Aerobic <scp>high‐intensity</scp> intervals improve VO_2max more than supramaximal sprint intervals in females, similar to males

Abstract

Abstract Introduction Maximal oxygen uptake (V̇O 2max ) 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 V̇O 2max 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 V̇O 2max , anaerobic capacity, and endurance performance in females is warranted. Methods We randomized 81 aerobically well‐trained females (22 ± 2 years, 51.8 ± 3.6 mL∙kg −1 ∙min −1 V̇O 2max ), 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. Results Only HIIT 4 × 4 min increased V̇O 2max (7.3 ± 3.1%), different from both SIT groups (all p &lt; 0.001). Anaerobic capacity (maximal accumulated oxygen deficit) increased following SIT 8 × 20 s (6.5 ± 10.5%, p &lt; 0.05), SIT 10 × 30 s (14.4 ± 13.7%, p &lt; 0.05; different from HIIT 4 × 4 min, p &lt; 0.05). SIT 10 × 30 s resulted in eight training‐induced injuries, different from no injuries following HIIT 4 × 4 min and SIT 8 × 20 s ( p &lt; 0.001). All groups improved long‐distance (3000‐meter) and sprint (300‐meter) running performance (all p &lt; 0.001). SIT protocols improved sprint performance more than HIIT 4 × 4 min ( p &lt; 0.05). Compared to previous male results, no increase in V̇O 2max following SIT 8 × 20 s ( p &lt; 0.01), and a higher injury rate for SIT 10 × 30 s ( p &lt; 0.001), were evident. Conclusions In aerobically well‐trained women, HIIT is superior to SIT in increasing V̇O 2max while all‐out treadmill running SIT is potentially more harmful.

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