Ritual in the spirit of debate I would say yes light does reflect differently off a smooth rounded woman’s body as opposed to a more craggy ridged male body. The more pronounced musculature on a man is going to create more extreme highlights and conversely deeper shadows. So while it’s true that light reflects the same after all its human skin whether male or female I would say very definitely that the level of contrast is greater on your ripped male barbarian as opposed to a smoother female form .
In my mind those points have more to do with the sculpting. When you paint, you paint the sculpt you've got in front of you. Of course you don't paint ripped musculature where there is none sculpted. But the contrast between the highlights and the shadows I would not handle differently. Under the chin, for instance, the shadow needs to be just as deep as on a bulky barbarian. And on exposed areas the highlights need to be just as bright.
Furthermore, if a sculptor actually did sculpt a woman with muscles (they do exist) or other more defined features, I would paint them as I would if it was a male figure.