Acute Neuromuscular Adaptations in Response to Low-Intensity Blood-Flow Restricted Exercise and High-Intensity...

Fatela, P, Reis, JF, Mendonca, GV, Freitas, T, Valamatos, MJ, Avela, J, and Mil-Homens, P. Acute neuromuscular adaptations in response to low-intensity blood flow restricted exercise and high-intensity resistance exercise: are there any differences? J Strength Cond Res 32(4): 902-910, 2018-Numerous studies have reported similar neuromuscular adaptations between low-intensity (LI) blood-flow restricted exercise (BFRE) and high-intensity (HI) resistance training. Unfortunately, none of these experimental designs individualized blood flow restriction (BFR) levels to each participant. Thus, their findings are difficult to interpret. We aimed at comparing the acute effects of LI BFR (80% of absolute vascular occlusion pressure) with LI non-BFR and HI training on muscle torque, activation, and neuromuscular fatigue. Ten men (23.8 ± 5.4 years) exercised at 20 and 75% of 1 repetition maximum with and without BFR (for LI). Blood flow restriction pressure was determined individually using resting blood-flow measurements. Torque was determined during maximal voluntary contractions (MVCs) at pre-exercise and postexercise time points. Surface electromyographic activity (root mean square [RMS] and median frequency [MF]) was recorded for the rectus femoris (RF) and vastus medialis (VM) muscles, before and after each session of training, during isometric contractions at 20% MVC. Torque decreased post-HI and LI BFR (-9.5 and -7.8%, respectively; p < 0.01), but not after LI non-BFR. The MF was reduced following HI training in the VM and the RF muscles (-5.3 and -12.5%, respectively; p ≤ 0.05). Conversely, the impact of LI BFR on reducing MF was limited to the RF muscle (-10.7%, p ≤ 0.05). Finally, when compared to all other conditions, RMS values were consistently higher during submaximal contractions performed after HI training (p ≤ 0.05). Thus, we conclude that, despite enhancing the acute magnitude of muscular activation and fatigue, LI BFR exercise exerts a less profound impact on neuromuscular function than HI resistance training.