There are two different types of stiffness. The first is caused by a build up of lactic
acid. The second is from muscle tissue damage and break down. The way you can
tell the difference is by the time it takes for you to get stiff. The lactic acid type of
stiffness sets in within twelve hours of training. The muscle tissue break down
soreness usually takes about twenty four hours to set in. Muscle tissue damage
soreness lasts much longer and cannot be flushed away. Though it is more painful
this is a good sign. Lactic acid build up can be prevented by eating a higher alkaline
diet and/or baking soda before you train. It can be relieved with just a brisk walk.

Thanks for this Subzero, good information there.

To be honest i ususally find that if i have worked very hard in the pool the lactic acid can and will set virtually straight away. In fact one coach actually had what she called 'lactic acid sets' with the intention of building it up and have the swimmers swim throught the pain of it. They were good sets, but my god you needed to be mentally fit in order to complete them!

Sean