Affiliation: College of Arts and Sciences, Department of Exercise and Sport Science
The purpose of this study was to examine the influence of age on muscle-tendon behavior during a bout of constant-torque (CT) stretching. Eighteen young and 16 older healthy men performed a 60-s CT stretch at their pre-determined torque threshold. Changes in ankle joint position and muscle and tendon lengths from pre- to post-stretch were examined using an electrogoniometer and ultrasonography, respectively. Ankle point position increased for both groups, however the younger men (2.01°) experienced a non-significant (P=0.072) greater increase when compared to the older men (1.41°) and a simultaneous greater increase in muscle-tendon unit length (P=0.043). Furthermore, muscle and tendon lengths increased for both groups; however the muscle increased more (P<0.001) in the young (Δmuscle length - 77%; Δtendon length - 23%) and the tendon increased more (P<0.001) in the old (Δmuscle length - 36%; Δtendon length - 64%). These findings may be due to the age-related increases in tendon compliance and muscle stiffness.