Lampropoulou Sofia I, Nowicky Alexander V
Physical Therapy Dept., Technological Education Institute of Western Greece, Aigio, Greece.
Motor Control. 2014 Apr;18(2):146-64. doi: 10.1123/mc.2013-0010. Epub 2013 Oct 25.
The way psychometric and neurophysiological measurements of fatigue are connected is not well understood. Thus, the time course of perceived effort changes due to fatigue, as well as the peripheral and central neurophysiological changes accompanying fatigue, were evaluated. Twelve healthy participants (35 ± 9 years old) undertook 10 min intermittent isometric fatiguing exercise of elbow flexors at 50% of maximum voluntary contraction (MVC). Perceived effort ratings, using the 0-10 numeric rating scale (NRS), were recorded at midrange of MVC. Single pulse TMS of the left motor cortex and electrical stimulation over the biceps muscle was used for the assessment of voluntary activation and peripheral fatigue. The fatiguing exercise caused a 44% reduction in the MVC (p < .001) accompanied by an 18% nonsignificant reduction of the biceps MEP amplitude. The resting twitch force decreased (p < .001) while the superimposed twitches increased (p < .001) causing a decrease (19%) of the voluntary activation (p < .001). The perceived effort ratings increased by 1 point at 30%, by 2 points at 50% MVC respectively on the NRS (p < .001) and were accompanied by an increase in mean biceps EMG. A substantial role of the perceived effort in the voluntary motor control system was revealed.
疲劳的心理测量和神经生理测量之间的联系尚未得到很好的理解。因此，评估了由于疲劳导致的主观用力变化的时间进程，以及伴随疲劳的外周和中枢神经生理变化。12名健康参与者（35±9岁）以最大自主收缩（MVC）的50%进行了10分钟的肘部屈肌间歇性等长疲劳运动。在MVC的中间范围使用0-10数字评分量表（NRS）记录主观用力评分。使用左运动皮层的单脉冲TMS和肱二头肌上的电刺激来评估自主激活和外周疲劳。疲劳运动导致MVC降低44%（p <.001），同时肱二头肌MEP幅度非显著降低18%。静息抽搐力下降（p <.001），而叠加抽搐增加（p <.001），导致自主激活下降（19%）（p <.001）。在NRS上，主观用力评分在MVC为30%时增加1分，在MVC为50%时增加2分（p <.001），同时肱二头肌平均肌电图增加。揭示了主观用力在自主运动控制系统中的重要作用。
