Acute performance, physiological, and perceptual changes in response to repeated cycling sprint exercise combined...

This study investigated the acute performance, physiological, and perceptual changes during repeated sprint exercise (RSE) under normobaric hypoxia and with blood flow restriction (BFR). Fourteen active males completed standardized RSE (6 × 10 s cycling sprints with 30 s passive rest) in three randomized conditions: under normobaric hypoxia (F_iO₂ ∼ 14.4%, HYP), normoxia (F_iO₂ ∼ 20.9%, SHAM), and with BFR (40% arterial occlusion pressure). The percentage decrement score of power output (S_dec) was used to quantify motor performance fatigue. During RSE, muscle oxygenation (total and oxygenated hemoglobin) and activity of the right quadriceps were measured. Perceived motor fatigue, physical strain, affective valence, and arousal were queried after each sprint. Blood lactate concentration (BLC) and peripheral oxygenation (S_pO₂) were measured before and after RSE. S_dec was greater in HYP and BFR compared to SHAM (p ≤ 0.008). BFR decreased mean power output (p < 0.001) and muscle activity (p = 0.027) compared to SHAM. Decrease in muscle oxygenated hemoglobin was higher in BFR during each rest (p ≤ 0.005) and in HYP during rest 4 (p = 0.006) compared to SHAM. HYP increased BLC and decreased S_pO₂ compared to BFR (p < 0.001) and SHAM (p = 0.002). There were no differences between conditions for any rating scale (p ≥ 0.060). HYP and BFR increased motor performance fatigue but with different physiological responses, whereas perceptual responses were unaffected during RSE.