High‐intensity Interval Training Combined With Blood‐flow Restriction Predominantly Alters Anaerobic Capacity in Endurance‐trained Athletes

Abstract

Blood‐flow restriction (BFR) training has gained popularity amongst athletes and sport practitioners to enhance training adaptations and performance. However, BFR has typically been associated with low‐intensity exercise, and there is still limited evidence of its impact when combined with high‐intensity training. This study investigated the impact of high‐intensity interval training (HIIT) with concurrent BFR on anaerobic and aerobic physical capacities and key physiological responses. In a pre‐post, parallel‐groups design, fifteen endurance‐trained males (VO2max 65.0±4.8 mL/min/kg) included three sessions of HIIT per week (sets of 15 s ON/15 s OFF at 100% maximal aerobic power) into their usual training for three weeks either with (BFR group, n=9) or without restriction (CTL group, n=6). In BFR, cuffs were worn proximal on both quadriceps and inflated progressively from 50 to 70% of arterial occlusion pressure across training weeks. Before and after training, athletes completed a maximal incremental step cycling test, a Wingate anaerobic test (WAnT) and a 5‐km cycling time trial. Blood samples were drawn during the time trials. Maximal aerobic power increased in BFR (364.8±60.7 vs 383.4±61.4 watts, p=0.003, Cohen’s effect size ES 0.27) but not in CTL (381.2±62.1 vs 385.5±64.4 watts, p=0.45, ES 0.05). Concomitantly, mean power output achieved during the WAnt also increased with BFR (23.8±4.0 vs 24.6±4.1 kJ, p=0.08, ES 0.28) but not in CTL (23.4±2.5 vs 23.4±2.4 kJ, p=0.95, ES 0.01). However, there was no change between groups in VO2max (BFR: 0.86% vs CTL: 1.77%, ES ‐0.15) and in both the mean power output (BFR: 1.81% vs CTL: 6.51%, ES ‐0.21) and completion time (BFR: ‐0.69% vs CTL: ‐2.55%, ES ‐0.21) of the 5‐km time trial. During the time trial, BFR also induced greater changes in pH (BFR: ‐0.05 vs CTL: ‐0.03 units, ES ‐0.43) and base excess (BFR: ‐1.55 vs CTL: ‐0.70 units, ES ‐0.37), and lowered the potassium ion concentration (BFR: ‐0.55 vs CTL: 0.44 mmol/L, ES ‐0.63). There was no change between groups in lactate production from pre‐ to post‐training. These findings suggest that short‐term HIIT combined with BFR improved anaerobic capacity in endurance‐trained athletes without meaningful effect on endurance exercise performance.