Six Weeks of Low‐Volume Sprint Interval Training Improves Peak Oxygen Uptake Compared to a Non‐Exercise Control: A Randomized Controlled Trial

ABSTRACT Low‐volume sprint interval training (LVSIT) increases peak oxygen uptake (VO 2peak ) when performed three times a week for 6 weeks. Methodological and statistical concerns, however, constrain the veracity of prior findings. We therefore reassessed the VO 2peak response to LVSIT using a randomized controlled trial design to mitigate bias and augment reporting quality. A generative model of VO 2peak was constructed as a function of group, baseline VO 2peak , age, sex, height, and change in body mass. Simulation experiments using previous data estimated that n = 15/group would achieve 80% power to detect a difference of 1 metabolic equivalent (MET) with a credible interval (CrI) of ≤ 1‐MET. Insufficiently active young adults (22 ± 3 years, body mass index: 24 ± 4 kg m −2 , baseline VO 2peak : 33 ± 7 mL kg −1 min −1 ) were randomized to perform 6 weeks of thrice weekly LVSIT ( n = 17) or no exercise (CTL; n = 20). The LVSIT protocol involved 3 × 20‐s “all out” sprints over a 10‐min session of low‐intensity cycling. Bayesian generative multivariate modeling revealed that LVSIT increased absolute +325 mL min −1 (101–605) and relative VO 2peak +5.6 mL kg −1 min −1 (2.2–8.1) versus CTL. All but one LVSIT participant (94%) were deemed a responder (i.e., mean estimate ± 95% CrI for relative VO 2peak > 0). In contrast, four CTL participants (20%) met this criterion. LVSIT also improved time to exhaustion by +133 s (101–160) versus CTL. We unequivocally demonstrate that 6 weeks of thrice weekly LVSIT increased VO 2peak in insufficiently active young adults compared to no exercise. By incorporating a robust design that included preregistration, concealed allocation assignment, statistical best practices, and applied Bayesian methods, and open data‐sharing, this study addresses prior methodological critiques of similar previous work.