Gamage Nishadi N, Altheyab Abdulmajeed, Guo Yuxiao, Phillips Bethan E, Opie George M, Semmler John G, Atherton Philip, Piasecki Mathew
Centre of Metabolism, Ageing & Physiology (COMAP), Academic Unit of Injury, Recovery & Inflammation Sciences, School of Medicine, Faculty of Medicine and Health Sciences, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, University of Nottingham, Royal Derby Hospital Centre, Derby, DE22 3DT, United Kingdom.
Neurophysiology of Human Movement Laboratory, Discipline of Physiology, School of Biomedicine, University of Adelaide, Adelaide, Australia.
Geroscience. 2025 May 8. doi: 10.1007/s11357-025-01693-8.
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.
抗阻运动（RE）可增强老年人的身体功能，并且已被证明在单侧肢体废用的情况下作为交叉训练手段是有效的。然而，单次单侧抗阻运动后老年人在运动单位（MU）水平上跨肢体转移的程度尚不清楚。13名健康老年人（74.9±4.8岁；5名女性）在单次单侧抗阻运动前后接受了双侧神经肌肉评估，该运动包括以1次最大重复量的75%进行优势（运动）腿的腿部伸展，每组12次重复，直至力竭。测量了最大自主收缩（MVC）和力量稳定性（FS）。在收缩过程中，当收缩强度归一化为25%MVC时，使用高密度表面肌电图和肌内肌电图（HDs/iEMG）记录单个运动单位的中枢和外周特征。单侧抗阻运动后，运动腿（-14.8%，p<0.001）和对照腿（-6.9%，p=0.003）的MVC均降低，与对照腿相比，运动腿的FS表现降低（p=0.002）。在运动腿中，当收缩强度归一化为25%基线MVC时，运动单位放电频率增加（p<0.05），而对照腿无适应性变化（p>0.05）。两侧所有肌内肌电图记录的运动单位电位测量值均保持不变（所有p>0.05）。急性单侧抗阻运动导致老年男性和女性双侧MVC降低，表明存在跨肢体转移效应。然而，运动单位特征的适应性仅在运动肢体中明显，非运动肢体力量下降的潜在机制仍不确定。
