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.