It is not necessary to test every day after exercise, and 3 months should be more appropriate. It also depends on whether you are around before exercise or after exercise. If it is after exercise, the muscles will be congested, so they are bigger than before. You can only measure your back with a tape measure. These two points are the tops of the two shoulder blades and the two bumps under the arm. The deltoid muscle can be measured in the same way as the bust, with both sides resting on the most prominent part of the shoulder.