Repeated-sprint training in hypoxia boosts up team-sport-specific repeated-sprint ability: 2-week vs 5-week training regimen

Purpose To investigate (1) the boosting effects immediately and 4 weeks following 2-week, 6-session repeated-sprint training in hypoxia (RSH 2-wk , n = 10) on the ability of team-sport players in performing repeated sprints (RSA) during a team-sport-specific intermittent exercise protocol (RSA IEP ) by comparing with normoxic counterpart (CON 2-wk , n = 12), and (2) the dose effects of the RSH by comparing the RSA alterations in RSH 2-wk with those resulting from a 5-week, 15-session regimen (RSH 5-wk , n = 10). Methods Repeated-sprint training protocol consisted of 3 sets, 5 × 5-s all-out sprints on non-motorized treadmill interspersed with 25-s passive recovery under the hypoxia of 13.5% and normoxia, respectively. The within- (pre-, post-, 4-week post-intervention) and between- (RSH 2-wk , RSH 5-wk , CON 2-wk ) group differences in the performance of four sets of RSA tests held during the RSA IEP on the same treadmill were assessed. Results In comparison with pre-intervention, RSA variables, particularly the mean velocity, horizontal force, and power output during the RSA IEP enhanced significantly immediate post RSH in RSH 2-wk (5.1–13.7%), while trivially in CON 2-wk (2.1–6.2%). Nevertheless, the enhanced RSA in RSH 2-wk diminished 4 weeks after the RSH (− 3.17–0.37%). For the RSH 5-wk , the enhancement of RSA immediately following the 5-week RSH (4.2–16.3%) did not differ from that of RSH 2-wk , yet the enhanced RSA was well-maintained 4-week post-RSH (0.12–1.14%). Conclusions Two-week and five-week RSH regimens could comparably boost up the effects of repeated-sprint training in normoxia, while dose effect detected on the RSA enhancement was minimal. Nevertheless, superior residual effects of the RSH on RSA appear to be associated with prolonged regimen.