Blood Flow Restriction induces hypoalgesia in recreationally active adult male anterior knee pain patients allowing therapeutic exercise loading

Objective: To evaluate if a single blood flow restriction (BFR)-exercise bout would induce hypoalgaesia in patients with anterior knee pain (AKP) and allow painless application of therapeutic exercise. Design: Cross-sectional repeated measures design. Setting: Institutional out-patients physiotherapy clinic. Patients: Convenience sample of 30 AKP patients. Intervention: BFR was applied at 80% of complete vascular occlusion. Four sets of low-load open kinetic chain knee extensions were implemented using a pain monitoring model. Main outcome measurements: Pain (0-10) was assessed immediately after BFR application and after a physiotherapy session (45 min) during shallow and deep single-leg squat (SSLS, DSLS), and step-down test (SDT). To estimate the patient rating of clinical effectiveness, previously described thresholds for pain change (>= 40%) were used, with appropriate adjustments for baseline pain levels. Results: Significant effects were found with greater pain relief immediate after BFR in SSLS (d = 0.61, p< 0.001), DSLS (d = 0.61, p< 0.001), and SDT (d = 0.60, p< 0.001). Time analysis revealed that pain reduction was sustained after the physiotherapy session for all tests (d((SSLS)) = 0.60, d((DSLS)) = 0.60, d((SDT)) = 0.58, all p < 0.001). The reduction in pain effect size was found to be clinically significant in both post-BFR assessments. Conclusion: A single BFR-exercise bout immediately reduced AKP with the effect sustained for at least 45 min. (C) 2018 Elsevier Ltd. All rights reserved.