Lots and lots of sources, magazines, web forums, wisdom, etc saw a wood floor is easier on your knees and feet than concrete. Runners choose asphalt over concrete for the reason. I have been searching for any research and have been unable to find any.
Gym floor systems look idea. The gym floor where I grew up was built as follows.
- Concrete slab base
- 3/4" plywood on top of the concrete but a 3" by 3" rubber pad every 12" between the plywood and the concrete
- 3/4" maple stapled on top
That floor had great feel and bounce.
I have a friend who built a shop that could later be a garage with a full basement. He had the floor engineered to handle a 10,000 lb truck parked on the wood floor system. He has joists 12" on center, and two layers of subfloor, 1 1/4" and a 3/4" glues and screwed. It's crazy rigid. Is a floor like that really easier on your knees and feet?