Muscle Imbalance?


Hi everyone! I've been doing FB workouts regularly (3-5 days a week) for about 6 months now. Recently I've noticed that while doing upper body workouts my left arm burns significantly more than my right. For example, while my left arm may start burning and shaking on rep 5, my right arm may not start to feel the same way until rep 8, 9 or 10. I'm wondering if this is a muscle imbalance, and my left arm is weaker than my right.. Or if somehow I'm working harder/have better form on my left arm? I always work out in front of a mirror to try to keep things even on both sides.

Anyway, I guess I'm just wondering if anyone has had a similar issue and what the problem might be?

Thanks in advance!

(Also I'm very new to the community forums and wasn't sure which category to put this in.. Let me know if I should move it to a different place!)