Faculty Collaboration Database

Human skeletal muscle responses vary with age and gender during fatigue due to incremental isometric exercise. J Appl Physiol (1985) 2002 Nov;93(5):1813-23

Date

10/17/2002

Pubmed ID

12381770

DOI

10.1152/japplphysiol.00091.2002

Scopus ID

2-s2.0-0036871995 (requires institutional sign-in at Scopus site)   266 Citations

Abstract

The purpose of this study was to compare the magnitude and mechanisms of ankle dorsiflexor muscle fatigue in 20 young (33 +/- 6 yr, mean +/- SD) and 21 older (75 +/- 6 yr) healthy men and women of similar physical activity status. Noninvasive measures of central and peripheral (neuromuscular junction, sarcolemma) muscle activation, muscle contractile function, and intramuscular energy metabolism were made before, during, and after incremental isometric exercise. Older subjects fatigued less than young (P < 0.01); there was no effect of gender on fatigue (P = 0.24). For all subjects combined, fatigue was modestly related to preexercise strength (r = 0.49, P < 0.01). Neither central (central activation ratio) nor peripheral (compound muscle action potential) activation played a significant role in fatigue in any group. During exercise, intracellular concentrations of P(i) and H(2)PO increased more and pH fell more in young compared with older subjects (P < 0.01) and in men compared with women (P < 0.01). These varied metabolic responses to exercise suggest a greater reliance on nonoxidative sources of ATP in young compared with older subjects and in men compared with women. These results suggest that the mechanisms of fatigue vary with age and gender, regardless of whether differences in the magnitude of fatigue are observed.

Author List

Kent-Braun JA, Ng AV, Doyle JW, Towse TF

Author

Alexander V. Ng PhD Associate Professor in the Exercise Science department at Marquette University

MESH terms used to index this publication - Major topics in bold

Action Potentials
Adult
Aged
Aged, 80 and over
Aging
Cross-Sectional Studies
Electric Stimulation
Electromyography
Energy Metabolism
Exercise
Female
Humans
Isometric Contraction
Magnetic Resonance Spectroscopy
Male
Muscle Fatigue
Muscle, Skeletal
Sex Characteristics