The Hypoalgesic Effect of Low-Load Exercise to Failure Is Not Augmented by Blood Flow Restriction.

To 1) examine whether blood flow restriction would provide an additional exercise-induced hypoalgesic response at an upper and lower limb when it is incorporated with low-load resistance exercise until failure, and 2) examine if increases in blood pressure and discomfort, with blood flow restricted exercise, would mediate the exercise-induced hypoalgesia over exercise without blood flow restriction. Forty healthy young participants completed two trials: four sets of unilateral knee extension exercise to failure at 30% of one-repetition maximum, with and without blood flow restriction. Pressure pain thresholds were assessed before (twice) and 5-min post exercise at an upper and lower limb. Blood pressure and discomfort ratings were recorded to examine mediating effects on exercise-induced hypoalgesia with blood flow restricted exercise. Pressure pain threshold increased following both exercise conditions compared to a control, without any differences between exercise conditions at the upper (exercise conditions vs. control: ~0.37 kg/cm) and lower (exercise conditions vs. control: ~0.60 kg/cm) limb. The total number of repetitions was lower for exercise with blood flow restriction compared to exercise alone [median difference (95% credible interval) of -27.0 (-29.8, -24.4) repetitions]. There were no mediating effects of changes in blood pressure, nor changes in discomfort, for the changes in pressure pain threshold at either the upper or lower limb. The addition of blood flow restriction to low-load exercise induces a similar hypoalgesic response to that of non-blood flow restricted exercise, with a fewer number of repetitions.