Each individual has his own limit or pace, at which he can do work most easily. If this pace is exceeded, effort follows and increased expenditure of power; a greater quantity of carbonic acid is produced to be given off; and fatigue is induced sooner than when working at the pace which can be kept without extraordinary exertion. Every bicyclist knows his own natural pace, and when departing from that must expect to be winded sooner or later.
Rapid work on the bicycle is similar, as muscular exertion, to running, racing, speeding, and sprinting. Here we have the time limit,—great speed produced in a short time; tissue consumed, and carbonic acid produced in large quantities to be quickly eliminated. Increased effort means more power expended. The fixed lung cavity means lessened capacity for increased air-consumption and greatly lessened means of inhaling and expelling air. One of the effects produced by carbonic acid in the blood is a stimulation to increased effort, which causes a desire to prolong work after reasonable limits have been exceeded, a feeling that more must be done, rather than a desire to stop and rest.
Second wind is the condition produced by the adjustment of the processes of the body to the new state of exertion, where the heart and lungs balance and work according to the demands of the new condition. A pendulum, slipped on its spindle and let go, swings irregularly until it finds its new rhythm. The rhythm that corresponds with its weight, momentum and length of spindle, leverage, is the rhythm of the work. All repeated work has a rhythm, and the movement disturbed requires a little time for readjustment. The heart and lungs work automatically and rhythmically, and any new movement disturbs their rhythm, which must be adjusted for change of occupation or exercise until the balance of the working functions is established.
The second wind usually comes after the first fifteen minutes of work. Quickly acquired, it means rapid and easy adjustment of processes, a quick response to effort, and little power wasted. Though individuals differ in this respect, a difficulty in getting the second wind, when exercise has been suspended for a time, will sometimes be experienced, and care should be taken not to overwork when taking up an exercise that has been for some time discontinued.
When you have had exercise enough, stop and rest. Change of occupation, turning from active mental work to active muscular work, has been said to give rest to the mental faculties. Though they perhaps do, in a sense, experience rest, it might be unwise to assert that this rest is really recuperative. Repeated alternation from active mental exercise to active physical exercise would inevitably result in a state of exhaustion, in which the reserve fund of energy or strength would be completely consumed. It is a more accurate statement that a certain amount of muscular work, which will restore the balance of the system, is a good preparation for rest after active mental exertion.
During mental work of any kind, muscular work must be performed; for breathing, seeing, moving the hands, require muscular movement. The question, therefore, resolves itself into one of degree of work done and equilibrium of forces to be maintained, rather than one of restoration of one set of faculties by the overtaxing of another set. Good muscular work cannot be accomplished without the exercise of brain and will; therefore, when the mind is actively employed, a certain amount of muscular tissue is consumed, though not enough to maintain the system in a state of bodily activity. For body and mind, to be in a state of perfect health or equilibrium, should be equally active.
The tissues of the body are constantly renewed, and the amount of work, mental or muscular, that can be accomplished is determined by these constantly renewing processes. The amount of material taken up and stored for use depends upon the amount of material needed; and this is gauged by the amount of work already done, and restricted by the amount of work the material is capable of performing. The balance of work and rest, quantity and quality, varies with different temperaments.
Training means nothing more than preparation. For those engaged in active mental occupation it is well to consider if they are giving themselves the best preparation for resisting the fatigue consequent upon their occupation. Cycling is a pastime and sport, and may be a relaxation and the alternate of other athletic exercises. After the machine is under control, the muscular work becomes virtually automatic; and for this reason cycling, in its various forms, has proved so beneficial as a relaxation.
Overwork produces the effect of poisoning of the system, and reduces its power of resistance. This poisoning is produced by the waste products of the system, which accumulate during work, as the forces for eliminating them are overtaxed; and before work can be properly resumed, the poison must be eliminated from the system, and the power-producing materials again stored for use.
Stiffness is a form of fatigue due to an accumulation of deposits in the tissues, which are best removed by exercising after a period of rest. With their removal, stiffness disappears, to return with fresh deposits if exercise is again prolonged. The amount of material not taken up by the system lessens with regular exercise, and the tendency to stiffness gradually disappears. The only remedy for stiffness is work, then rest, then work again. Sleep does not always come to the over-tired, and we may therefore conclude that it is better to be rested before attempting to sleep.