Effects of Combined Blood Flow Restriction and Inter‐Effort Recovery Hypoxia On Repeated‐Sprint Performance And Physiological Responses: A Randomized And Single‐Blinded Crossover Trial

We investigated the acute effects of local and/or systemic hypoxia on performance and psycho‐physiological responses during repeated cycle sprints. Eleven physically active young adults (six men, five women) performed four sessions on separate days, each involving three sets of five 5‐s all‐out efforts on a cycle ergometer (25 seconds rest between efforts and 5 minutes rest between sets). Sessions were conducted under four conditions, combining blood flow restriction [BFR; 45% of arterial occlusion pressure (AOP)] or control (CON; 5% of AOP) applied bilaterally to the legs during sprints, with inter‐effort recovery hypoxia [IEH; inspired oxygen fraction (FiO 2 ) = 13.5%] or normoxia (NOR; FiO 2 = 20.9%). Power output decreased across sprints and heart rate increased over sets, with no differences between conditions (Δ = −9.18%). IEH resulted in lower peripheral oxygen saturation (Δ = −8.0%) but higher oxygen uptake (Δ = 6.7 mL·kg −1 min −1 ) and minute ventilation (Δ = 6.1 L·kg −1 min −1 ), compared to normoxic conditions. Blood lactate concentration increased (Δ = 6.5 mM) post‐session similarly across all conditions. Vastus lateralis muscle oxygenation during sprints and inter‐set recovery was comparable across conditions, although the mean tissue saturation index during inter‐set recovery was lower in BFR + IEH versus CON + NOR conditions (Δ = −4.0%). Ratings of perceived exertion (Δ = 22.5%), limb discomfort (Δ = 34.2%), and breathing difficulty (Δ = 43.7%) increased throughout the sets, independently of conditions. Despite physiological and perceptual adjustments across sprint repetitions, neither BFR during sprints nor systemic hypoxia during recovery altered mechanical output in physically active individuals.