At first, I would have said, "What's a Fitness Jacket?" But the phrase is in use -- at least within the article you cite. At this point, it may be too early to know whether the category and phrase will remain around. But if they do -- or if the company featured in that article wants to emphasize the "fitness jacket" phrase -- then you could be onto something.
I don't see the topic becoming huge. But maybe you're onto something that you can sell for mid $xxx to low $x,xxx. I'd say explore the web to see how much it's used and by whom. See if the trend is upward. If so, maybe try to pitch it to a company that makes them.
