Aside from the arrangement of a suitable diet, the most important task in reduction cures is insistence upon a sufficient amount of muscular exercise. We possess no better, more certain, or more readily controlled means of increasing the output of energy and chiefly the consumption of fat than exercise. In certain cases this element is the most important part of the treatment, namely, in the category that must be included under the group of "Obesity from Inactivity" (see Vol. VIII). One must always remember, however, that it is rarely possible to accomplish the desired purpose in such cases without at the same time regulating the diet; for if the patients are left to their own initiative in regard to the amount of physical exercise they are to perform, the increased appetite and thirst engendered by muscular labor frequently exceed the rise in the oxydative processes produced by the latter. Under such conditions a very desirable strengthening of the musculature is obtained, but at the same time the fat layers of the body also become increased.

In each individual case of obesity the degree of physical exercise and the particular kind of exercise that the patient should perform must be determined. Individuals with a strongly developed muscular system must be ordered to perform much more strenuous physical labor than fat individuals with a weak musculature. In cases of the latter kind, that predominate, of course, in women, but that are not uncommon in men, it is often necessary to begin very moderately, otherwise the fatigue becomes too severe and persists for too long a time, so that the patients become exhausted and lose in energy. Still greater care must, of course, be exercised if the heart is involved. In the latter case it is often necessary to limit physical labor to breathing exercises, for the latter strengthen the heart much more directly than any other form of muscular exertion. It need hardly be emphasized that the most careful daily control on the part of the physician is essential under these conditions.

Whatever the initial amount of physical labor may be, one should always remember that this is an educational process, and one should be quite sure that a given amount of physical exertion can be tolerated without detriment to the patient before proceeding to more strenuous exercises; otherwise the heart may become injured and this injury is apt to remain quite permanent in obese individuals, for here the heart disposes of a smaller amount of reserve force than in a perfectly healthy individual. If all these precautions are carefully observed, muscular exercise will be found to be an exceedingly effective means for reducing flesh. At the same time the danger is obviated of leaving the patient in a weakened condition after the reduction cure is terminated. I have already mentioned in a previous section that there is no more efficient means to produce the optimum of muscular development in an adult than physical exercise (see Vol. VIII). Not only is the retention of nitrogen and albumen favored hereby, but the muscle fibres themselves are increased. An obese individual that attempts to reduce weight merely by undernutrition always incurs the danger of sacrificing body albumen and of reducing the strength of the whole body. If undernutrition, however, is combined with muscular labor the strength of the whole body is rather increased than decreased.

There are many fallacies current relative to the effect of different forms of muscular exercise. The ideal form and, at the same time, the form that can be best regulated is mountain climbing. I have already previously shown how one can calculate that an individual weighing 100 kg. rising to an elevation of 1000 m. consumes at least 706 calories (see Vol. VIII). Unfortunately, mountain climbing cannot be carried out everywhere, partially for lack of time and partially on account of geographical conditions. In watering places, that are usually situated in a hilly or mountainous country, mountain climbing, however, constitutes one of the most important factors in the treatment. Walking on the level is only a poor substitute. The amount of energy consumed by this form of walking stands in no proper proportion to the amount of time consumed and to the amount of fatigue that is engendered. A much better means are sports, and among these rowing, tennis playing, gymnasium work, swimming occupy first place. Under certain conditions medical gymnastics must be utilized, but the significance of this form of exercise should not be overestimated. For the amount of active calorie-consuming labor that is performed during one hour daily with Zander's, or Herz's apparatus is not very great. Nevertheless, exercise at home may be utilized to supplement other forms of physical labor. I prefer the exercise that Müller describes in his book "My System" to all other methods.

Massage exercises no appreciable influence upon the fat metabolism of the individual who is being massaged, but a considerable influence upon the metabolism of the masseur. Neither can horseback riding be considered an efficient means for reducing flesh. The passive vibration incident to horseback riding produces only a very mild increase of metabolism in the musculature. The effect of horseback riding upon the bowel action may, of course, be very considerable, and is always welcome, but this advantage is neutralized by the danger of an increased appetite and resulting greater intake of food.