I found a solution to the fatigue caused by heavy racquets, actually.
1. Find a lighter racquet you play well with.
2. Practice a bit
3. Buy a couple more of the lighter racquets
4. Stick 'em in your bag
5. Take your heavy racquets out of your bag.
6. Sell 'em to a TTer for a reasonable price.
7. Be happy!
hope this helps
5.0 all courter. Dunlop Bio 400T with cyclone @ 50, Prince CTS Precision 90
"Tennis isn't easy" - Corners