The key thing I am conscious of while writing superheroic / mythos stories is not to make a femuscular character come off sounding masculine in build. For example, I wouldn't use the word "robust" in reference with a female character any more then I would use "Herculean". Instead, "Junoesque" would be my choice, since it denotes that she's both impressively majestic in form as well as powerfully built.
In the end, there's only a limited number of words (and the combinations thereof) that you can work with to describe a well-honed, flawlessly sculpted musculture (male or female) - its all in how you use them to produce a positive effect in the mind of the reader.
BTW - since its on a somewhat related subject, the FMG clichés thread might be of interest to you.
http://amaz0ns.com/index.php?option=com_smf&Itemid=135&topic=4797.0