Number of Sprint Repetitions in a Sprint Interval Training Session Does Not Moderate Improvements in V̇O₂max With...

Sprint interval training (SIT) is promoted as a time-efficient method for improving maximal aerobic capacity (V̇O₂max); however, the "classic" protocol (4-6 × 30-s all-out sprints) is less time-efficient than claimed, may be poorly tolerated, and is expected to lead to low adherence. The present study examined the effect of the number of sprint repetitions per session on training-induced changes in V̇O₂max through meta-analysis of the available literature. PubMed and Web of Science were searched (May 2016-September 2024) for eligible studies involving ≥ 2 weeks of training involving repeated all-out cycling with pre- and post-training V̇O₂max data. Forty-four eligible studies were combined with 34 studies from a previous meta-analysis, totalling 93 trials across 78 studies (n = 1188). A hierarchical random-effects meta-regression model was used to assess the influence of key moderators on the change in V̇O₂max. SIT produced an 8.3% increase in V̇O₂max (95% CrI: 7.0 to 9.5%). Increasing sprint repetitions showed a trivial association with changes in V̇O₂max (-0.04% per additional sprint, 95% CrI: -0.32 to 0.24%). Increasing intervention duration was associated with the largest improvements in V̇O₂max (0.7% per additional week; 95% CrI: 0.3 to 1.0%). The present study confirms that increasing sprint repetitions does not meaningfully enhance V̇O₂max improvements in untrained populations. As performing fewer sprint repetitions increases time-efficiency and attenuates reductions in affect, future research into interventions for improving general health in physically inactive populations should focus on low-volume SIT protocols. Trial Registration: PROSPERO database (registration number CRD42022349104).