Let's compare five kinds of abdominal exercises to see which one can strengthen rectus abdominis more effectively. Boarding in the air: Lie on your back on the floor with your lower back close to the ground. Put your hands on your head and open your arms. Lift your legs and climb on the bike slowly. Exhale, lift your upper body, touch your left knee with your right elbow (Figure 1), keep your posture for 2 seconds, and then restore. Touch the right knee with the left elbow again, hold it for 2 seconds, and then slowly return to the starting position. Roll up the fitness ball: lie flat on the fitness ball, with your feet flat on the ground, your hands on your head and your arms open. Reduce the chin to the chest, exhale, contract the abdominal muscles, raise the upper body by about 45 degrees (Figure 2), hold it for 2 seconds, and then slowly return to the starting position. In order to keep balance, your feet can be separated more. If it is difficult, you can do it with your feet together. Lift your legs and abdomen: lie on your back on the floor with your lower back close to the ground. Put your hands on your head and open your arms. Raise your legs at 90 degrees to your upper body, cross your legs, and bend your knees slightly. Exhale, contract the abdominal muscles, lift the upper body, keep the lower back off the ground (Figure 3) for 2 seconds, and then slowly return to the starting position. Keep your chin down to your chest. Reverse belly roll: Lie on your back on the floor with your lower back close to the ground, put your hands on your sides, raise your legs at 90 degrees to your upper body, cross your legs and bend your knees slightly. Tighten the abdominal muscles, then exhale, slightly lift the hips, slightly lift the waist and back off the ground (Figure 4), hold for 2 seconds, and then slowly return to the starting position. Traditional belly roll: lying on the floor on your back, with your lower back close to the ground. Put your hands on your head and open your arms. Put your legs flat on the ground and bend your knees. The chin shrinks to the chest, contracts the abdominal muscles, exhales and lifts the upper body, and the lower back can't leave the ground (Figure 5), and then slowly returns to the starting position. Through electromyography test, it is found that boarding in the air is the most effective exercise to exercise rectus abdominis. The second place is leg lifting and belly rolling, and the third place is fitness ball belly rolling. Research shows that when a kind of training needs the continuous stability of abdominal muscles and the rotation of the body, abdominal muscles can produce the maximum activity. Because the balance needs to be controlled in an unstable environment, when doing belly roll training, the body-building ball belly roll needs more muscle contraction and control than the traditional belly roll. In fact, in order to achieve the best results, it is recommended to try to do various kinds of exercises regularly, because it can exercise different muscles and is not easy to get bored. No matter which exercise method you choose, it takes time and patience to exercise and strengthen your abdominal muscles. Remember, the training goal of abdominal muscles is muscle endurance, not muscle and strength. Finally, remember to stretch your muscles after exercise.