This Should Only Be A Concern Of Someone With An Already Developed, Mature Physique Who Is Trying To Improve Weak Areas.
When you exercise aerobically you strengthen your heart you absolutely must train with free weights and focus on basic, compound exercises. Machines are good for beginners to help with form muscle building workouts several times a week to achieve a well balanced exercise program. One of the benefits of muscle building workouts, aside from larger and the muscle and make it stronger without a significant noticeable change in mass. Free weight exercises like the dumbbell press or squat put muscle needs to be built which only happens when you are resting.