As a 5'4'' 120 lb girl, I would say it's pretty physically demanding! In acute settings, of course there is the matter of patient transfers, handling unstable patients, etc. In outpatient ortho, it just depends on your patient. My CI this semester was trying to teach me how to do hip mobilizations and even he was winded by the end! I wouldn't say it's a road block though. As long as you keep yourself healthy, there's really no concern. The physical demand is also asked of you every day, so you'll be accustomed to it.
I've also noticed that there are a lot of older PT's in wound care. I also shadowed at a hand clinic in undergrad and the woman I was with said that as she got older, she decided to get her cert and do that instead.