Key result
Very low-load exercise with moderate blood flow restriction increases acute muscle thickness ~73% vs high-load exercise.
Why the study?
To compare the acute muscular response to resistance exercise across high-load, very low-load, and very low-load with moderate or high blood flow restriction pressures.
Does very low-load resistance exercise with blood flow restriction augment acute muscular responses compared to high-load or low-load exercise without restriction in trained participants?
RCT (n=23)
Open-label
Randomized and counterbalanced
No
Does very low-load resistance exercise with blood flow restriction augment acute muscular responses compared to high-load or low-load exercise without restriction in trained participants?
Answers are grounded in this paper and cite their sources.
Very low-load resistance exercise combined with blood flow restriction augments acute changes in muscle thickness and torque compared to high-load exercise without restriction.
The purpose of this study was to compare the acute muscular response with resistance exercise between the following conditions [labeled (% one-repetition maximum/% arterial occlusion pressure)]: high-load (70/0), very low-load (15/0), very low-load with moderate (15/40), and high (15/80) blood flow restriction pressures. Twenty-three participants completed four sets of unilateral knee extension to failure (up to 90 repetitions) with each condition, one condition per leg, each day. Muscle thickness and maximal voluntary contraction (MVC) were measured before (Pre), immediately after (Post-0), and 15 min after (Post-15) exercise and electromyography (EMG) amplitude during exercise. Pre to Post-0 muscle thickness changes in cm [95% CI] were greater with 15/40 [0.57 (0.41, 0.73)] and 15/80 [0.49 (0.35, 0.62)] compared to 70/0 [0.33 (0.25, 0.40)]. Pre to Post-0 MVC changes in Nm [95% CI] were higher with 15/40 [-127.0 (-162.1, -91.9)] and 15/80 [-133.6 (-162.8, -104.4)] compared to 70/0 [-48.4 (-70.1, -26.6)] and 15/0 [-98.4 (-121.9, -74.9)], which were also different. Over the first three repetitions, EMG increased across sets, whereas in the last three repetitions it did not. EMG was also different between conditions and was generally greater during 70/0. Repetitions decreased across sets reaching the lowest for 70/0, and for very low loads decreased with increased pressure. In trained participants exercising to failure, lower load and the application of restriction pressure augment changes in muscle thickness and torque. The EMG amplitude was augmented by load. Training studies should compare these conditions, as the results herein suggest some muscular adaptations may differ.
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Jessee et al. (2019) conducted an RCT in Healthy resistance-trained individuals (n=23). Very low-load resistance exercise with blood flow restriction vs. High-load (70% 1RM) and very low-load (15% 1RM) without restriction was evaluated on Pre to Post-0 muscle thickness change (cm) (MD -0.24, 95% CI -0.42 to -0.06, p=<0.05). Very low-load resistance exercise with moderate blood flow restriction augmented acute muscle thickness changes compared to traditional high-load exercise.
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