It is extremely subjective to your situation but I would say it could. It won't be like taking am anti-stuttering pill but I have found that exercise helps reduce my stutter because it is something that calms me down (less stress means less stuttering for me) and it physically makes me more tired (meaning I need to focus a bit more to operate normally, thus reducing the capacity to think about stuttering.) In terms of a confidence boost that is totally dependant on your situation. Again it won't be a slam dunk but if you think it will build your confidence it likely will. I like cycling and find that when I am able to ride my bike consistently my stress goes down, I'm happier, and as such my stutter is slightly better.