If you have abdominal muscles, you can do leg lifts and sit-ups. Lift your legs flat, put your palms down at your sides, lift your legs up, and then pay attention. Your legs can't touch the ground, and then add rotation. It's simple. You can try it yourself.

When doing sit-ups, you must not hold your head. Many people have this bad habit, which will cause serious damage to your cervical spine for a long time. You can put your hands gently on both sides of your ears and do sit-ups together. But if you want to practice perfect abdominal muscles, you must practice the middle two sides when you get up.

The exercise of biceps brachii is very simple. All you have to do is bend inward with your hands. The number of exercises on both sides must be the same. You can constantly challenge muscle growth from low weight to high weight. It's not difficult to practice at once. it is not good to do this. You must practice step by step.

As for the specific time, I can't guarantee it, because everyone's physical condition is very different. Don't practice for too long, otherwise it will only be harmful. As long as you follow the above method, you will feel your muscles grow slowly.