A new study has demonstrated that in people with hemophilia who are undergoing prophylaxis, blood flow resistance (BFR) exercise training appears to be safe and well tolerated.

However, the study, published in the European Journal of Haematology, found no changes in normalized root-mean-square (nRMS) as determined by high-density surface electromyography (HDsEMG), in nRMS spatial distribution, or in muscle fiber-conduction velocity (MFCV).

“The main objective of the present study was to compare the safety, feasibility, and neuromuscular response to acute lower-body [low-load] exercises performed with and without BFR,” the authors wrote. “We hypothesized that the addition of BFR would not increase the neuromuscular response of [low-load] exercise and that this type of training would be safe and tolerable in [people with hemophilia].”

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The research team assessed 8 patients with severe hemophilia A or B, aged 18 or older, who were undergoing prophylaxis. All participants completed an experimental session 2 to 4 hours after receiving their prophylactic treatment.

The session included clinical measurements, a questionnaire about leisure time physical activity, and an ultrasound scan of the dominant, exercising leg. Next, after placement of electrodes, the participants completed several muscle contraction and extension exercises with or without BFR and with encouragement by the researchers to achieve maximal effort.

Post-session measurements determined arterial occlusion pressure (AOP), arterial blood flow, and patient ratings of perceived exertion, pain intensity, and tolerability of the exercises. The ultrasound scan was repeated to check for bleeds.

The results showed that low-load knee extension exercise with BFR at 20% or 40% AOP appeared to be safe and tolerable in the patients, without causing bleeds or acute or delayed pain. No adverse events were reported up to the 1-week follow-up. However, BFR alone was not found to affect HDsEMG activity or fatigue as measured by MFCV.


Calatayud J, Ogrezeanu DC, Carrasco JJ, et al. Safety, feasibility, and neuromuscular activity of acute low-load resistance exercise with or without blood flow restriction in patients with severe hemophiliaEur J Haematol. Published online March 23, 2023. doi:10.1111/ejh.13965