Safety, feasibility, and neuromuscular activity of acute low‐load resistance exercise with or without blood flow restriction in patients with severe hemophilia

Objective To compare the safety, feasibility, and neuromuscular activity of acute low‐load resistance exercise with/without blood flow restriction (BFR) in people with severe hemophilia (PwH). Methods Eight PwH under prophylaxis (5 with resistance training experience) performed 6 randomly ordered conditions of 3 intensity‐matched knee extensions: no external load and no BFR, no external load and light BFR (20% of arterial occlusion pressure [AOP]), no external load and moderate BFR (40% AOP), external low load and no BFR, external low load with light BFR, and external low load with moderate BFR. Rated perceived exertion, pain, exercise tolerability, and adverse effects were assessed. Normalized root‐mean‐square (nRMS), nRMS spatial distribution, and muscle fiber‐conduction velocity (MFCV) were determined using high‐density surface electromyography for the vastus medialis and lateralis. Results Exercises were tolerated, without pain increases or adverse events. Externally resisted conditions with/without BFR provided greater nRMS than nonexternally resisted conditions (p