The Impact Of Blood Flow Restriction Resistance Training On Pain Modulation In Pain Free Individuals

Abstract

Blood flow restriction (BFR) resistance training (RT) is beneficial for enhancing muscle size and strength at low intensity and is effective and feasible in musculoskeletal rehabilitation. However, the effects of BFR RT on pain modulation remain unclear. PURPOSE: To evaluate the effects of low-intensity BFR and conventional moderate intensity (MI) RT on pain modulation in pain-free adults METHODS: Nineteen adults without current pain (10 M, mean age = 27 yrs., mean BMI = 23 kg/m2) participated in this study. Participants were screened for contraindications of BFR training (e.g., immobilization) and conditions that may influence pain modulation (e.g., neuropathy).A repeated measures design with counterbalanced order of RT conditions were applied. All participants completed two RT visits (MI or BFR) approximately 9 days apart. At each visit, dominant leg one-repetition maximum (1RM) was determined on a leg press machine after standardized warm-up. For both RT conditions, participants performed a unilateral leg press with the dominant leg. For MI, participants performed the unilateral leg press at 50% 1RM. For BFR RT, a 20-cm width cuff was placed at the proximal thigh during exercise. Participants performed the leg press at 30% 1RM with the cuff inflated to 60% limb occlusion pressure. Participants performed four sets of RT in each visit with a protocol of 30-15-15 repetitions at the first three sets and exercise to failure at the fourth set. Failure was defined as failing to maintain the form. A rate of two seconds per repetition was applied with a 30-second rest between sets. Pressure pain threshold (PPT) was measured over the rectus femoris immediately after exercise using a hand-held algometer. Exercise-induced hypoalgesia (EIH) was calculated as the change in PPT. Statistical Analysis: Paired t-tests (α = 0.05) and Cohen’s d for effect size were used to assess statistical significance. RESULTS: Mean (SD) baseline PPT was 46.6 N (15.2) and 45.2 N (10.4) at Visit 1 and Visit 2, respectively. Greater EIH was found with BFR compared to MI RT (31.23% vs. 14.21%, p = 0.039, d = 0.62) CONCLUSIONS: Low-intensity BFR RT elicited a greater EIH effect compared to MI RT in pain-free adults. Future studies are needed to evaluate mechanisms underlying EIH with RT and to extend this work to clinical populations