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June 26 - September 11, 2019
The limits of endurance running, according to physiologists, could be quantified with three parameters: aerobic capacity, also known as VO2max, which is analogous to the size of a car’s engine; running economy, which is an efficiency measure like gas mileage; and lactate threshold, which dictates how much of your engine’s power you can sustain for long periods of time.
physiologists have found that the will to endure can’t be reliably tied to any single physiological variable.
endurance is “the struggle to continue against a mounting desire to stop.”
You judge what’s sustainable based not only on how you feel, but on how that feeling compares to how you expected to feel at that point in the race.
Knowing (or believing) that your ultimate limits are all in your head doesn’t make them any less real in the heat of a race.
what matters in many cases is how the brain interprets these distress signals.
efficiency gurus like Frederick Winslow Taylor argued that the only true limits on the productive power of workers were inefficiency and lack of will—the toddlers-on-a-plane kind of endurance. Labor reformers, meanwhile, insisted that the human body, like an engine, could produce only a certain amount of work before requiring a break
results emerging from the Harvard Fatigue Lab offered a middle ground, acknowledging the physiological reality of fatigue but suggesting it could be avoided if workers stayed in “physicochemical” equilibrium—the
rarity of deaths from exhaustion, like Henry Worsley’s. Whatever our limits are, something must prevent us from exceeding them by too much. And that something, he reasoned, must be the brain.
First, the limits we encounter during exercise aren’t a consequence of failing muscles; they’re imposed in advance by the brain to ensure that we never reach true failure. And second, the brain imposes these limits by controlling how much muscle is recruited at a given effort level
Noakes argued that physiologists’ focus on VO2max had “produced a brainless model of human exercise performance.”
There’s no doubt that some athletes are able to wring more out of their bodies than others, and those who finish with the most in reserve would dearly love to be able to reduce that margin of safety. But is this really a consequence of the brain’s subconscious decision to throttle back muscle recruitment—or is it, as a rival brain-centered theory of endurance posits, simply a matter of how badly you want it?
When their brains were tired, pedaling a bike simply felt harder.
If effort is the yin of Marcora’s psychobiological model, motivation is the yang. We’re not always willing to push to an effort of 20, which is one reason athletes rarely produce world records or even personal bests in training.
If you could train the brain to become more accustomed to mental fatigue, then—just like the body—it would adapt and the task of staying on pace would feel easier.
“intellectual labor” had sapped their muscular endurance.
physical fatigue stunted mental growth in overworked child miners,
arsenal of techniques meant to help us perform optimally—visualization, relaxation, and so on. We memorized a five-step self-talk technique for stopping negative thoughts that might arise during a race: Recognize, Refuse, Relax, Reframe, Resume.
A truly universal theory of endurance, he felt, should be able to use the same theoretical framework to explain how both mental and physical factors—self-talk and sports drinks, say—alter your performance.
just as emotions trigger a physical response, that physical response can amplify or perhaps even create the corresponding emotion.
extended this finding to clusters of related mental states: smiling, for instance, makes you happier, but it also enhances feelings of safety and—intriguingly—cognitive ease, a concept intimately tied to effort.
jaw-clenching muscles to effort. It’s no coincidence, then, that coaches have long instructed runners to “relax your face” or “relax your jaw.”
Seeing a smiling face, even subliminally, evokes feelings of ease that bleed into your perception of how hard you’re working at other tasks, like pedaling a bike.
Just like a smile or frown, the words in your head have the power to influence the very feelings they’re supposed to reflect.
Military Energy Gum, a chewing gum containing 100 milligrams of caffeine that is quickly absorbed
impulse inhibition matters because you have to suppress the urge to let your mind wander,
response inhibition really is an important mental component of endurance—and that it’s a finite resource that runs low if you use it too much.
long years of training help the mind adapt to resist mental fatigue, just as the body adapts to resist physical fatigue.
these traits are partly inherited but also can be improved with training.
His “open acknowledgment of pain as a state of mind to be combated, repressed and ultimately overcome,” Cycling Weekly opined, “is perhaps part of the reason he is revered by cycling fans as the hardman of the peloton.” Voigt
regular physical training, especially if it involves unpleasant high-intensity workouts, increases your pain tolerance.
“Pain is more than one thing,”
It’s a sensation, like vision or touch; it’s an emotion, like anger or
sadness; and it’s also a “drive state” that compels ac...
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Zatsiorsky reported that most of us can summon about 65 percent of our theoretical maximum strength. Elite weightlifters can do better, hefting more than 80 percent
The supposed reserve of muscular strength, in other words, was an illusion—a result, Merton concluded,
Under normal conditions, in other words, we’re utilizing pretty much all the strength our muscles have to offer.
possible loopholes, Enoka notes. One is that you can’t sustain 100 percent activation indefinitely, so the idea of a hidden muscle reserve makes more sense for cyclists and rowers and runners than for piano movers.
complex real-world actions make it harder to reach full voluntary activation in all the relevant muscle groups, meaning there might be some reserve accessible in stressful situations.
mind, Tom Boyle’s Camaro-hoisting
By the time you’ve been out there for about 24 hours, your leg muscles will be 35 to 40 percent weaker, and they won’t lose much more.
For ultra-endurance runs, it turns out, the muscles themselves typically only lose about 10 percent of their force-producing capacity; the rest is central, reflecting a progressive decline in the brain’s voluntary activation of muscle.
But, he adds, that doesn’t necessarily mean the brain is responsible for this decline.
Even though voluntary activation is, by definition, a reduction in the command signal from your brain, it appears to respond to what’s happening in your muscles.
Trying to make a clean divide between “brain fatigue” and “muscle fatigue,” in other words, is inevitably an oversimplification, because they’re inseparably linked.
legs are merely unwilling, not incapable. So if it’s not muscle fatigue, what is it? Both
the 10- and 40-minute trials, these EMG signals mirrored the actual force produced by the muscles, with a sharp increase in both EMG and force near the end of the trials. But in the three-minute trials, the patterns were different: while the force was gradually decreasing, the EMG signal was still increasing.
In a three-minute trial (and presumably in 800-meter races), the brain still calls for a sprint as the finish line approaches; the muscles are simply unable to obey.
The urge to breathe (which is actually driven by a build-up of carbon dioxide rather than a lack of oxygen) turns out to be a warning signal that you can choose to ignore—up to a point.
concluded that immersion in water had triggered a set of automatic responses, including a dramatic slowing of the heartbeat, that conserved oxygen.
