The easiest way to practice biceps brachii is to grasp large objects that can be fixed with one hand, such as doorframes and railings. Get close to the object with your feet, then hold the object's arm as straight as possible and bend and stretch repeatedly.
You can use triceps brachii as abdominal support to practice.
Doing sit-ups and practicing abdominal muscles is simple and effective. You can also lie flat on the bed and touch your toes with both hands (lift your body). Do it slowly. If it is fast, there will be inertia, which will affect the effect. Be sure to do it to the end and do it in place. Or, grab the horizontal bar with both hands, lift your legs horizontally, and repeat.
It is advisable to have muscle aches every time. Remember not to do it every day. Every time you do anaerobic exercise, you should destroy the abdominal muscle tissue as much as possible, and then use enough time and nutrition to repair the damaged muscle tissue. To put it bluntly, muscles grow out at rest after anaerobic exercise.
Also combine aerobic exercise, such as jogging, and be sure to sweat. If you simply do sit-ups, the fat layer will not decrease, the muscle layer will thicken and the waist will be thicker.
The fitness methods recommended to you above are all without equipment. All aerobic exercises are good ways to lose fat, such as running, skipping and swimming. There is also summer, buy a disposable raincoat to wear, run at home (don't turn on the air conditioner), wave your arms quickly and sweat more, which can reduce fat and detoxify. Replenish water in time. The above exercises should last for more than half an hour at a time, otherwise they will be invalid. I recommend a very time-saving method to reduce waist. When watching TV, sit in the corner of the sofa, hang your legs upside down close to the armrest of the sofa, put your hands on your chest (you can cross them), and turn your waist at the maximum angle. In this way, you have already consumed the fat around your waist when watching TV. Eat less high-calorie and high-oil food. Never do sit-ups. Sit-ups belong to anaerobic exercise and have little effect on reducing fat. If you only do sit-ups without aerobic exercise, the fat layer will not decrease, the muscle layer will thicken and the waist will be thicker.