BACKGROUND Understanding the root cause of the age-related impairment in muscle adaptive remodelling with resistance exercise training (RET) and developing pragmatic and accessible resistance exercise for older adults, are essential research directives. METHODS We sought to determine whether indices of quadriceps muscle EMG activity in response to different modes of RET and activities of daily living (ADL), differed between 15 healthy younger (25 ± 3 years) and 15 older (70 ± 5 years) adults. On four separate days, participants completed a maximal voluntary contraction (MVC) of the knee extensors, followed by a 15 m walking task, stair climbing task (i.e. ADL) and lower-limb RET through body-weight squats (BW-RET) and seated knee extensions on a machine (MN-RET) or via elastic bands (EB-RET). Surface quadriceps electromyography (EMG) was measured throughout all tasks to provide indirect estimates of changes in muscle activity. RESULTS MVC was significantly greater in young vs. older adults (Young: 256 ± 72 vs. Old: 137 ± 48 N·m, P < 0.001). EMG activity during all exercise tasks was significantly higher in older vs. younger adults when expressed relative to maximal EMG achieved during MVC (P < 0.01, for all). In addition, relative quadriceps muscle EMG activity was significantly greater in EB-RET (Young: 20.3 ± 8.7 vs. Old: 37.0 ± 10.7%) and MN-RET (Young: 22.9 ± 10.3, vs. Old: 37.8 ± 10.8%) compared with BW-RET (Young: 8.6 ± 2.9 vs. Old: 27.0 ± 9.3%), in young and older adults (P < 0.001). However, there was no significant difference in quadriceps EMG between EB-RET and MN-RET (P > 0.05). CONCLUSIONS In conclusion, relative quadriceps muscle EMG activity was higher across a range of activities/exercise modes in older vs. younger adults. The similar quadriceps muscle EMG activity between EB-RET and MN-RET provides a platform for detailed investigation of the neuromuscular and muscle metabolic responses to such pragmatic forms of RET to strengthen the evidence-base for this mode of RET as a potential countermeasure to sarcopenia.

中文翻译：

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年轻人和老年人体力活动和阻力运动模式期间股四头肌肌电图活动。

背景了解抗阻运动训练（RET）肌肉适应性重塑中与年龄相关的损伤的根本原因，并为老年人开发实用且易于使用的抗阻运动，是重要的研究方向。方法 我们试图确定 15 名健康的年轻人（25​​ ± 3 岁）和 15 名老年人（70 ± 5 岁）之间股四头肌肌电图活动指数对不同 RET 模式和日常生活活动 (ADL) 的反应是否存在差异。在不同的四天内，参与者完成了膝伸肌的最大自愿收缩（MVC），然后是 15 m 步行任务、爬楼梯任务（即 ADL）和通过自重深蹲（BW-RET）进行的下肢 RET 和坐在机器上（MN-RET）或通过松紧带（EB-RET）进行膝关节伸展。在所有任务中均测量表面股四头肌电图 (EMG)，以间接估计肌肉活动的变化。结果 年轻人的 MVC 显着高于老年人（年轻人：256 ± 72 vs. 老年人：137 ± 48 N·m，P < 0.001）。与 MVC 期间达到的最大 EMG 相比，老年人在所有运动任务期间的 EMG 活动均显着高于年轻人（P < 0.01）。此外，EB-RET（年轻：20.3 ± 8.7 vs. 老年：37.0 ± 10.7%）和 MN-RET（年轻：22.9 ± 10.3 vs. 老年：37.8 ± 10.8%）的相对股四头肌肌电图活动显着更高与 BW-RET 相比（年轻：8.6 ± 2.9 vs. 老年：27.0 ± 9.3%），在年轻人和老年人中（P < 0.001）。但EB-RET和MN-RET的股四头肌肌电图差异无统计学意义（P>0.05）。结论 总之，老年人与年轻人相比，在一系列活动/运动模式中，相对股四头肌肌电图活动更高。EB-RET 和 MN-RET 之间相似的股四头肌肌电图活动为详细研究神经肌肉和肌肉代谢对这种实用形式 RET 的反应提供了一个平台，以加强这种 RET 模式作为肌肉减少症潜在对策的证据基础。