Aerobic high‐intensity intervals improve V̇O2max more than supramaximal sprint intervals in females, similar to males

IntroductionMaximal oxygen uptake (V̇O2max) is a pivotal factor for aerobic endurance performance. Recently, aerobic high‐intensity interval training (HIIT) was documented to be superior to sprint interval training (SIT) in improving V̇O2max in well‐trained males. However, as mounting evidence suggests that physiological responses to training are sex‐dependent, examining the effects of HIIT versus SIT on V̇O2max, anaerobic capacity, and endurance performance in females is warranted.MethodsWe randomized 81 aerobically well‐trained females (22 ± 2 years, 51.8 ± 3.6 mL∙kg−1∙min−1 V̇O2max), training three times weekly for 8 weeks, to well‐established protocols: (1) HIIT 4 × 4 min at ~95% of maximal aerobic speed (MAS), with 3 min active recovery (2) SIT 8 × 20 s at ~150% of MAS, with 10 s passive recovery (3) SIT 10 × 30 s at ~175% of MAS, with 3.5 min active recovery.ResultsOnly HIIT 4 × 4 min increased V̇O2max (7.3 ± 3.1%), different from both SIT groups (all p