[N.B. I reached the article size limits at TW, thus I must divide the old thread in two.]
I found these non-commercial sites very useful for the tennis player mindful of his/her conditioning:
Great Fitness Sites I (Conditioning)
http://tt.tennis-warehouse.com/showthread.php?t=52164
Great Fitness Sites II (Aches and Pains)
http://tt.tennis-warehouse.com/showthread.php?t=52165
(go here for tennis elbow, wrist and shoulder probs, etc)
Have a good workout!:-)