Muscle mutability. Part 2. Adaptation to drugs, metabolic factors, and aging.
Muscle fibers undergo changes in response to a variety of stimuli. This review examines metabolic, endocrine, and pharmacological factors that lead to alterations in muscle structure and function. These various stimuli may be considered nonphysical. This review also examines the interaction between physical stimuli (eg, exercise) and hormonal influences (eg, diabetes) on muscle. It is suggested that physical stimuli may often have a more potent effect on muscle than do nonphysical stimuli.