Upper-extremity blood flow restriction: the proximal, distal, and contralateral effects-a randomized controlled trial.

BACKGROUND: Blood flow restriction (BFR) training with low weight is purported to induce similar physiological changes to high-weight regimens with the benefit of less tissue stress. We hypothesized that low-weight training with BFR would produce increased gains in strength and hypertrophy for muscle groups proximal, distal, and contralateral to tourniquet placement compared with low-weight training alone. METHODS: In this prospective, randomized controlled trial, healthy subjects were randomized into a 6-week low-weight training program either with or without BFR on 1 extremity. Outcome measures included limb circumference and strength. Comparisons were made between the BFR and non-BFR extremities, BFR and control groups, and non-BFR extremity and control groups. RESULTS: A total of 24 subjects (14 BFR and 10 control subjects) completed the protocol. Significantly greater gains were observed in dynamometric strength both proximal (shoulder scaption [30% greater], flexion [23%], and abduction [22%]) and distal (grip strength [13%]) to the tourniquet in the BFR limb compared with both the non-BFR extremity and the control group (P < .05). Arm and forearm circumferences significantly increased in the BFR limb compared with the non-BFR limb and control group (P = .01). The non-BFR extremity demonstrated greater grip strength than the control group (9%, P < .01). No adverse events were reported. CONCLUSION: Low-weight BFR training provided a greater increase in strength and hypertrophy in the upper-extremity proximal and distal muscle groups compared with the control group. The non-BFR extremity showed a significant increase in grip strength compared with the control group, indicating a potential systemic effect.

Proximal, Distal, and Contralateral Effects of Blood Flow Restriction Training on the Lower Extremities: A Randomized Controlled Trial.

BACKGROUND:: Blood flow restriction (BFR) training involves low-weight exercises performed under vascular occlusion via an inflatable cuff. For patients who cannot tolerate high-load exercises, BFR training reportedly provides the benefits of high-load regimens, with the advantage of less tissue and joint stress. HYPOTHESIS:: Low-load BFR training is safe and efficacious for strengthening muscle groups proximal, distal, and contralateral to tourniquet placement in the lower extremities. STUDY DESIGN:: Randomized controlled trial. LEVEL OF EVIDENCE:: Level 1. METHODS:: This was a randomized controlled trial of healthy participants completing a standardized 6-week course of BFR training. Patients were randomized to BFR training on 1 extremity or to a control group. Patients were excluded for cardiac, pulmonary, or hematologic disease; pregnancy; or previous surgery in the extremity. Data collected at baseline and completion included limb circumferences and strength testing. RESULTS:: The protocol was completed by 26 patients, providing 16 BFR and 10 control patients (mean patient age, 27 years; 62% female). A statistically greater increase in strength was seen proximal and distal to the BFR tourniquet when compared with both the nontourniquet extremity and the control group ( P < 0.05). Approximately twice the improvement was seen in the BFR group compared with controls. Isokinetic testing showed greater increases in knee extension peak torque (3% vs 11%), total work (6% vs 15%), and average power (4% vs 12%) for the BFR group ( P < 0.04). Limb circumference significantly increased in both the thigh (0.8% vs 3.5%) and the leg (0.4% vs 2.8%) compared with the control group ( P < 0.01). Additionally, a significant increase occurred in thigh girth (0.8% vs 2.3%) and knee extension strength (3% vs 8%) in the nontourniquet BFR extremity compared with the control group ( P < 0.05). There were no reported adverse events. CONCLUSION:: Low-load BFR training led to a greater increase in muscle strength and limb circumference. BFR training had similar strengthening effects on both proximal and distal muscle groups. Gains in the contralateral extremity may corroborate a systemic or crossover effect. CLINICAL RELEVANCE:: BFR training strengthens muscle groups proximal, distal, and contralateral to cuff placement. Patients undergoing therapy for various orthopaedic conditions may benefit from low-load BFR training with the advantage of less tissue stress.