Chu Yu-Hsiu, Tang Pei-Fang, Chen Hui-Ya, Cheng Chih-Hsiu
Department of Physical Therapy, China Medical University, Taichung, Taiwan, ROC.
Clin Biomech (Bristol). 2009 Nov;24(9):735-43. doi: 10.1016/j.clinbiomech.2009.06.012. Epub 2009 Aug 7.
Middle-aged adults show a higher incidence of falls compared to young adults when performing outdoor physical activities. This study investigated whether or not the patterns and quantitative characteristics of the trunk and lower extremity muscle activations associated with stepping, which represents an important movement for arresting falls, differ between middle-aged adults and young adults.
Nine healthy young adults (age=22[3] years) and nine healthy middle-aged adults (age=52[8] years), performed a single-step, volitional, fast forward stepping movement with each leg. The stepping movement was divided into the step-initiation, single-leg-support, and landing phases based on foot-switch signals. The activation sequence, occurrence rate, onset latency, burst duration, and normalized co-contraction duration of the tibialis anterior, medial gastrocnemius, rectus femoris, biceps femoris, and gluteus medius of the stance and swing legs and that of bilateral erector spinae muscles were analyzed using surface electromyography. We defined the essential muscle activation as exhibiting an occurrence rate of 90% or more in all of these trials.
As compared to young adults, the middle-aged adults demonstrated several additional essential bursts throughout the stepping movement. Middle-aged adults also displayed significantly longer burst durations of the biceps femoris and medial gastrocnemius of the swing leg after landing, as well as longer co-contraction of the rectus femoris and biceps femoris of the stance leg in the single-leg-support phase (P<0.05).
Age-related changes in step-related neuromuscular control exist in healthy middle-aged adults. We propose that training focused on improving or maintaining neuromuscular control associated with volitional leg movements may benefit middle-aged individuals.
与年轻人相比，中年成年人在进行户外体育活动时摔倒的发生率更高。本研究调查了与踏步相关的躯干和下肢肌肉激活模式及定量特征（踏步是防止摔倒的重要动作）在中年成年人和年轻人之间是否存在差异。
9名健康的年轻成年人（年龄=22[3]岁）和9名健康的中年成年人（年龄=52[8]岁），每条腿进行一次单步、自主、快速向前的踏步动作。根据足部开关信号，将踏步动作分为步起始、单腿支撑和着地阶段。使用表面肌电图分析站立腿和摆动腿以及双侧竖脊肌的胫骨前肌、腓肠肌内侧头、股直肌、股二头肌和臀中肌的激活顺序、发生率、起始潜伏期、爆发持续时间和标准化协同收缩持续时间。我们将在所有这些试验中发生率达到90%或更高的肌肉激活定义为基本肌肉激活。
与年轻人相比，中年成年人在整个踏步运动中表现出几次额外的基本爆发。中年成年人在着地后摆动腿的股二头肌和腓肠肌内侧头的爆发持续时间也明显更长，并且在单腿支撑阶段站立腿的股直肌和股二头肌的协同收缩时间更长（P<0.05）。
健康中年成年人存在与步相关的神经肌肉控制的年龄相关变化。我们建议，专注于改善或维持与自主腿部运动相关的神经肌肉控制的训练可能对中年个体有益。
