.
    Bengtsson, Oscar
    Petersson, Johan
    Maximal strength in one leg squat correlates with acceleration capacity and agility2010Conference paper (Refereed)
    Abstract [en]

    INTRODUCTION: In many intermittent team sports capacities such as speed, agility and explosiveness are important for performance and are evaluated by sprint-, agility- and strength tests. Earlier studies have shown strong correlations between strength in the two leg squat exercise and sprint performance in various distances but not in sprint performance in agility. Studies evaluating squat strength predominantly perform tests on two legs even when they test athletes involved in intermittent sports where sprinting and agility are common features. Thus, the purpose of this study was to investigate the correlation between maximal strength in a one leg squat (Bulgarian split squat) and acceleration capacity in various sprint distances and agility.

    METHODS: The test group consisted of 19 men (mean age 24 ± 2 years ) with experience in intermittent team sports. Acceleration capacity was assessed by sprint tests at 5, 10 and 20 meters and agility was evaluated using the zigzag agility test. The timing was made using photocells (Muscle lab,Ergotest Technology,Norway). The Bulgarian split squat was performed in a smith machine with the barbell on the shoulders to a depth of 110 degrees between tibia and femur.

    RESULTS: The results show significant correlation between maximal strength in the Bulgarian split squat and sprint capacity in the 5 and 10 meter sprint test (Rp= -0,56; p<0.01) as well as the agility test. Maximal strength relative to bodyweight showed significant correlation with the 5 and 20 meter sprint (Rp=-0,62; p< 0,01) as well as the agility test. The zigzag agility test also showed significant correlation between all distances in the sprint tests (p<0.01).

    CONCLUSION: The results from this study show that there maximal strength in one leg correlate significantly with both acceleration capacity and agility. Implementing one leg exercises in the strength and conditioning routine can be useful for athletes in intermittent sports wanting to improve agility and short sprinting capacity. Further implications is that the Bulgarian split squat could be a more functional test for agility performance than the squat on two legs which  predominantly is being used today.

  • 6.
    Brorsson, Sofia
    et al.
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS), Biomechanics and Biomedicine.
    Olsson, M Charlotte
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS), Biomechanics and Biomedicine.
    Fredriksson, Daniel
    Training program for young female soccer players with focus on increasing the acceleration capacity2010Conference paper (Refereed)
    Abstract [en]

    INTRODUCTION: Soccer is the world’s most popular team sport with over 240 million players around the world. About 20 million of the 240 million players are women and 80% of these women are adolescence or juniors. Acceleration capacity is one of the most important physical qualities for a soccer player. The aim of this study was to design, perform and evaluate a training program for young female soccer players with focus on increasing the acceleration capacity.

    METHODS: There were 22 young females (14,6 ± 1,0 years, 50,3 ± 5,1 kg, 160,2 ± 3,0 cm) from two different soccer teams participating. They were split into two groups, one test group (TG) (n=8) and one control group (CG) (n=14). The training period was 12 weeks, with soccer training 3 times per week for both groups. In the TG one workout per week was specifically designed to increase the acceleration capacity and took about 40 minutes to perform. The acceleration capacity was evaluated by a sprint test of 10-20-30 meter and vertical countermovement jump test using photocells.

    RESULTS: The TG showed a tendency to increased acceleration at the sprint test (p=0,08) and significant improvement at the jump test (p<0.05) after 12 weeks of training. The acceleration training also showed significant correlations between the sprint- and jump test in the TG after completed the 12 week training period (p<0.05). The CG showed decreased acceleration at the sprint test (p<0.05) and the vertical jump height was not significantly different. There were no significant differences between the two groups pre and post training.

    CONCLUSION: A 12 week training program can increase the acceleration capacity and the vertical jump height on young female soccer players. In sport were acceleration capacity is important it seems relevant to specifically train those qualities.

  • 7.
    Brorsson, Sofia
    et al.
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS), Biomechanics and Biomedicine.
    Olsson, M Charlotte
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS), Biomechanics and Biomedicine.
    Westerberg, Martin
    Maximal multiple repetitions in free weight strength training with different bar sizes2010Conference paper (Refereed)
    Abstract [en]

    INTRODUCTION: An individual’s grip strength is vital for performance of physical demanding tasks such as give some other example here? As well as strength training with free weights. Performing strength training with a thicker grip around the bar may enhance the strength of the grip in the athlete without other special routines for grip strength development. The purpose of this study was a) to examine the difference in performance in multiple repetitions in two strength training exercises using two different sizes on the bar, b) to investigate correlations between hand grip strength and the amount of repetitions performed with two different sizes of the  bar and c) to correlate hand size with the amount of performed repetitions with two different bar sizes.

    METHODS: Fifteen male participants (24 ± 4 years) with at least one year of strength training experience performed bench press and a prone lying rowing exercise with two different bar sizes (normal Olympic lifting bar with and with out Fat Gripz™). The participants performed test of maximal number of repetitions at a level of 80% of one repetition maximum (1RM), hand size was measured as well as maximum grip strength (using JAMAR).

    RESULTS: The use of a thicker diameter bar resulted in 22 % (p<0.01) reduction of weight performance in number of performed repetitions in the bench press compared to the normal diameter of the bar.  When performing lying bench row a 66 % (p<0.01) reduction in number of performed repetitions was seen with the thicker diameter of the bar. There was no significant correlation between hand size and the submaximal strength test (rp = 0,33 ; p = 0,23) or grip strength and submaximal strength test (rp = 0,31 ; p = 0,27).

    CONCLUSION: The results from this study indicated that the size of the bar diameter influences the performance in maximal number of repetitions in a prone lying rowing exercise and bench press.  Further studies have to be done to analyses the effect of strength training with thicker bar.

     

  • 8.
    Ek, Staffan
    et al.
    Department of Translational Medicine, Lund University, Lund, Sweden & Department of Medical Imaging and Physiology, Skåne University Hospital, Malmö, Sweden.
    Wollmer, Per
    Department of Translational Medicine, Lund University, Lund, Sweden & Department of Medical Imaging and Physiology, Skåne University Hospital, Malmö, Sweden.
    Karlsson, Magnus K.
    Clinical and Molecular Osteoporosis Research Unit, Department of Clinical Sciences and Orthopaedics, Lund University, Skåne University Hospital, Malmö, Sweden.
    Peterson, Tomas
    Department of Sport Sciences, Malmö University, Malmö, Sweden.
    Thorsson, Ola
    Department of Translational Medicine, Lund University, Lund, Sweden & Department of Medical Imaging and Physiology, Skåne University Hospital, Malmö, Sweden.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Malmborg, Julia
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Dencker, Magnus
    Department of Translational Medicine, Lund University, Lund, Sweden & Department of Medical Imaging and Physiology, Skåne University Hospital, Malmö, Sweden.
    Relative Age Effect of Sport Academy Adolescents, a Physiological Evaluation2020In: Sports, E-ISSN 2075-4663, Vol. 8, no 1Article in journal (Refereed)
    Abstract [en]

    The relationship between birth quarter distribution and physiological characteristics related to athletic skills, in adolescent sport academy students has not been fully investigated. In a cross-sectional study, we recruited 86 boys and 52 girls aged 12-14 years during their first term at a sport academy school. We measured body size, cardiac size, pulmonary function, body composition, lower body power, cardiorespiratory fitness parameters, and running endurance by standard methods and analyzed these estimates in relation to birth quarter by ANOVA. Birth quarter distribution in our cohort was compared with birth quarter distribution in the same ages in the whole of Sweden and analyzed by logistic regression. The academy had an overrepresentation of students born in the first quartile of the year compared to those born in the last quartile (odds ratio 2.3 (95% CI: 1.1-4.7)). When comparing the physiological characteristics between birth quarters, uniformity is prominent since out of 26 performed physiological and anthropometric tests only four showed statistically significant group differences. We thus believe that the selection process to the sport academy favours athletes with higher chronological age, i.e., a so-called relative age effect is present. © 2020 MDPI (Basel, Switzerland).

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  • 9.
    Frandsen, Björn
    et al.
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Olsson, M Charlotte
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Biomechanics and Biomedicine.
    Hip and Trunk Muscle Electromyography Differences Between Bilateral and Unilateral Bodyweight Resistance Exercises2015Conference paper (Other academic)
    Abstract [en]

    Introduction

    In sports, force production and movement are predominantly generated in a unilateral weight-bearing stance. Therefore, unilateral resistance training may possibly elicit more sport-specific strength gains compared to traditional bilateral strength training. Hip- and trunk- muscles stabilize the pelvis and trunk to maintain proper technique and posture in resistance training and are thought to play a central role in sports performance as well as injury prevention. Hip- and trunk- muscle activity increases as the body weight balance change from a bilateral to a unilateral stance. Little research has examined the magnitude of change in muscle activation differences between bilateral and unilateral stance in lower body exercises.

    Aim

    The aim of this study was to examine the electromyographic (EMG) activity in hip and trunk muscles in three bodyweight exercises performed in a bilateral and a unilateral stance.

    Methods

    14 healthy, young adults participated in a single session, single-group, observational study. Manual muscle testing was used to attain a maximal voluntary isometric contraction (MVC) value for gluteus medius, gluteus maximus, rectus abdominis, and erector spinae. EMG measurements (4 channel ME6000, MegaWin Software, Kuopio, Finland) were taken during performance of squat, bridge, and plank exercises in both a bilateral and a unilateral stance.

    Results

    In all three exercises, EMG activity (presented as magnitude of change) was greater in the unilateral stance compared to the bilateral stance (p< 0.05), for the muscles gluteus medius (squat 478%, bridge 204%, plank 285%) and gluteus maximus (squat 371%, bridge 172%, plank 233%). In addition, in plank, EMG activity was greater in unilateral stance compared to the bilateral stance (p< 0.05) in rectus abdominis (120%) and erector spinae (127%). In the squat and bridge, no differences were identified in EMG activity for rectus abdominis and erector spinae between the bilateral and the unilateral stance.

    Discussion

    Nearly all unilateral exercises activated the hip muscles (gluteus medius, gluteus maximus) more than double compared to the same exercises performed bilaterally. In particular, gluteal muscle activity during the unilateral squat was more than 3.5 fold greater as compared to the bilateral stance. This greater magnitude of change in the unilateral squat might be explained by the single contact point with the ground in the squat, whereas the bridge and plank exercises include more ground contact points even in their unilateral stance. A unilateral training program including squat exercises might be beneficial for developing hip strength which is of great importance in sports performance.

  • 10.
    Helland, Christian
    et al.
    The Norwegian Olympic and Paralympic Committee and Confederation of Sports, Oslo, Norway.
    Hole, Eirik
    The Norwegian Olympic and Paralympic Committee and Confederation of Sports, Oslo, Norway.
    Iversen, Erik
    The Norwegian Olympic and Paralympic Committee and Confederation of Sports, Oslo, Norway.
    Olsson, Monica Charlotte
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Seynnes, Olivier
    Norwegian School of Sport Sciences, Oslo, Norway.
    Solberg, Paul Andre
    Defense Institute, Norwegian School of Sport Sciences, Oslo, Norway.
    Paulsen, Gøran
    The Norwegian Olympic and Paralympic Committee and Confederation of Sports, Oslo, Norway & Norwegian School of Sport Sciences, Oslo, Norway.
    Training Strategies to Improve Muscle Power: Is Olympic-style Weightlifting Relevant?2017In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 49, no 4, p. 736-745Article in journal (Refereed)
    Abstract [en]

    INTRODUCTION: This efficacy study investigated the effects of (1) Olympic-style weightlifting (OWL), (2) motorized strength and power training (MSPT), and (3) free weight strength and power training (FSPT) on muscle power.

    METHODS: Thirty-nine young athletes (20±3 yr.; ice hockey, volleyball and badminton) were randomized into the three training groups. All groups participated in 2-3 sessions/week for 8 weeks. The MSPT and FSPT groups trained using squats (two legs and single leg) with high force and high power, while the OWL group trained using clean and snatch exercises. MSPT was conducted as slow-speed isokinetic strength training and isotonic power training with augmented eccentric load, controlled by a computerized robotic engine system. FSPT used free weights. The training volume (sum of repetitions x kg) was similar between all three groups. Vertical jumping capabilities were assessed by countermovement jump (CMJ), squat jump (SJ), drop jump (DJ), and loaded CMJs (10-80 kg). Sprinting capacity was assessed in a 30 m sprint. Secondary variables were squat 1-repetition-maximum, body composition and quadriceps thickness and architecture.

    RESULTS: OWL resulted in trivial improvements, and inferior gains compared to FSPT and MSPT for CMJ, SJ, and DJ. MSPT demonstrated small, but robust effects on SJ, DJ and loaded CMJs (3-12%). MSPT was superior to FSPT in improving 30 m sprint performance. FSPT and MSPT, but not OWL, demonstrated increased thickness in the vastus lateralis and rectus femoris (4-7%).

    CONCLUSION: MSPT was time-efficient and equally or more effective than FSPT training in improving vertical jumping and sprinting performance. OWL was generally ineffective and inferior to the two other interventions. Copyright © 2016 by the American College of Sports Medicine.

  • 11. Horwath, Oscar
    et al.
    Paulsen, Gøran
    The Norwegian Olympic and Paralympic Committee and Confederation of Sports, Oslo, Norway & Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.
    Esping, Tobias
    Seynnes, Olivier
    Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Isokinetic resistance training combined with eccentric overload improves athletic performance and induces muscle hypertrophy in young ice hockey players.2019In: Journal of Science and Medicine in Sport, ISSN 1440-2440, E-ISSN 1878-1861, Vol. 22, no 7, p. 821-826Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: To determine the combined effects of slow isokinetic resistance training and eccentric overload and compare it to traditional resistance training on strength, power, body composition and muscle hypertrophy in young ice hockey players.

    DESIGN: Experimental, randomized trial.

    METHODS: Twenty-two resistance-trained ice hockey players (18±1year) were assigned to either isokinetic resistance training and eccentric overload (ISO/ECC; n=11) or traditional resistance training (TRAD; n=11). Participants underwent supervised progressive resistance training for 8 weeks (2-3 sessions/week) involving lower body multiple-joint exercises (heavy squats and explosive jump squats). The ISO/ECC group performed their training using a computerized robotic engine system (1080 Quantum synchro, Sweden), whereas the TRAD group performed the same resistance exercises with isotonic loading. Before and after the intervention, participants were evaluated in 1RM back squat, loaded jump squats, sprint- and jump performance, body composition and muscle thickness using ultrasound measurement.

    RESULTS: Similar moderate increases in 1RM back squat and power output in the jump squats were found in both the ISO/ECC and TRAD groups (11-17%, P<0.01), whereas only the ISO/ECC group showed improvements in drop jump performance (9.8%, P=0.01). Moreover, similar trivial changes in body composition were observed in both groups, while only the ISO/ECC training group increased muscle thickness in the vastus intermedius (P=0.01) and rectus femoris muscles (P=0.03).

    CONCLUSIONS: Both modalities effectively increased maximal strength and power output, whereas isokinetic resistance training, combined with eccentric overload, improved drop jump performance and induced greater muscle hypertrophy than traditional training in young ice hockey players. © 2019 Sports Medicine Australia

  • 12.
    Khan, Taha
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Lundgren, Lina
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS). Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Järpe, Eric
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Wiberg, Pelle
    Raytelligence AB, Halmstad, Sweden.
    A Novel Method for Classification of Running Fatigue Using Change-Point Segmentation2019In: Sensors, E-ISSN 1424-8220, Vol. 19, no 21, article id 4729Article in journal (Refereed)
    Abstract [en]

    Blood lactate accumulation is a crucial fatigue indicator during sports training. Previous studies have predicted cycling fatigue using surface-electromyography (sEMG) to non-invasively estimate lactate concentration in blood. This study used sEMG to predict muscle fatigue while running and proposes a novel method for the automatic classification of running fatigue based on sEMG. Data were acquired from 12 runners during an incremental treadmill running-test using sEMG sensors placed on the vastus-lateralis, vastus-medialis, biceps-femoris, semitendinosus, and gastrocnemius muscles of the right and left legs. Blood lactate samples of each runner were collected every two minutes during the test. A change-point segmentation algorithm labeled each sample with a class of fatigue level as (1) aerobic, (2) anaerobic, or (3) recovery. Three separate random forest models were trained to classify fatigue using 36 frequency, 51 time-domain, and 36 time-event sEMG features. The models were optimized using a forward sequential feature elimination algorithm. Results showed that the random forest trained using distributive power frequency of the sEMG signal of the vastus-lateralis muscle alone could classify fatigue with high accuracy. Importantly for this feature, group-mean ranks were significantly different (p < 0.01) between fatigue classes. Findings support using this model for monitoring fatigue levels during running. © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

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  • 13.
    Kroos, G.
    et al.
    Dept. of Exercise and Sport Sciences, Univ. of Copenhagen, Copenhagen, Denmark.
    Hansen, A
    Dept. of Exercise and Sport Sciences, Univ. of Copenhagen, Copenhagen, Denmark.
    Hanskov, D J A
    Dept. of Exercise and Sport Sciences, Univ. of Copenhagen, Copenhagen, Denmark.
    Olsson, M Charlotte
    Dept. of Exercise and Sport Sciences, Univ. of Copenhagen, Copenhagen, Denmark.
    Olsen, K.
    Dept. of Exercise and Sport Sciences, Univ. of Copenhagen, Copenhagen, Denmark.
    Hellsten, Y.
    Dept. of Exercise and Sport Sciences, Univ. of Copenhagen, Copenhagen, Denmark.
    Gene expression of angiogenic factors in muscle tissue during age-related development of hypertension in spontaneously hypertensive rats2008In: Abstracts 25th Conference of the European Society for Microcirculation: Integrating Vascular Biology and Medicine: Basic and Clinical Science / [ed] Akos Koller, Basel: S. Karger, 2008, Vol. 45, p. 120-120Conference paper (Refereed)
    Abstract [en]

    Essential hypertension has been associated with capillary rarefaction but little is known about the cellular mechanisms underlying this process. We examined the gene expression of angiogenic factors during age-related development of hypertension in spontaneously hypertensive rats (SHR). Wild-type Wistar Kyoto (WKY) rats served as controls. White gastrocnemius muscle was obtained and blood pressure was monitored at 5, 10 and 15 weeks of age. In the SHR group, systolic blood pressure increased from 5 to 10 and 15 weeks of age and the levels were higher than in the WKY group at 10 and 15 weeks (~70%; P<0.05). The mRNA content for MMP-2 was overall lower (P<0.05) in SHR compared to WKY. VEGFmRNA increased (p<0.05) from 5 to 10 weeks in SHR and there was a general increase (P<0.05) in the VEGF receptor flt-1. There was a trend for a lower content of eNOS and CYP 2C11 in the SHR than in WKY group. There were no alterations in the mRNA content of KDR, AMP 5'- nucleotidase, or Cytochrome P450 4A. The results show that the age-related development of hypertension from 5 to 15 weeks in SHR rats is not associated with major changes in mRNA content of the herein included angiogenic factors.

  • 14.
    Larsson, Jonas
    et al.
    Halmstad University, School of Business, Innovation and Sustainability. Department of Medical Imaging and Physiology, Skåne University Hospital, Department of Translational Medicine, Lund University, Sweden; Swedish Armed Forces, Eksjö, Sweden.
    Dencker, Magnus
    Department of Medical Imaging and Physiology, Skåne University Hospital, Department of Translational Medicine, Lund University, Sweden.
    Bremander, Ann
    Halmstad University, School of Business, Innovation and Sustainability. Department of Clinical Sciences, Lund, Section of Rheumatology, Lund University, Sweden; Department of Regional Health Research, University of Southern Denmark, Odense, Denmark.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Innovation and Sustainability.
    Cardiorespiratory responses of load carriage in female and male soldiers2022In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 101, article id 103710Article in journal (Refereed)
    Abstract [en]

    Purpose

    To investigate the effect of sex and load carriage on cardiorespiratory responses to high intensity exercise in male and female soldiers.

    Methods

    Soldiers (9 women, 9 men) performed a graded treadmill test until exhaustion with no load (NL) and combat-gear with body armor (CG). Cohen's d effect sizes, paired t-tests and ANOVA were used to study differences between conditions. A mixed linear regression model analyzed the relationship between heart rate (HR) and oxygen uptake (V̇O2) with load and between sexes.

    Results

    Wearing CG resulted in, for both sexes, a decreased time to exhaustion (−11 min), lower V̇O2peak (L/min) ES = 0.56; VO2peak (mL//kg/min) ES = 2.44, both p < 0.001, a net decrease in minute ventilation (ES = 3.53) and no change in HRmax. No sex-difference were present except for absolute V̇O2peak. The VO2 and HR relationship showed a cardiorespiratory reduction wearing CG vs. NL. Added load was equal between sexes, although female soldiers' CG relative to body mass was higher (25%) than male soldiers’ (20%), p < 0.01.

    Conclusion

    Wearing CG reduces soldiers’ cardiorespiratory capacity and exercise performance level, although the reduction cannot be explained solely based on the added load of CG, instead CG seems to restrict the capacity to fully ventilate. No sex differences were found in relative cardiorespiratory responses to wearing CG compared to NL.

  • 15.
    Larsson, Jonas
    et al.
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS). Department of Medical Imaging and Physiology, Skåne University Hospital Department of Translational medicine, Lund University, Lund, Sweden & Swedish Armed Forces, Eksjö, Sweden.
    Dencker, Magnus
    Department of Medical Imaging and Physiology, Skåne University Hospital Department of Translational medicine, Lund University, Lund, Sweden.
    Bremander, Ann
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS). Department of Clinical Sciences, Section of Rheumatology, Lund University, Lund, Sweden.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Cardiovascular responses of load carriage in female and male soldiers2020In: 5th International Congress on Soldiers Physical Performance: Book of Abstracts, 2020, p. 260-260Conference paper (Refereed)
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  • 16.
    Larsson, Jonas
    et al.
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS). Department of Medical Imaging and Physiology, Skåne University Hospital Department of Translational Medicine, Lund University, Lund, Sweden & Swedish Armed Forces, Eksjö, Sweden.
    Dencker, Magnus
    Department of Medical Imaging and Physiology, Skåne University Hospital Department of Translational Medicine, Lund University, Lund, Sweden.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Bremander, Ann
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS). Department of Clinical Sciences, Section of Rheumatology, Lund University, Lund, Sweden.
    Development and application of a questionnaire to self-rate physical work demands for ground combat soldiers2020In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 83, article id 103002Article in journal (Refereed)
    Abstract [en]

    Purpose: The aim of the present study was to identify the most physically demanding work tasks for Swedish ground combat soldiers through the development and application of a questionnaire survey. This is the first in a series of studies aiming to describe the development process and validation of physical selection standards in the Swedish armed forces.

    Methods: Based on procedural documentation, combat manuals and job analyses, a questionnaire was developed that defined and rated the perceived physical strain of 30 work tasks for ground combat soldiers. To assess validity, an expert focus group was used and psychometric analysis performed. The questionnaire was then distributed to 231 ground combat soldiers, of whom 165 responded (71%).

    Results: The questionnaire was validated in three steps to achieve face and content validity, and internal consistency was acceptable (Chronbach's alpha ≥0.95). Of the 30 work tasks included in the survey, transport of wounded was rated as the most demanding task for both aerobic capacity and strength. Other highly demanding tasks for aerobic capacity included combat movement (low/high crawl), dismounted attack in close country, urban and rough terrain and carrying heavy loads. There were no gender differences for either aerobic or strength demands in the top five most challenging tasks based on proportions.

    Conclusions: This study identified the most physically demanding tasks performed in the Swedish ground combat forces. Almost all the physically demanding tasks found in the present study contain elements of lifting and carrying, which require muscular strength and muscular endurance, with no gender differences. © 2019 Elsevier Ltd. All rights reserved.

  • 17.
    Larsson, Jonas
    et al.
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS). Lund University, Lund, Sweden & Swedish Armed Forces, Eksjö, Sweden.
    Dencker, Magnus
    Lund University, Lund, Sweden.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Bremander, Ann
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS). Department of Clinical Sciences, Section of Rheumatology, Lund University, Lund, Sweden.
    Self-rated physical work demands for ground combat soldiers2018In: PES 2018 3rd International Conference on Physical Employment Standards, University of Portsmouth, United Kingdom, 17-19 July 2018: Conference Book of Abstracts, 2018, p. 31-31Conference paper (Refereed)
    Abstract [en]

    Introduction: Military tasks are physically demanding, and the ability to achieve and maintain the physical capacity required to perform all military tasks are important. Previous studies in other countries have identified the most physically demanding work tasks to be carrying, lifting heavy loads, and digging. The aim of the present study was to identify the most physically demanding work tasks for Swedish ground combat soldiers and to study gender differences in perceived difficulty of the tasks.

    Methods: Based on procedural documentation, field manuals and job analyses, a questionnaire was developed that defined 30 work tasks for ground combat soldiers. To assess face and content validity, an expert focus group was used. The questionnaire was distributed to 231 ground combat soldiers, 165 of whom responded (71.4%), rating the perceived physical strain of the identified work tasks.

    Results: Of the 30 item work tasks included in the survey, five were selected as the most physically demanding. Transport of wounded was rated as the most demanding task both for aerobic endurance and strength. Other highly demanding tasks for aerobic capacity were low/high crawl, dismounted attack in close country, urban and rough terrain, and carrying heavy loads. For muscle strength demands there were a total of 11 different work task ranked for hand-, arm-, leg-, and core strength although many of them only occurred in one of the areas of interest. Carrying heavy loads were ranked in second place except for leg and core strength there it was in third place, instead high and low crawl was ranked very strenuous for leg and core strength. Care of wounded were ranked high for hand strength but not so hard for the rest of the areas.

    Conclusions: Swedish ground combat soldiers rate many tasks as physically demanding. Almost all the identified tasks were physically challenging and contains elements of lifting and carrying, which demand personnel’s muscular strength and muscular endurance capabilities for the soldiers. There were no significant differences in ranked physical requirements between male and female soldiers although they sometimes ranked the tasks in different order. 

  • 18.
    Larsson, Jonas
    et al.
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS). Department of Medical Imaging and Physiology, Skåne University Hospital Department of Translational medicine, Lund University, Lund, Sweden.
    Engberg, Amanda
    Halmstad University, School of Business, Engineering and Science.
    Turnstedt, Max
    Halmstad University, School of Business, Engineering and Science.
    Dencker, Magnus
    Department of Medical Imaging and Physiology, Skåne University Hospital Department of Translational medicine, Lund University, Lund, Sweden.
    Bremander, Ann
    FoU Spenshult, Halmstad, Sweden.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Cardiovascular Effects of Load Carriage in Soldiers; A Pilot Study2019In: Book of Abstracts of the 24th Annual Congress of the European College of Sport Science – 3rd - 6th July 2019, Prague – Czech Republic / [ed] Bunc, V. & Tsolakidis, E., European College of Sport Science , 2019, p. 422-423Conference paper (Refereed)
    Abstract [en]

    Introduction: Previous studies have shown that risk of physical fatigue increases if prolonged average work intensity exceeds 50% of oxygen uptake (VO2). In order to avoid persistent fatigue in a work setting, it is important to conduct suitable work capacity analyses. In physically demanding jobs where wearing protective gear and/or external load is mandatory, monitoring of cardiovascular demands through heart rate (HR) is one way to track the workers’ relative effort.  There are limited studies examining effects of load carrying on cardiovascular capacity where it appears that VO2peak differ when soldiers and firefighters are tested with work-related equipment/clothing compared to light clothing. The aim of this pilot study was to investigate effects of load (combat gear) on HR, VO2 and muscle oxygen saturation (SmO2) compared to no load in soldiers during a graded treadmill protocol.

    Methods: Eight volunteer army soldiers (1 woman, 7 men) performed a graded treadmill test until exhaustion. All soldiers performed the test twice, once with light clothes and no load (NL) and once with added load, their personal combat gear (CG), with at least 48 h between sessions. The treadmill protocol stages included supine and standing positions, followed by marching speeds of 5.4 km/h and 8 km/h at 0 incline (all 5 min) immediately followed by a set marching speed of 8 km/h with a starting incline of 2 % increasing the incline 2 % every third minute until voluntary exhaustion. Measurements of HR, VO2 and SmO2 were collected continuously and the last 30 s of each stage were averaged and used for statistical analyses (paired t-tests).

    Results: The mean added load for all soldiers with CG was 16.8 ± 1.1 kg. All soldiers completed at least 6 stages (range 6-11 stages) with both NL and CG, where time to exhaustion with NL was longer (19.1 ± 3.2 min) compared to CG (9.1 ± 2.9 min; p <0.01). Submaximal HR and VO2 were both significantly higher with CG compared to NL (at absolute intensities) at all marching speeds all soldiers completed (5.4 km/h 0 % grade - 8 km/h 4% grade; all p<0.05). For SmO2, marching with CG compared to NL resulted in increased muscle oxygen utilization, at submaximal stages 8 km/h 0% -4% grade (all p<0.05). For values at maximal effort the CG had a significantly lower VO2peak (3.7 ± 0.5 L/min) compared to NL (4.1 ± 0.6 L/min, p <0.01), whereas there was no difference in HRpeak or the lowest value of SmO2 between CG (193.1 ± 7.2 bpm; 42.4 ± 30.3%) and NL (195.4 ± 8.9 bpm; 47.0 ± 29.2%).

    Conclusions: This pilot study suggests that assessment of aerobic capacity in soldiers should be conducted with combat gear to help determine their actual work capacity during combat and other load carrying tasks. These results suggest that if soldiers’ work performance is determined without added load it overestimates their aerobic capacity (VO2peak) in tasks wearing combat gear, which might lead to added fatigability and deleterious effect on performance.

  • 19.
    Larsson, Jonas
    et al.
    Halmstad University, School of Business, Innovation and Sustainability. Göta Engineer Regiment, Swedish Armed Forces, Eksjö, Sweden.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Innovation and Sustainability.
    Bremander, Ann
    Lund University, Lund, Sweden; Department of Regional Health Research, University of Southern Denmark, Odense, Syddanmark, Denmark.
    Dencker, Magnus
    Skåne University Hospital, Department of Translational medicine, Lund University, Malmö, Sweden.
    Physiological Demands and Characteristics of Movement During Simulated Combat2022In: Military medicine, ISSN 0026-4075, E-ISSN 1930-613X, Vol. 188, no 11-12, p. 3496-3505Article in journal (Refereed)
    Abstract [en]

    INTRODUCTION: Military tasks place considerable physiological demands on the soldier. It is therefore important to know the energy expenditure of soldiers while solving tasks in different environments. The purpose of this study was to describe the cardiorespiratory demands of certain movements and activities on ground combat soldiers during military field operations using body sensors and simulated combat.

    MATERIALS AND METHODS: Movement characteristics and cardiorespiratory responses were assessed in 42 soldiers (three women) in the Swedish Army. The different posts assessed were commander, combat engineer, driver, and gunner. The military field exercises examined were urban operations and retrograde operations in rough terrain. Measurements included (1) body mass, (2) heart rate (HR) including maximal (HRmax), (3) velocity, (4) accelerations/decelerations, and (5) distance moved. Maximal aerobic capacity (V̇O2peak, mL·kg-1·min-1) was tested in a laboratory setting when wearing combat gear and body armor.

    RESULTS: There was a weak positive correlation (r = 0.41 and 0.28, both P < .05) between VO2peak and percentage of time over 40% and 50% of maximal aerobic capacity during simulated combat. No differences were found for the different posts in time spent over 40% or 50% of maximal aerobic capacity and 76% of their HRmax (P > .05). Wearing combat gear and additional load while solving tasks resulted in mean HR varying between 98 and 111 beats·min-1, corresponding with 50-57% of the soldiers HRmax. Studying all exercises, mean HR was 105 ± 11 beats min-1, 54 ± 5% of HRmax corresponding to light work intensity. Soldiers performed between 2.8 and 4.9 accelerations/min in the different exercises. A significant correlation between V̇O2peak (mL kg-1 min-1) and acceleration and m/min were found, implying that soldiers with good aerobic capacity were able to cope better with tasks requiring quick movements.

    CONCLUSION: Conducting military operations in urban terrain and retrograde operations in rough terrain strains ground combat soldiers' cardiorespiratory system, with work intensities close to 40% of maximal aerobic capacity in 15-33% of mission time. Tasks with external load carriage include change of direction, accelerations, bounds, and jumping over obstacles, and physical fitness tests should replicate this. Findings in this study also add objective data to the physiological demands of work performed by combat soldiers while conducting urban operations and retrograde operations in rough terrain. These findings could be used to develop a model for classifying work demands for ground combat forces. © The Association of Military Surgeons of the United States 2022.

  • 20.
    Larsson, Jonas
    et al.
    Halmstad University, School of Business, Innovation and Sustainability. Swedish Armed Forces, Eksjö, Sweden; Department of Translational medicine, Lund University, Lund, Sweden.
    Olsson, M. Charlotte
    Bremander, Ann
    Department of Clinical Sciences, Lund, Section of Rheumatology, Lund University, Lund, Sweden; Spenshult Research and Development Centre, Halmstad, Sweden.
    Larsson, Ingrid
    Halmstad University, School of Health and Welfare. Department of Clinical Sciences, Lund, Section of Rheumatology, Lund University, Lund, Sweden; Spenshult Research and Development Centre, Halmstad, Sweden.
    Swedish soccer coaches' experiences and application of physical training in male elite soccer: A qualitative content analysis study2021In: Scandinavian Sport Studies Forum, E-ISSN 2000-088X, Vol. 12, p. 159-181Article in journal (Refereed)
    Abstract [en]

    In elite soccer, training becomes more systematic and soccer clubs try to optimise their physiological training programs. Previous research has investigated many aspects of soccer, but research into the coaches’ own experiences and continuous improvement of physical training is lacking. The aim of this study was to describe the coaches’ experiences and their application of physical training in male elite soccer. The design of the study was explorative and based on a qualitative content analysis with an abductive approach based on a custom version of the four-step quality model—the plan-do-check-act (PDCA) cycle. Fifteen elite soccer coaches in Sweden were interviewed. The result showed that physical training in male elite soccer is an ongoing continuously improvement process that contains four different categories: 1) planning, containing gained experiences, teamwork, and lack of resources; 2) executing with different training methods, weekly rotation, and individual training; 3) evaluating containing monitor training load and physiological testing, and 4) improving with search for knowledge and long-term development. The coaches try to absorb new knowledge and continuously improve their training methods, although lack of resources sometimes does not allow them to introduce new training methods.

  • 21.
    Malmborg, Julia
    et al.
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS). Spenshult Research and Development Center, Halmstad, Sweden.
    Bremander, Ann
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS). Spenshult Research and Development Center, Halmstad, Sweden; Department of Regional Health Research, University of Southern Denmark, Odense, Denmark; Danish Hospital for Rheumatic Diseases Sønderborg, University Hospital of Southern Denmark, Sønderborg, Denmark; Department of Clinical Sciences Lund, Section of Rheumatology, Lund University, Lund, Sweden.
    Bergman, Stefan
    Spenshult Research and Development Center, Halmstad, Sweden; Department of Clinical Sciences Lund, Section of Rheumatology, Lund University, Lund, Sweden; Primary Health Care Unit, Department of Public Health and Community Medicine, Institute of Medicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Haglund, Emma
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS). Spenshult Research and Development Center, Halmstad, Sweden; Department of Clinical Sciences Lund, Section of Rheumatology, Lund University, Lund, Sweden.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Musculoskeletal pain in adolescent sportschool students – a two-year follow-up2021Conference paper (Refereed)
  • 22.
    Malmborg, Julia
    et al.
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Bremander, Ann
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS). Department of Regional Health Research, University of Southern Denmark, Odense, Denmark; Department of Clinical Sciences Lund, Section of Rheumatology, Lund University, Lund, Sweden.
    Bergman, Stefan
    Department of Clinical Sciences Lund, Section of Rheumatology, Lund University, Lund, Sweden; Primary Health Care Unit, Department of Public Health and Community Medicine, Institute of Medicine, The Sahlgrenska Academy, University of Gothenburg,Gothenburg, Sweden.
    Haglund, Emma
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS). Department of Clinical Sciences Lund, Section of Rheumatology, Lund University, Lund, Sweden.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Risk Factors for Persistence and Development of Frequent Musculoskeletal Pain in Adolescent Athletes2020In: Annals of the Rheumatic Diseases, ISSN 0003-4967, E-ISSN 1468-2060, Vol. 79, no Suppl 1, p. 206-206Article in journal (Refereed)
  • 23.
    Malmborg, Julia
    et al.
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Bremander, Ann
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS). Lund University, Lund, Sweden & Spenshult Research and Development Center, Halmstad, Sweden.
    Bergman, Stefan
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI). Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Lund University, Lund, Sweden & Spenshult Research and Development Center, Halmstad, Sweden.
    Olsson, Charlotte M.
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Pain and its association to health, orthorexia nervosa, sports performance, and physical maturity in sport school adolescents2017In: Proceedings of the Nordic Sport Science Conference – ‘The Double-Edged Sword of Sport: Health Promotion Versus Unhealthy Environments’ / [ed] Hertting, K. & Johnson, U., Halmstad: Halmstad University Press, 2017, p. 56-57Conference paper (Refereed)
  • 24.
    Malmborg, Julia
    et al.
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Bremander, Ann
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS). Spenshult Research and Development Center, Halmstad, Sweden & Lund University, Lund, Sweden.
    Olsson, Charlotte M.
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Bergman, Stefan
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI). University of Gothenburg, Gothenburg, Sweden; Spenshult Research and Development Center, Halmstad, Sweden & Lund University, Lund, Sweden.
    Health status, physical activity, and orthorexia nervosa: A comparison between exercise science students and business students2017In: Appetite, ISSN 0195-6663, E-ISSN 1095-8304, Vol. 109, p. 137-143Article in journal (Refereed)
    Abstract [en]

    Orthorexia nervosa is described as an exaggerated fixation on healthy food. It is unclear whether students in health-oriented academic programs, highly focused on physical exercise, are more prone to develop orthorexia nervosa than students in other educational areas. The aim was to compare health status, physical activity, and frequency of orthorexia nervosa between university students enrolled in an exercise science program (n = 118) or a business program (n = 89). The students completed the Short Form-36 Health Survey (SF-36), the International Physical Activity Questionnaire (IPAQ), and ORTO-15, which defines orthorexia nervosa as a sensitive and obsessive behavior towards healthy nutrition. The SF-36 showed that exercise science students scored worse than business students regarding bodily pain (72.8 vs. 82.5; p = 0.001), but better regarding general health (83.1 vs. 77.1; p = 0.006). Of 188 students, 144 (76.6%) had an ORTO-15 score indicating orthorexia nervosa, with a higher proportion in exercise science students than in business students (84.5% vs. 65.4%; p = 0.002). Orthorexia nervosa in combination with a high level of physical activity was most often seen in men in exercise science studies and less often in women in business studies (45.1% vs. 8.3%; p < 0.000). A high degree of self-reporting of pain and orthorexia nervosa in exercise science students may cause problems in the future, since they are expected to coach others in healthy living. Our findings may be valuable in the development of health-oriented academic programs and within student healthcare services. © 2016 Elsevier Ltd

  • 25.
    Malmborg, Julia
    et al.
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Bremander, Ann
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Olsson, M. Charlotte
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Bergman, A.-C.
    Spenshult Research and Development Center, Halmstad, Sweden.
    Brorsson, Sofia
    Spenshult Research and Development Center, Halmstad, Sweden.
    Bergman, Stefan
    Primary Health Care Unit, Department of Public Health and Community Medicine, Institute of Medicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Sleeping Problems and Anxiety is Associated to Chronic Multisite Musculoskeletal Pain in Swedish High School Students2018In: Annals of the Rheumatic Diseases, ISSN 0003-4967, E-ISSN 1468-2060, Vol. 77, no Suppl. 2, p. 226-226, article id OP0361-HPRArticle in journal (Other academic)
    Abstract [en]

    Background: The relationship between chronic multisite musculoskeletal pain (CMP) and sleep is complex, where pain can lead to sleeping problems and lack of sleep can intensify the pain perception. Most previous studies relates to adults, but adolescents may also suffer from CMP, and there is a need for more knowledge regarding the relationships between CMP and sleeping problems, stress, anxiety, depression, and health status.

    Objectives: To study background factors associated to CMP in first year Swedish high school students.

    Methods: First year Swedish high school students (n=296) were invited to complete questionnaires on chronic pain (mannequin with 18 body regions), sleeping problems (Uppsala Sleep Inventory, four items scored from 1–5), stress (ELO questions, scored from 1–5), anxiety and depression (Hospital Anxiety and Depression Scale, scored from 0–21), health status (EQ-5D, scored from 0 to 1, worst to best) and physical activity (International Physical Activity Questionnaire, categorised into low, moderate and high levels). Stress and sleeping items were dichotomized into 1–3 points (best) vs 4–5 points (worst). Individuals scoring at least severe problems (4 points) at one or more sleeping items were classified as having severe sleeping problems. HADS were categorised as non-cases (0–7), possible7–10 and probable cases (11–21 points). Students were grouped as having CMP (pain present in ≥3 regions) or not (no chronic pain or chronic pain in 1–2 regions). Multiple logistic regression analyses (adjusted for sex) with CMP as dependent variable were performed in SPSS, version 24.

    Results: 254 students (86% of total sample, 87 boys and 167 girls) with a mean age of 16.1 (SD 0.6) years participated in the study. CMP was present in 25 (9.8%) students with no differences between boys and girls (8.0% vs 10.8%; p=0.488). Having CMP was associated with reporting severe sleeping problems (OR 2.49, 95% CI: 1.06 to 5.81, p=0.035) with initiating sleep, maintaining sleep, early morning awakenings and/or not feeling restored after sleep in comparison to the other students. Students with CMP were more likely to be categorised as probable cases for anxiety (OR 3.06, 95% CI: 1.09 to 8.61, p=0.034), but there were no associations for possible cases for anxiety (OR 1.15, 95% CI: 0.38 to 3.51, p=0.800), possible cases (OR 2.03, 95% CI: 0.63 to 6.54), or probable cases for depression (OR 3.35, 95% CI: 0.33 to 33.83). There was a nearly significant association between stress and belonging to the CMP group (OR 2.31, 95% CI: 0.97 to 5.53, p=0.059). A higher self-reported health status was associated to a lower likelihood for CMP (OR 0.04, 95% CI: 0.01 to 0.27, p=0.001). Distribution of physical activity levels of low, moderate and high was not significantly associated to having CMP in comparison with not having it.

    Conclusions: One in ten high school students fulfilled criteria for having chronic multisite musculoskeletal pain. CMP was associated to sleeping problems, anxiety, and a worse health status. The results from this study may be used by school health-care professionals in their preventive work to promote student’s health.

    Disclosure of Interest: None declared

  • 26.
    Malmborg, Julia
    et al.
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Olsson, Charlotte M.
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Bergman, Stefan
    Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden.
    Bremander, Ann
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Daily Musculoskeletal Pain Affects Health And Sports Performance Negatively In Youth Athletes2017In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 49, p. 972-972Article in journal (Refereed)
    Abstract [en]

    In sports, musculoskeletal pain (MSP) is often studied from the perspective of sport specific injuries, why little is known about the prevalence of daily or multisite MSP that does not affect participation in sports. It is also unclear if daily or multisite MSP is a risk factor for worse health-related quality of life (HRQoL) and worse sports performance in youth athletes.

    PURPOSE: To study how HRQoL and sports performance is affected by daily MSP in youth athletes that are able to participate in sports.

    METHODS: 136 Swedish youth athletes attending a sport school (13 to 14 years, boys n=83, girls n=53) completed the EQ-5D measuring HRQoL (range 0 to 1, worst to best), a pain questionnaire including current pain (yes/no), pain in 18 body regions (never to rarely/monthly to weekly/more than once a week to almost daily), and pain intensity in the last week (0 to 10, best to worst), anthropometric measures to estimate biological age, and sports performance tests (grip strength, 20 meter sprint, and countermovement jump(CMJ)).

    RESULTS: 109 to 117 of the 136 students answered the different pain questions. 53 of 113 (47%) reported current MSP, and 28 of 109 (26%) experienced MSP ‘more than once a week to almost daily’ from one or more body regions (frequent MSP group), while 28% (n=30) stated ‘never to rarely’ in MSP (no MSP group). Boys in the frequent MSP group reported worse HRQoL, higher pain intensity, performed worse in all sports performance tests, and had a younger biological age than boys in the no MSP group. Girls in the frequent MSP group reported worse HRQoL and higher pain intensity than the girls in the no MSP group. No other differences were found (table).

    CONCLUSIONS: Every other youth athlete attending a sport school reported current MSP and one out of four reported almost daily MSP. MSP affects HRQoL negatively in both boys and girls, and sports performance negatively in boys. The prevalence of MSP in youth athletes is concerning since pain in younger ages may predict pain in adult ages.

    © 2017 American College of Sports Medicine

  • 27.
    Malmborg, Julia S.
    et al.
    Halmstad University, School of Business, Innovation and Sustainability. Spenshult Research and Development Centre, Halmstad, Sweden.
    Bremander, Ann
    Halmstad University, School of Business, Innovation and Sustainability. Spenshult Research and Development Center, Halmstad, Sweden; University of Southern Denmark, Odense, Denmark; University Hospital of Southern Denmark, Sønderborg, Denmark; Lund University, Lund, Sweden.
    Bergman, Stefan
    Spenshult Research and Development Center, Halmstad, Sweden; Lund University, Lund, Sweden; The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Haglund, Emma
    Halmstad University, School of Business, Innovation and Sustainability. Spenshult Research and Development Center, Halmstad, Sweden; Lund University, Lund, Sweden.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Innovation and Sustainability.
    Musculoskeletal pain and its association with health status, maturity, and sports performance in adolescent sport school students: a 2-year follow-up2022In: BMC Sports Science, Medicine and Rehabilitation, E-ISSN 2052-1847 , Vol. 14, no 1, article id 43Article in journal (Refereed)
    Abstract [en]

    Background: Musculoskeletal pain and its risk factors are rarely assessed in studies on adolescent athletes. The aim was to identify risk factors at baseline that were associated with the persistence or development of musculoskeletal pain at a two-year follow-up in adolescent sport school students, and to study cross-sectional associations at follow-up between musculoskeletal pain and sports performance.

    Methods: Sport school students (79 boys and 52 girls, aged 14 years at baseline) were divided into infrequent (never–monthly) or frequent (weekly–almost daily) pain groups, based on frequency of pain using a pain mannequin. Logistic regression analyses were performed to study longitudinal associations between frequent pain at follow-up and baseline variables: pain group, number of regions with frequent pain, health status by EQ-5D, maturity offset (pre, average, or post peak height velocity), and sports (contact or non-contact). Linear regression analyses were used to study cross-sectional associations between pain groups and 20-m sprint, agility T-test, counter-movement jump, and grip strength at follow-up. Results were stratified by sex.

    Results: A higher percentage of girls than boys reported frequent pain at follow-up (62% vs. 37%; p = 0.005). In boys, frequent pain at follow-up was associated with being pre peak height velocity at baseline (OR 3.884, CI 1.146–13.171; p = 0.029) and participating in non-contact sports (OR 3.429, CI 1.001–11.748; p = 0.050). In girls, frequent pain at follow-up was associated with having frequent pain in two or more body regions at baseline (OR 3.600, CI 1.033–12.542; p = 0.044), having a worse health status at baseline (OR 3.571, CI 1.026–12.434; p = 0.045), and participating in non-contact sports (OR 8.282, CI 2.011–34.116; p = 0.003). In boys, frequent pain was associated with worse performances in 20-m sprint and counter-movement jump, but not in agility T-test and grip strength.

    Conclusions: Baseline risk factors for having frequent pain at follow-up were late maturation in boys, frequent pain and worse health status in girls, and participation in non-contact sports in both sexes. Boys with pain performed worse in sports tests. Coaches and school health-care services should pay attention to the risk factors and work towards preventing pain from becoming persistent. © 2022, The Author(s).

  • 28.
    Malmborg, Julia S
    et al.
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS). Spenshult Research and Development Center, Halmstad, Sweden.
    Bremander, Ann
    University of Southern Denmark, Odense, Denmark & University Hospital of Southern Denmark, Sønderborg, Denmark & Lund University, Lund, Sweden.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Bergman, Anna-Carin
    Spenshult Research and Development Center, Halmstad, Sweden.
    Brorsson, A Sofia
    Spenshult Research and Development Center, Halmstad, Sweden.
    Bergman, Stefan
    Lund University, Lund, Sweden & The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden..
    Worse health status, sleeping problems, and anxiety in 16-year-old students are associated with chronic musculoskeletal pain at three-year follow-up2019In: BMC Public Health, E-ISSN 1471-2458, Vol. 19, no 1, article id 1565Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Chronic musculoskeletal pain is common in adolescents, and it has been shown that adolescents with pain may become young adults with pain. Pain often coincides with psychosomatic symptoms in adults, but little is known about longitudinal associations and predictors of pain in adolescents. The aim was to investigate chronic musculoskeletal pain and its associations with health status, sleeping problems, stress, anxiety, depression, and physical activity in 16-year-old students at baseline, and to identify risk factors using a three-year follow-up.

    METHODS: This was a longitudinal study of 256 students attending a Swedish upper secondary school. Questionnaires regarding chronic musculoskeletal pain and distribution of pain (mannequin), health status (EQ-5D-3 L), sleeping problems (Uppsala Sleep Inventory), stress symptoms (single-item question), anxiety and depression (Hospital Anxiety and Depression Scale), and physical activity (International Physical Activity Questionnaire) were issued at baseline and follow-up. Student's t-test and chi2 test were used for descriptive statistics and logistic regression analyses were used to study associations between chronic pain and independent variables.

    RESULTS: Fifty-two out of 221 students at baseline (23.5%) and 39 out of 154 students at follow-up (25.3%) were categorized as having chronic musculoskeletal pain. Chronic musculoskeletal pain at follow-up was separately associated with reporting of an EQ-5D value below median (OR 4.06, 95% CI 1.83-9.01), severe sleeping problems (OR 3.63, 95% CI 1.69-7.82), and possible anxiety (OR 4.19, 95% CI 1.74-10.11) or probable anxiety (OR 3.82, 95% CI 1.17-12.48) at baseline. Similar results were found for associations between chronic musculoskeletal pain and independent variables at baseline. In multiple logistic regression analysis, chronic musculoskeletal pain at baseline was a predictor of chronic musculoskeletal pain at follow-up (OR 2.99, 95% CI 1.09-8.24, R2 = 0.240).

    CONCLUSION: Chronic musculoskeletal pain at baseline was the most important predictor for reporting chronic musculoskeletal pain at the three-year follow-up, but a worse health status, severe sleeping problems, and anxiety also predicted persistence or development of chronic musculoskeletal pain over time. Interventions should be introduced early on by the school health services to promote student health.

  • 29.
    Malmborg, Julia S
    et al.
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS). Spenshult Research and Development Center, Halmstad, Sweden.
    Olsson, M Charlotte
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS). Malmö Sports Academy, Malmö, Sweden.
    Bergman, Stefan
    The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden & Lund University, Lund, Sweden.
    Bremander, Ann
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS). Lund University, Lund, Sweden.
    Musculoskeletal pain and its association with maturity and sports performance in 14-year-old sport school students2018In: BMJ Open Sport & Exercise Medicine, ISSN 2055-7647, Vol. 4, no 1, article id e000395Article in journal (Refereed)
    Abstract [en]

    Objectives: In youth sports, musculoskeletal pain is often studied from the standpoint of sports injuries, but little is known about pain conditions in which athletes still participate. The aim was to study the frequency of pain and associations with maturity offset, health status and sports performance in 14-year-old sport school students.

    Methods: Cross-sectional design. One hundred and seventy-eight students (108 boys and 70 girls) completed anthropometric measures for maturity offset (height, weight and sitting height), questionnaires (pain mannequin and EQ-5D for health status) and sports performance tests (sprint, agility, counter-movement jump and grip strength). Differences between groups were analysed with Student’s t-test and analysis of covariance.

    Results: Thirty-one students (18.6%) reported infrequent pain, 85 (50.9%) frequent pain and 51 (30.5%) constant pain. Students in the constant pain group had worse health status than those in the infrequent pain group. Boys with constant pain (n=27) had a lower mean maturity offset (–0.38 vs 0.07 years; p=0.03) than boys with infrequent pain (n=22), and pain was associated with worse sports performance. There was no difference in maturity or sports performance between girls with constant pain (n=24) and girls with infrequent pain (n=9).

    Conclusion: Musculoskeletal pain is common in sport school students and coincides with worse health status and with a younger biological age in boys. The high prevalence of pain should be acknowledged by coaches and student healthcare workers in order to promote a healthy and sustainable development in young athletes. © Author(s) (or their employer(s)) 2018.

  • 30.
    Marx, James O
    et al.
    Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, United States.
    Olsson, M Charlotte
    Department of Clinical Neurophysiology, Uppsala University Hospital, 751 85 Uppsala, Sweden.
    Larsson, Lars
    Department of Clinical Neurophysiology, Uppsala University Hospital, 751 85, Uppsala, Sweden.
    Scaling of skeletal muscle shortening velocity in mammals representing a 100,000-fold difference in body size2006In: Pflügers Archiv: European Journal of Physiology, ISSN 0031-6768, E-ISSN 1432-2013, Vol. 452, no 2, p. 222-230Article in journal (Refereed)
    Abstract [en]

    To fully understand the effect of scaling on skeletal muscle shortening velocity (V 0), it is important to know which phenotypic characteristics drive the changes between species. The purpose of the current investigation was to compare the effects of body mass and femur length, as an estimate of total limb length, on V 0 in species that cover a 100,000-fold range of body masses. Using the slack test procedure, V 0 was determined for fibers expressing types I and IIa myosin heavy chain (MyHC) isoforms in the mouse, rat, dog, human, horse, and rhinoceros under identical experimental conditions. A significant scaling effect on V 0 was detected when compared to body mass (type I fibers, r=0.95, p<0.01; type IIa fibers, r=0.83, p<0.05). However, the horse's V 0 for both fiber types was faster than the human's, despite having a 5-fold greater body mass than the human. When V 0 was scaled vs limb length, the strength of the relationships improved in fibers expressing both types I and IIa MyHC (r=0.98, p<0.001, and r=0.89, p<0.05, respectively) and scaled with the expected relationship, with the species with the shorter femur, the horse, having the faster V 0. A similar effect can be seen with stride frequency scaling more closely with limb length than body mass. These results suggest that limb length, not body mass, is a more relevant factor driving the scaling effect on skeletal muscle shortening velocity.

  • 31.
    Olsson, Charlotte M.
    et al.
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Bernhardsson, Lina
    Halmstad University, School of Business, Engineering and Science.
    Bremander, Ann
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Electromyographic Analysis of Left and Right Side Gluteus Medius in Unilateral and Bilateral Bodyweight Exercises2017In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 49, no 5S, p. 464-465Article in journal (Refereed)
  • 32.
    Olsson, Charlotte M.
    et al.
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Fälth, Jenny
    Halmstad University, School of Business, Engineering and Science.
    Ahlebrand, August
    Halmstad University, School of Business, Engineering and Science.
    Bremander, Ann
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Sex-Differences In Bench Press Muscle Activation With Pre-Exhaustion Of Triceps Brachii2018In: Conference Abstracts, 2018, p. 67-68Conference paper (Refereed)
    Abstract [en]

    Purpose: Pre-exhaustion is a resistance training method which activates a stronger single-joint muscle to momentary exhaustion directly before a multi-joint exercise including the pre-exhausted muscle. This results in greater recruitment of muscles in the multi-joint exercise to further increase muscle strength. The pre-exhaustion method in bench press has mainly been studied in men and it is uncertain if sex-differences exists. Men are stronger than women in absolute strength, especially in the upper body but if this holds true for upper body relative strength is debated. The purpose was to investigate muscle activity by surface electromyography (EMG) between women and men in bench press with and without pre-exhaustion of triceps brachii (TB) and to compare relative strength in 10RM bench press between the sexes.

    Methods: 15 women and 15 men in their 20s with weight lifting experience were recruited to the study. During the first session body composition and 10 repetition maximum (10RM) bench press were determined Participants performed both protocol A and B in a cross-over design on separate days. Protocol A began with 10 RM bench press, five minutes recovery, pre-exhaustion exercise (triceps extensions to failure) immediately followed by a second round of bench press with the same 10RM load as before pre-exhaustion. Protocol B started with triceps extensions to failure immediately before bench press at their before established 10RM, five minutes of recovery then they performed 10RM bench press again. IN both protocols, EMG electrodes were attached to TB), pectoralis major (PM) and deltoideus anterior (DA). EMG values were normalized to maximum voluntary isometric contraction (MVIC) and expressed as % MVIC.

    Results: Bench press only EMG activity in %MVIC was similar between women and men, but analysis of variance (TB interaction p=0.02) showed that women had higher %MVIC in TB after pre-exhaustion whereas muscle activity decreased in men compared to bench press without pre-exhaustion. Yet, the number of repetitions completed in bench press after pre-exhaustion of TB were the same (women 4.3 ± 2.6 vs men 3.8 ± 2.2; p=0.55). As expected, in 10RM weight men (64.0 ± 7.1 kg) were stronger than women (37.1 ± 6.5 kg; p<0.01), however when related to fat free mass no difference was evident in relative strength between women and men.

    Conclusion: Men and women have similar muscle activation patterns during a 10RM bench press, but TB pre-exhaustion followed by a bench press appears to have a greater effect on TB activation in women compared to men. Absolute strength was greater in men, but normalized to fat free mass women and men had similar upper body relative strength.

  • 33.
    Olsson, M Charlotte
    et al.
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Biomechanics and Biomedicine.
    Frandsen, Björn
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Electromyography Muscle Activity in Unilateral and Bilateral Squats with Relative Loads2015Conference paper (Other academic)
    Abstract [en]

    Introduction

    Unilateral strength training is becoming popular as a complement to bilateral training particularly in athletes active in sports performed primarily on one leg. Some studies have shown improved performance after unilateral compared to bilateral strength training, however the underlying cause for this improvement is unclear. The aim of this study was to compare electromyography (EMG) muscle activity in unilateral and bilateral squats performed with 80% of 1repetition maximum (RM) performed in a smith machine.

    Methods

    Participants in the study were 12 healthy women and men (mean age 25±2 years) with previous weight-lifting experience. EMG activity was measured during the concentric phase in the muscles vastus lateralis, biceps femoris, gluteus medius and erector spinae during A) a maximal voluntary isometric contraction (MVIC), B) 1RM squat (90 degree knee flexion) bilaterally and unilaterally, and C) 3 repetitions 80% of 1RM for both the unilateral and bilateral stance, where each squat was performed at a set speed with the aid of a metronome.

    Results

    EMG activities, calculated as percent of MVIC, in thigh and hip muscles (vastus lateralis, biceps femoris, gluteus medius) were significantly higher (p<0.01 for all) in the unilateral compared to the bilateral stance. The highest increase in EMG activity was in the gluteus medius where the unilateral squat elicited a 2.9 increase compared to bilateral stance. Unilateral stance muscle activation was in vastus lateralis 1.2 times higher and in biceps femoris 1.5 times higher compared to the bilateral stance. For the trunk muscle erector spinae, the opposite was apparent. EMG activity was 0.6 times lower (p<0.01) when the squat was performed unilaterally compared to bilaterally.

    Discussion

    Even when the load is made relative to the 1RM for each stance the muscles in especially the gluteus medius but also vastus lateralis and biceps femoris is activated to a higher degree when performed unilaterally which could be a partial explanation as to why the unilateral stance can be beneficial to include in a strength training regime despite the absolute load being lower.

  • 34.
    Olsson, M Charlotte
    et al.
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Frandsen, Björn
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Lower body electromyography muscle activity differences between unilateral and bilateral squats with relative loads2014In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 46, no 5S, p. 962-963Article in journal (Refereed)
  • 35.
    Olsson, M. Charlotte
    et al.
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Fälth, Jenny
    Halmstad University, School of Business, Engineering and Science.
    Ahlebrand, August
    Halmstad University, School of Business, Engineering and Science.
    Andersson, Åsa
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Haglund, Emma
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS). Spenshult Research and Development Center, Halmstad, Sweden.
    Bench press muscle activation with triceps brachii pre-exhaustion in females and males2019In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 37, no Supp1, p. 71-72, article id D2.P6.Article in journal (Refereed)
  • 36.
    Olsson, M Charlotte
    et al.
    Uppsala University, Department of Neuroscience, Clinical Neurophysiology, Ing 85 3 tr., 751 85 Uppsala, Sweden.
    Krüger, Martina
    University of Münster, Physiology and Biophysics Unit, Schlossplatz 5, D-48149 Münster, Germany .
    Meyer, Lars-Henrik
    University of Münster, Physiology and Biophysics Unit, Schlossplatz 5, D-48149 Münster, Germany .
    Ahnlund, Lena
    Rehabilitation Medicine, 75185 Uppsala, Sweden.
    Gransberg, Lennart
    Uppsala University, Department of Neuroscience, Clinical Neurophysiology, Ing 85 3 tr., 751 85 Uppsala, Sweden.
    Linke, Wolfgang A
    University of Münster, Physiology and Biophysics Unit, Schlossplatz 5, D-48149 Münster, Germany.
    Larsson, Lars
    Uppsala University, Department of Neuroscience, Clinical Neurophysiology, Ing 85 3 tr., 751 85 Uppsala, Sweden.
    Fibre type-specific increase in passive muscle tension in spinal cord-injured subjects with spasticity2006In: Journal of Physiology, ISSN 0022-3751, E-ISSN 1469-7793, Vol. 577, no 1, p. 339-352Article in journal (Refereed)
  • 37.
    Olsson, M Charlotte
    et al.
    Department of Integrative Physiology, University of Colorado, Boulder, CO, United States.
    Palmer, B M
    Department of Integrative Physiology, University of Colorado, Boulder, CO, United States.
    Stauffer, B L
    Dept. Molec., Cell.,/Devmtl. Biol., University of Colorado, Boulder, CO, United States.
    Leinwand, L A
    Dept. Molec., Cell.,/Devmtl. Biol., University of Colorado, Boulder, CO, United States.
    Moore, R L
    Department of Integrative Physiology, University of Colorado, Boulder, CO, United States.
    Morphological and functional alterations in ventricular myocytes from male transgenic mice with hypertrophic cardiomyopathy2004In: Circulation Research, ISSN 0009-7330, E-ISSN 1524-4571, Vol. 94, no 2, p. 201-207Article in journal (Refereed)
  • 38.
    Olsson, M Charlotte
    et al.
    Department of Physiology, Univ. Wisconsin Cardiovasc. Res. C., Univ. of Wisconsin Medical School, Madison, WI 53706, United States.
    Patel, J R
    Department of Physiology, Univ. Wisconsin Cardiovasc. Res. C., Univ. of Wisconsin Medical School, Madison, WI 53706, United States.
    Fitzsimons, D P
    Department of Physiology, Univ. Wisconsin Cardiovasc. Res. C., Univ. of Wisconsin Medical School, Madison, WI 53706, United States.
    Walker, J W
    Department of Physiology, Univ. Wisconsin Cardiovasc. Res. C., Univ. of Wisconsin Medical School, Madison, WI 53706, United States.
    Moss, R L
    Department of Physiology, Univ. Wisconsin Cardiovasc. Res. C., Univ. of Wisconsin Medical School, Madison, WI 53706, United States.
    Basal myosin light chain phosphorylation is a determinant of Ca2+ sensitivity of force and activation dependence of the kinetics of myocardial force development2004In: American Journal of Physiology. Heart and Circulatory Physiology, ISSN 0363-6135, E-ISSN 1522-1539, Vol. 287, no 6, p. H2712-H2718Article in journal (Refereed)
  • 39.
    Parker, James
    et al.
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS). Scandinavian College of Sport, Gothenburg, Sweden.
    Hellström, John
    Halmstad University, School of Business, Engineering and Science. Swedish Golf Federation, Stockholm, Sweden.
    Ivarsson, Andreas
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI).
    Johnson, Urban
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI).
    Olsson, Charlotte
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    The Variability in Kinematics and Carry in a Longitudinal Intra-individual Study of Elite Golfers2016In: Abstracts: July 18-22, 2016, 2016, p. 47-48Conference paper (Refereed)
    Abstract [en]

    Purpose: To hit further and with high accuracy is important for success in the long game in golf. Even for very accomplished golfers a certain degree of between shot variance is evident even when trying to consistently repeat a successful shot. The consistency is determined by the biomechanics of the golfer, which influences club head speed (CHS) and position, and initial ball launch conditions, which in combination with environmental factors determine shot outcome. Previous research has identified several biomechanical variables associated with variance in CHS, including thorax rotation speed  and lead arm speed (LAS). Pilot data from our laboratory have indicated moderate non-significant relationship between CHS and carry in elite male golfers when studied over time. Thus, the aim of this study was to explore the relationship between peak speed of the pelvis, thorax, and lead upper arm and carry over time, investigating both within and between session variability in elite male golfers.

    Methods: Six elite male golfers (handicap range -3 to +0.5) (age range 21-23 years) were included in this study. The golfers were studied on four separate occasions over a year.  Each test occasion included a golf specific warm-up of the golfers’ choice, then subjects were instructed to hit five balls with their driver and use the swing that was as ‘normal ‘as possible. Data on swing kinematics was collected using a four sensor electromagnetic motion capture system at 120Hz (Polhemus Inc. USA). Nine landmarks were digitized to define segment lengths, orientations and joint axes. CHS and carry were collected using a launch monitor (Trackman3e, v.3.2, Trackman, Denmark). The swing events were determined from sensors on the club; top of backswing was determined when the club changes direction from backswing to downswing. Impact was determined when the clubhead reaches the horizontal position equivalent to where it was at address. Angular velocities and displacements of the pelvis, thorax, and lead arm were calculated using standard biomechanics principles in conjunction with advanced motion measurement software (AMM 3D, USA). No data smoothing techniques were used before data analysis. IBM SPSS v.22 was used to analyse the data through hierarchical multilevel modelling (MLM). First a baseline model without predictors was run, then MLM was repeated with predictors where the first level of the data contained carry and kinematic data from each shot (within session level). At the second level, the carry scores were nested within sessions and analysed between sessions. Lastly, at the third level, the sessions were nested within players (between players). Carry was used as outcome variable and kinematics as predictor variables with a probability level of 0.05.

    Results: Initially MLM baseline model for carry only, was tested) without predictors. The results showed a statistical significant intercept (Estimate = 226.24, p<.001). Intraclass correlations (ICC) suggested that 32.5% of the variance in carry were present within sessions (level 1), whilst 38.0% were attributed to differences in carry between sessions (level 2). Results from the second MLM generated an improved model fit (-2 LL & BIC) where peak speeds of the pelvis, thorax, and lead upper arm were included as fixed effect covariates on level 1. The result showed that peak LAS was a statistically significant predictor of carry (β=.17, p=.001) whereas peek speed of neither thorax (β=-.04, p=.364) nor pelvis (β=.02, p=.673) had any statistically significant relationship with carry.

    Discussion: The present study found that 32.5% of variation in shot consistency can be explained at the within session level (influenced by for example variance in centeredness of impact), and 38% of variation in shot consistency can be explained at the between session level (influenced by for example environmental factors). Furthermore, LAS was the only significant predictor of within session variance in carry. Our results indicated peak LAS speed as a predictor of within session variance in carry and this is partly supported by previous research who found golfers with higher arm speed had higher ball velocity than golfers with lower arm speed(Healy et al., 2011). However, results from our pilot study differ from previous research which reports a relationship between peak thorax speed and driver performance. The difference could be due to our results being based on longitudinal data at intra-individual level, whereas previous studies have used a cross-sectional study design, different analysis methods and reported at an inter-individual level. In conclusion, our preliminary data show that within session LAS is a predictor of carry distance when the objective is shot consistency. Practitioners may consider training strategies to optimize arm speed when improve driving consistency among elite golfers. 

    References

    Healy, A., Moran, K. A., Dickson, J., Hurley, C., Smeaton, A. F., O'Connor, N. E., . . . Chockalingam, N. (2011). Analysis of the 5 iron golf swing when hitting for maximum distance. Journal of sports sciences, 29(10), 1079-1088. 

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  • 40.
    Parker, James
    et al.
    Halmstad University, School of Health and Welfare. Scandinavian College of Sport, Gothenburg, Sweden.
    Hellström, John
    Swedish Golf Federation, Stockholm, Sweden.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Innovation and Sustainability.
    Differences in kinematics and driver performance in elite female and male golfers2022In: Sports Biomechanics, ISSN 1476-3141, E-ISSN 1752-6116, Vol. 21, no 6, p. 731-747Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to compare swing kinematic differences between women and men and investigate which variables predict clubhead speed (CHS) and carry distance (CD) whilst accounting for individual variation. Methods: Swing kinematics and driver performance data were collected on 20 (10 women) elite golfers (HCP 0.7 ± 1.4). We used Bayesian T-test for between sex comparison of swing kinematics and Bayesian Analysis of covariance (ANCOVA) to produce general linear models for CHS and carry distance for elite female and male golfers separately. Results: There was strong evidence that the driver performance variables CHS and CD were decreased in women compared to men, and two kinematic variables; time to arm peak speed downswing and angular wrist peak speed were slower in women. The ANCOVAs identified very strong to overwhelming evidence that participant as a fixed factor was a determinant of CHS for both women and men but was not a determinant of CD. Conclusion: when looking to enhance driver performance among high-level golfers, coaches should be aware that variables that determine CHS and CD differ among women and men and if the aim is to improve CHS coaches should not forget the importance of individual swing characteristics. © 2019 Parker, Hellström & Olsson. Published by Informa UK Limited, trading as Taylor & Francis Group.

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  • 41.
    Parker, James
    et al.
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Hellström, John
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS). Swedish Golf Federation, Stockholm, Sweden.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Relationships between golf swing kinematics and driver performance in elite golfersManuscript (preprint) (Other academic)
    Abstract [en]

    Swing kinematics and driver performance are considered important factors in golf performance. In golf research clubhead speed (CHS) is commonly used as the driver performance measure, whereas carry distance (CD) is less investigated and together with final ball position determine the success of a drive. The aim of this study was to investigate which kinematic factors of the pelvis, thorax, and lead arm explain CHS and/or CD. Swing kinematics data on 15 elite golfers were collected using an electromagnetic 3-D system and a doppler-radar launch monitor system. Variables that emerged as important for both CHS and CD were: reduced pelvis rotation top of backswing (TOB); reduced X-factor TOB; and more thorax lateral bend TOB, along with greater thorax peak speed during the downswing. Variables that were distinctive for the CHS model were mainly during the downswing: greater X-factor stretch; and higher pelvis peak speed. Finally, factors distinctive to the regression model for CD were: reduced thorax rotation; and greater thorax lateral bend. Implications from the results suggest whilst greater peak pelvis speed and x-factor stretch effect CHS they do not significantly influence CD. Likewise, the variables unique to CD do not significantly influence CHS but may be a technical attributes which allow for more optimal clubhead delivery leading to improved CD.

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    Swing kinematics and driver performance
  • 42.
    Parker, James
    et al.
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS). 2Scandinavian School of Golf, Gothenburg, Sweden.
    Hellström, John
    Swedish Golf Federation, Stockholm, Sweden.
    Olsson, M. Charlotte
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    The Relationship of the Lead Arm, Upper Torso, and Pelvis with Driver Club Head Speed Among Elite Golf Players2015In: International Journal of Golf Science, ISSN 2168-7595, Vol. 4, no Suppl., p. S73-S75Article in journal (Refereed)
  • 43.
    Parker, James
    et al.
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS). Scandinavian College of Sport, Gothenburg, Sweden.
    Lagerhem, Charlie
    Halmstad University, School of Business, Engineering and Science.
    Hellström, John
    Halmstad University, School of Business, Engineering and Science. Swedish Golf Federation, Stockholm, Sweden.
    Olsson, Charlotte M.
    Halmstad University, School of Business, Innovation and Sustainability, The Rydberg Laboratory for Applied Sciences (RLAS).
    Effects of nine weeks isokinetic training on power, golf kinematics, and driver performance in pre-elite golfers2017In: BMC Sports Science, Medicine and Rehabilitation, E-ISSN 2052-1847 , Vol. 9, article id 21Article in journal (Refereed)
    Abstract [en]

    Background

    It has previously been shown that isotonic strength training can improve driver performance among golfers, though few studies have investigated effects of strength training on swing kinematics together with driver performance. In this study we investigated whether isokinetic rotational training could improve driver performance and swing kinematic variables amongst elite golfers.

    Methods

    Twenty competitive pre-elite golfers (handicap better than −3.0), 13 men and 7 women, were split into two groups, one group received the isokinetic power training (IK) alongside their normal isotonic pre-season strength-training and the other group continued with their normal isotonic pre-season strength-training regime (IT). The IK group completed 12 sessions of isokinetic power training on a standing rotation exercise (10% body weight at 1 m/s) and barbell squat (25 kg plus 10% body weight at 0.5 m/s). The IT group continued with their normal isotonic pre-season strength-training regime. Participants were tested for rotational power, lower body power, golf swing kinematics, and driver performance before and after a nine-week training period.

    Results

    After the nine-week training period both the IK and the IT groups increased their dominant side rotational force and power (effect sizes between 0.50–0.96) and magnitude based inference indicated that IK had a likely (> 80%) more beneficial increase in dominant side rotational force and power. For swing kinematics, IK had a likely (> 80%) more beneficial improvement in lead arm speed and acceleration compared to the IT group. For driver performance, IK had a possible (65%) beneficial effect on ball speed and likely (78%) beneficial effect on carry distance when compared to IT, whereas neither of the groups improved club head speed.

    Conclusion

    In the present study on pre-elite golfers we found that 9 weeks of isokinetic training increased seated rotational force and power, peak arm speed and arm acceleration, ball speed, and carry distance more compared to isotonic training. Even though isokinetic training did not increase CHS, it did result in greater carry distance. © The Author(s). 2017

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  • 44.
    Parker, James
    et al.
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS). Scandinavian School of Golf, Gothenburg, Sweden.
    Lagerhem, Charlie
    Halmstad University, School of Business, Engineering and Science.
    Olsson, M Charlotte
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Biomechanics and Biomedicine.
    Effects of 8 Weeks of Isokinetic Training on Power, Golf Kinematics, and Club Head Speed In Elite Golfers2015Conference paper (Other academic)
    Abstract [en]

    Introduction: Elite competitive golfers commonly use physical conditioning as a way of improving playing results. Multiple studies have investigated the use of different training methods for improving performance but few studies have investigated the use of isokinetic power training as a way of improving swing kinematics and/or club head speed (CHS). The specific objective of the study was to investigate if eight weeks of isokinetic power training was more effective than traditional power training in improving swing kinematics and CHS.

    Methods: 20 competitive elite golfers (handicap better than -3.1), 13 men and 7 women, (age 22±2 years) were tested for lower body power (countermovement jump and loaded vertical squat jump 20,40 & 60kg), rotational power (seated upper body rotational power at 10% of body weight; bw) and golf swing kinematics (pelvis, thorax and lead arm peak rotational velocities using electromagnetic motion capture system; Polhemus Inc. USA ) and club head speed (doppler-radar launch monitor system; Flightscope, South Africa), Participants were split into a control (CTL) group (n=10) who continued with the regular strength and power training and an intervention (IK) group (n=10) performing isokinetic power training in the isokinetic 1080Quantum system (1080Motion, Sweden) during 8 weeks. The intervention focused on barbell squat (22kg at 0.5 ms-1) and standing rotation (10% body weight at 1 ms-1).

    Statistical analysis: a 2 (between; groups) x 2 (within; time) ANOVA assessed any differences in power, club and swing kinematics.

    Results: Statistically significant improvements were observed in both the IK and CTL group for rotational power (p<0.001), CHS (p=0.025), and peak arm speed (p=0.001). There were no significant differences in countermovement jump height, peak power during squats, peak pelvis speed, or peak thorax speed following the intervention period.

    Discussion: After 8 weeks of power training, both rotational power and peak arm speed improved as did the performance measure of CHS in both the IK and CTL group. However no significant changes were found between the two groups. In conclusion, there was no evidence suggesting that isokinetic training, as performed in this study, is neither detrimental, nor more effective, than traditional strength training when it comes to increasing CHS in golf performance.

  • 45.
    Parker, James
    et al.
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS), Biomechanics and Biomedicine.
    Olsson, Charlotte
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS), Biomechanics and Biomedicine.
    Brorsson, Sofia
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS), Biomechanics and Biomedicine.
    A One Year Study on Changes in Flexibility and Stability Characteristics in Elite Golfers2011Other (Other academic)
    Abstract [en]

    The results from this study show that training strategies can lead to improved flexibility and stability in golfers during the off season, however maintaining these improvements, particularly flexibility, during the in-season is not as easy. Decreased flexibility on the left side leads to reduced ROM to manage deceleration of  forces produced in the golf swing that probably lead to an increased risk of injury. Significant improvements can be made after no more than 3 months of  training, including flexibility and stability training. Technique training may be more successful if it follows a period of concentrated physical training.  During the in-season, emphasis ought to be on maintaining ROM by effective implementation of stretching programs.

  • 46.
    Parker, James
    et al.
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Olsson, Charlotte
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Brorsson, Sofia
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Grip force and muscle activity are associated with kinematics in the golf swing2012In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 44, no Suppl. 2, p. 474-474Article in journal (Refereed)
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  • 47.
    Parker, James
    et al.
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Biomechanics and Biomedicine.
    Olsson, M Charlotte
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Biomechanics and Biomedicine.
    Are There Stretch Shortening Cycle like Actions in the Shoulder and Torso in Upper Body Striking Actions2013Conference paper (Other academic)
  • 48.
    Petersson, Johan
    et al.
    Halmstad University, School of Business, Engineering and Science.
    Riggberger, Kenneth
    Stadionkontoret, Malmö Sports Academy, Malmö, Sweden.
    Brorsson, Sofia
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Olsson, Charlotte M.
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Unilateral Strength Training With Maximal Velocity Improves Lower Body Power Outcome And Movement Velocity2012In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 44, no Suppl. 2, p. 671-671Article in journal (Other academic)
  • 49.
    Razanskas, Petras
    et al.
    Kaunas University of Technology, Kaunas, Lithuania.
    Verikas, Antanas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Olsson, Charlotte
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Wiberg, Per-Arne
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Time Domain Features of Multi-channel EMG Applied to Prediction of Physiological Parameters in Fatiguing Bicycling Exercises2015In: Frontiers in Artificial Intelligence and Applications, ISSN 0922-6389, E-ISSN 1879-8314, Vol. 278, p. 118-127Article in journal (Refereed)
    Abstract [en]

    A set of novel time-domain features characterizing multi-channel surface EMG (sEMG) signals of six muscles (rectus femoris, vastus lateralis, and semitendinosus of each leg) is proposed for prediction of physiological parameters considered important in cycling: blood lactate concentration and oxygen uptake. Fifty one different features, including phase shifts between muscles, active time percentages, sEMG amplitudes, as well as symmetry measures between both legs, were defined from sEMG data and used to train linear and random forest models. The random forests models achieved the coefficient of determination R2 = 0:962 (lactate) and R2 = 0:980 (oxygen). The linear models were less accurate. Feature pruning applied enabled creating accurate random forest models (R2 >0:9) using as few as 7 (lactate) or 4 (oxygen) time-domain features. sEMG amplitude was important for both types of models. Models to predict lactate also relied on measurements describing interaction between front and back muscles, while models to predict oxygen uptake relied on front muscles only, but also included interactions between the two legs. © 2015 The authors and IOS Press. All rights reserved.

  • 50.
    Ražanskas, Petras
    et al.
    Kaunas University of Technology, Kaunas, Lithuania.
    Verikas, Antanas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research. Kaunas University of Technology, Kaunas, Lithuania.
    Olsson, Charlotte
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Wiberg, Per-Arne
    Swedish Adrenaline, Halmstad, Sweden.
    Predicting Blood Lactate Concentration and Oxygen Uptake from sEMG Data during Fatiguing Cycling Exercise2015In: Sensors, E-ISSN 1424-8220, Vol. 15, no 8, p. 20480-20500Article in journal (Refereed)
    Abstract [en]

    This article presents a study of the relationship between electromyographic (EMG) signals from vastus lateralis, rectus femoris, biceps femoris and semitendinosus muscles, collected during fatiguing cycling exercises, and other physiological measurements, such as blood lactate concentration and oxygen consumption. In contrast to the usual practice of picking one particular characteristic of the signal, e.g., the median or mean frequency, multiple variables were used to obtain a thorough characterization of EMG signals in the spectral domain. Based on these variables, linear and non-linear (random forest) models were built to predict blood lactate concentration and oxygen consumption. The results showed that mean and median frequencies are sub-optimal choices for predicting these physiological quantities in dynamic exercises, as they did not exhibit significant changes over the course of our protocol and only weakly correlated with blood lactate concentration or oxygen uptake. Instead, the root mean square of the original signal and backward difference, as well as parameters describing the tails of the EMG power distribution were the most important variables for these models. Coefficients of determination ranging from R2 = 0:77 to R2 = 0:98 (for blood lactate) and from R2 = 0:81 to R2 = 0:97 (for oxygen uptake) were obtained when using random forest regressors.

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