Casamento-Moran Agostina, Chen Yen-Ting, Lodha Neha, Yacoubi Basma, Christou Evangelos A
Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida; and.
Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida; and
J Neurophysiol. 2017 Apr 1;117(4):1483-1488. doi: 10.1152/jn.00640.2016. Epub 2017 Jan 11.
Older adults exhibit altered activation of the agonist and antagonist muscles during goal-directed movements compared with young adults. However, it remains unclear whether the differential activation of the antagonistic muscles in older adults results from an impaired motor plan or an altered ability of the muscle to contract. The purpose of this study, therefore, was to determine whether the motor plan differs for young and older adults. Ten young (26.1 ± 4.3 yr, 4 women) and 16 older adults (71.9 ± 6.9 yr, 9 women) participated in the study. Participants performed 100 trials of fast goal directed movements with ankle dorsiflexion while we recorded the electromyographic activity of the primary agonist (tibialis anterior; TA) and antagonist (soleus; SOL) muscles. From those 100 trials we selected 5 trials in each of 3 movement end-point categories (fast, accurate, and slow). We investigated age-associated differences in the motor plan by quantifying the individual activity and coordination of the agonist and antagonist muscles. During similar movement end points, older adults exhibited similar activation of the agonist (TA) and antagonist (SOL) muscles compared with young adults. In addition, the coordination of the agonist and antagonist muscles (TA and SOL) was different between the two age groups. Specifically, older adults exhibited lower TA-SOL overlap ( = 41.2, < 0.001) and greater TA-SOL peak EMG delay ( = 35.5, < 0.001). This finding suggests that although subjects in both age groups displayed similar movement end points, they exhibited a different motor plan, as demonstrated by altered coordination between the agonist and antagonist muscles. We aimed to determine whether the altered activation of muscles in older adults compared with young adults during fast goal-directed movements is related to an altered motor plan. For matched movements, there were differences in the coordination of antagonistic muscles but no differences in the individual activation of muscles. We provide novel evidence that the differential activation of muscles in older adults is related to an altered motor plan.
与年轻人相比，老年人在目标导向运动中表现出主动肌和拮抗肌的激活改变。然而，目前尚不清楚老年人拮抗肌的差异激活是由于运动计划受损还是肌肉收缩能力改变所致。因此，本研究的目的是确定年轻人和老年人的运动计划是否不同。10名年轻人（26.1±4.3岁，4名女性）和16名老年人（71.9±6.9岁，9名女性）参与了本研究。参与者在进行100次快速目标导向的踝关节背屈运动试验时，我们记录了主要主动肌（胫骨前肌；TA）和拮抗肌（比目鱼肌；SOL）的肌电活动。从这100次试验中，我们在3种运动终点类别（快速、准确和缓慢）中各选择了5次试验。我们通过量化主动肌和拮抗肌的个体活动及协调性来研究运动计划中的年龄相关差异。在相似的运动终点时，与年轻人相比，老年人的主动肌（TA）和拮抗肌（SOL）表现出相似的激活。此外，两个年龄组之间主动肌和拮抗肌（TA和SOL）的协调性不同。具体而言，老年人的TA-SOL重叠较低（=41.2，<0.001），TA-SOL肌电图峰值延迟较大（=35.5，<0.001）。这一发现表明，尽管两个年龄组的受试者表现出相似的运动终点，但他们表现出不同的运动计划，这表现为主动肌和拮抗肌之间协调性的改变。我们旨在确定与年轻人相比，老年人在快速目标导向运动中肌肉激活的改变是否与运动计划的改变有关。对于匹配的运动，拮抗肌的协调性存在差异，但肌肉的个体激活没有差异。我们提供了新的证据，表明老年人肌肉的差异激活与运动计划的改变有关。
