Acute neuromuscular and perceptual responses to blood flow restriction exercise in adults with severe haemophilia: A pilot study

Introduction: No previous studies have implemented a standard blood flow restriction (BFR) training session in people with severe haemophilia (PwH), where this type of training has been contraindicated.
Aims: The purpose of this study was to evaluate the tolerability, adverse events, and neuromuscular and perceptual responses to an acute session of low load (LL) knee extensions with BFR in PwH under prophylaxis.
Methods: Eight PwH performed one LL-BFR session with 40% arterial occlusion pressure (AOP). Perceptual responses and adverse effects were assessed, together with high-density surface electromyography of vastusmedialis (VM) and lateralis (VL).
Results: Significant normalized root mean square differences were found within each set, but not between sets. Spatial distribution (centroid displacement (p > .05), modified entropy (VM, set two, cycles three and five, p = .032) and coefficient of variation (VM, set two, cycles four and five lower than cycle three (p = .049; p = .036)) showed changes within each set.Median frequency showed a slight increase during cycle four of set four (p = .030). Rate of perceived exertion slightly increased with each set while tolerability slightly decreased in the last set and fear of training with BFR generally decreased after the session.
Conclusions: In PwH, a LL-BFR session at 40% AOP is safe and feasible. Our results suggest that potential muscle impairments may blunt neuromuscular adaptations induced by BFR.