Aging, Visuomotor Correction, and Force Fluctuations in Large Muscles

• Autores: Brian L. Tracy, Devin V. Dinenno, Bjorn Jorgensen
• Localización: Medicine & Science in Sports & exercise: Official Journal of the American College of Sports Medicine, ISSN 0195-9131, Vol. 39, Nº. 3, 2007, págs. 469-479
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • Purpose: To determine the contribution of visuomotor correction to increased force fluctuations in the elbow flexor and knee extensor muscles of elderly adults.

    Methods: Young (N = 22, 23 ± 3 yr) and elderly (N = 23, 74 ± 7 yr) adults performed constant-force contractions at target forces of 2.5, 30, and 65% MVC. Visual feedback was provided (6-8 s) and then removed (6-8 s). After removal of drift (< 0.5 Hz) from the force, the standard deviation (SD) and coefficient of variation (CV) of force were calculated from vision and no-vision data.

    Results: Maximal voluntary contraction (MVC) force was 19% lower for elbow flexors and 37% lower for knee extensors in elderly adults than in young adults. Overall, the CV of force was 27% greater in the vision condition compared with the no-vision condition. The CV of force for vision was greater for elderly adults than for young adults at the 2.5% MVC target force and lower at 30 and 65% MVC. For the 2.5% MVC target force, the decline in CV of force from vision to no vision was greater for elderly adults than for young adults. At 30 and 65% MVC, the decline was significant but similar for young and elderly adults. For elbow flexors, the change in power from vision to no vision was greater for 0- to 4-Hz (reduced power) and 8- to 12-Hz (increased power) frequencies for elderly adults compared with young adults.

    Conclusion: Visuomotor correction contributed to force fluctuations in large proximal muscles. The contribution was greater for healthy elderly adults at low forces. Visuomotor processes thus contributed to the age-related increase in force fluctuations.