I worked in the fitness industry the past 7 years, and the CSCS is probably considered the cream of the crop in terms of fitness certifications for personal training and the most highly regarded certification for athletic training (of course a degree in kines and whatnot would be regarded higher). But I was wondering the same myself about the OT world though. I'm not sure how much it would count because what's learned is parallel... but not quite the same. I have several fitness certifications (NASM CPT, CES, and PES), but I'm not sure how OT job opps would look at that.