Blood Flow Restriction Training in Hemophilic Knee Arthropathy – Results from a Randomized Crossover Trial

Introduction Hemophilic arthropathy is a complication of recurrent joint bleeding in patients with hemophilia, leading to chronic pain, functional impairment, and reduced mobility. Blood Flow Restriction (BFR) training combines low-intensity resistance exercise with pneumatic cuffs that partially restrict venous return, thereby inducing a metabolic stimulus comparable to high-load training. We are conducting a randomized crossover trial to evaluate the effects of BFR training on pain perception and joint health in hemophilic knee arthropathy. Here we report an interim analysis after inclusion of eight participants. Method Patients with hemophilia and chronic knee arthropathy were investigated in a randomized crossover design. Each participant completed two leg press interventions at 30% of the individual one-repetition maximum: one session with BFR and one control session without BFR, separated by a six-week washout. BFR was applied with thigh cuffs inflated to 50% of the individual arterial occlusion pressure determined by duplex sonography. Each intervention comprised four sets to exhaustion. Pain intensity (Visual Analogue Scale, VAS), pressure pain threshold (PPT, algometry with 1 cm² probe, expressed in kPa), training volume, perceived exertion (Borg scale), and serum lactate dehydrogenase (LDH) as a marker of muscle damage were assessed. Data are presented as median with interquartile range. Results Eight participants completed both interventions in this interim analysis. Training volume was significantly lower with BFR (117.5; 81.3-126.0 repetitions) compared with the control intervention (162.0; 105.3-470.0; p=0.016). Pain intensity increased more strongly during BFR, rising from a baseline of 7.5 (4.8-11.3) to 33.0 (27.5-73.5; p=0.012), while during the control intervention pain rose from 9.5 (7.8-16.3) to 24.0 (5.0-42.0; p=0.250). The between-condition difference in pain increase was significant (BFR:+28.5; 21.0-54.8 vs. control:+14.5; 0.3-23.5; p=0.023). Following exercise, LDH levels did not differ, with values of 184.5; 180.8-203.3 U/l after BFR and 199.5; 188.3-215.8 U/l after the control intervention (p=0.181). For PPT, baseline thresholds were 405.0; 344.8-678.8 kPa with BFR and 541.7; 405.7-728.0 kPa with the control condition. Compared with baseline, PPT showed a tendency to increase by+22.8% following BFR (p=0.078), whereas no significant change was observed after the control intervention (p=0.641). Conclusion Interim results show that BFR training induces a stronger acute pain response during exercise but simultaneously improves pressure pain thresholds without biochemical evidence of muscle damage. These statistically significant findings support BFR as a safe and effective adjunctive training modality in hemophilic arthropathy, with potential benefits for pain tolerance and joint function. Publication History Article published online: 17 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany