1, left biceps strain, solution: please see a doctor.

But the next day, your biceps were stiff, and it was preliminarily speculated that it was DOMS, that is, exercise-induced delayed pain. See the extended reading section in:/menu/113044/item/103163/for details.

2, the left hand exercise in place, the right hand is not in place. That is to say, the left hand has done enough centrifugal movement, while the right hand has not done centrifugal movement, but it is unlikely. Generally speaking, novice practitioners are not in place or sore.

3. It is most likely that this article and 1 article, the original muscle is unbalanced. Generally speaking, the left hand is almost weaker than the right hand, so training with the same number of times and weight will lead to the difference between the left and right hands. This problem is very common, so your left hand muscle has reached failure under the same weight, while your right hand is still relaxed. Solution: Keep the weight and frequency of hands unchanged and exercise step by step. Otherwise, the muscle gap will be bigger and uglier in the future.