Laboratory of Applied Biology, Faculty for Motor Sciences, Neuroscience Institute, Université Libre de Bruxelles, 808, Route de Lennik, CP 640, 1070 Brussels, Belgium.
Eur J Appl Physiol. 2013 Jul;113(7):1895-904. doi: 10.1007/s00421-013-2618-7. Epub 2013 Mar 8.
This study investigated the changes in muscular activity and tissue oxygenation while lifting and lowering a load of 20, 40, 60 or 80 % of one repetition maximum (1RM) with elbow flexor muscles until failure. The surface electromyogram (EMG) was recorded in biceps brachii (BB), brachioradialis (BRD) and triceps brachii (TB). For BB, a tissue oxygenation index (TOI) and a normalized total hemoglobin index (nTHI) were recorded by near-infrared spectroscopy. The number of repetitions decreased with the increase in load (P < 0.001), and the four loading conditions induced a decrease in MVC force immediately after failure (P < 0.001). The average of rectified EMG amplitude (aEMG) of elbow flexors increased for all loads during muscle shortening (SHO) and lengthening (LEN) phases of the movement (P < 0.05), except for the 80 % load during LEN phase. At failure, the aEMG was greater during the SHO than the LEN phase (P < 0.05), except for the 20 % load. TOI decreased for all loads and phases (P < 0.05) but less (P < 0.01) for the 20 % than 60 and 80 % loads (P < 0.01), and for LEN compared with SHO phase. At failure, TOI was negatively associated with aEMG during the SHO (r(2) = 0.99) and LEN (r(2) = 0.82) phases, while TOI and aEMG were positively associated with load magnitude (r(2) > 0.90) in both movement phases. This study emphasizes the influence of load magnitude and movement phase (SHO and LEN) on neuromuscular and oxydative adjustments during movements that involve lifting and lowering a load until failure.
本研究调查了在以 20%、40%、60%和 80%的 1 次最大重复（1RM）举重和降低负荷直至力竭时，肘屈肌肌肉活动和组织氧合的变化。肱二头肌（BB）、肱桡肌（BRD）和肱三头肌（TB）记录表面肌电图（EMG）。通过近红外光谱记录 BB 的组织氧合指数（TOI）和归一化总血红蛋白指数（nTHI）。随着负荷的增加，重复次数减少（P<0.001），并且四种加载条件在失败后立即降低 MVC 力（P<0.001）。在运动的缩短（SHO）和延长（LEN）阶段，所有负荷的肘屈肌的整流 EMG 幅度（aEMG）平均值均增加（P<0.05），除 80%的负荷在 LEN 阶段外。在失败时，SHO 阶段的 aEMG 大于 LEN 阶段（P<0.05），除 20%的负荷外。所有负荷和阶段的 TOI 均降低（P<0.05），但 20%的负荷与 60%和 80%的负荷（P<0.01）相比以及与 LEN 阶段相比，降低较少（P<0.01）。在失败时，SHO 阶段的 TOI 与 aEMG 呈负相关（r(2)=0.99）和 LEN 阶段（r(2)=0.82），而 TOI 和 aEMG 与运动阶段的负荷大小呈正相关（r(2)>0.90）。本研究强调了负荷大小和运动阶段（SHO 和 LEN）对涉及举重和降低直至力竭的运动中的神经肌肉和氧化调整的影响。
