Yuxiao Guo, Eleanor J. Jones, Thomas F. Smart, Abdulmajeed Altheyab, Nishadi Gamage, Daniel W. Stashuk, Jessica Piasecki, Bethan E. Phillips, Philip J. Atherton, Mathew Piasecki
{"title":"Sex disparities of human neuromuscular decline in older humans","authors":"Yuxiao Guo, Eleanor J. Jones, Thomas F. Smart, Abdulmajeed Altheyab, Nishadi Gamage, Daniel W. Stashuk, Jessica Piasecki, Bethan E. Phillips, Philip J. Atherton, Mathew Piasecki","doi":"10.1113/JP285653","DOIUrl":null,"url":null,"abstract":"<div>\n \n <section>\n \n \n <div>Females typically live longer than males but, paradoxically, spend a greater number of later years in poorer health. The neuromuscular system is a critical component of the progression to frailty, and motor unit (MU) characteristics differ by sex in healthy young individuals and may adapt to ageing in a sex-specific manner due to divergent hormonal profiles. The purpose of this study was to investigate sex differences in vastus lateralis (VL) MU structure and function in early to late elderly humans. Intramuscular electromyography signals from 50 healthy older adults (M/F: 26/24) were collected from VL during standardized submaximal contractions and decomposed to quantify MU characteristics. Muscle size and neuromuscular performance were also measured. Females had higher MU firing rate (FR) than males (<i>P</i> = 0.025), with no difference in MU structure or neuromuscular junction transmission (NMJ) instability. All MU characteristics increased from low- to mid-level contractions (<i>P</i> < 0.05) without sex × level interactions. Females had smaller cross-sectional area of VL, lower strength and poorer force steadiness (<i>P</i> < 0.05). From early to late elderly, both sexes showed decreased neuromuscular function (<i>P</i> < 0.05) without sex-specific patterns. Higher VL MUFRs at normalized contraction levels previously observed in young are also apparent in old individuals, with no sex-based difference of estimates of MU structure or NMJ transmission instability. From early to late elderly, the deterioration of neuromuscular function and MU characteristics did not differ between sexes, yet function was consistently greater in males. These parallel trajectories underscore the lower initial level for older females and may offer insights into identifying critical intervention periods.\n\n <figure>\n <div><picture>\n <source></source></picture><p></p>\n </div>\n </figure>\n </div>\n </section>\n \n <section>\n \n <h3> Key points</h3>\n \n <div>\n <ul>\n \n <li>Females generally exhibit an extended lifespan when compared to males, yet this is accompanied by a poorer healthspan and higher rates of frailty.</li>\n \n <li>In healthy young people, motor unit firing rate (MUFR) at normalized contraction intensities is widely reported to be higher in females than in age-matched males.</li>\n \n <li>Here we show in 50 people that older females have higher MUFR than older males with little difference in other MU parameters. The trajectory of decline from early to late elderly does not differ between sexes, yet function is consistently lower in females.</li>\n \n <li>These findings highlight distinguishable sex disparities in some MU characteristics and neuromuscular function, and suggest early interventions are needed for females to prevent functional deterioration to reduce the ageing health–sex paradox.</li>\n </ul>\n </div>\n </section>\n </div>","PeriodicalId":50088,"journal":{"name":"Journal of Physiology-London","volume":"603 1","pages":"151-165"},"PeriodicalIF":4.7000,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1113/JP285653","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Physiology-London","FirstCategoryId":"3","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1113/JP285653","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"NEUROSCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Females typically live longer than males but, paradoxically, spend a greater number of later years in poorer health. The neuromuscular system is a critical component of the progression to frailty, and motor unit (MU) characteristics differ by sex in healthy young individuals and may adapt to ageing in a sex-specific manner due to divergent hormonal profiles. The purpose of this study was to investigate sex differences in vastus lateralis (VL) MU structure and function in early to late elderly humans. Intramuscular electromyography signals from 50 healthy older adults (M/F: 26/24) were collected from VL during standardized submaximal contractions and decomposed to quantify MU characteristics. Muscle size and neuromuscular performance were also measured. Females had higher MU firing rate (FR) than males (P = 0.025), with no difference in MU structure or neuromuscular junction transmission (NMJ) instability. All MU characteristics increased from low- to mid-level contractions (P < 0.05) without sex × level interactions. Females had smaller cross-sectional area of VL, lower strength and poorer force steadiness (P < 0.05). From early to late elderly, both sexes showed decreased neuromuscular function (P < 0.05) without sex-specific patterns. Higher VL MUFRs at normalized contraction levels previously observed in young are also apparent in old individuals, with no sex-based difference of estimates of MU structure or NMJ transmission instability. From early to late elderly, the deterioration of neuromuscular function and MU characteristics did not differ between sexes, yet function was consistently greater in males. These parallel trajectories underscore the lower initial level for older females and may offer insights into identifying critical intervention periods.
Key points
Females generally exhibit an extended lifespan when compared to males, yet this is accompanied by a poorer healthspan and higher rates of frailty.
In healthy young people, motor unit firing rate (MUFR) at normalized contraction intensities is widely reported to be higher in females than in age-matched males.
Here we show in 50 people that older females have higher MUFR than older males with little difference in other MU parameters. The trajectory of decline from early to late elderly does not differ between sexes, yet function is consistently lower in females.
These findings highlight distinguishable sex disparities in some MU characteristics and neuromuscular function, and suggest early interventions are needed for females to prevent functional deterioration to reduce the ageing health–sex paradox.
女性的寿命通常比男性长，但矛盾的是，女性晚年的健康状况却比男性差。神经肌肉系统是走向衰弱的关键组成部分，在健康的年轻人身上，运动单位（MU）的特征因性别而异，并可能因荷尔蒙特征的不同而以性别特异性的方式适应衰老。本研究的目的是调查早期和晚期老年人肌肉外侧肌（VL）结构和功能的性别差异。研究人员收集了 50 名健康老年人（男/女：26/24）在标准亚马力收缩过程中的肌肉肌电图信号，并对信号进行分解，以量化肌肉单位的特征。同时还测量了肌肉尺寸和神经肌肉性能。女性的 MU 发火率（FR）高于男性（P = 0.025），但 MU 结构或神经肌肉接头传输（NMJ）不稳定性没有差异。从低级收缩到中级收缩，所有 MU 特性都有所增加（P = 0.025）。
期刊介绍：
The Journal of Physiology publishes full-length original Research Papers and Techniques for Physiology, which are short papers aimed at disseminating new techniques for physiological research. Articles solicited by the Editorial Board include Perspectives, Symposium Reports and Topical Reviews, which highlight areas of special physiological interest. CrossTalk articles are short editorial-style invited articles framing a debate between experts in the field on controversial topics. Letters to the Editor and Journal Club articles are also published. All categories of papers are subjected to peer reivew.
The Journal of Physiology welcomes submitted research papers in all areas of physiology. Authors should present original work that illustrates new physiological principles or mechanisms. Papers on work at the molecular level, at the level of the cell membrane, single cells, tissues or organs and on systems physiology are all acceptable. Theoretical papers and papers that use computational models to further our understanding of physiological processes will be considered if based on experimentally derived data and if the hypothesis advanced is directly amenable to experimental testing. While emphasis is on human and mammalian physiology, work on lower vertebrate or invertebrate preparations may be suitable if it furthers the understanding of the functioning of other organisms including mammals.
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号
