Does aerobic exercise training significantly strengthen the muscles involved in the activity (e.g., does running significantly strengthen the leg muscles)?
A regular program of aerobic exercise can produce a number of health benefits, including an increase in aerobic capacity, reduced body weight and fat stores, an improved blood lipid-lipoprotein profile, and lowered arterial blood pressure. For healthy, active adults, however, significant strength gains are not among the benefits of aerobic training. The leg muscles of elite distance runners, for example, have not been found to be significantly stronger than those of healthy, relatively inactive individuals of similar age and gender.
