contractile and elastic ankle joint muscular properties in young and older adults收缩和弹性踝关节肌肉在年轻人和老年人.pdfVIP

Contractile and Elastic Ankle Joint Muscular Properties in Young and Older Adults ¤ Christopher J. Hasson* , Ross H. Miller, Graham E. Caldwell Biomechanics Laboratory, Department of Kinesiology, University of Massachusetts Amherst, Amherst, Massachusetts, United States of America Abstract The purpose of this study was to investigate age-related differences in contractile and elastic properties of both dorsi- (DF) and plantarflexor (PF) muscles controlling the ankle joint in young and older adults. Experimental data were collected while twelve young and twelve older male and female participants performed maximal effort isometric and isovelocity contractions on a dynamometer. Equations were fit to the data to give torque-angle (Th) and torque-angular velocity (Tv) relations. Muscle series-elasticity was measured during ramped dynamometer contractions using ultrasonography to measure aponeurosis extension as a function of torque; second order polynomials were used to characterize the torque- extension (TDL) relation. The results showed no age differences in DF maximal torque and none for female PF; however, older males had smaller maximal PF torques compared to young males. In both muscle groups and genders, older adults had decreased concentric force capabilities. Both DF and PF TDL relations were more nonlinear in the older adults. Older PF, but not DF muscles, were stiffer compared to young. A simple antagonism model suggested age-related differences in Th and Tv relations would be magnified if antagonistic torque contributions were included. This assessment of static, dynamic, and elastic joint properties affords a comprehensive view of age-related modifications in muscle function. Although many clinical studies use maximal isometric strength as