During life the muscles are always in a state of tension; that is, every muscle is more or less active even when it seems to be at rest. This tension is increased by cold to the point of producing visible movements of shivering. It is also increased by pain or inflammation, as is seen in the rigid contraction of the abdominal muscles in appendicitis. Tension may also be increased by a simple effort of the will. The mere thinking of a bodily movement, in fact, increases the tension of the muscles which are concerned in the movement, and to such a degree that long-coritinued fatigue may result, showing that work has been done, as when one watches the performance of acrobats, or a closely contested athletic game. This fact may be made of practical value. Thus if one's feet are cold, they may be quickly warmed by alternately tensing and relaxing the muscles of the legs, or by making slow, tense, flexion and extension movements of the feet.
In like manner all the muscles of the legs may be brought into active play by simply setting or tensing the muscles of the legs that is, holding the limbs rigid with as much force as possible. The muscles of the trunk and arms may be tensed in like manner. All the muscles may be tensed at once, or different sections as arm muscles, trunk muscles, or the muscles of a single limb may be exercised in succession. Tension exercises may be taken in may cases without the slightest interference with one's work; and when the work is very sedentary one may by this means, without loss of time, secure a large part of the benefit of such active exercises as walking, tennis, playing, etc. Such exercises should not be considered as a substitute, however, for out-of-door exercise, but rather as a supplement to such exercise.
One very excellent form of exercise which may be taken while sitting at desk at work or when reading or studying is rapid raising or lowering of heels, either together or in alternation. The heels are raised so that the weight of the limbs rests on the toes, and the limbs are then set in rapid motion. Bracing the feet together, a similar movement may be executed with the knees rapidly separating and closing. The movement is so rapid that the exercise closely resembles shivering.
One excellent use for movements of this kind is to prevent taking cold when one is exposed to a draft. If, for example, one feels a draft of cold air on the back of the neck, he may prevent ill effects by simply tensing muscles of the neck, or indeed, by holding the muscles rigid while making slow movements of the head, either forward and backward or side-wise. In out-of-door sleeping, exercises of this sort may be resorted to as a means of warming the feet and limbs. These warming exercises are important for persons suffering from constipation, because of the tendency that such persons have to coldness of the extremities, the result of spasm of the blood vessels, due to the influence of intestinal poisons upon the vasomotor centers.
The general aim of all the exercises given in this book is to aid defecation by strengthening the muscles of the trunk and abdomen, and forming the breathing movements. There are special exercises which may be employed during defecation which render effective aid in evacuation of the bowels.
The natives of India, as mentioned elsewhere, aid evacuation when the bowels are constipated by pressing a ball formed by a folded cloth upon the lower left side of the abdomen. Many constipated persons have found by experience the advantage of pressing upon this part of the abdomen with one or both closed fists, during defecation.
Persons who have very relaxed abdominal walls often find it very advantageous to compress and knead the abdomen during defecation, especially upon the left side. A medicine ball may be used for the purpose. The ball is held firmly against the abdomen, the under side resting on the separated thighs. By bringing the thighs together at the same time pressing with the hands, the ball is forced against the abdomen. The abdomen may in this way be compressed with considerable force. The closed fist may be used in place of the ball.
When possible exercise should always be taken in a rhythmical way. This effect may be secured by means of counting, or better still by the aid of music, for which a phonograph, victrola or a graph-aphone serves an excellent purpose.
The following is an excellent program of exercises for a person of average strength:
1. On rising, take an exercise bath (see page 242), beginning with the water at a temperature of 90 degrees and ending at 70 degrees to 60 degrees or pipe temperature. Row 100 to 200 strokes counting.
2. Inclined plane breathing and replacement exercises. (See page 281.)
3. Inclined plane exercise to strengthen abdominal muscles. (See page 282.)
4. Special exercise to aid defecation. (See page 289.)
After exercise make an attempt to move the bowels if a movement has not already been secured.