Sit-ups: the body is lying on the floor mat, the knees are bent about 90 degrees, and the feet are flat on the ground. Don't fix your feet on the flat ground (for example, your partner presses your ankles with his hands), otherwise the flexors of thighs and buttocks will also join the work, thus reducing the workload of abdominal muscles. Furthermore, straight leg sit-ups will increase the burden on the back and easily cause damage to the back. Determine the position of your hands according to the strength of your abdominal muscles, because the closer your hands are to your head, the more difficult it will be to do sit-ups. Novices can put their hands on their sides, and when they get used to it or improve their physical fitness, they can cross their hands on their chests.
Matters needing attention in expanding data
1. Gradually increase the number of sit-ups.
For a participant who has just started to train abdominal muscles with sit-ups, the number of sit-ups should not exceed 10 repetitions (train your abdominal muscles first). After each sit-up, stand up or lie down to rest and let the abdominal muscles relax 10 minutes or more.
Do sit-ups slowly.
Mainly for the endurance of abdominal muscles. Therefore, only by doing sit-ups slowly can we really train the endurance of abdominal muscles.
3. The action of sit-ups
The muscles in the upper abdomen of human body mainly include rectus abdominis, external oblique abdominis and internal oblique abdominis. Therefore, if sit-ups are all carried out in the sagittal plane (shoulder-parallel sit-ups), the training effect of external oblique muscle and internal oblique muscle will be obviously limited. Only by increasing the rotation of the longitudinal axis of the body (from the right shoulder to the left leg and from the left shoulder to the right leg) can abdominal muscle training's uncoordinated state be avoided.
In addition to the movements of the upper body, in order to avoid overloading the lower abdominal muscles to bend the hip joint during sit-ups, the knee joint should also bend during sit-ups. However, this supine posture will limit the training effect of lower abdominal muscles after doing sit-up training. Therefore, for middle-aged men and women whose main training area is lower abdominal fat, proper knee bending and leg lifting can train lower abdominal muscles more reliably and achieve the purpose of training abdominal muscles (upper abdomen and lower abdomen).
References:
Baidu encyclopedia sit-ups