Eight weeks of eccentric training at long-muscle length increases fascicle length independently of adaptations in passive mechanical properties.

IF 3.3 3区 医学 Q1 PHYSIOLOGY
Journal of applied physiology Pub Date : 2025-04-01 Epub Date: 2025-03-06 DOI:10.1152/japplphysiol.00859.2024
Baptiste Bizet, Antoine Nordez, Tristan Tallio, Lilian Lacourpaille, Thomas Cattagni, Julian Colard, Yohan Betus, Sylvain Dorel, Aurélie Sarcher, Olivier Seynnes, Ricardo J Andrade
{"title":"Eight weeks of eccentric training at long-muscle length increases fascicle length independently of adaptations in passive mechanical properties.","authors":"Baptiste Bizet, Antoine Nordez, Tristan Tallio, Lilian Lacourpaille, Thomas Cattagni, Julian Colard, Yohan Betus, Sylvain Dorel, Aurélie Sarcher, Olivier Seynnes, Ricardo J Andrade","doi":"10.1152/japplphysiol.00859.2024","DOIUrl":null,"url":null,"abstract":"<p><p>Eccentric exercise training is believed to induce an increase in muscle fascicle length. However, the mechanisms underlying this adaptation are not fully understood. This study aimed to determine if an increase in gastrocnemius medialis fascicle length following an 8-wk eccentric training is linked to changes in muscle tissue and joint mechanical properties. Thirty-three physically active young adults were assigned to one of the two training protocols targeting the plantar flexors: eccentric exercise at <i>1</i>) long-muscle length or <i>2</i>) short-muscle length. Fascicle length and muscle shear modulus of the gastrocnemius medialis were assessed using ultrasound imaging during passive ankle rotations, alongside measurements of passive ankle torque. A total of 27 participants successfully completed the training program and data processing stage (long-muscle length, <i>n</i> = 15; short-muscle length, <i>n</i> = 12). Maximal voluntary isometric torque increased significantly following the training programs (9.5%), with no differences between training groups. An increase in fascicle length (mean 8.5%) was observed in the long-muscle length group, from 39.5 ± 0.7° to 36.8 ± 0.8° in plantar flexion, but not in the short-muscle length group. Notably, this macrostructural adaptation was detected only at muscle lengths shorter than the slack length (i.e., absence of any muscle passive tension). The eccentric training did not alter the muscle shear modulus or slack length. Collectively, these findings suggest that fascicle length adaptations in response to eccentric training were unrelated to changes in passive muscle-tendon mechanical properties. Consequently, the increase in fascicle length may be attributed to an increase in sarcomere length and/or an addition of sarcomeres in series.<b>NEW & NOTEWORTHY</b> We demonstrate that an 8-wk eccentric training program significantly increases gastrocnemius medialis fascicle length in humans, independent of any adaptions in passive muscle-tendon mechanical properties. Fascicle length adaptions were specific to the group that trained at long-muscle lengths, highlighting the importance of the muscle-tendon length range during eccentric exercise programs. This factor may be crucial for fine-tuning structural adaptations at the fascicle level, likely through the addition of sarcomeres in series.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"939-949"},"PeriodicalIF":3.3000,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of applied physiology","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1152/japplphysiol.00859.2024","RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2025/3/6 0:00:00","PubModel":"Epub","JCR":"Q1","JCRName":"PHYSIOLOGY","Score":null,"Total":0}
引用次数: 0

Abstract

Eccentric exercise training is believed to induce an increase in muscle fascicle length. However, the mechanisms underlying this adaptation are not fully understood. This study aimed to determine if an increase in gastrocnemius medialis fascicle length following an 8-wk eccentric training is linked to changes in muscle tissue and joint mechanical properties. Thirty-three physically active young adults were assigned to one of the two training protocols targeting the plantar flexors: eccentric exercise at 1) long-muscle length or 2) short-muscle length. Fascicle length and muscle shear modulus of the gastrocnemius medialis were assessed using ultrasound imaging during passive ankle rotations, alongside measurements of passive ankle torque. A total of 27 participants successfully completed the training program and data processing stage (long-muscle length, n = 15; short-muscle length, n = 12). Maximal voluntary isometric torque increased significantly following the training programs (9.5%), with no differences between training groups. An increase in fascicle length (mean 8.5%) was observed in the long-muscle length group, from 39.5 ± 0.7° to 36.8 ± 0.8° in plantar flexion, but not in the short-muscle length group. Notably, this macrostructural adaptation was detected only at muscle lengths shorter than the slack length (i.e., absence of any muscle passive tension). The eccentric training did not alter the muscle shear modulus or slack length. Collectively, these findings suggest that fascicle length adaptations in response to eccentric training were unrelated to changes in passive muscle-tendon mechanical properties. Consequently, the increase in fascicle length may be attributed to an increase in sarcomere length and/or an addition of sarcomeres in series.NEW & NOTEWORTHY We demonstrate that an 8-wk eccentric training program significantly increases gastrocnemius medialis fascicle length in humans, independent of any adaptions in passive muscle-tendon mechanical properties. Fascicle length adaptions were specific to the group that trained at long-muscle lengths, highlighting the importance of the muscle-tendon length range during eccentric exercise programs. This factor may be crucial for fine-tuning structural adaptations at the fascicle level, likely through the addition of sarcomeres in series.

偏心运动训练被认为会导致肌肉筋膜长度增加。然而,这种适应性的机制尚未完全明了。本研究旨在确定为期 8 周的偏心训练后腓肠肌内侧筋膜长度的增加是否与肌肉组织和关节机械性能的变化有关。33 名身体活跃的年轻人被分配到两种针对跖屈肌的训练方案中的一种:1)长肌肉长度或 2)短肌肉长度的偏心运动。在踝关节被动旋转时,使用超声波成像评估腓肠肌内侧的筋膜长度和肌肉剪切模量,同时测量踝关节被动扭矩。共有 27 名参与者成功完成了训练计划和数据处理阶段(长肌肉长度,n=15;短肌肉长度,n=12)。训练计划实施后,最大自主等长扭力显著增加(9.5%),各训练组之间无差异。在长肌肉长度组中观察到筋膜长度增加(平均 8.5%),跖屈从 39.5±0.7° 增加到 36.8±0.8°;但在短肌肉长度组中没有观察到。值得注意的是,只有在肌肉长度短于松弛长度(即没有任何肌肉被动张力)时,才能检测到这种宏观结构适应。偏心训练没有改变肌肉剪切模量或松弛长度。这些发现共同表明,偏心训练导致的筋膜长度适应与肌肉-肌腱被动机械特性的变化无关。因此,筋膜长度的增加可能是由于肌节长度的增加和/或增加了串联的肌节。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
求助全文
约1分钟内获得全文 求助全文
来源期刊
CiteScore
6.00
自引率
9.10%
发文量
296
审稿时长
2-4 weeks
期刊介绍: The Journal of Applied Physiology publishes the highest quality original research and reviews that examine novel adaptive and integrative physiological mechanisms in humans and animals that advance the field. The journal encourages the submission of manuscripts that examine the acute and adaptive responses of various organs, tissues, cells and/or molecular pathways to environmental, physiological and/or pathophysiological stressors. As an applied physiology journal, topics of interest are not limited to a particular organ system. The journal, therefore, considers a wide array of integrative and translational research topics examining the mechanisms involved in disease processes and mitigation strategies, as well as the promotion of health and well-being throughout the lifespan. Priority is given to manuscripts that provide mechanistic insight deemed to exert an impact on the field.
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信