TY - JOUR

T1 - Intramuscular connective tissue content and mechanical properties: Influence of aging and physical activity in mice

AU - Olesen, Annesofie Thorup

AU - Malchow-møller, Lasse

AU - Bendixen, Rune D.

AU - Kjær, Michael

AU - Mackey, Abigail L.

AU - Magnusson, S. Peter

AU - Svensson, Rene B.

PY - 2022/7/1

Y1 - 2022/7/1

N2 - Aging is accompanied by morphological and mechanical changes to the intramuscular connective tissue (IMCT) of skeletal muscles, but whether physical exercise can influence these changes is debated. We investigated the effects of aging and exercise with high or low resistance on composition and mechanical properties of the IMCT, including direct measurements on isolated IMCT which has rarely been reported.Middle-aged (11 months, n = 24) and old (22 months, n = 18) C57BL/6 mice completed either high (HR) or low (LR) resistance voluntary wheel running or were sedentary (SED) for 10 weeks. Passive mechanical properties of the intact soleus and plantaris muscles and the isolated IMCT of the plantaris muscle were measured in vitro. IMCT thickness was measured on picrosirius red stained cross sections of the gastrocnemius and soleus muscle and for the gastrocnemius hydroxyproline content was quantified biochemically and advanced glycation end-products (AGEs) estimated by fluorometry.Mechanical stiffness, IMCT content and total AGEs were all elevated with aging in agreement with previous findings but were largely unaffected by training.Conclusion: IMCT accumulated with aging with a proportional increase in mechanical stiffness, but even the relatively high exercise volume achieved with voluntary wheel-running with or without resistance did not significantly influence these changes.

AB - Aging is accompanied by morphological and mechanical changes to the intramuscular connective tissue (IMCT) of skeletal muscles, but whether physical exercise can influence these changes is debated. We investigated the effects of aging and exercise with high or low resistance on composition and mechanical properties of the IMCT, including direct measurements on isolated IMCT which has rarely been reported.Middle-aged (11 months, n = 24) and old (22 months, n = 18) C57BL/6 mice completed either high (HR) or low (LR) resistance voluntary wheel running or were sedentary (SED) for 10 weeks. Passive mechanical properties of the intact soleus and plantaris muscles and the isolated IMCT of the plantaris muscle were measured in vitro. IMCT thickness was measured on picrosirius red stained cross sections of the gastrocnemius and soleus muscle and for the gastrocnemius hydroxyproline content was quantified biochemically and advanced glycation end-products (AGEs) estimated by fluorometry.Mechanical stiffness, IMCT content and total AGEs were all elevated with aging in agreement with previous findings but were largely unaffected by training.Conclusion: IMCT accumulated with aging with a proportional increase in mechanical stiffness, but even the relatively high exercise volume achieved with voluntary wheel-running with or without resistance did not significantly influence these changes.

U2 - 10.1016/j.exger.2022.111893

DO - 10.1016/j.exger.2022.111893

M3 - Journal article

C2 - 35870752

SP - 111893

JO - Experimental Gerontology

JF - Experimental Gerontology

SN - 0531-5565

ER -