Clinical ADAPTations To Blood Flow Restriction Training In UK Military Personnel With Persistent Knee Pain

PURPOSE: Persistent knee pain is often associated with low function, pain, and muscle weakness. Rehabilitation typically involves resistance training (RT) at ≥70% of an individual’s one repetition maximum (1-RM) for effective muscular adaptation, but many cannot tolerate such high loads. Low load blood flow restriction (LL-BFR) offers an alternative approach. This study examines the effects of high frequency LL-BFR versus heavier load resistance training (HL-RT) on physical function, muscular strength, and pain in military personnel with knee pain delivered within a residential rehabilitation setting. METHODS: A multicentre, randomised controlled trial across five sites enrolled fifty-eight military personnel with persistent knee pain (LL-BFR: n = 30; HL-RT: n = 28) attending a 3-week residential rehabilitation course. Participants were randomised to either: a) LL-BFR, twice daily at 20% 1-RM or b) HL-RT three-times per week at 70% 1-RM. Outcomes at admission (T1) and discharge (T2) included the Lower Extremity Functional Scale (LEFS), Knee Injury and Osteoarthritis Outcome Score Pain Subscale (KOOS-P) and 5-RM single leg press test. A mixed ANOVA evaluated intervention effect across timepoints. RESULTS: No significant baseline differences were observed between groups. No significant interaction was found between intervention group and time. - LL-BFR (x̄ ± SD) HL-RT (x̄ ± SD) T1 T2 Change T1 T2 Change LEFS 56.47 ± 11.28 62.10 ± 11.89 5.63 ± 10.30 54.11 ± 11.51 56.89 ± 12.65 2.79 ± 7.91 KOOS-P 69.44 ± 12.40 76.76 + 12.35 7.31 ± 10.56 67.76 ± 14.41 70.04 ± 14.29 2.28 ± 9.53 LEG PRESS (kg) 72.20 ± 25.46 93.83 + 26.28 21.63 ± 13.19 63.02 ± 21.32 81.21 ± 24.07 18.20 ± 17.88 A significant main effect of time indicated improvement across all measures: LEFS, F(1,56) = 12.03, p < 0.001, partial η2 = .177; KOOS-P F(1,56) = 13.13, p < 0.001, partial η2 = .190; and leg press F(1,56) = 94.09, p < 0.001, partial η2 = .627. No main effect of intervention group was found for LEFS, KOOS-P or leg press (p > 0.05). CONCLUSION: High frequency LL-BFR over three weeks within residential rehabilitation can improve knee function, reduce pain, and enhance muscle strength comparably to HL-RT, offering an effective RT alternative for those unable to tolerate high loads. Supported by: Versus Arthritis UK, University of Bath UK, Ministry of Defence UK