When several experimental protocols apply active recovery between repetitions, there is a need to stop the participant for blood sampling. Thus, part of the interval between sprints is passive recovery and the remaining is active. This means that although the recovery is characterized as active, in fact, it is partially active and partially passive. The extent of this passive rest period within an active interval may affect the recovery process. In the studies of Felix et al., (1993), Siebers and McMurray (1981), Toubekis et al. (2008), during active recovery conditions, almost 1/3 of the interval was passive recovery. Only one study has examined the effects of active recovery duration on performance. Toubekis et al. (2008a) found that when a 15-min interval is provided, a 5-min active recovery was appropriate to enhance performance compared to a 10-min active and 15-min passive recovery. In the study of Del Coso et al. (2010), the different duration of active recovery of 4.5, 6 or 9 min, was designed to demand the same energy expenditure applying intensities corresponding to 24, 18 or 12% of the respiratory compensation threshold.
Despite the differences in duration and intensity of active recovery, the performance on a subsequent 4 s sprint was not different between conditions. It is likely that a combination of active and passive recovery may be beneficial between long duration sprints, and the appropriate duration of active recovery which may also depend on the intensity and duration of the tested sprint remains to be examined.