Abdominal muscles are the most difficult muscle group in human body, because people use abdominal muscles more or less every day, which leads to a strong recovery ability of abdominal muscles, so we should work hard to practice abdominal muscles.

The plan is as follows: the waist muscles and abdominal muscles are difficult to practice, so you have to work hard. Basic action: 1. Inclined sit-ups. I won't say much about this action. 2. Lift your legs on your back, lie flat on the bench, grab the stool head with both hands, lift your feet with the contraction of your waist and abdomen, and then bend your body. 3. From both ends, lie flat on the bench, straighten your upper arms and legs, swing your arms straight, take your hips as the fulcrum, close your upper body and legs at the same time, and touch your raised toes with your hands. 4. Bow the weight behind the neck, put the barbell behind the neck, slowly lean forward, make 90 degrees with the leg, and then use the waist strength to restore the original position. (Practice six groups, each group 12- 15 times).

Arm strength? Please be specific, or it's not easy to answer.