Meeting Abstract
Mammalian muscles are extremely plastic, rapidly remodeling in response to exercise, disuse, or aging. Aging is associated with decline in muscle performance, whereas exercise results in mechanical or energetic changes that enhance performance. We aim to understand how exposures to regular exercise, and the genetic propensity for exercise, counteract age-related declines in muscle performance. Although numerous studies have documented age-related changes to muscle and locomotor performance, our understanding of how genetics and exercise alter the normal pattern of muscle ageing is limited. We use mice from two genetic lines (control and selected for over 70 generations for high wheel running) that were divided into four cohorts (Control/wheel access, control/no wheel access, HWR/wheel access, HWR/no wheel access) to test effects of exercise and genotype on muscle aging. We use muscle force-velocity relationships in situ for plantarflexor muscles to compare contractile performance in our cohorts. We predict that mice with genetic propensity for endurance running will have more slow fibers with higher endurance capabilities, resulting in slow contractile speed. We also predict that maximum shortening velocity of muscle fibers across both lines will decrease with age. Finally, we predict that mice from the young control group will have higher contractile velocity than HWR mice. Results of this study will serve as an important step in understanding how endurance training and age affect muscle performance. In addition, this study may provide insight into relative contributions of genotypic selection and phenotypic plasticity as mechanisms that determine muscle variation and performance.
