Effects of muscle length and age on neuromuscular responses to maximal eccentric contractions of the plantar flexors
Abstract
INTRODUCTION: Eccentric contractions induce greater neuromuscular impairment and muscle damage than concentric contractions. Muscle length is a key modulator of these responses, yet the combined effects of eccentric contractions and muscle length on neuromuscular function in older adults remain unclear. We investigated acute and delayed neuromuscular responses to eccentric plantar flexor contractions performed at different muscle lengths in young and older adults. METHODS: Twenty-four young and 26 older adults performed 10 sets of 10 maximal eccentric plantar flexor contractions at either short (30°-0° plantar flexion) or long (0°-30° dorsiflexion) muscle lengths (12 young and 13 older adults per condition). Maximal voluntary isometric contraction, voluntary activation, and evoked responses (100 Hz and 10 Hz doublets) were measured before, immediately after, and 1, 24, and 48 h post-exercise. Changes were compared between groups and conditions. RESULTS: Despite similar torque-time integrals between young and older adults within the same muscle length condition, a muscle length effect was only found in young adults, with a greater (p = 0.021) MVIC decrease at long (-33.6 ± 13.2%) than short lengths (-8.4 ± 15.7%). Older adults showed similar reductions across conditions (≈ - 14-21%). Voluntary activation decreased only at long lengths, with no age difference. Evoked responses showed an age effect (p = 0.032), and the 10/100 Hz ratio decreased only in young after long muscle lengths. Neuromuscular function returned to baseline within 24 h indicating no evidence of severe alteration, although muscle soreness remained elevated at 48 h. CONCLUSION: Long muscle length eccentric contractions induced greater force loss in young but not older adults, with no evidence of prolonged functional impairment in healthy, physically active older adults.
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BibTeX
@article{betus2026effects,
title = {{Effects of muscle length and age on neuromuscular responses to maximal eccentric contractions of the plantar flexors}},
author = {Yohan Betus and Thomas Cattagni and Alexandra Perrin and Julian Colard and Kazunori Nosaka and Anne Sophie Boureau and Guillaume Chapelet and Christophe Cornu and Marc Jubeau},
journal = {Experimental Gerontology},
year = {2026},
month = oct,
doi = {10.1016/j.exger.2026.113359},
url = {https://hal.science/hal-05836983v1},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Effects of muscle length and age on neuromuscular responses to maximal eccentric contractions of the plantar flexors
AU - Yohan Betus
AU - Thomas Cattagni
AU - Alexandra Perrin
AU - Julian Colard
AU - Kazunori Nosaka
AU - Anne Sophie Boureau
AU - Guillaume Chapelet
AU - Christophe Cornu
AU - Marc Jubeau
PY - 2026
DA - 2026/10/23
JO - Experimental Gerontology
DO - 10.1016/j.exger.2026.113359
UR - https://hal.science/hal-05836983v1
AB - INTRODUCTION: Eccentric contractions induce greater neuromuscular impairment and muscle damage than concentric contractions. Muscle length is a key modulator of these responses, yet the combined effects of eccentric contractions and muscle length on neuromuscular function in older adults remain unclear. We investigated acute and delayed neuromuscular responses to eccentric plantar flexor contractions performed at different muscle lengths in young and older adults. METHODS: Twenty-four young and 26 older adults performed 10 sets of 10 maximal eccentric plantar flexor contractions at either short (30°-0° plantar flexion) or long (0°-30° dorsiflexion) muscle lengths (12 young and 13 older adults per condition). Maximal voluntary isometric contraction, voluntary activation, and evoked responses (100 Hz and 10 Hz doublets) were measured before, immediately after, and 1, 24, and 48 h post-exercise. Changes were compared between groups and conditions. RESULTS: Despite similar torque-time integrals between young and older adults within the same muscle length condition, a muscle length effect was only found in young adults, with a greater (p = 0.021) MVIC decrease at long (-33.6 ± 13.2%) than short lengths (-8.4 ± 15.7%). Older adults showed similar reductions across conditions (≈ - 14-21%). Voluntary activation decreased only at long lengths, with no age difference. Evoked responses showed an age effect (p = 0.032), and the 10/100 Hz ratio decreased only in young after long muscle lengths. Neuromuscular function returned to baseline within 24 h indicating no evidence of severe alteration, although muscle soreness remained elevated at 48 h. CONCLUSION: Long muscle length eccentric contractions induced greater force loss in young but not older adults, with no evidence of prolonged functional impairment in healthy, physically active older adults.
SN - 0531-5565
SN - 1873-6815
ER -