Running, jumping, accelerating forwards and backwards, stopping and starting, sliding and knocking a few balls are all part of your warm-up. You use all the muscles in your body when you play tennis, and it's tough on them. To avoid getting injured, you need to spend a good 15 minutes warming up.
Start with a general warm-up: a bit of running round the court with knee-raises and heel flicks, chassis steps both ways and running backwards.
Then target specific areas to prepare your body for exercise: neck, shoulder, wrist, ankle and waist rotations and muscle stretches. Then have a gentle knock-up, and finish with routine serves, smashes and net volleys.