. A text-book of human physiology . OF MUSCLES AND NERVES 445 D show that exhaustion comes on more rapidly the smaller the interval betweencontractions. In Fig. 181, A we find only fourteen contractions before completeexhaustion, mechanical work = kg. m. In Fig. 181, B the number of con-tractions is eighteen, and the mechanical work done kg. m. In Fig. 181, Cthe number of contractions is thirty-one and the mechanical work kg. a rhythm of one contraction every ten seconds no fatigue at all appears(Fig. 181, D). An interval of ten seconds, therefore, is sufficient to per
. A text-book of human physiology . OF MUSCLES AND NERVES 445 D show that exhaustion comes on more rapidly the smaller the interval betweencontractions. In Fig. 181, A we find only fourteen contractions before completeexhaustion, mechanical work = kg. m. In Fig. 181, B the number of con-tractions is eighteen, and the mechanical work done kg. m. In Fig. 181, Cthe number of contractions is thirty-one and the mechanical work kg. a rhythm of one contraction every ten seconds no fatigue at all appears(Fig. 181, D). An interval of ten seconds, therefore, is sufficient to permit askeletal muscle to recover completely. When a muscle is worked at a rapid rhythm to the point of complete exhaus-tion, it requires a rather long time to recover completely—in the experiments ofMaggiora from one and one-half to two hours. It was also shown in theseexperiments that the last contractions of a series ending in complete exhaustion,are the most fatiguing. If only the first part, say the first fifteen D Fig. 181.—The onset of fatigue under stimuli of the same strength, given at different intervals,after Maggiora. ^1, once a second; B, once every two seconds; C, once in four seconds;D, once in ten seconds. To be read from right to left. of a fatigue series be carried out and rest be then permitted, the muscle willrecover in a much shorter time proportionally than if it were completely the total amount of work which can be done in a day is consider-ably greater if the muscles be not pushed at any time to the limit of theirpowers. For example, a muscle making fifteen contractions every thirty min-utes for fourteen hours did mechanical work of kg. m.; the same musclewhen made to perform the whole series of fatigue curves every two hours accom-plished a mechanical work of only kg. m.; a difference of kg. m. Ancemia, fasting, want of sleep, among other things, reduce the workingpower, and favor the onset of fatigu
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