My advice is this: divide the category of "workout clothes" into two or three main aspects, and assign each aspect to one of your identities.
- Fabric is a key aspect of workout clothing. You can assign that aspect to your Dramatic, your Natural, or your Gamine. Shiny spandex and Lycra can read as Dramatic or Gamine, tightly woven cottons can read as Gamine, and cotton in general can read as Natural.
(If you don't have any of these masculine essences, you'll just have to compromise a bit on this element.)
- Color is another key aspect of your ensemble. That one can be assigned to any of your essences, so let's save it.
- Silhouettes and lines can be a third aspect. In workout clothes, you can create a workable silhouette for Classic, Dramatic, Natural, or Gamine. A Classic workout silhouette will be modest and perfectly proportioned; a Dramatic silhouette will be long and narrow; A Gamine silhouette will be boxy and choppy; and a Natural silhouette will be relaxed and loose.
So color is left for your Ethereal, Ingenue, or Romantic essence. The good news is that these days, workout clothes are available in pretty much every color.
You also might not give a dang what you look like when you're working out. :-) I don't always care. But it's a fun challenge to try to manifest our Style Identities, isn't it?