Effect of number of sprints in a SIT session on change in VO2max: A meta-analysis

Purpose: Recent meta-analyses indicate that sprint interval training (SIT) improves cardiorespiratory fitness (V̇O2max), but the effects of various training parameters on the magnitude of the improvement remain unknown. The present meta-analysis examined the modifying effect of the number of sprint repetitions in a SIT session on improvements in V̇O2max.Methods: The databases PubMed and Web of Science were searched for original studies that have examined pre- and post-training V̇O2max in adults following ≥2 weeks of training consisting of repeated (≥2) Wingate-type cycle sprints, published up to 1 May 2016. Articles were excluded if they were not in English, involved patients, athletes, or participants with a mean baseline V̇O2max of >55 mL·kg-1·min-1 or a mean age <18 years, and if a SIT trial was combined with another intervention or used intervals shorter than 10 s. A total of 38 SIT trials from 34 studies were included in the meta-analysis. Probabilistic magnitude-based inferences were made to interpret the outcome of the analysis. Results: The meta-analysis revealed a likely large effect of a typical SIT intervention on V̇O2max (mean ± 90 CL %: 7.8% ± 4.0%) with a possibly small modifying effect of the maximum number of sprint repetitions in a training session (-1.2 ± 0.8% decrease per 2 additional sprint repetitions). Apart from possibly small effects of baseline V̇O2max and age, all other modifying effects were unclear or trivial. Conclusion: We conclude that the improvement in V̇O2max with SIT is not attenuated with fewer sprint repetitions, and possibly even enhanced. This means that SIT protocols can be made more time-efficient, which may help SIT to be developed into a viable strategy to impact public health.