In a 2002 study published in the Journal of Applied Physiology, Asker Jeukendrup of England's Birmingham University put a group of cyclists through six weeks of varied training. During the first two weeks the athletes trained at their normal level. In week three, they were subjected to a massive increase in training load that continued through week four. At the end of that fourth week, the cyclists' perceived effort at a power output of 200 watts (a relatively low intensity for these individuals) was 8.9 percent higher than it had been three weeks earlier, indicating severe fatigue. Not surprisingly, their time trial performance was down 6.5 percent over the same span.
Any athlete who was silly enough to attempt such an abrupt increase in training load on her own could use the spike in perceived effort that ensued to catch her mistake and then give her body a chance to recover. This was shown in the third part of Jeukendrup's study, in which two weeks of reduced training caused perceived effort at 200 watts to drop to a level 9.5 percent lower than it had been after week one.
In the real world, athletes seldom double their training load from one week to the next, but they do routinely train a little too hard and ignore patterns of rising perceived effort even in low-intensity workouts. Each athlete has her own optimal training formula that is defined by individual physiological limits. Getting the most out of the training process requires that these personal limits be respected. An athlete gets herself into trouble when, instead of listening to her body and its intuitions, she begins to worry about what her competitors are doing and tries to "outwork" them. The answers to the most pressing questions that athletes face in their day-to-day quest for improvement ("Should I push? Should I back off?") lie within them.
A coach may either help or hinder this train-by-feel approach-- hinder it by forcing a one-size-fits-all methodology on every athlete, or help it by encouraging athletes to share how they feel and by saving athletes from themselves when they are tempted to do too much. But even the best coach cannot completely take the place of an athlete's gut instincts.
Bernard Lagat is a good example. He began his running career in his native Kenya, where nearly all promising young runners are subjected to severe, unindividuated training that causes large numbers of them to burn out quickly (a system that undermines to some degree the benefits of group training discussed in the next chapter). But instead of putting himself through this meat grinder Bernard chose to emigrate, attending Washington State University, where he was coached by James Li, who shared Tim Noakes's philosophy of doing the least amount of training that sufficed for goal attainment. Li's measured program delivered three NCAA Championship titles to Bernard in his final year as a Huskie.
After graduating, Bernard surprised many by staying with Li and continuing to train rather gently by elite standards. Unlike most of his peers, he ran just once a day, and every fall he took a five-week break from training. This balanced formula resulted in a remarkably extensive record of achievement that included 11 world championship medals between 2001 and 2014, and Olympic medals in 2000 and 2004. Bernard improved year after year without training harder, recording a career-best 12:53.60 for 5000 meters at age 36 and three years later becoming the oldest runner to win a world championship medal in a distance event, taking silver in the 3000-meter indoors.