Effects of repeated sprint training with constant or incremental rest intervals on the decrement score, blood lactate...

The effects of repeated sprint training with constant rest intervals (CRIs) vs. incremental rest intervals (IRIs), without matching the total rest duration, on muscle fatigue, glycolytic metabolism, and anaerobic work capacity remain unclear. Therefore, we aimed to examine the effects of repeated sprint training with CRIs vs. IRIs on the decrement score, a measure of muscle fatigue; blood lactate concentration; and Wingate anaerobic test performance. We hypothesized that the decrement score, a measure of muscle fatigue, would be significantly lower after repeated sprint training with IRIs than after repeated sprint training with CRIs. Furthermore, we hypothesized that the blood lactate concentration would be equivalent with IRIs or CRIs and that the Wingate anaerobic test performance would be equally improved. In total, 17 male participants performed nine sessions of repeated sprint training (10 sets × 10-s maximal pedaling) within 3 weeks. They were assigned to either the group that underwent repeated sprint training with CRIs (30-s rest intervals between sets) or the same training with IRIs (30-s rest intervals until the fifth set, and then the rest interval was increased by 10-s for each set from the sixth set onwards). The decrement score showed no statistically significant difference between the groups in all sessions. The blood lactate concentration was measured in sessions one and nine and significantly decreased from sessions one to nine in both groups (p < 0.05). However, the blood lactate concentration did not differ significantly between the groups in sessions one and nine. From pre-training to post-training, the peak power during the Wingate anaerobic test did not increase in either group. The mean power during the Wingate anaerobic test increased significantly in both groups (p < 0.05), but there was no significant difference between the groups. These results suggest that RST with IRIs may not provide additional benefits compared to RST with CRIs in untrained young adults.