Blood Flow Restricted Low-Load Resistance Exercise in Patients with Knee Pain: A Pilot Cohort Study.

Background: Blood flow restricted low-load exercise (LL-BFR) has been shown to elicit beneficial adaptations in muscle size and strength. The aim was to investigate if LL-BRF was feasible in patients with knee pain in a rehabilitation setting. A secondary objective was to investigate functional performance, knee muscle strength and patient-reported outcomes. Methods: : Data were collected from April-June 2018. Patients with knee Osteoarthritis or knee pain/functional loss after previous knee surgery were included. LL-BRF was performed twice weekly for 4-8 weeks as unilateral leg press with an individualized pressure (40% LOP) at 30% of one repetition maximum. Two protocols were tested (3-4 rounds, 30 second pauses). Patients were assessed by a 30-second chair-stand-test, Timed Up & Go, thigh circumference (TC), knee extensor strength (MVC) by handheld dynamometer, and completed the Knee Osteoarthritis Outcome Score (KOOS) score at baseline and follow-up. Results: : Adherence to training was 95.6%. Few and minor adverse events were observed. One opatient dropped out due to pain aggravation in relation to baseline testing. Scores on three out of five KOOS subscales improved more than 10 points. Also, functional tests and MVC of the affected limb improved (p ≤ 0.05). Conclusion: The study indicates that supervised LL-BFR is feasible in patients with knee pain. At follow-up, the patients experienced subjective and functional gains. Trial registration: Danish Data Protection Agency (Journal No 1-16-02-90-18).