Neural and Muscular Contributions to the Age-Related Differences in Peak Power of the Knee Extensors in Men and Women

Authors

David J. Wrucke, Marquette University
Andrew Kuplic, Marquette University
Mitchell D. Adam, Marquette University
Sandra K. Hunter, Marquette UniversityFollow
Christopher W. Sundberg, Marquette UniversityFollow

Document Type

Article

Publication Date

2024

Publisher

American Physiological Society

Source Publication

Journal of Applied Physiology

Source ISSN

8750-7587

Original Item ID

DOI: 10.1152/japplphysiol.00773.2023

Abstract

The mechanisms for the loss in limb muscle power output in old (60–79 yr) and very old (≥80 yr) adults and whether the mechanisms differ between men and women are not well understood. We compared maximal peak power of the knee extensor muscles between young, old, and very old men and women and identified the neural and muscular factors contributing to the age-related differences in power. Thirty-one young (22.9 ± 3.0 yr, 15 women), 82 old (70.3 ± 4.9 yr, 38 women), and 16 very old adults (85.8 ± 4.2 yr, 9 women) performed maximal isokinetic contractions at 14 different velocities (30–450°/s) to identify peak power. Voluntary activation (VA) and contractile properties were assessed with transcranial magnetic stimulation to the motor cortex and electrical stimulation of the femoral nerve. The age-related loss in peak power was ∼6.5 W·yr⁻¹ for men (R² = 0.62, P < 0.001), which was a greater rate of decline (P = 0.002) than the ∼4.2 W·yr⁻¹ for women (R² = 0.77, P < 0.001). Contractile properties were the most closely associated variables with peak power for both sexes, such as the rate of torque development of the potentiated twitch (men: R² = 0.69, P < 0.001; women: R² = 0.57, P < 0.001). VA was weakly associated with power in women (R² = 0.13, P = 0.012) but not in men (P = 0.191). Similarly, neuromuscular activation [rates of electromyography (EMG) rise] during the maximal power contraction was associated with power in women (R² = 0.07, P = 0.042) but not in men (P = 0.456). These data suggest that the age-related differences in maximal peak power of the knee extensor muscles are due primarily to factors within the muscle for both sexes, although neural factors may play a minor role in older women.

Comments

Journal of Applied Physiology, Vol. 137, No. 4 (2024): 1021-1040. DOI.

Recommended Citation

Wrucke, David J.; Kuplic, Andrew; Adam, Mitchell D.; Hunter, Sandra K.; and Sundberg, Christopher W., "Neural and Muscular Contributions to the Age-Related Differences in Peak Power of the Knee Extensors in Men and Women" (2024). Physical Therapy Faculty Research and Publications. 248.
https://epublications.marquette.edu/phys_therapy_fac/248