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Effect of tendon mechanical properties on force steadiness in young and old adults

University of British Columbia

The contribution of the tendon to age-related differences in elbow flexor force steadiness has not been studied. The purpose of this study was to investigate the effect of tendon compliance on force steadiness in young compared with old males during sustained submaximal isometric elbow flexion contractions. Force steadiness and tendon properties were measured in ten young (22.4 ± 3.7 years; 166.9 ± 11.8 cm; 74.3 ± 13.2 kg), and ten old (77.3 ± 5.3 years; 168.9 ± 14.1 cm; 84.6 ± 13.5 kg) healthy physically active males at 6 submaximal forces of 2.5%, 5%, 10%, 20%, 40%, and 60% maximal voluntary contraction (MVC). Muscle-tendon characteristics were assessed by ultrasonography and force steadiness with an isometric dynamometer. Young and old did not differ in height, weight, muscle-tendon, and bone parameters (p > 0.05). The main findings of the present study were that a) Young were ~20.4% (p < 0.001) stronger than old and this was not due to a difference in voluntary activation (p > 0.05), b) Young were steadier (1.1 ± 1.0 CV % MVC) than old (1.9 ± 1.5 CV % MVC) across the 6 submaximal forces (p < 0.001), c) Tendon mechanical properties such as stress (p > 0.07, n²= 0.19), stiffness (p > 0.07, n²= 0.17), and Young’s Modulus (p > 0.07, n²= 0.17) were moderately less in old than young, and d) Tendon mechanical properties become stiffer as force increases (p < 0.05). Tendon displacement, strain, and stress were correlated with force steadiness (p < 0.001). These data suggest that tendon properties are one of the primary factors contributing to differences in steadiness across submaximal forces, and these mechanical properties contribute modestly to age-related differences.

Text

2015-08-04

Attribution-NonCommercial-NoDerivs 2.5 Canada

http://hdl.handle.net/2429/54270

Interdisciplinary Studies

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/2.5/ca/