No shrinkage will occur. Practice more muscles and you will develop. Of course, the premise is to use a lot of protein food after each exercise, such as beef, eggs and chicken, as long as you can stick to it! Also, push-ups are the best in the group, and the effect is ideal, but if the times are the same every time, the effect is not very good. If you think you are in good health, you can do this: do push-ups to your limit for the first time, and add another one for the second time (of course, you can add 5 to 10), which is better in turn, if possible, two a day, if not, one a day. Good luck!