I discovered a few years ago that I could no longer sustain a 4-minute kilometre running pace for more than 4 minutes. Now I don't bother to time myself when training! I get more aches and pains with running, and get injured sooner whenever I increase my training load.

At any age, the most important predictor of performance is genetics! The next time someone sprints past you in a fun run, think of the good "speed genes" his/her parents has! Fortunately we are able to train ourselves to run faster and further. Most runners eventually discover their genetic limit when it comes to performance in endurance events. The trick is to maintain their speed and endurance performance for as many years as possible.

In general, runners reach their peak in the 20's and 30's, with a noticeable decline in performance from the 40's. This is thought to be mainly due to normal age-related decline in the maximal oxygen consumption (VO2 max). {VO2 max is usually measured during an incremental treadmill test in a laboratory.}

It seems that there are other factors causing decline in performance, but these are not easily quantifiable. The number of years of (competitive) running seems to relate to the running life span. It is thought that a 40-year-old runner who trained and competed intensely for 20 years will find it more difficult to maintain their performance after 40 years than a 40-year-old of equal ability who starts competing.

Runners tend to accumulate a list of injuries over the years. If our bodies were perfect (and pronation was not a dirty word), and we had the ideal training programmes, we may not get overuse injuries. Perhaps this is why the Ethiopians and Kenyans are so good at distance running.

After the age of about 40 years, the body is unable to repair as quickly (and perfectly) as before. This applies especially to the big joints- knees especially. The joint lining and menisci (commonly called "cartilages") are not as supple as before, and are more prone to "wear and tear". Similarly, muscles, tendons (rubbery bits connecting muscles to bones), and ligaments (rubbery bits connecting bones to bones) are less elastic in the older ages.

The best advice I have for the "ageing athlete", is to vary ones training as much as possible. This minimises overuse injuries, and provides variety. After years of punishing you body, treat yourself to massages, and frequent visits to cafes! Muscles and tendons need more stretching to minimise stiffness.

There is GOOD NEWS though! Researchers found that regular exercise over the years leads to an increased lifespan of 2-4 years! (Not including those will medical conditions.)  However, half of this time is spent exercising!