PASSIVE EXERCISE WON'T MAKE YOU FIT
Gabe Mirkin, M.D.
What do you think when you see an ad for a stationary bicycle with motor driven pedals? A report in the medical journal, Medicine and Science in Sports and Exercise, shows that it won't make you fit.
Exercise strengthens your heart only when you do it vigorously enough to increase your heart rate at least 20 beats a minute above resting. Men were asked to sit on a stationary bicycle with their feet on motor-driven pedals. When their feet were driven slowly, their hearts did not beat faster, but when their feet were driven at a high speed, their hearts did beat faster, but it didn't strengthen their hearts because the faster heart rate produced by the motor is due to hormones, such as adrenalin, rather than increased circulation of blood. Only the increased circulation of blood strengthens your heart.
To become fit, you must move your own muscles. Machines that move your legs or arms for you will not make you fit.