Department of Nutrition and Health Sciences, Human Performance Laboratory, University of Nebraska-Lincoln, Lincoln, Nebraska.
J Strength Cond Res. 2021 Jan 1;35(1):33-40. doi: 10.1519/JSC.0000000000002632.
Hill, EC, Housh, TJ, Smith, CM, Keller, JL, Schmidt, RJ, and Johnson, GO. High- vs. low-intensity fatiguing eccentric exercise on muscle thickness, strength, and blood flow. J Strength Cond Res 35(1): 33-40, 2021-The purpose of this investigation was to examine the acute effects of equal volumes of fatiguing high- vs. low-intensity eccentric muscle actions on changes in muscle thickness, echo intensity, muscle blood flow, and adipose thickness. Eighteen men (mean ± SD = 23.2 ± 3.0 years) performed eccentric peak torque (PT) and maximal voluntary isometric contraction (MVIC) trials before (pretest), immediately after (posttest), and 5 minutes after (recovery) performing randomly ordered fatiguing eccentric, isokinetic (180°·s-1) muscle actions of the elbow flexors at 40% (72 repetitions) or 80% (36 repetitions) of eccentric PT. Muscle thickness, exercise-induced edema, muscle blood flow, and adipose thickness were also assessed via ultrasound at pretest, posttest, and recovery. There were no intensity-specific effects on the patterns of responses for eccentric PT, MVIC, muscle thickness, echo intensity, muscle blood flow, or adipose thickness. There were, however, effects across time that decreased from pretest to posttest and from pretest to recovery for eccentric PT (21.5 and 13.0%), MVIC (14.6 and 5.8%), and adipose thickness (10.0 and 6.0%), but increased for muscle thickness (7.6 and 5.9%), echo intensity (13.7 and 9.9%), and muscle blood flow (129.6 and 90.1%) (collapsed across 40 and 80%). These findings indicated that when matched for exercise volume, there were no intensity-related effects on the increases in muscle thickness, echo intensity, muscle blood flow, or the decreases in eccentric PT, MVIC, and adipose thickness after fatiguing eccentric muscle actions. Therefore, exercise volume, independent of exercise intensity and number of repetitions, may be a mediating factor of muscle fatigue and performance during eccentric muscle actions.
希尔、豪什、史密斯、凯勒、施密特和约翰逊。高强度与低强度疲劳性离心运动对肌肉厚度、力量和血流的影响。《力量与体能研究杂志》35（1）：33-40，2021-本研究旨在探讨等容量疲劳性高强度与低强度离心运动对肌肉厚度、回声强度、肌肉血流和脂肪厚度变化的急性影响。18 名男性（平均±标准差=23.2±3.0 岁）在进行离心峰值扭矩（PT）和最大自主等长收缩（MVIC）试验前（预测试）、即刻后（后测试）和 5 分钟后（恢复），以随机顺序进行疲劳性离心、等速（180°·s-1）的肘屈肌运动，强度分别为 40%（72 次重复）或 80%（36 次重复）的离心 PT。肌肉厚度、运动引起的水肿、肌肉血流和脂肪厚度也通过超声在预测试、后测试和恢复时进行评估。对于离心 PT、MVIC、肌肉厚度、回声强度、肌肉血流或脂肪厚度，强度没有特异性影响。然而，存在跨时间的影响，即离心 PT（21.5%和 13.0%）、MVIC（14.6%和 5.8%）和脂肪厚度（10.0%和 6.0%）从预测试到后测试，以及从预测试到恢复都有所下降，但肌肉厚度（7.6%和 5.9%）、回声强度（13.7%和 9.9%）和肌肉血流（129.6%和 90.1%）则增加（40%和 80%合并）。这些发现表明，当运动容量相匹配时，疲劳性离心运动后肌肉厚度、回声强度、肌肉血流的增加以及离心 PT、MVIC 和脂肪厚度的减少与强度无关。因此，运动容量，独立于运动强度和重复次数，可能是离心运动中肌肉疲劳和表现的中介因素。
