Stand shoulder-width apart in front of an object lying on the floor (e.g. helmet or tyre - one leg inside and one leg outside the tyre), bend your knees to sit on the object (buttocks only just touching the object) and stretch back to the starting position.
Attention:
Do not put your full weight down. Move your buttocks backwards, not your knees forwards. Keep your knees behind your toes. Keep your back straight at all times (tense your torso), distribute your weight over your entire foot, push your knees outwards (do not tilt inwards).
Lighten:
Do not lower your buttocks too low (greater angle at the knees, do not touch the object with your buttocks).
Harden:
Hold additional weight (on your shoulders, in front of you or with your arms hanging in your hands).
