Part 13 (1/2)

196. Facts ill.u.s.trative of the inutility of calling the muscles into action, without the coperation of the mind, are seen in the spiritless aspect of many of our boarding school processions, when a walk is taken merely for exercise, without having in view any attainable object. But present to the mind a botanical or geological excursion, and the saunter will be exchanged for the elastic step, the inanimate appearance for the bright eye and glowing cheek. The difference is, simply, that, in the former case, the muscles are obliged to work without that full nervous impulse so essential to their energetic action; and that, in the latter, the nervous influence is in full and harmonious operation.

195. Give an ill.u.s.tration of mental stimulus coperating with muscular activity in the case of the dispirited French army in their retreat from Russia. How can a union of mental impulse and muscular action be beneficial to an invalid? Does this same principle apply to those who labor? 196. Give an instance of the different effects produced by the absence and presence of the mental stimulus.

197. It must not, however, be supposed that a walk simply for the sake of exercise can never be beneficial. Every one, unless prevented by disease, should consider it a duty to take exercise every day in the open air; if possible, let it be had in combination with harmonious mental exhilaration; if not, let a walk, in an erect position, be made so brisk as to produce rapid respiration and circulation of the blood, and in a dress that shall not interfere with free motions of the arms and free expansion of the chest.

_Observation._ The advantages of combining harmonious mental excitement, with muscular activity, is thus given by Dr. Armstrong:--

”_In whate'er you sweat, Indulge your taste._ Some love the manly toils The tennis some, and some the graceful dance; Others, more hardy, range the purple heath Or naked stubble, where, from field to field, The sounding covies urge their lab'ring flight, Eager amid the rising cloud to pour The gun's unerring thunder; and there are Whom still the mead of the green archer charm.

_He chooses best whose labor entertains His vacant fancy most; the toil you hate Fatigues you soon, and scarce improves your limbs._”

197. May not a walk, simply as an exercise, be beneficial? What is preferred?

CHAPTER XI.

HYGIENE OF THE MUSCLES, CONTINUED.

198. _The erect att.i.tude lessens the exhaustion of the muscles._ A person whose position is erect will stand longer, walk further, and perform more labor, than an individual whose position is stooping, but equal in all other respects. The manly port in an erect att.i.tude, depends chiefly upon the action of the muscles of the back; and it follows that the fewer the muscles in a state of tension, the less the draught upon the nervous system, and the less its exhaustion. Another advantage which attends the erect position is, the trunk and head are balanced upon the bones and cartilages of the spinal column. If the body slightly incline forward, the muscles attached to the posterior side of the spine, by a gentle contraction, will bring it to the perpendicular, and even incline it backward. This is immediately removed by a slight contraction of the muscles upon the anterior side of the spinal column.

199. In the erect position, there is a constant slight oscillation of the body backward and forward, like the movement of a pendulum; while, in the stooping posture, the muscles on the posterior side of the spinal column are kept in a state of continued tension and contraction, to prevent the body from falling forward. This enfeebles the muscles of the back, and exhausts the nervous energy, while the erect position favors their development and power, because there is an alternate contraction and relaxation of the muscles. Again, in the stooping position, the lower limbs are curved at the knee. In this att.i.tude, there is a constant tension of the muscles of the lower extremities, which produces muscular exhaustion.

198. Why will a person who stands erect walk further, and perform more labor, than if he a.s.sumed the stooping posture? 199. Why are the muscles of the back so soon exhausted in the stooping position?

[Ill.u.s.tration: Fig. 48. 1, A perpendicular line from the centre of the feet to the upper extremity of the spinal column, where the head rests.

2, 2, 2, The spinal column, with its three natural curves. Here the head and body are balanced upon the spinal column and joints of the lower extremities, so that the muscles are not kept in a state of tension. This erect position of the body and head is always accompanied with straight lower limbs.]

[Ill.u.s.tration: Fig. 49. 1, A perpendicular line from the centre of the feet. 2, Represents the unnatural curved spinal column, and its relative position to the perpendicular, 1. The lower limbs are curved at the knee, and the body is stooping forward. While standing in this position, the muscles of the lower limbs and back are in continued tension, which exhausts and weakens them.]

What is represented by figs. 48 and 49?

200. When it is necessary to call into action a part of the muscles of the system in the performance of any duty, as those of the lower limbs in walking, if the muscles of other parts are in a state of inaction, the influence of the nervous system can be determined in an undivided manner upon those parts of the lower limbs in action; hence they will not so soon become wearied or exhausted, as when this influence is divided between a greater number of muscles. In performing any labor, as in speaking, reading, singing, mowing, sewing, &c., there will be less exhaustion, and the effort can be longer maintained in the erect position of the body and head, than in a stooping att.i.tude.

_Experiment._ Hold in each hand a pail of water or equal weights, in a stooping posture, as long as it can be done without much suffering and injury. Again, when the muscular pain has ceased, hold the same pails of water, for the same length of time, in an erect posture, and note the difference in the fatigue of the muscles.