Adaptive stretch-shortening contractions: diminished regenerative capacity with aging

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Abstract:

This study determined the age-related changes in acute events responsible for initiating skeletal muscle remodeling and (or) regeneration in the tibialis anterior muscle following a bout of stretch-shortening contractions (SSCs). Changes in muscle performance and morphology were quantified in young and old rats, following an acute exposure to adaptive SSCs at 6, 24, 48, 72, and 120 h postexposure (n = 6 for each age at each recovery period). Following SSC exposure, all performance measures were decreased in old rats throughout the 120 h acute phase. Estimates of edema were increased in the old vs. young exposed muscle at 120 h recovery. Both young and old rats displayed an increase in developmental myosin heavy chain (MHCdev +) labeling in the exposed muscle, indicating muscle regeneration. However, old rats displayed diminished MHCdev + labeling, compared with young rats, suggesting limited remodeling and (or) regenerative capacity. Based on these data, diminished local muscle remodeling and (or) regeneration with aging may limit skeletal muscle adaptation following mechanical loading.

Cette étude se propose de déterminer les événements immédiats qui sont associés au vieillissement et qui déclenchent le remodelage et (ou) régénération du muscle jambier antérieur après une série d’actions d’étirement-contraction (SSCs). On évalue chez des rats jeunes et âgés les variations de performance musculaire et les modifications morphologiques observées 6, h, 24 h, 48 h, 72 h et 120 h après les brèves expositions aux SSCs à caractère adaptatif (n = 6 par groupe d’âge et par période de récupération). Après l’exposition au SSCs, on observe durant les 120 h d’adaptation une baisse de performance chez les rats âgés. D’après des estimations, le degré de l’œdème observé 120 h après l’exposition aux SSCs est plus prononcé chez les rats âgés que chez les jeunes rats. On observe tant chez les jeunes rats que chez les plus âgés une augmentation du marquage de la chaîne lourde de myosine en croissance (MHCdev +), signe de régénération musculaire. Cependant, on observe moins de marquage de la MHCdev + chez les rats âgés comparativement aux jeunes rats, ce qui suggère une diminution de la capacité de remodelage et (ou) régénération chez ces premiers. D’après ces observations, la diminution de la capacité de remodelage et (ou) régénération observée avec le vieillissement semble limiter l’adaptation du muscle au chargement mécanique.

Document Type: Research Article

Publication date: December 1, 2008

More about this publication?
  • This bimonthly journal has a 30-year history of publishing, first as the Canadian Journal of Sport Sciences, and later as the Canadian Journal of Applied Physiology. It publishes original research articles, reviews, and commentaries, focussing on the application of physiology, nutrition, and metabolism to the study of human health, physical activity, and fitness. The published research, reviews, and symposia will be of interest to exercise physiologists, physical fitness and exercise rehabilitation specialists, public health and health care professionals, as well as basic and applied physiologists, nutritionists, and biochemists.
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