Welcome to the Q&A Forum

I'm going to go against the grain here and say that I don't think you need or want separate pages. These are synonyms. The phrases are obviously semantically related. When I type "elliptical machine" and search on Google I see results with the world "elliptical trainer" in bold as well. If it were me and I had one category page to optimize I would title it something like: Elliptical Machines - StoreName Has the Best Elliptical Trainer Brands in Stock for Less! Or some variation that allows you to get both of those two-word phrases in there once. If you do have the opportunity to optimize more than one page, and both are equally relevant to the searches (e.g. Home page and category page), then I agree that you should target one per page, though I would intersperse the other variation here and there on each page too. Product pages are likely going to rank best for the brand/model of machine/trainer so you can just write naturally and use each keyword interchangeably (e.g. The BrandX elliptical machine is an excellent value, combining affordability with the features, style and durability of the more costly elliptical trainers on the market...)

What about the data that comes from Moz reports, like error counts and data points that are proprietary to Moz?  Do you guys just dump that data?