walks across room, picks up Singer Sewing Activewear.....
It would likely be useful, especially if you need to make bodysuit type leotards including good directions on color blocking and tights ,including how to add stirrups. It's sections are : Getting started, Actionwear-leotards & swimwear, tights and biking clothes; Comfortwear-think sweats and warm up clothes, rugby shirts & shorts; Outerwear- wind breakers, rain poncho, insulated stuff and Personal Style- fashion add ons in the form of ribbon trims, braids, piping, etc.
It's from 1986, so doesn't address any of the newer technical fabrics and of course styles are passe. There are a lot of photos with captions that clearly take you through techniques being shown.
As a wanna-be active wear sewist I find it a good starting place for me. There is a lot of good information that shopld apply for dance wear as well.
The Sewing with an Overlock book from the same series is really good, as is Sewing Pants That Fit.