Originally Posted by tlm
The level does not have near as much to do with it as opposed to age and being out of shape. Actually many of the higher level players play more efficient with big serves and net games that keep the points shorter, as opposed to good 3.5 - 4.0 players that play a lot of long grinding points.
How many of these older players that you know play singles 3 times a week? I know a lot of those type of players to but they play 99% doubles, they can not move good enough for singles anymore and are not in good enough shape.
I myself play 4.0 singles once or twice and 4.0 doubles once or twice a week, totally around 6 hours a week on the average. The only exercise I do is 15 minutes of stretching every day, and using the stairs at work. I am afraid of ruining my knees with extra exercise, like running. I figure that I am running during tennis, so why run more? I have never been injured, except once when I had TE when I was learning with bad technique, and once when I mistakenly switched to a demo racket in the middle of a session. Nothing that has kept me out for more than a day.