Can You Control Fatigue?

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When Dave Scott and Mark Allen waded into Kailua Bay to the start line of the 13th Ironman World Championship on October 14, 1989, the existing race record was 8:28:37, a time that Scott had established in 1986. The record for the marathon run portion of the race was 2:49:11, a mark set by the same man in the same race.

Based on these standards, anyone would have considered what Dave Scott and Mark Allen achieved in the 1989 Ironman World Championship, forever remembered as Iron War, to be impossible. Allen won the race in 8:09:15, demolishing Scott's record by nearly 20 minutes. Scott finished second, just 58 seconds back, after having raced at his rival's side for the first 138.9 miles of the 140.6-mile contest. Allen's and Scott's marathon splits were 2:40:04 and 2:41:02, respectively. Third-place finisher Greg Welch did not cross the line until 23 minutes after Allen had.

Impossible is impossible. When athletes do the seemingly impossible, they are actually redefining the possible. Put another way, they are exposing existing limits as illusions. But the question remains: How were Dave Scott and Mark Allen able to push so far beyond the illusory limit of Dave Scott's 8:28:37 event record in their unforgettable Iron War?

I spent a year trying to answer this question while writing my newly published book, Iron War: Dave Scott, Mark Allen & The Greatest Race Ever Run. Part of the answer I arrived at is that fatigue—the ultimate performance limiter in endurance sports—is voluntary. Fatigue is not itself an illusion, but it is essentially a choice. Every athlete must make the choice to submit to fatigue at some point, but the most motivated and mentally strong athletes are sometimes able to resist making that choice better than they ever have before, and that's when records are broken.

Fatigue in an event such as an Ironman hardly feels like a choice, but scientists have proven it is. Among the more powerful proofs is a study conducted by an exercise physiologist named Samuele Marcora. In this study, Marcora asked athletes to hop on stationary bikes and perform a pair of all-out five-second sprints. The first sprint was performed in a fresh and rested state. But the second sprint was performed immediately after the athletes had ridden to complete exhaustion at a high but sub-maximal intensity.

Basically, these athletes were required to pedal at a high, fixed wattage until they were totally wrecked and could not sustain the required output a second longer. They were then immediately required—without forewarning—to perform the second all-out sprint.

Now, if the fatigue that caused these athletes to fail in the second part of the experiment was purely physical and involuntary, then it would have been impossible for them to produce any more wattage in the second sprint than they had been required to sustain during that fixed-intensity ride to exhaustion. Think about it.

If an athlete pedals a bike at a fixed power output of 242 watts (which was in fact the average power output for the subjects in this study) until his body breaks down and is utterly incapable of continuing at that level, then he cannot possibly exceed that power output level even for five seconds immediately afterward. That would be like a car driving at 50 mph until it runs out of gas, stalling, and stopping, then "finding a way" to start again and go 60 or 70 mph for a few seconds without any opportunity to refuel.

Yet the athletes in Marcora's study found a way to put out 731 watts, on average, in the five-second sprint that immediately followed their ride to total exhaustion at 242 watts. Those 731 watts were substantially less than the 1,075 average watts the athlete churned out in the first, fresh-legged five-second sprint, which indicates there was some pure physical fatigue at play. But if the athletes had truly quit part two of the test involuntarily, because their bodies had run up against a hard, physical limit like a car running out of gas, then they could not have reached even 243 watts in their second sprint, let alone 731 watts.

On the basis of these results, Marcora concluded that the athletes in his study had quit the ride to exhaustion simply because they couldn't stand the suffering any longer. What's more, Marcora believes that performance in endurance exercise is always limited by the athlete's tolerance for suffering, not by hard physical limitations. Of course, those purely physical limitations do exist, but we never reach them, because continuing to swim or ride or run becomes too painful first.

Think of your true physical limits as an athlete as a wall that lies at the end of a bed of hot coals. Those hot coals represent the purely psychological feeling of suffering that you experience in walking barefoot over them toward the wall of your physical limits in a race such as Ironman. There is not an athlete on earth who has a suffering tolerance so great that he can walk all the way to the wall. Everyone jumps off the coals at some point. But some athletes can stand the pain longer than others, and every athlete can find ways to stand the pain longer than ever before, and thereby reach closer to that wall and achieve a breakthrough performance.

On October 14, 1989, Dave Scott and Mark Allen took advantage of their career-long training in refusing to quit, plus the motivation of their great rivalry, as well as the lucky accident of each man's having his best day physically, to walk farther on that bed of coals than ever before and dramatically expose past limits to Ironman performance as illusions. How can you expose your own current limits as illusions in your next race? There is no single trick you can employ. But the first step, for sure, is simply to recognize that your current limits are illusions, because fatigue is voluntary.

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