As you stress your body, it reacts to make the stressed systems stronger. This is sometimes called the "training effect". Once you begin running it will strengthen your heart and leg muscles, and increase the number of small blood-vessels within them. You will get better at moving oxygen to your muscles, and at getting rid of the waste products of muscle activity. You should cease to be so breathless when running. Over time your resting pulse may drop. Altogether, your body should adapt to make running easier and to allow you to run further.

Unfortunately, your muscles adapt faster than your bones and connective tissues, so just as you find you can run faster and further, you become liable to injuries. (See "* 17 Possible injuries for a beginner"). Injuries tend to strike beginners after 8-12 weeks, so it is a good idea to slow down your progression at this point to let your skeleton catch up.

Noakes observes that there is a dramatic increase in performance after 20 weeks.

Last updated on May 4, 2007 by David Ardley