Discipline of Physiology, School of Medical Sciences, The University of Adelaide, Adelaide, Australia.
J Appl Physiol (1985). 2012 Sep;113(6):929-36. doi: 10.1152/japplphysiol.00361.2012. Epub 2012 Jul 26.
The purpose of this study was to use paired-pulse transcranial magnetic stimulation (TMS) to examine the effect of eccentric exercise on short-interval intracortical inhibition (SICI) after damage to elbow flexor muscles. Nine young (22.5 ± 0.6 yr; mean ± SD) male subjects performed maximal eccentric exercise of the elbow flexor muscles until maximal voluntary contraction (MVC) force was reduced by ∼40%. TMS was performed before, 2 h after, and 2 days after exercise under Rest and Active (5% MVC) conditions with motor-evoked potentials (MEPs) recorded from the biceps brachii (BB) muscle. Peripheral electrical stimulation of the brachial plexus was used to assess maximal M-waves, and paired-pulse TMS with a 3-ms interstimulus interval was used to assess changes in SICI at each time point. The eccentric exercise resulted in a 34% decline in strength (P < 0.001), a 41% decline in resting M-wave (P = 0.01), changes in resting elbow joint angle (10°, P < 0.001), and a shift in the optimal elbow joint angle for force production (18°, P < 0.05) 2 h after exercise. This was accompanied by impaired muscle strength (27%, P < 0.001) and increased muscle soreness (P < 0.001) 2 days after exercise, which is indicative of muscle damage. When the test MEP amplitudes were matched between sessions, we found that SICI was reduced by 27% in resting and 23% in active BB muscle 2 h after exercise. SICI recovered 2 days after exercise when muscle pain and soreness were present, suggesting that delayed onset muscle soreness from eccentric exercise does not influence SICI. The change in SICI observed 2 h after exercise suggests that eccentric muscle damage has widespread effects throughout the motor system that likely includes changes in motor cortex.
本研究旨在使用成对脉冲经颅磁刺激（TMS）来检查离心运动对肱二头肌屈肌损伤后短程皮质内抑制（SICI）的影响。9 名年轻男性（22.5±0.6 岁；均值±标准差）进行最大离心运动直至最大自主收缩（MVC）力量减少约 40%。TMS 在运动诱发电位（MEPs）记录于肱二头肌（BB）肌肉之前、运动后 2 小时和 2 天在休息和主动（5% MVC）条件下进行。用臂丛神经外周电刺激评估最大 M 波，用 3 毫秒刺激间隔的成对脉冲 TMS 评估各时间点 SICI 的变化。离心运动导致力量下降 34%（P＜0.001），静息 M 波下降 41%（P=0.01），静息肘关节角度变化 10°（P＜0.001），以及产生力的最佳肘关节角度变化 18°（P＜0.05）运动后 2 小时。这伴随着肌肉力量受损（27%，P＜0.001）和肌肉酸痛增加（P＜0.001）运动后 2 天，表明肌肉损伤。当两次测试的 MEP 振幅在各次测试之间匹配时，我们发现运动后 2 小时休息时 SICI 降低 27%，主动 BB 肌肉时 SICI 降低 23%。当肌肉疼痛和酸痛存在时，运动后 2 天 SICI 恢复，表明离心运动引起的迟发性肌肉酸痛不会影响 SICI。运动后 2 小时观察到的 SICI 变化表明，离心性肌肉损伤对运动系统有广泛影响，可能包括运动皮层的变化。
