How to increase the strength of the left arm while exercising, because the strength of the left arm is not as good as that of the right arm, and it is more sore than the right arm after exercising.

Generally speaking, balanced exercise is ok, but if you want to exercise deliberately, you can exercise your left arm with dumbbells alone, which can narrow the gap between your two arms. The average person's right hand is not the same strength. If you don't feel much difference, you don't need to exercise deliberately. It will be much better if you practice with the same hands for a period of time.