Most runners train too hard, too often.
A couple years ago I went for a run with Adam and Kara Goucher around the Nike campus in Beaverton, Ore. Not only was I thrilled to have the opportunity to run with such great athletes, but I was also very pleased to be able to keep up with them. It wasn’t even hard, because they didn’t run terribly fast. When I asked Kara if she normally ran so slowly in her easier sessions she told me that she did.
Scott Douglas had a similar experience in Kenya. The Runner’s World online editor traveled there expecting to have his butt handed to him in his attempts to keep up with the world’s best runners but was surprised to discover that the world’s best runners dawdle in their designated easy runs.
Studies on the training intensity distribution of elite runners have found that most elite runners run at low intensities most of the time. For example, a survey of male and female runners who competed in the 2004 U.S. Olympic Trials Marathons revealed that the men did almost three-quarters of their training slower than their marathon race pace, while women did more than two-thirds of their training at slower paces.
Why do the fastest runners do most of their running at slow speeds? Because they run a lot, and if they ran a lot and did most of their running at high intensities they would quickly burn out. But you can also turn this answer upside down and say that elite runners run slowly most of the time so that they can run a lot. Research has shown that average weekly running mileage is the best training predictor of racing performance in runners. The more we run, the faster we race. Keeping the pace slow most of the time enables runners to run more without burning out.