Damn, she's ripped! Great idea and execution on this shot. I like the dramatic lighting. Only thing I see that I might change is to move her right hand in more of a ready position to strike. I'm sure you could do this and still accomplish covering her breast. Kudos to the brave and beautiful model!
The hue of the yellows are vivid, bold, and really pop visually off of the black background. Lighting on the model is very good illuminating her while keeping good skin tones. This is a good 'portrait' shot but I think there are some elements that can be added to improve the composition and help it better match the (heavyweight or lightweight) title (sorry, could not stop myself from making a boxing reference) you have bestowed upon it. First off, I think she should be poised with her gloved fists up like she is about to spar with someone. This will show action and be better suited to match the title of the composition. I know that would remove her hand from her chest but she need not bare her breast at all - all she would have to do is keep her head in the same position and turn her back slightly more to us. Next the model's facial expression should look like she is ready to fight (them's fighting words mister) with the eyes narrowed in irritation/anger and the lips tightly pursed. Her expression in the photo as it is now has neither.
Would have been better with a top on her. I'm not against showing some skin, but this just seems unneccessary. It wouldn't lose any impact (tee hee) if she wore a top.
It's a fine photo, but the not wearing a top just throws it off for me.