=The one great hygienic effect of muscular exercise= is an _active circulation_, and from an active circulation _nine chief effects_ may be traced. The effects upon the body will be given in order, beginning with the surface--skin, fat, muscles, bones; and the effects upon the internal organs are given in order of position, beginning with the highest--brain, lungs, heart, digestive organs. =Effects of Exercise and Improved Circulation.=--1. _The skin_ is made fresh, pink, and smooth from the flushing of the capillaries; it is purified by the perspiration and the renewal of cells. 2. If _the fat_ is too great in amount, it is burned up; if it is too small in amount, the better nourishment brought by the blood increases it. 3. _The muscles_ are better fed (see Fig. 48) and grow firm, strong, and large. 4. _The skeleton_ is held in proper position by the stronger muscles, and deformity is prevented. 5. _The brain._ The pure, fresh blood, loaded with oxygen from expanded lungs, flushes every capillary of the brain, clears the mind, and doubles or trebles its power to work. 6. _The lungs_ are expanded by deep breathing if the exercise be rapid and vigorous. A slow stroll or saunter is not of value. 7. _The circulation._ Every contracting muscle aids the heart in its work. The deep breathing moves stagnant lymph. 8. _The stomach._ Exercise burns up the food and increases the appetite. 9. _General effects._ Exercise promotes good humor, decreases loafing, cigarette smoking, gossiping, and other vices. =The effect of tobacco on the heart=, if cigarettes or cigars are used, is sometimes to cause attacks of irregular beating; the heart flutters faintly for a while, then palpitates strongly, then flutters again. This condition is called _tobacco heart_, or _trotting heart_. =Effect of Alcohol upon the Circulation.=--After a person has taken an alcoholic drink his face and skin are likely to become flushed, and perhaps his heart beats faster. Most investigators have found that the _alcohol itself does not directly increase or strengthen the action of the heart_. Hence it is probably wrong to call alcohol a heart stimulant. The flushing of the skin is believed to be due to the relaxing effect of alcohol. It relaxes, it paralyzes, the vasomotor nerves which control the little muscle fibers in the walls of the blood vessels. The relaxing and enlarging of the blood vessels decreases the resistance to the blood flow, and the heart beats faster under its lighter load. The narcotic effect of alcohol is much more powerful than its irritating or stimulating effect. The effect of alcohol in causing fatty degeneration of the muscles often weakens the heart and other blood vessels.