* I can see some market for this, but I have a strong feeling you've burned through a good bit of funds and may not see much come out of it immediately (like 3-7 years).
* Trainers will most likely provide sheets on what to do via printed sheets to their patients. This is cost effective and much easier than even logging in to a site and entering a patient's email address.
* To me you are not answering the question of how you are really making a trainer's life easier via this site until the demo is viewed. You need to have that front and center in the top of the page, not a big picture of a laptop with hard to read writing. Just the fact that it is online, does SMS (?), and email, is not describing the need or how it fills it.
* Could you pivot to aim the site at health insurance companies or others that might want to actually replace the trainer and provide physical training online? For example, there have to be some people that need rehab in hard to reach places. Maybe you could provide trainers via webcam that could interact with these patients. It wouldn't necessarily be that scalable, but it might get you more business than you would have had otherwise.
You can spend time getting the link to your site out in various blogs by posting them yourselves in forums, etc. like others mentioned. But, I'd address these questions asap.