Which other factors affect muscle size and strength?

How much muscle and strength an individual gains in response to a resistance exercise program is influenced by a myriad of factors, including their age, genetics,^[1][2][3] lifestyle (i.e., sleep, nutrition, and stress management), and training history. For instance, the magnitude of muscle gain tends to decrease with age^[4][5][6] and training experience.^[7][8]

Generally speaking, the majority of a person’s strength can be attributed to their muscle mass, ^{[9][10][11][12][13]} which is supported by the mechanistic rationale that a larger muscle has greater force-generating capacity.^[14] Put simply, in most cases, the best way to improve one’s strength is to increase one’s muscle mass. Neural factors (e.g., the threshold at which motor units are recruited and the motor unit discharge rate^[15]) also contribute to muscle strength, and the muscle strength one can deploy in a given exercise can be increased simply by practicing that exercise.^[16][17]