Exercise Promotes Healthy Aging of Skeletal Muscle

Abstract

Primary aging is the progressive and inevitable process of bodily deterioration during adulthood. In skeletal muscle, primary aging causes defective mitochondrial energetics and reduced muscle mass. Secondary aging refers to additional deleterious structural and functional age-related changes caused by diseases and lifestyle factors. Secondary aging can exacerbate deficits in mitochondrial function and muscle mass, concomitant with the development of skeletal muscle insulin resistance. Exercise opposes deleterious effects of secondary aging by preventing the decline in mitochondrial respiration, mitigating aging-related loss of muscle mass and enhancing insulin sensitivity. This review focuses on mechanisms by which exercise promotes "healthy aging" by inducing modifications in skeletal muscle.

Copyright © 2016 Elsevier Inc. All rights reserved.

Figures

Figure 1. Exercise Is a Potent Countermeasure against Secondary Aging

Endurance exercise enhances muscle insulin sensitivity in older individuals and prevents declines in mitochondrial respiratory capacity with aging. Resistance exercise induces remarkable gains in strength and power in older adults.

Figure 2. Age-Related Changes in Body Composition and Insulin Sensitivity in Older Individuals Are Influenced by Physical Activity and Exercise Training

Advancing age is typically characterized by altered body composition (increased abdominal and ectopic fat accumulation and attenuated mass and metabolic quality of skeletal muscle) together with reduced physical activity, leading to insulin resistance in skeletal muscle. These age-related changes can be exacerbated by lifestyle behaviors that produce a major imbalance between energy expenditure and energy intake, leading to further dysregulation of glucose metabolism and increasing the likelihood of type 2 diabetes.

Figure 3. Conceptual Model of Aging Muscle Atrophy and the Impact of Progressive Resistance Exercise Training