Reduced Achilles tendon stiffness in aging associates with higher metabolic cost of walking.

Autor: Gray AJ; Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, North Carolina, United States., Krupenevich RL; Division of Behavioral and Social Research, National Institute on Aging, Bethesda, Maryland, United States., Batsis JA; Division of Geriatric Medicine, Center for Aging and Health, University of North Carolina, Chapel Hill, North Carolina, United States.; Department of Nutrition, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, United States., Sawicki GS; George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States., Franz JR; Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, North Carolina, United States.
Jazyk: angličtina
Zdroj: Journal of applied physiology (Bethesda, Md. : 1985) [J Appl Physiol (1985)] 2024 Dec 01; Vol. 137 (6), pp. 1541-1548. Date of Electronic Publication: 2024 Nov 07.
DOI: 10.1152/japplphysiol.00377.2024
Abstrakt: The mechanisms responsible for increased metabolic cost of walking in older adults are poorly understood. We recently proposed a theoretical premise by which age-related reductions in Achilles tendon stiffness (k AT ) can disrupt the neuromechanics of calf muscle force production and contribute to faster rates of oxygen consumption during walking. The purpose of this study was to objectively evaluate this premise. We quantified k AT at a range of matched relative activations prescribed using electromyographic biofeedback and walking metabolic cost and ankle joint biomechanics in a group of 15 younger (age: 23 ± 4 yr) and 15 older (age: 72 ± 5 yr) adults. Older adults averaged 44% lower k AT than younger adults at matched triceps surae activations during isokinetic dorsiflexion tasks on a dynamometer ( P = 0.046). Older adults also walked with a 17% higher net metabolic power ( P = 0.017) but indistinguishable peak Achilles tendon forces than younger adults. Thus, data implicate altered tendon length-tension relations with age more than differences in the operating region of those length-tension relations between younger and older adults. In addition, we discovered empirical evidence that lesser k AT -likely due to the shorter muscle lengths and thus higher relative activations it imposes-was positively correlated with higher net metabolic power during walking ( r = -0.365, P = 0.048). These results pave the way for interventions focused on restoring ankle muscle-tendon unit structural stiffness to improve walking energetics in aging. NEW & NOTEWORTHY This study provides the first empirical evidence to our knowledge that age-related decreases in k AT exact a potentially significant metabolic penalty during walking. These results pave the way for interventions focused on restoring ankle muscle-tendon unit structural stiffness to improve walking energetics in aging.
Databáze: MEDLINE
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