I obviously agree with your point about racketball. But it's not apples to apples. Even into my forites I wwas doing 7 min miles, before my knes went. To run a hour would be about 7.5 miles. So to compare an hour of running to an hour of tennis (for me) that would have to be the comparison.
Playing tennis for an hour would wear me down, but I would enjoy it. Running for an hour would normally bore me to death.