How blood flow restriction resistance training has been studied on non-restricted muscles in healthy, injured and clinical populations: a scoping review and evidence gap map.

OBJECTIVES

Blood flow restriction (BFR) resistance training enhances muscle growth in restricted limbs, but its effects on non-restricted muscles remain unclear. This scoping review, accompanied by an evidence gap map, aims to systematically chart current literature on BFR's impact on non-restricted muscles, summarise key outcomes and identify methodological trends to guide future research.

METHODS

Searches were conducted in PubMed, Scopus and Web of Science. Studies included adults-healthy or with musculoskeletal conditions-undergoing BFR resistance training, with passive or active comparator groups in two-arm or multi-arm designs. Data focused on chronic physiological (eg, muscle properties) and physical fitness (eg, strength, power) adaptations. Risk of bias was assessed using RoB 2 (Cochrane Risk of Bias 2 tool) for randomised and ROBINS-I (Risk of Bias in Non-Randomised Studies - of Interventions) for non-randomised studies.

RESULTS

From 1740 records, 19 studies (540 participants; 6 women) met the criteria. Intervention durations ranged from 2 to 12 weeks, with training frequencies of 2-6 sessions per week and cuff pressures of 50-270 mm Hg. The most reported outcomes were 1-repetition maximum strength, muscle cross-sectional area and thickness. The pectoralis major and shoulder rotators were the most frequently studied muscles. Most studies implemented BFR training two to three times weekly for an average of 8 weeks.

CONCLUSIONS

Evidence suggests BFR training may benefit non-restricted muscles, but variability in study protocols, small sample sizes and limited standardisation hinder broad conclusions. Future research should employ consistent methodologies, larger cohorts and extended interventions to enhance comparability and generalisability.

TRIAL REGISTRATION DETAILS: OSF identifier: osf-registrations-q8wcz-v1.