Fatela Pedro, Reis Joana F, Mendonca Goncalo V, Avela Janne, Mil-Homens Pedro
Faculdade de Motricidade Humana, CIPER, Universidade de Lisboa, Estrada da Costa, Cruz Quebrada, 1499-002, Lisboa, Portugal.
Department of Biology and Physical Activity, Neuromuscular Research Center, University of Jyvaskyla, Jyvaskyla, Finland.
Eur J Appl Physiol. 2016 May;116(5):985-95. doi: 10.1007/s00421-016-3359-1. Epub 2016 Mar 26.
There is some evidence that muscular activation during exercise is enhanced by higher levels of blood flow restriction (BFR). However, the impact of different relative levels of BFR on the acute neuromuscular response to resistance exercise is not yet fully understood. We examined the acute effects of low-intensity knee extensions [20 % of 1-repetition maximum (1RM)] with BFR on muscle activation, neuromuscular fatigue and torque in the rectus femoris (RF) and vastus medialis (VM) muscles.
Fourteen men (24.8 ± 5.4 years) exercised at 20 % 1RM combined with 40, 60 and 80 % BFR. Restrictive pressures were calculated based on direct blood-flow measurements taken at rest on each participant. Torque was determined during pre- and post-exercise maximal voluntary contractions. Surface electromyographic activity [root mean square (RMS)] was obtained during dynamic and sustained isometric contractions before and after exercise. The median frequency (MF) of the electromyographic power spectrum was computed for isometric contractions.
Torque only decreased in the 80 % BFR condition (-5.2 %; p < 0.01). Except for the VM in the 40 % BFR, MF decreased in both muscles post-exercise in all conditions (p < 0.01). MF decrements were of greater magnitude post-exercise at higher levels of BFR. RMS increased within all sets in both muscles (p < 0.01) and attained higher values in the 80 % BFR condition; except for set 1 in the RF muscle (p < 0.01).
Muscular activation, as well as neuromuscular fatigue, varies as a function of relative BFR intensity. Therefore, the individual determination of vascular restriction levels is crucial before engaging in BFR exercise.
有证据表明，更高水平的血流限制（BFR）可增强运动期间的肌肉激活。然而，不同相对水平的BFR对阻力运动急性神经肌肉反应的影响尚未完全明确。我们研究了低强度伸膝运动[1次重复最大值（1RM）的20%]结合BFR对股直肌（RF）和股内侧肌（VM）肌肉激活、神经肌肉疲劳和扭矩的急性影响。
14名男性（24.8±5.4岁）以1RM的20%进行运动，并结合40%、60%和80%的BFR。根据每位参与者静息时的直接血流测量结果计算限制压力。在运动前和运动后最大自主收缩期间测定扭矩。在运动前后的动态和持续等长收缩期间获取表面肌电图活动[均方根（RMS）]。对等长收缩计算肌电图功率谱的中位频率（MF）。
仅在80%BFR条件下扭矩降低（-5.2%；p<0.01）。除了40%BFR时VM的情况外，所有条件下运动后两块肌肉的MF均降低（p<0.01）。在更高水平的BFR下，运动后MF的降低幅度更大。两块肌肉在所有组内RMS均增加（p<0.01），并且在80%BFR条件下达到更高值；RF肌肉的第1组除外（p<0.01）。
肌肉激活以及神经肌肉疲劳随相对BFR强度而变化。因此，在进行BFR运动之前，个体血管限制水平的确定至关重要。
