Calf muscle-tendon properties and postural balance in old age

Onambélé-Pearson, Gladys, Narici, Marco V. and Maganaris, Constantinos N. (2006) Calf muscle-tendon properties and postural balance in old age. Journal of Applied Physiology, 100 (6). pp. 2048-2056. ISSN 8750-7587

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Abstract

We tested the hypothesis that compromised postural balance in older subjects is associated with changes in calf muscle-tendon physiological and mechanical properties. Trial duration and centre of pressure (COP) displacements were measured in 24 younger (aged 24+/-1 years), 10 middle-aged (aged 46+/-1 years) and 36 older (aged 68+/-1 years) healthy subjects under varying levels of postural difficulty. Muscle-tendon characteristics were assessed by dynamometry, twitch superimposition and ultrasonography. In tandem and single-leg stances, trial duration decreased (</=65% lower, P<0.001) and COP displacements increased (</=90% higher, P<0.05) with age. Muscle strength, size, activation capacity and tendon mechanical properties decreased with age by 55, 13, 13 and 36-48%, respectively (P<0.05). Regressions with these parameters and balance indices were significant (P<0.05) for single-leg and tandem (0.69<r(2)<0.90) postures only, indicating that the age-related changes in muscle-tendon characteristics may explain the majority of the variance in balance performance during tasks more difficult than habitual bipedal stance.