Fatigue of the wrist extensor muscles decreases palmar grip strength

ABSTRACT The objective of this study was to evaluate the effects of a wrist extensor muscles fatigue protocol at the handgrip and lateral pinch strength through dynamometry and surface electromyography (EMG). Forty male individuals were divided into two groups: handgrip and lateral pinch group. The fatigue protocol was based on the 1 Maximal Repetition (1-MR) test, followed by wrist extension movement repeated multiple times with a load of 75% of 1-MR. The volunteers performed hand grip and lateral pinch with a dynamometer. Surface EMG was performed by both groups to analyze the behavior of median frequency (MF) during a fatigue protocol. The muscles extensor carpi radialis longus and brevis, extensor carpi ulnaris, extensor digitorum and flexor digitorum superficialis were analyzed. The strength and EMG evaluations were carried out before and after the fatigue protocol in both groups. The fatigue protocol was effective on hand grip strength reduction (43.5±3.85 kgf in baseline and 36.50±5.1 kgf final) and lateral pinch strength reduction (10.26±1.01 kgf in baseline and 8.54±0.86 kgf final) (p摘要 本研究旨在通过测力法与表面肌电图（surface electromyography, EMG），评估腕伸肌疲劳方案对握力及侧捏力的影响。招募40名男性受试者，分为握力组与侧捏力组。该疲劳方案以1次最大重复（1-Maximal Repetition, 1-MR）测试为基础，随后以75%的1-MR负荷重复进行多次腕伸运动。受试者使用测力计完成握力与侧捏力测试。两组均接受表面肌电图检测，以分析疲劳过程中中位频率（median frequency, MF）的变化特征。本次分析涉及的肌肉包括桡侧腕长伸肌、桡侧腕短伸肌、尺侧腕伸肌、指伸肌及指浅屈肌。两组均在疲劳方案实施前后完成肌力与肌电图评估。结果表明，该疲劳方案可有效降低握力（基线值为43.5±3.85 kgf，终值为36.50±5.1 kgf）与侧捏力（基线值为10.26±1.01 kgf，终值为8.54±0.86 kgf）（p