Background: Osteoporosis is a disorder of the bones in which the bones become brittle, weak, and easily damaged or broken. A decrease in the mineralization and strength of the bones over time causes osteoporosis. Bone mineral content (BMC) is a measurement of bone mineral which found in a specific area. Physical activity helps to prevent osteoporosis by maintaining bone mass, stimulating bone formation, strengthening muscles, and improving balance. Moreover, loss of grip strength is associated with less skeletal muscle mass and low bone mineral content. Women are at greater risk of osteoporosis, age-related muscle loss occurs at an earlier time because of ensuing changes in hormonal status in menopause.

Aim: The aim of the study was to examine whether bone mineral content is associated with handgrip muscle strength, lean body mass, fat free mass and bone specific physical activity scores, and to determine possible unique predictors of BMC in adult women.

Methods: A total number of 33 women aged 21 to 64 years old took part in the study. Participants body composition were assessed by using Bio impedance analysis (BIA), hand grip strength was measured by using hand grip dynamometer and physical activity was evaluated by using a Bone Specific Physical Activity Questionnaire (BPAQ). Variables that significantly correlated with BMC were applied to a Hierarchical Multiple Regression analysis.

Results: The main outcome of this study was that BMC was strongly correlated with the body composition variables soft lean mass (SLM) (r=0.936, p=0.000), fat free mass (FFM) (r=0.943, p=0.000) and skeletal muscle mass (SMM) (r=0.936, p=0.000) and with hand grip strength (r=0.752, p=0.000) in both hands and moderately correlated with BPAQ scores for current physical activity (cBPAQ r_s= 0.466,p=0.011). Moreover, only weak correlations were found for past physical activity (pBPAQ r_s = 0.302, p=0.136) and total physical activity (tBPAQ r_s=0.349, p= 0.057). However, based on a Hierarchical Multiple regression analysis, where the most important predictor was SLM explaining 87.6% of variance by SLM, while cBPAQ accounted for a further 2% of variance. Together, these two factors predicted 89.5% of the variability in BMC.

Conclusion: This study concluded that in women age 21 to 64 years, although bone mineral content is significantly associated with SLM, FFM, SMM, hand grip strength, current BPAQ and total body mass, only soft lean mass and current BPAQ were unique predictors of BMC. These findings further emphasise the importance of SLM for determining BMC in women and engage in physical activity to prevent future osteoporosis.