. Applied anatomy and kinesiology. ll of the flexorsof the hip, and in case of lifting the knees above the level of the hipto raise the front edge of the pelvis through flexion of the spinalcolumn. Lifting one knee while standing on the opposite foot is oftenused as an abdominal exercise, but it brings the abdominal musclesinto action too mildly to be of much use, the pelvis being held innormal position by the hamstring muscles of the supporthig the limb is raised to horizontal with knee straight there is a mildaction of the abdominal group, to jibout the same degree as in 204 MOVEMENT
. Applied anatomy and kinesiology. ll of the flexorsof the hip, and in case of lifting the knees above the level of the hipto raise the front edge of the pelvis through flexion of the spinalcolumn. Lifting one knee while standing on the opposite foot is oftenused as an abdominal exercise, but it brings the abdominal musclesinto action too mildly to be of much use, the pelvis being held innormal position by the hamstring muscles of the supporthig the limb is raised to horizontal with knee straight there is a mildaction of the abdominal group, to jibout the same degree as in 204 MOVEMENTS OF THE SPINAL COLUMN walking. Teachers of gymnastics and athletic trainers have greatlyoverestimated the effect of this exercise to develop the abdominalmuscles, overlooking the action of the hamstring group to holdup the pelvis when standing on one foot. By throwing the knee upviolently, especially when the supporting knee is allowed to bendand the pelvis is flexed, the abdominal muscles come into action,but the posture is Fig. 123. -Inclining backward from erect sitting position: R, rectus abdominis;E, external oblique; F, flexors of hip. Lifting the Feet.—Lifting the feet while lying on the back isaccomplished by the same muscles as the preceding exercises butis less suitable for beginners and weak subjects because the move-ment begins at the point where the work is greatest. The weightof the limb, pulling at right angles to the weight arm when themuscles are at rest, requires the most force to lift it through thefirst few inches, the strain gradually diminishing as the limb israised toward the vertical, where it becomes nothing. The amountof work can be graded by varying the length of the weight armby flexion of the knee. When the knees are allowed to separatewidely as they flex the feet can be drawn up toward the hips with- GYMNASTIC MOVEMENTS 205 out using the abdominal muscles; then by lifting the flexed limbsthe latter are used moderately. When the knees are k
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