I read a Frederic Delavier’s book « Strength Training Anatomy » and I learned good stuff.
Your legs are strained with your back against the backrest. Your shoulders are wedged under the pads with your feet averagely apart :
Inhale, unblock security and bend legs.
Back to the start position and exhale at the end of the movement.
This exercise works quadriceps :
More your feet placed forward and more your glutes work.
More your feet are spread and more your adductors work.
Attention : To protect your back, it’s necessary to squeeze your abs to avoid lateral movements of the pelvis and spine.
Adaptation to bipedalism
Chimpanzee (who is our close relative) has a large torso size and poorly developed glutes. Because of this, chimpanzee has difficulty in straightening the core and difficulty walking in biped mode.
Human being is the only primate to be adapted to a totally bipedal movement.
The human being developed the gluteus maximus muscles to adapt to bipedalism. It’s for this reason that the torso’s size decreased to facilitate to put the core in the upright position. The human being has something more that the gorilla and the chimpanzee can’t do. The human being can block the knee joint in extension to stay upright with less energy.
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