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<p>Resistance exercise (RE) enhances functionality in older adults and has proven effective as a means of cross-education in scenarios of unilateral disuse. However, the extent to which older adults demonstrate cross-limb transfer at the motor unit (MU) level following a single bout of unilateral RE is unclear. Thirteen healthy older adults (74.9 ± 4.8&#xa0;years; 5 females) underwent bilateral neuromuscular assessments pre- and post- a single bout of unilateral RE consisting of sets of 12 repetitions of leg extension of the dominant (exercise) leg, at 75% of 1 repetition maximum, performed to failure. Maximum voluntary contraction (MVC) and force steadiness (FS) were measured. Central and peripheral features of individual MU were recorded using high-density surface electromyography and intramuscular electromyography (HDs/iEMG), during contractions normalised to 25% MVC. Following unilateral RE, MVC reduced in exercise (-14.8%, <i>p</i> &lt; 0.001) and control (-6.9%, <i>p</i> = 0.003) legs, with reduced FS performance in the exercise leg compared to the control <i>(p</i> = 0.002). MU firing rate increased during contractions normalised to 25% baseline MVC in the exercised leg (<i>p</i> &lt; 0.05), with no adaptation in the control leg (<i>p</i> &gt; 0.05). All iEMG recorded measures of MU potentials remained unchanged in both legs (all <i>p</i> &gt; 0.05). Acute unilateral RE leads to bilateral MVC reduction in older males and females, demonstrating the cross-limb transfer effect. However, adaptation of MU features was only apparent in the exercised limb, and mechanisms underlying the force decline in the non-exercised limb remain uncertain.</p>

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Bilateral neuromuscular adaptation to acute unilateral resistance exercise in healthy older adults

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年5月8日

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  • Nishadi N. Gamage,
  • Abdulmajeed Altheyab,
  • Yuxiao Guo,
  • Bethan E. Phillips,
  • George M. Opie,
  • John G. Semmler,
  • Philip Atherton,
  • Mathew Piasecki

摘要

Resistance exercise (RE) enhances functionality in older adults and has proven effective as a means of cross-education in scenarios of unilateral disuse. However, the extent to which older adults demonstrate cross-limb transfer at the motor unit (MU) level following a single bout of unilateral RE is unclear. Thirteen healthy older adults (74.9 ± 4.8 years; 5 females) underwent bilateral neuromuscular assessments pre- and post- a single bout of unilateral RE consisting of sets of 12 repetitions of leg extension of the dominant (exercise) leg, at 75% of 1 repetition maximum, performed to failure. Maximum voluntary contraction (MVC) and force steadiness (FS) were measured. Central and peripheral features of individual MU were recorded using high-density surface electromyography and intramuscular electromyography (HDs/iEMG), during contractions normalised to 25% MVC. Following unilateral RE, MVC reduced in exercise (-14.8%, p < 0.001) and control (-6.9%, p = 0.003) legs, with reduced FS performance in the exercise leg compared to the control (p = 0.002). MU firing rate increased during contractions normalised to 25% baseline MVC in the exercised leg (p < 0.05), with no adaptation in the control leg (p > 0.05). All iEMG recorded measures of MU potentials remained unchanged in both legs (all p > 0.05). Acute unilateral RE leads to bilateral MVC reduction in older males and females, demonstrating the cross-limb transfer effect. However, adaptation of MU features was only apparent in the exercised limb, and mechanisms underlying the force decline in the non-exercised limb remain uncertain.