The burden of labor is thrown upon the liver, lungs, kidneys, etc., and these internal organs are compelled to do the work of the skin. The blood is not enabled to expel the impurities as it would if active circulation were induced by exercise. In some cases, want of exercise causes the muscles of the bowels to become enfeebled and shrunken, and these organs that have become enfeebled for want of use will be strengthened by exercise. Moderate exercise every day will impart strength to the muscles, which without exercise become flabby and enfeebled. Bind up the arm, and permit it to remain useless, even for a few weeks, then free it from its bondage, and you will discover that it is weaker than the one you had been using moderately during the same time.
Inactivity produces the same effect upon the whole muscular system.