A trouble often experienced is breathlessness. For this there are several causes. Sometimes the machine is started too hurriedly and before the processes of the body have had time to adjust themselves. To work easily, the muscles must be heated gradually, until they are brought to the proper point of tension. Again, the easy movement of the wheel often causes the cyclist to become oblivious of the fact that the muscles are working quickly while doing easy work, that the power applied is being converted into speed with little appreciable effort, until suddenly his breath becomes labored, and a halt must be made for rest. We need not attempt here to give the figures for power expended and work done, though both factors may be estimated.
Technically, effort is a physiological condition involving complicated chemical changes and concentration of power. The work of the lungs is done mechanically, automatically, is muscular work, involving chemical changes and giving chemical results. We breathe in air full of oxygen; we exhale air loaded with carbonic acid. Muscular effort produces carbonic acid through chemical changes in the tissues of the body. The oxygen of the air, taken into the lungs to purify the blood, is absorbed and stored. Easy muscular movements give off a limited quantity of carbonic acid and other products, but not more than can be eliminated without readjustment of processes. When a succession of efforts is made, involving the manufacture of larger quantities of carbonic acid, the eliminating capacity is correspondingly taxed.
In making an effort, the lungs become momentarily fixed, and their regular respiratory movement is suspended. Carbonic acid is held, not given off, and a feeling of suffocation is observed. Unless respiration is restored by a pause, poisoning by the waste products ensues, they being reabsorbed, and inducing discomfort and fatigue. Working with effort, the lungs should be free to expand and contract. To this end it is all-important to exhale, expelling the air from the lungs by compression of the chest after severe exertion. Air rushes naturally into the chest cavity; attention, therefore, should be directed, not to getting in air, but to expelling the air already in the lungs. This successfully done assists materially in bringing about that desirable condition known as “second wind,” and gives control over the muscles of the chest, which enables waste products to be readily eliminated.
“The intensity of breathlessness during exercise is in direct proportion to the expenditure of force demanded by the exercise in a given time.” Breathlessness is due to power expended in a limited time. This, at least, is one of the inducing causes. On the bicycle, power is converted into speed. In hill-climbing, shortness of wind is due not so much to position on the wheel as to the amount of power expended in doing the work. If power is wasted, the work attempted is usually not accomplished; if intelligently expended, the work is done easily and well, leaving the bicyclist in condition to renew the effort when necessary.
Hill-climbing is like stair-climbing; power is expended in a succession of efforts made in raising the weight on an ascending plane. The weight must be lifted, either pushed up or pulled up, and the respiratory need is increased. The hill-climber must aim to mount with as little effort as possible and to make the ascent with the minimum expenditure of power.
Rapidly increased heart-beat is accompanied by deeply inflated lungs and a tendency the bicyclist should guard against to work open-mouthed. Here the question of tight clothing comes prominently forward. Sitting erect and holding by the handle-bars, the bicyclist’s upper chest muscles are held comparatively fixed or rigid; the arms, being used for support, act as levers holding down the upward expansion of the chest. The air, being compressed, is forced laterally and downward. The downward expansion of the chest is checked by the movement of pedaling, there being a constant upward pressure in the ascending stroke and an increased muscular compression in the descending stroke. With a tight belt, the breathing is chiefly upward, and downward when sitting or walking, the lateral expansion depending on the width and compression of the belt.
When working on a bicycle, with the hands fixed and holding hard, the upper chest is comparatively rigid, the muscles below the diaphragm hard at work; and muscles at work do not admit of compression, which prevents the diaphragm from moving downward. The diaphragm is a muscular wall, stretched across the trunk below the lung cavity and near the waist-line. If the lower muscles of the trunk are actively at work, the diaphragm can be distended but a little way in a downward direction by lung pressure. The air in the lungs, which are hard at work, and over-full, presses against the heart, and makes harder work for that organ. When the lungs are distended, any clothing that can be felt about the waist exerts more or less pressure. The lungs of a bicyclist at work are constantly distended, seldom deflated, and an equal pressure is exerted in all directions. The diaphragm is forced downward, pressure comes on the large blood-vessels, and the legs feel tired as one of the results of the constriction. Pressure on the heart and the large blood vessels of the lung cavity causes rush of blood to the head and gives a heated look to the face and a feeling of faintness and headache.
The muscles of the waist are elastic, but lose their elasticity when not in use. Fat accumulates, and is pressed down, usually below the belt, causing the muscles of the figure to sag and the trunk to lose its proper lines. Compression of the waist while cycling is dangerous, and will cause enlargement of the hips and distort the lines of the figure below and above the waist. If tight clothing must be worn, do not wear it while exercising any more than while sleeping.
Bicycling is a great equalizer of tissue. The system, when this exercise is moderately indulged, is freshened as is a city by a heavy rain, all accumulations and deposits being swept away.
There is a difference, a very great difference, between muscular fatigue and breathlessness, and the two conditions should not be confused. Breathlessness is general fatigue; muscular fatigue is fatigue localized. When you are breathless, all your muscles are tired; they do not want to work and are indeed incapable of performing work. Work performed by the lower limbs causes breathlessness more quickly than any other kind of exertion, and the bicyclist must bear this fact in mind. The respiratory need is increased in proportion to the amount of carbonic acid in the blood. The lower limbs can perform a great deal of work in a few seconds, the large masses of muscle in the legs at work throwing large quantities of carbonic acid into the blood to be given off or eliminated by the lungs.