For some athletes, it’s a matter of mind over muscle
New theory says it’s the brain that tires
Pro cyclist Jens Voigt — who’s well known for his “shut up legs” mantra, which he repeats when propelling the bike forward becomes physically unbearable — offers a pretty accurate description of the battle between mind and body during a long, hard workout.
“Sometimes, you can hear your body start talking to you like, ‘I can’t do it anymore, I can’t do it anymore,’ and your mind goes, ‘Shut up body, and do what I tell you,’ ” Voigt has said.
Interestingly, that battle between mind and body is mirrored in the scientific community, which is at odds about the origins of the type of fatigue experienced by anyone who has pushed their body to its physical limits.
Traditional thinking suggests that the kind of fatigue Voigt describes occurs when athletic demands exceed the capacity of the heart to supply oxygen to the working muscles. That shortage of oxygen causes a buildup in metabolites, which leads to muscular distress and the failure of the muscles to contract. In short, your muscles are spent.
The only way to extend the time to fatigue then is to improve the heart’s ability to pump blood at a greater rate as exercise intensity heats up. It also suggests that the most successful athletes, those who compete and win at the elite level, possess a superior heart that delivers more oxygenated blood to the working muscles.
What this theory doesn’t take into account, however, is the role the brain plays in fatigue. Tim Noakes, author of the popular book Lore of Running and a renowned sports scientist, believes that fatigue isn’t the result of muscular failure. Instead, he floats the theory that the brain signals the body to slow down as a protective response to keep it from overworking itself to the point of damage.
According to Noakes, there are too many unanswered questions around the idea that muscular failure causes fatigue, including the fact that at the end of a race, when muscular power should be exhausted, exercisers somehow find the reserves to speed up.
Noakes calls his theory that fatigue is more mental than physical the Central Governor Model, which suggests the brain, not the muscles, is calling the shots during a tough workout. And unlike the muscles, which respond only to the level of oxygen delivery, the brain takes in all sorts of information.
That feedback includes the athlete’s emotional status, level of sleep deprivation, mental fatigue and recovery from a previous workout. Also taken into account by the brain is the duration of the workout and other intangibles like how strongly the athlete believes he can succeed.
Armed with all that information, the brain keeps the exerciser moving at an intensity the body can safely sustain using a continuous loop of physiological feedback to adjust the pace accordingly. Fatigue, suggests Noakes and others who believe in the Central Governor Theory, is not a measure of the capacity of the muscles to sustain highintensity exercise, but rather a feeling that the brain transmits to keep the body from overextending itself.
Central to this theory is the idea that successful athletes possess more than just a physiological edge based on a genetic or trained ability to sustain an enhanced delivery of oxygen to the working muscles during high-intensity exercise. Instead, it’s the brain that delivers success.
So while the traditional theory behind crossing the finish line behind the winner suggests a lesser ability to sustain muscular effort, Noakes believes that somewhere during the course of the race, the brains of all those who fail to win have sent out a stronger sensation of fatigue than that experienced by the fastest competitor.
This decrease in perform- ance doesn’t suggest a lack of mental fortitude, but rather that the level of fatigue felt by the exerciser is uniquely generated in an athlete’s brain based on the physiological feedback provided. It also suggests that having a winning attitude, or at the very least an “I can do it” attitude is an important component to achieving athletic goals.
“Athletes who finish behind the winner may make the conscious decision not to win, perhaps even before the race begins,” Noakes said.
Admittedly, Noakes’s theory of a Central Governor isn’t fully endorsed by the scientific community. But his idea that there’s more behind fatigue than just a physical response is worth exploring.
That said, there’s no agreedupon strategy for training the brain to stop sending out such strong signals of fatigue as exercise intensity heats up. So while more intuitive than based in science, Voigt’s attempt at mind over muscle could very well be the key to achieving athletic success.