Exercise in education and medicine / by R. Tait McKenzie.

  • R. Tait McKenzie
Date:
1909
Catalogue details

Licence: Public Domain Mark

Credit: Exercise in education and medicine / by R. Tait McKenzie. Source: Wellcome Collection.

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    muscles will refuse to contract, or may actually tear, and if habitu¬ ally overworked, they may atrophy, and become hard and fibrous, with weak, uncertain movements. When muscles are over¬ developed, they become parasites on the vitality, which is sapped in the struggle to provide for their nourishment. Exercises of effort do not cultivate constitutional vigor to the same extent as those of endurance. In exercises of endurance the range and variety of movement are usually much more limited. They are confined to a few well-known varieties, such as walking, running, and rowing, and though each movement is well within one’s power, the total amount of muscular work is great, but as the contraction and relaxation is comparatively slow, the poisonous waste matter pro¬ ducing fatigue is removed from the muscles as it accumulates. In exercises of effort there is no time for the scavengers to work, fatigue of the most active muscles setting in rapidly, while in exercises of endurance they can, at least, postpone its onset. This class is, then, milder and more general in character. It deals with coordinations familiar from infancy. It is not neces¬ sary to concentrate the attention on every movement in walking, running, and rowing,—typical exercises of endurance,—in them the mind may be occupied with other thoughts. Breathing, which is a muscular action of endurance, is entirely automatic, but is not subject to the ordinary laws of fatigue. The qualities cultivated by exercises of endurance are different from those required in effort. Skill is not prominent among them. Concentration is replaced by the attempt to liberate the attention, and the development of any one group of muscles is secondary to the indirect effect on the circulation and respiration in training them to remove the fatigue products of muscular contraction. When carried to excess, exercises of endurance are accompanied by acute constitutional exhaustion, shown in breathlessness, from which recovery is rapid; by fatigue of the whole muscular system, from which a rest of a day or two is necessary, and by the chronic or nerve fatigue known as “staleness” among trainers, from which recovery may be a matter of weeks or even months.