Exercise-induced hypoalgesia with end-stage knee osteoarthritis during different blood flow restriction levels: Sham-controlled crossover study

BackgroundBlood flow restriction (BFR) training could be a valuable treatment to induce exercise-induced hypoalgesia (EIH) in patients with end-stage knee osteoarthritis. However, the use of BFR in these patients is poorly explored and there is no evidence about the training dosage needed.ObjectiveTo evaluate the effect of resistance training protocols with different occlusion levels of blood flow restriction (BFR) on EIH in patients with end-stage knee osteoarthritis.DesignCrossover study.SettingUniversity physical exercise laboratory.Participants26 adults with end-stage knee osteoarthritis.InterventionsPatients performed four sets (30, 15, 15, and 15 repetitions) separated by 1-minute rests of three protocols/sessions of low-load (30% one-repetition-maximum) seated knee extensions with elastic bands and BFR: placebo (sham BFR), BFR at 40% arterial occlusion pressure (AOP) and BFR at 80% AOP.Main Outcome MeasuresPressure Pain Thresholds (PPT) and Visual Analog Scale (VAS) collected before, immediately after session, and after 10 minutes.ResultsNo differences in EIH were found between the different levels of BFR. However, 80% AOP protocol worsened VAS scores immediately (mean difference [MD]: -21.2 (95% confidence interval [CI] -33.9 to -8.5) while improving PPT immediately (MD affected limb: -.6 [95% CI -1.1 to -.2]); contralateral: -.6 (95% CI -1.0 to -.2]) and at 10 minutes (MD affected limb: -.6 [95% CI) -1.2 to -.1]; contralateral: -.7 [95% CI -1.1 to -.2]; and forearm: -.5 [95% CI -.9 to -.05]) post-exercise compared to baseline.ConclusionsThere is no EIH difference after using different occlusion levels. EIH is modulated by pain-related psychological constructs and self-perceived health status.