The effects of high-pressure versus low-pressure blood flow restriction resistance exercise in individuals with lower limb musculoskeletal injuries and persistent pain: a randomised controlled trial

Objectives: Compare the efficacy and acceptability of low load blood flow restriction (BFR) using two different limb occlusion pressures (LOP) on pain and function in individuals with lower-limb musculoskeletal injury (MSKI) and associated persistent pain. Design: Randomised controlled trial within a military residential rehabilitation setting. Participants: Twenty-eight individuals (N = 21 male; N = 7 female) with lower-limb MSKI were randomly allocated into: 1) BFR-RE with 80% LOP (BFR80), or 2) BFR-RE with 40% LOP (BFR40). Both groups completed 7x BFR-RE sessions during 5-days of residential rehabilitation at 20% 1-repetition maximum. Main outcome measures: The primary outcome measure was the Brief Pain Inventory (BPI). Secondary outcomes include injury-specific outcomes, pain pressure threshold (PPT) and lower-limb muscle strength assessment. All reported outcomes reflect changes in scores. Results: BPI ‘worst’ displayed a time × group interaction (p = .013), driven by higher pain in BFR80 from pre-to post-intervention (standardised mean difference [SMD] = 1.532, p = .006). There was a significant time × group interaction for BPI ‘severity’ (p = .022), driven by significant between-group differences at T3 (BFR80-BFR40: SMD = 1.305, p = .015). PPTs improved within-session and over time. Conclusion: Both pressures demonstrated cumulative exercise-induced hypoalgesia via rising PPTs. BFR80 reported increased ‘worst’ pain score. Lower LOP may better preserve training volume and exercise tolerability.