Background: High-intensity interval training (HIIT) is a useful method for promoting general health and improving cardiovascular fitness and athletic performance in soccer. HIIT intensity is generally monitored using heart rate (HR) and rating of perceived exertion (RPE), while recovery is assessed by heart rate recovery (HRR) and lactate clearance (LC). However, it remains unclear which active recovery (AR) method between running and cycling is most effective for HRR and LC.

Aim: The aim of the study was to investigate which active recovery method- running or cycling - is most effective for lactate clearance and heart rate recovery between the 4 x 4 treadmill running intervals with 3-minute active recovery periods in female soccer players performing HIIT. A secondary aim was to investigate if the recovery methods had effects on interval peak HR (HRpeak), lactate accumulation or RPE and if it differed between each interval.

Methods: This experimental crossover study involved 13 female soccer players who participated in two HIIT sessions (4 x 4-minute intervals), with either 3 minute cycling (ARcycle) or running (ARrun) as AR methods. Participants served as their own control and randomisation determined the order of the recovery methods. HR, RPE and the concentration of lactate (La-) in the blood were measured throughout the sessions. HRR and LC were used to evaluate recovery efficiency. A repeated-measures analysis of variance (RM ANOVA) was used to investigate significant differences in La- accumulation, LC, HRpeak, and HRR.

Results: No significant differences were observed in HRpeak or La- accumulation between running and cycling as AR (p>0.05). However, HRR was greater with ARcycle than with ARrun during the first three recovery periods (p<0.01). For LC ARcycle and ARrun were significantly different (p=0.02), where LC during ARrun was higher compared to LC during ARcycle for the first (p=0.01) and second (p<0.01) recovery period only. 

Conclusion: HRR was greater in ARcycle and LC was greater in ARrun, which implies that there is a difference between the recovery methods in terms of recovery between the intervals in HIIT.