Upper abdomen: Sit-ups, lie flat on the ground, knees bent, hands behind your ears, and use the contraction force of abdominal muscles to lift the upper body. Don't leave your waist on the ground, or the pertinence will be wasted. Four groups, each group 20-40 times, each time 1-2 seconds, not too short! Lower abdomen: 1 Hold the parallel bars with both hands and raise your legs at right angles to your body; Hold the horizontal bar with both hands and hang your legs; Step back, raise your legs, and be at right angles to your body; Lying flat on the ground, with your back close to the ground, your arms at your sides and your palms facing down, helps to keep your body balanced; Toes straight, legs at an angle of 45-50 degrees; Be careful not to let your body twist or your waist leave. The number of times is the same as above. Side waist: Lie flat on the ground, knees bent, right hand reaching left knee, left hand alternately reaching right knee, the same number of times. The upper abdomen is mainly aimed at the upper four abdominal muscles, and the lower abdomen is mainly aimed at the lower four abdominal muscles. What you said is that the middle is not obvious because you haven't practiced comprehensively, so it is not obvious. The lateral waist, that is, the oblique muscle outside the abdomen, is also very important, which will make your mermaid line more obvious. I said no equipment.