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

BACKGROUND: blood 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.

OBJECTIVE: To 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.

DESIGN: Crossover study.

SETTING: University physical exercise laboratory.

PARTICIPANTS: 26 adults with end-stage knee osteoarthritis.

INTERVENTIONS: Patients performed 4 sets (30, 15, 15 and 15 repetitions) separated by 1-minute rests of three protocols/sessions of low-load (30% 1RM) 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 MEASURES: Pressure Pain Thresholds (PPT) and Visual Analog Scale (VAS) collected before, immediate post session and post 10 minutes.

RESULTS: No differences in EIH between the different levels of BFR were found. However, 80% AOP protocol worsened VAS scores immediately (Mean difference, MD (95%CI): -21.190 (-33.897 to -8.484)) while improving PPT immediately (MD (95%CI); affected limb: -.629 (-1.080 to -.177); contralateral: -.590 (-.986 to -.195)) and at 10 min (MD (95%CI); affected limb: -.633 (-1.153 to -.113); contralateral: -.676 (-1.136 to -.216); and forearm: -.467 (-.881 to -.053)) post-exercise compared to baseline.

CONCLUSIONS: There is no EIH difference after using different occlusion levels. EIH is modulated by pain-related psychological constructs and self-perceived health status.