Exercise also helps to increase aerobic capacity. Aerobic exercises are those that use large muscle groups and that are continuous and rhythmic in nature. Examples of aerobic exercise are running, cycling, swimming, stair stepping, aerobic dance, and walking. Exercises that require heavy muscle contractions such as weight training and sprinting produce little change in VO2max. According to research, greater than normal physiologic levels of testosterone DO NOT increase muscle size.
Muscular hypertrophy occurs with the natural levels of testosterone found in the body.
There appears to be no correlation between muscular response and levels of testosterone to resistance training. Individuals with limited flexibility are more susceptible to muscle strains. Specific limitations in flexibility may contribute to particular problems. For example, lack of flexibility in the hamstrings is associated to low back pain. Any time of the day is as good as another.