I'm a sprint specialist, and I've competed in four Olympics, broken eight world records and won five world championships in my career.

Watch my training tips

I'm going to show you a few simple training methods that will help improve your technique.

Here's what we'll be working on:

• Strokes - The longer the better. A good exercise to lengthen your stroke is to see you few you can take in a length of the pool. I did it in 10 strokes - how about you?

• Backstroke bottle - When swimming backstroke your head should be back - and as straight as possible.

  A good way to test this is to swim a length of the pool with a plastic bottle balanced on your head. If it stays put, your head's in the right place.

• Pushing power - How far can you push yourself away from the wall? Give it a try and see how far you go.

Did you know?

Mark has been swimming for 20 years - but he still doesn't like jumping in cold water!