Harwood B, Edwards D L, Jakobi J M
School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, Arthur & Sonia Labatt Health Sciences Building, London, Ontario, Canada.
Eur J Appl Physiol. 2008 Aug;103(6):677-86. doi: 10.1007/s00421-008-0765-z. Epub 2008 May 17.
Electromyography (EMG) recordings for a typical 8-h day have indicated that burst activity is greater in old adults compared with young adults; these age-related adaptations might be due to the tasks undertaken. The purpose of the present study was to determine whether EMG burst activity differs between young and old men and women for a discrete task of daily living, and to assess whether the time of day when the task is performed influences the EMG burst patterns. Subjects completed a discrete functional task of a grocery bag carry prior to and following 8 h of daily activity. Surface EMG was recorded from the biceps brachii, triceps brachii, vastus lateralis, and biceps femoris. Spatial and temporal characteristics of the bursts were quantified as a period of EMG activity being greater than 2% maximum EMG and for a duration longer than 0.1 s. Burst activity did not differ between the morning and evening recordings, which indicate that the time of day does not influence burst activity recorded for a discrete task. Although there were no differences in burst number between young (10.9 +/- 1.0) and old (11.4 +/- 0.7) adults, burst duration and area were 3-7 times larger in old adults compared with young adults. The number of bursts in women (7.9 +/- 1.0) were ~85% less compared with men (14.6 +/- 0.7), but burst duration and burst area were approximately three times larger in women compared with men. Thus, older adults demonstrate higher levels of burst activity compared with young adults, and these age-related changes in burst activity are augmented in women.
针对典型的8小时工作日的肌电图（EMG）记录表明，与年轻人相比，老年人的爆发性活动更强；这些与年龄相关的适应性变化可能归因于所执行的任务。本研究的目的是确定在一项日常生活的离散任务中，年轻男性和女性与老年男性和女性的肌电图爆发性活动是否存在差异，并评估执行任务的时间是否会影响肌电图爆发模式。受试者在进行8小时日常活动之前和之后完成了一项携带购物袋的离散功能任务。从肱二头肌、肱三头肌、股外侧肌和股二头肌记录表面肌电图。爆发的空间和时间特征被量化为肌电图活动期大于最大肌电图的2%且持续时间超过0.1秒。早晨和晚上的记录之间爆发性活动没有差异，这表明一天中的时间不会影响为离散任务记录的爆发性活动。虽然年轻人（10.9±1.0）和老年人（11.4±0.7）之间的爆发次数没有差异，但与年轻人相比，老年人的爆发持续时间和面积大3至7倍。女性的爆发次数（7.9±1.0）比男性（14.6±0.7）少约85%，但女性的爆发持续时间和爆发面积比男性大约大三倍。因此，与年轻人相比，老年人表现出更高水平的爆发性活动，并且这些与年龄相关的爆发性活动变化在女性中更为明显。
