Gao Ying, Melin Martti, Mäkäräinen Karoliina, Rantalainen Timo, Pesola Arto J, Laukkanen Arto, Sääkslahti Arja, Finni Taija
Neuromuscular Research Center, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland.
Active Life Lab, South-Eastern Finland University of Applied Sciences, Mikkeli, Finland.
PeerJ. 2018 Aug 21;6:e5437. doi: 10.7717/peerj.5437. eCollection 2018.
This research compared accelerometry (ACC)-derived and muscle electromyography (EMG)-based estimates of physical activity (PA) and sedentary time in typical PA tasks and during the daily lives of children.
Data was included from two exploratory studies. In Study I, 6-7-year-old children ( = 11, 64% girls) were assessed for eight PA tasks (walking, stair negotiation, climbing, crawling, swinging, balancing, trampoline jumping and a game of tag). In Study II, 7-9-year-old children ( = 14, 38% girls) were assessed for six PA tasks (walking, sitting, static squat, single leg hops, jump for height and standing long jump), and daily PA during one day with and one day without structured exercise. Quadriceps and hamstring muscle activity and inactivity using EMG shorts and acceleration by waist-mounted accelerometer were simultaneously measured and classified as sedentary, light, moderate and vigorous activity. Data from ACC was further analyzed using five different published cut-off points and varying time windows (1-60 s) for comparison with EMG.
In the PA tasks ACC counts and EMG amplitude showed marked differences in swinging, trampoline jumping, crawling, static squat, single leg hops, standing long jump and jump for height, the difference being over 170% when signals were normalized to that during walking. Furthermore, in walking, swinging, trampoline jumping, stair negotiation and crawling ACC classified over 60% of the time as vigorous-intensity activity, while EMG indicated primarily light- and moderate-intensity activities. During both days with and without exercise, ACC resulted in greater proportion of light activity ( < 0.01) and smaller proportion of moderate activity compared to EMG ( < 0.05). The choice of cut-off points and epoch length in ACC analysis influenced the classification of PA level and sedentary time. In the analysis of daily activities the cut-off points by Evenson et al. (2008) with epochs of 7.5 s and 15 s yielded the smallest difference (less than 10% of recording time at each intensity) against EMG-derived PA levels.
This research provides novel insight on muscle activity and thereby on neuromuscular loading of major locomotor muscles during normal daily activities of children. While EMG and ACC provided similar estimates of sedentary time in 13 typical PA tasks, duration of light, moderate and vigorous PA varied considerably between the methods especially during walking, stair negotiation, crawling, swinging and trampoline jumping. Evenson et al.'s (2008) cut-off points with ≤15 s epoch provided similar classification of PA than EMG during daily life. Compared to impacts recorded using ACC, EMG can provide understanding on children's neuromuscular loading during motor tasks that is useful when studying effects of PA interventions on, and development of, motor competence and coordination.
本研究比较了通过加速度计（ACC）得出的以及基于肌肉肌电图（EMG）的儿童在典型身体活动任务及日常生活中的身体活动（PA）和久坐时间估计值。
数据来自两项探索性研究。在研究I中，对6 - 7岁儿童（n = 11，64%为女孩）进行了八项身体活动任务（行走、上下楼梯、攀爬、爬行、荡秋千、平衡、蹦床跳跃和捉人游戏）的评估。在研究II中，对7 - 9岁儿童（n = 14，38%为女孩）进行了六项身体活动任务（行走、坐着、静态蹲姿、单腿跳跃、纵跳摸高和立定跳远）的评估，以及在有一天有结构化运动和一天没有结构化运动的情况下的日常身体活动评估。使用肌电图短裤同时测量股四头肌和腘绳肌的肌肉活动和静止状态，并通过佩戴在腰部的加速度计测量加速度，将其分类为久坐、轻度、中度和剧烈活动。对ACC数据进一步使用五个不同的已发表的截止点和不同的时间窗口（1 - 60秒）进行分析，以与EMG进行比较。
在身体活动任务中，ACC计数和EMG幅度在荡秋千、蹦床跳跃、爬行、静态蹲姿、单腿跳跃、立定跳远和纵跳摸高方面显示出显著差异，当信号相对于行走时进行标准化后，差异超过170%。此外，在行走、荡秋千、蹦床跳跃、上下楼梯和爬行过程中，ACC将超过60%的时间分类为剧烈强度活动，而EMG主要表明是轻度和中度强度活动。在有运动和无运动的两天中，与EMG相比，ACC导致轻度活动的比例更高（P < 0.01），中度活动的比例更小（P < 0.05）。ACC分析中截止点和时段长度的选择影响了身体活动水平和久坐时间的分类。在日常活动分析中，Evenson等人（2008年）提出的7.5秒和15秒时段的截止点与基于EMG得出的身体活动水平相比，差异最小（每种强度下记录时间的不到10%）。
本研究为儿童正常日常活动期间的肌肉活动以及主要运动肌肉群的神经肌肉负荷提供了新的见解。虽然在13项典型身体活动任务中，EMG和ACC对久坐时间提供了相似的估计，但轻度、中度和剧烈身体活动的持续时间在两种方法之间差异很大，尤其是在行走、上下楼梯、爬行、荡秋千和蹦床跳跃期间。Evenson等人（2008年）提出的≤15秒时段的截止点在日常生活中与EMG对身体活动的分类相似。与使用ACC记录的影响相比，EMG可以提供对儿童运动任务期间神经肌肉负荷的理解，这在研究身体活动干预对运动能力和协调性的影响以及运动能力和协调性的发展时很有用。
