I play tennis on hard courts usually 1 - 3 times per week. Several times a year there are weekend tournaments or other competitive weekend events that I like to participate in. Typically, by the end of the one of these weekends my calves and/or knees are so sore I have a lot of trouble reacting to the ball. It goes away after a few days though and doesn't bother me on daily basis. Is this normal? Are there exercises I can do to prepare myself better for these weekends?
Since you work so much longer and harder than usual at tournaments, it's not surprising that you're feeling some soreness (see this Wikipedia article on delayed onset muscle soreness for more info), but I can think of a couple things that might help your calves and knees hold out a little better:
I had these experiences, these are quite normal for anyone who is playing for long. I guess you can reduce the stress on them by following methods:
Stretch before beginning any activity(walking, running, playing tennis, gym, etc) it warms up the muscles and they will be ready to take the load/stress.
Stretching should be done very slowly, even though they consume some time, you should always stretch.
Very important you should be keep stretching in between the activity, this relaxes the muscle group and the muscle.
Stretch at end of the session, I know this would be boring and people would tend to skip this, but it is very important for your progress and safety.
2. Do some weight training for legs
There are many exercises, like squats, half squats, sitted leg extension, donkey calf rise, reverse curls, etc which will strengthen your legs.
3. After the session
Give yourself a hot water(water should be hot enough and not very hot) treatment, place your feet in hot water tub with little salt(common salt) added to it, for sometime. This would easy the soreness.
4. Take rest
This is very very very important, this is the time when muscles recover the max. Increases strength of your muscle and muscle group.
5. Wear proper attire
You should be wearing proper dress like, shock absorbing shoe, socks(cotton sports socks), etc
6. Proper technique
You should constantly update your knowledge about the techniques used from internet, magazine, articles, talking with people who are good at it, keeping reading about the activity and keep seeing the pros. You should be able get proper techniques from them.
7. Perfect practice.
Practice not just practice but perfect practice, with the proper techniques you learn, practice them, you'll become stronger and perfect.