The influence of age on the assessment of motor unit activation in a human hand muscle.
The influence of age on the assessment of motor unit activation in a human hand muscle.
复制标题
年龄对人类手部肌肉运动单位激活评估的影响。
DOI：
10.1113/expphysiol.1996.sp003978
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发表时间：
1996
影响因子：
2.7
通讯作者：
Enoka,RM
中科院分区：
文献类型：
--
作者：
Spiegel,KM;Stratton,J;Burke,JR;Glendinning,DS;Enoka,RM
在10名年轻受试者和12名老年受试者的第一骨间背侧肌中比较了运动单位募集的两个指标，即斜坡力阈值和重复放电阈值。目的是确定年龄对两个募集阈值与运动单位的棘波触发平均力之间关系的影响。每名受试者执行三项需要左食指等长外展的任务：最大随意收缩（MVC）、斜坡保持收缩和重复放电任务。在斜升-保持收缩期间，老年受试者比年轻受试者更频繁地使用拮抗肌（第二骨间掌侧肌）的共激活。许多老年受试者表示难以控制斜升-保持收缩的斜降阶段，并且在该任务中更喜欢共激活策略而不是去募集策略。各组之间的斜升力阈值不存在年龄或性别差异。然而，年轻受试者和男性受试者的标准化重复放电阈值显著更低。尽管如此，两个募集阈值能够预测棘波触发的平均力，对于年轻受试者和老年受试者的成功率相似。这些数据表明，对于年轻受试者和老年受试者，第一骨间背侧肌运动单位的募集阈值通过斜坡力或重复放电测量同样具有特征，但老年受试者在斜坡和保持任务期间更频繁地使用共激活。
Two indices of motor unit recruitment, the ramp‐force and repetitive‐discharge thresholds, were compared in the first dorsal interosseus muscle of ten young and twelve elderly subjects. The purpose was to determine the effect of age on the relationship between the two recruitment thresholds and the spike‐triggered average force of motor units. Each subject performed three tasks requiring isometric abduction of the left index finger: a maximum voluntary contraction (MVC), a ramp‐and‐hold contraction, and a repetitive‐discharge task. The elderly subjects used coactivation of the antagonist muscle (second palmar interosseus) more frequently than the young subjects during the ramp‐and‐hold contraction. Many elderly subjects expressed difficulty with the controlled ramp‐down phase of the ramp‐and‐hold contraction and preferred a coactivation strategy to a derecruitment strategy for this task. There were no differences due to age or gender in the ramp‐force thresholds between the various groups. However, the normalized repetitive‐discharge threshold was significantly less for the younger subjects and for the male subjects. Nonetheless, the two recruitment thresholds were able to predict the spike‐triggered average force with similar success for both the young and the elderly subjects. These data suggest that the recruitment threshold of a motor unit in first dorsal interosseus was characterized equally well by either the ramp‐force or repetitive‐discharge measurement for both young and elderly subjects but that coactivation was used more frequently by the elderly subjects during the ramp‐and‐hold task.