The Effect of Cuff Width on Muscle Adaptations after Blood Flow Restriction Training.

UNLABELLED: Blood flow restriction in combination with low-load resistance training has been shown to increase muscle size and strength; however, the influence of cuff width on these adaptations is unknown. PURPOSE: The objective of this study is to determine the influence of different cuff widths on muscle size and strength, and also investigate whether a wider cuff would result in less adaptation compared with a narrow cuff when inflated to the same relative pressure (80% arterial occlusion pressure). METHODS: Eleven physically active males had their arms randomly divided into two separate conditions: low-load blood flow restriction exercise with a narrow cuff (BFR + N, 5 cm) and low-load blood flow restriction exercise with a wide cuff (BFR + W, 10 cm). All participants underwent 12 wk of unilateral elbow flexion at 20% of their one-repetition maximum (1RM). The elbow flexion strength (1RM), elbow flexor muscle cross-sectional area (CSA), arterial blood flow, training volume, RPE, and rating of perceived pain were assessed before and after training. RESULTS: Elbow flexion 1RM and CSA significantly increased in both conditions (BFR + N = 13.5% and 9% vs BFR + W = 11.9% and 11.2%, respectively). The arterial blood flow was significantly reduced when 80% of the arterial occlusion pressure was applied in both conditions (BFR + N = 61.2% and BFR + W = 63.5%). There were no significant differences in the training volume, RPE, or rating of perceived pain between conditions (P > 0.05). CONCLUSION: We wish to suggest that, regardless of cuff width, both protocols produced similar increases in 1RM and elbow flexor muscle CSA, and these responses may be related to the similar training volume and/or similar reductions in arterial blood flow produced when both cuffs were inflated to the same relative pressure.

The acute muscle swelling effects of blood flow restriction.

The purpose of this study was to investigate the potential mechanisms behind the blood flow restriction (BFR) stimulus in the absence of exercise. Nine participants completed a 10 minute time control and then a BFR protocol. The protocol was five, 5-minute bouts of inflation with 3-minutes of deflation between each bout. The pressure was set relative to each individual's thigh circumference. Significant increases in muscle thickness were observed for both the vastus lateralis (VL) [6%, p = 0.027] and rectus femoris (RF) [22%, p = 0.001] along with a significant decrease in plasma volume [15%, p = 0.001]. Ratings of discomfort during the BFR protocol peaked at 2.7 (light discomfort). There were no significant changes with whole blood lactate, electromyography (EMG), or heart rate (HR), however, there was a trend for a significant increase in HR during the 5th inflation (p = 0.057). In conclusion, this is the first study to demonstrate that the attenuation of both muscle atrophy and declines in strength previously observed with brief applications of BFR may have been mediated through an acute fluid shift induced increase in muscle size. This is supported by our finding that the changes in muscle thickness are maintained even after the cuffs have been removed.