ELBOW Upper-extremity blood flow restriction: the proximal, distal, and contralateral effectsda randomized controlled trial Eric N. Bowman, MD, MPH a, *, Rami Elshaar, MD b , Heather Milligan, PT c , Gregory Jue, PT d , Karen Mohr, PT e , Patty Brown, PT f , Drew M. Watanabe, BS e , Orr Limpisvasti, MD e a Department of Orthopaedics, Vanderbilt University Medical Center, Nashville, TN, USA b Rochester Regional Health Orthopaedics, Pittsford, NY, USA c Elite OrthoSport Physical Therapy, Los Angeles, CA, USA d Select Physical Therapy, Los Angeles, CA, USA e Kerlan Jobe Institute, Los Angeles, CA, USA f Patty Brown Physical Therapy & Associates, El Segundo, CA, USA 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 ¼ .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. Level of evidence: Level I; Randomized Controlled Trial; Treatment Study Ó 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved. Keywords: Blood flow restriction; BFR; training; therapy; rehabilitation; upper extremity Institutional review board approval for this study was received from Asentral (study no. 2018-501A). *Reprint requests: Eric N. Bowman, MD, MPH, Department of Or- thopaedics, Vanderbilt University Medical Center, 1215 21st Ave S, 4200 Medical Center East, Nashville, TN 37232-8774, USA. E-mail address: Eric.N.Bowman@vumc.org (E.N. Bowman). J Shoulder Elbow Surg (2020) 29, 1267–1274 www.elsevier.com/locate/ymse 1058-2746/$ - see front matter Ó 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved. https://doi.org/10.1016/j.jse.2020.02.003