Impact of Sprint Duration With Fixed Recovery on Acute Physiological and Performance Responses to Repeated Cycle Sprints in Hypoxia in Male and Female Sprinters

ABSTRACT Repeated short sprints (≤ 10 s) in hypoxia are often used to enhance performance, but acute responses to longer sprints (> 10 s) performed in a repeated‐sprint format with short recovery periods (∼30 s) remain unclear. We examined performance and physiological strain during repeated short (10‐s) and long (15‐s) sprints with identical recovery (30 s) comparing acute responses between sexes. Sixteen highly trained sprinters (7 females) performed 7 × 10‐s (10:30) and 15‐s (15:30) sprints with 30‐s rest in normobaric hypoxia (FiO 2 : 0.15), using a randomized cross‐over design. Average mean power output across the seven sprints was lower in 15:30 than 10:30 (6.30 ± 0.44 vs. 6.85 ± 0.82 W/kg; p < 0.001). Sprint decrement score (S dec ) was larger in 15:30 than 10:30 (−17.9 ± 4.8% vs . −13.1 ± 4.6%; p < 0.001). Average pulse oximetry‐derived peripheral oxygen saturation (SpO 2 ) across the seven sprints was lower in 15:30 than 10:30 (87.1 ± 4.2% vs. 89.7 ± 2.7%; p < 0.001), whereas the magnitude of change from sprint 1 to sprint 7 did not clearly differ between conditions. Heart rate increased across sprints (Δsprint1‐7: +9.2 ± 5.3% and p < 0.001), independently of condition ( p = 0.652). ΔSpO 2 correlated with ΔS dec ( r = 0.609 and p = 0.012). Female athletes experienced smaller performance declines than males in both conditions ( p = 0.001). Longer repeated sprints with identical rest in hypoxia impair mechanical output while inducing greater physiological strain, with comparatively smaller performance reductions in females.