Influence of different rest intervals during active or passive recovery on repeated sprint swimming performance.

The purpose of this study was to investigate the effect of active or passive recovery after two different rest intervals on performance during repeated bouts of maximal swimming exercise. Sixteen swimmers (eight males and eight females) performed four trials in a counterbalanced order. Eight repetitions of 25-m sprints (8 x 25 m), with a rest interval of 45 or 120 s, followed by a 50-m sprint test 6 min later, were performed in each trial. The 45 or 120-s interval was either active (A45 and A120) or passive (P45 and P120). The intensity of the active recovery corresponded to 60% of the individual best 100-m velocity. Performance time was recorded using an official competition timing system. The first 25-m sprint was comparable across trials (P>0.05), but performance was decreased after the second sprint during active compared to passive recovery, irrespective of the interval duration (P<0.05). The 50-m sprint time was 2.4% better in the P120 and A120 compared to the A45 and P45 trials (P<0.05). After completing the 8x25 m, blood lactate was decreased with active recovery when the interval period was 120 s (P120 vs A120, P<0.05). Blood lactate concentration at the start as well as 5 min after the 50-m sprint was lower in the A120 and A45 compared to the P120 and P45 trials respectively (P<0.05). Plasma glycerol was not different between trials (P>0.05), whereas plasma ammonia was higher in the A45 compared to the P120 trial (P<0.05). The interval period separating short-duration sprints may therefore alter performance when subsequent maximum exertion is applied. For sustained sprinting ability, passive recovery is advised during repeated swimming sprints of short duration.