The effects of intensity of active recovery on sprint performance
The intensity of active recovery may be crucial for the performance outcome. Athletes should follow active recovery at a low energetic cost while at the same time muscle blood flow must be adequately increased. A low energetic cost may be necessary for a fast recovery of high energy phosphates while an adequate muscle blood flow is required for the removal of metabolic by-products. Recent studies examined the effects of different intensities of active recovery on performance.
The intensity is expressed as a percentage of VO2maxduring cycling and team-game activities (Dupont et al., 2007; Spencer et al., 2008; Maxwell et al., 2008) as a percentage of the best time or as a percentage relative to the lactate threshold during swimming (Toubekis et al.,2006; Toubekis et al., 2010; Greenwood et al., 2008). During the 21 s interval between 6x4 s sprints, both active recovery intensities were applied at 20 or 35% of the VO2max and equally decreased peak power and total work compared to passive recovery in team-sport trained individuals (Spencer et al., 2008). Similarly, when active recovery intensities corresponding to 20 or 40% of the VO2maxwere compared to passive recovery, both decreased performance in a 30 s sprint performed shortly (15 s) after a 15 s sprint (Dupont et al., 2007). It is possible that the short interval duration or the small difference between intensities of active recovery applied in the studies of Spencer et al. (2008) and Dupont et al. (2007) have masked the effects of active recovery.
This may have also occurred during repeated 25 m sprints with a 45 s interval when the active recovery intensity was 50 or 60% of the 100 m velocity (Toubekis et al., 2006). Using longer interval duration (120 s) and a greater difference between active recovery intensities on the same repeated swimming sprint protocol, the results were different from previous studies (Toubekis et al., 2010). In that study the low and high intensity active recovery were estimated to correspond to 36% and 59% of the VO2max (40% and 60% of the 100-m velocity). During passive recovery and active recovery at low intensity trials, performance was better compared to high intensity active recovery (Toubekis et al., 2010). However, in the repeated swimming sprint studies, performance of a subsequent 50 m sprint (duration ~30s) swum after six minutes, was unaffected by active recovery intensity (Toubekis et al., 2006; Toubekis et al., 2010). Therefore, it is likely that long interval duration (i.e. work to interval ratio 1:10 to 1:12) in combination with very low intensity of active recovery have a beneficial effect on performance compared to a high intensity active recovery.
A different approach to test the effects of swimming intensity during active recovery was applied by Greenwood et al., (2008). The authors calculated the velocity corresponding to the lactate threshold using a speed-lactate test and subsequently asked their swimmers to perform 2x200-yard sprints with a 10-min interval using passive recovery or active recovery. The active recovery intensities reported, were below, above or at the lactate threshold. It is interesting to note that performance during the second 200 yard sprint was improved not only compared to passive recovery but also compared to the first 200 yard sprint after active recovery at a velocity corresponding to the lactate threshold (Greenwood et al., 2008). It should be noted however, that the lactate threshold velocity can be calculated using different methods and readers should be aware that no single method can be used as a gold standard (Tokmakidis et al., 1998).
During game-sports activities, it has been shown that low intensity is beneficial compared to high intensity of active recovery (35 vs. 50% of VO2max) allowing a 3% better peak power during repeated 5 s cycling sprints (Maxwell et al., 2008). These 5 s sprints were performed within 20x2-min blocks. Within each 2 min block, a 10 s standing, 5 s sprint and 105 s of active recovery were performed (Maxwell et al., 2008). During a different protocol applied by Del Coso et al. (2010), the mean power output during a 4 s cycling sprint was not different after intermittent sets performed with different active recovery intensity and different interval duration but with equal energy expenditure. In summary, it seems that very low intensity combined with a long interval duration (exercise to interval ratio 1:10) may maintain performance similar to passive recovery during short duration sprints. In contrast, active recovery intensity at the lactate threshold velocity, which is still very low intensity, may be beneficial not only to maintain but in some cases may improve performance on a subsequent sprint of 60 to 120 s duration.
