(1) "Squat in front of the chest": Keep your feet shoulder width apart, put the barbell on the clavicle and shoulders of the chest, and raise your elbows as far as possible so that the weight of the barbell can be fully supported on the chest. Chest out, abdomen in, waist in, head slightly raised. Then kneel down until your legs are fully flexed, and then stop. Then stretch your legs and stand up until the quadriceps is completely tightened.

(2) "Squat on the back of the neck": put the barbell behind the neck, and the preparation posture and squatting posture are the same as "squat on the chest".

(3) "Half Squat": The preparation posture is the same as above. Kneel down slowly until your thighs are parallel to the ground, rest for 3 seconds, pause for a while, and then stretch your legs and stand up.