If you live in an aparment building and have an enclosed fire escape, play fetch on the stairs. Thats what my roommate in NYC did with his dog. We lived on the 8th floor of an apartment building with an enclosed fire escape inside the building. He just threw the ball down the stairs in the afternoon when the neighbors weren't home. The dog loved it.
Otherwise use a treadmill. thats how i survived vet school with my hyper dogs.
Nah he gets plenty of exercise. 45min walk every morning, sometimes only 5-6 days. Also, I'd never trust him on the steps like that. He is so vigorous, and barrels up and down the steps at my home, I can't imagine him chasing a toy, lol.
Question for you vet, going to PM u.