1. Lie on your back on the mat with your knees bent about 90 degrees and your feet 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.

2. 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.

Finally, you can also try to put your hands crossed behind your head, but put your hands on the shoulders on the other side of your body.

4. Note: Never cross your fingers at the back of your head, so as not to strain the neck muscles when exerting force, and this will also reduce the workload of abdominal muscles.

Use a slower speed, just like slow-motion playback. When the abdominal muscles pull you up, you have to exhale, so as to ensure that all the muscles deeper in the abdomen participate in the work at the same time.