This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1912 Excerpt: ... raising to erect position again? Which muscles are chiefly developed by trunk bendings forward? 3. Try the exercise shown in Fig. 43 to see how far you can flex the hips while back and knees are kept extended. Try several others persons and observe the number of degrees through which they are able to bend. How far can ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1912 Excerpt: ... raising to erect position again? Which muscles are chiefly developed by trunk bendings forward? 3. Try the exercise shown in Fig. 43 to see how far you can flex the hips while back and knees are kept extended. Try several others persons and observe the number of degrees through which they are able to bend. How far can the average person flex the hips in this way? See how this is affected if the knees are allowed to bend a trifle. Explain. 4. To how many degrees are the hips flexed in fundamental sitting position, Fig. 44? Can you flex them still farther from this position? Why is the flexion so much more free than in standing? 5. Why is it so difficult to take erect sitting position on the floor with legs extended forward? Where is the resistance? Why more easily done when the legs are crossed, tailor-wise? 6. When one tries for the first time to take the gymnastic exercises shown in Fig. 45 he usually inclines the. trunk forward and finds it quite difficult to keep the trunk erect. Why is it? What muscles are contracted to keep the trunk erect? 7. In strength tests of separate muscle groups it is found that the exten-sors of the hips are stronger than the flexors in the average man in the ratio of 135 to 125. What causes the greater strength of the extensors? 8. Why do some persons incline trunk forward in climbing stairs? What muscles aid in this position that are not Fig.44. Fundamental sitting position, used if they keep trunk erect? How about the crouching start used by sprinters? 9. What acts as the lever in inclining trunk forward as in Fig. 43? Using a ruler or tape, show how to measure the length of the power arm. What is the weight here? Where is the center of gravity of the trunk? How affected by positions of the arms? What position of arms will...
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