Division of Kinesiology, School of Kinesiology and Physical Therapy, University of Central Florida, 12494 University Boulevard, Orlando, FL, 32816, USA.
Florida Space Institute, Partnership I, University of Central Florida, Research Parkway, Orlando, FL, 32826, USA.
Eur J Appl Physiol. 2021 May;121(5):1473-1485. doi: 10.1007/s00421-021-04627-2. Epub 2021 Feb 27.
The purpose of this investigation was to examine the individual and composite patterns of responses and time-course of changes in muscle size, strength, and edema throughout a 4 week low-load blood flow restriction (LLBFR) resistance training intervention.
Twenty recreationally active women (mean ± SD; 23 ± 3 years) participated in this investigation and were randomly assigned to 4 weeks (3/week) of LLBFR (n = 10) or control (n = 10) group. Resistance training consisted of 75 reciprocal isokinetic forearm flexion-extension muscle actions performed at 30% of peak torque. Strength and ultrasound-based assessments were determined at each training session.
There were quadratic increases for composite muscle thickness (R = 0.998), concentric peak torque (R = 0.962), and maximal voluntary isometric contraction (MVIC) torque (R = 0.980) data for the LLBFR group. For muscle thickness, seven of ten subjects exceeded the minimal difference (MD) of 0.16 cm during the very early phase (laboratory visits 1-7) of the intervention compared to three of ten subjects that exceeded MD for either concentric peak torque (3.7 Nm) or MVIC (2.2 Nm) during this same time period. There was a linear increase for composite echo intensity (r = 0.563) as a result of LLBFR resistance training, but eight of ten subjects never exceeded the MD of 14.2 Au.
These findings suggested that the increases in muscle thickness for the LLBFR group were not associated with edema and changes in echo intensity should be examined on a subject-by-subject basis. Furthermore, LLBFR forearm flexion-extension resistance training elicited real increases in muscle size during the very early phase of training that occurred prior to real increases in muscle strength.
本研究旨在探讨个体和综合反应模式以及肌肉大小、力量和水肿在四周低负荷血流限制（LLBFR）抗阻训练干预过程中的时程变化。
20 名有规律运动的女性（平均±标准差；23±3 岁）参与了本研究，并被随机分为 4 周（每周 3 次）的 LLBFR（n=10）或对照组（n=10）。抗阻训练包括 75 次 30%峰值扭矩的反向等速前臂屈伸运动。每次训练均进行力量和超声评估。
LLBFR 组的复合肌肉厚度（R=0.998）、向心峰力矩（R=0.962）和最大自主等长收缩（MVIC）力矩（R=0.980）数据呈二次增加。对于肌肉厚度，在干预的早期阶段（实验室访问 1-7），有 7/10 的受试者超过了 0.16cm 的最小差值（MD），而在同一时期，有 3/10 的受试者的向心峰力矩（3.7Nm）或 MVIC（2.2Nm）超过 MD。LLBFR 抗阻训练导致复合回声强度呈线性增加（r=0.563），但有 8/10 的受试者从未超过 14.2Au 的 MD。
这些发现表明，LLBFR 组肌肉厚度的增加与水肿无关，应根据个体情况检查回声强度的变化。此外，LLBFR 前臂屈伸抗阻训练在训练的早期阶段（即在肌肉力量真正增加之前）引起了肌肉大小的真实增加。
