Applied anatomy and kinesiology; the mechanism of muscular movement . g action. Asthe body nears the bar the trunk and limbs a-e lifted by con fac-tion of the flexors of all the joints and the arm depressors and henextended to the position shown in Fig. 190 by the extensors. Thehands hold to the pole long enough for the body to clear the barand for the feet to begin the downward movement due to gra /ity, PLAYS. GAMES AND SPORTS 315 then drop it with a push that will vary in force with the exactposition of the body and the pole. On alighting the extensormuscles of trunk and limbs come into acti
Applied anatomy and kinesiology; the mechanism of muscular movement . g action. Asthe body nears the bar the trunk and limbs a-e lifted by con fac-tion of the flexors of all the joints and the arm depressors and henextended to the position shown in Fig. 190 by the extensors. Thehands hold to the pole long enough for the body to clear the barand for the feet to begin the downward movement due to gra /ity, PLAYS. GAMES AND SPORTS 315 then drop it with a push that will vary in force with the exactposition of the body and the pole. On alighting the extensormuscles of trunk and limbs come into action to lessen the jar bya lengthenmg contraction, followed by a shortening contraction tobring the body to erect posture unless the balance is lost. Mountain climbing is essentially like walking up stairs, using theflexors of the limbs to lift the feet and the extensors of trunk andlimbs to lift the body, the complete flexion giving the gluteusmaximus a chance to help. In going do^N-n the mountain theweight is lowered at each step by a lengthening contraction of the. Fig. 190.—The vaiilt with the pole. extensor muscles. There is much turning and bending that variesthe work of the trunk muscles and brings all of them into action apart of the time. Climbing the ro^e or yole, using both hands and feet, starts bygrasping it with the hands, using the flexor group. Then the feetare lifted by action of the flexors of the trunk and limbs and thewhole body may be lifted at the same time with arm depressorsand flexors of the elbow. The rope is now grasped by the feet,usmg the adductors of both thighs and the flexors of one limbactmg agamst the extensors of the other; then the hands are moved 316 PLAYS, GAMES AND SPORTS up the rope by use of the arm-raising muscles and the extensors ofthe trunk and hips, after which the movement is repeated. In practically all forms of swimming the body is propelled alongor through the water by the use of the arm depressors and theextensors of the lower
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