POWER UP ON INSTANT ENERGY
The new psychology behind peak performance.
KARL MELTZER HAD RUN NEARLY 2 100 KILOMETRES ON THE APPALACHIAN TRAIL before he thought about giving up. He was in a maple forest near McAfee Knob in Virginia. He’d camped on the trail the night before but woke up exhausted, dreading another 80km slog. He’d already run almost two marathons a day for 32 days. He’d scampered over the White Mountains of New Hampshire and chop-stepped through the rock gardens of Pennsylvania. “It was one of those mornings when my body just wasn’t working,” he says. “I had no energy left.” He set off alone anyway, before dawn. If he was going to break the AT speed record, running 3 500km in under 46 days, he couldn’t rest. Not even for a morning. He didn’t get far. After a few kilometres, exhaustion overwhelmed him. He lay down in the dirt and fell asleep. It wasn’t a long nap – “Maybe 20 minutes?” Meltzer says – but it gave him the strength to make it a few more kays to his
support van, where he had a sleeping bag and mattress. He woke up three hours later, still feeling weak. He was sick of eating peanut butter and jam sandwiches from his bum bag and dealing with ticks. Meltzer lay there in his hot van, thinking of the hundreds of kilometres he still had to run. For the first time, he began to doubt whether he could make it. “When your muscles are junk is when you start wondering, ‘Why am I doing this? What’s the point?’” Although he did pull off two more sections of 11km and 16km each that afternoon, fuelled by half a litre of ice cream and some fried chicken, he collapsed in bed before 7pm. It was his worst day on the trail.
The next morning wasn’t much better. “I was in such a shitty mood,” Meltzer says. “And it’s like 5am, and I’m a couple of kays in, and I’m just not feeling it.” Meltzer had failed to break the AT record twice; maybe he just couldn’t do it at all. Maybe, at 48, he was too old. Maybe he wasn’t tough enough. “I’m thinking all these negative thoughts, how I’m super-fatigued and I still had so far to go,” Meltzer says. “Honestly, going on didn’t seem possible.”
BACK IN THE EARLY 1920S, THE BRITISH physiologist and Nobel laureate Archibald Hill and his colleagues began running around a grass track while exhaling into rubberised canvas bags strapped to their backs. The objective was to measure the oxygen consumed at various speeds. It was at this point that Hill, a serious middle-distance runner, found that running creates an “oxygen debt” as muscles demand far more oxygen than your lungs can provide. Although your body tries to erase this debt – that’s why respiration and heart rate increase – it’s never enough. When you run fast, you’re denying your body the air it needs to create energy.
Hill’s insight was that this oxygen debt had far-reaching consequences. Based on some previous experiments on frog legs by Frederick Hopkins (another Nobel laureate) and physiologist Walter Fletcher, Hill concluded that muscles forced to generate energy without sufficient oxygen produced a toxic byproduct: lactic acid. If the muscles continued to contract, then the acid accumulated in the cells, causing a distinct burning sensation.
This chemistry set a hard limit on performance. It doesn’t matter how determined you are to keep going; the acid always wins. In his Nobel speech, Hill made this clear: “Ultimately, the muscle is a chemical mechanism,” he said. “If we were aware of all the chemical events, we should know all that was necessary about the machine which we are studying.”
It’s hard to overstate the influence of Hill’s science. It was written into countless textbooks, a chemical explanation for athletic performance. Over time, lactic acid became a scapegoat for gym rats, exercise buffs, and Olympic announcers. When your body gives out or your muscles ache the day after a workout, this compound is typically cited. Lactic acid is what stole your energy, making your body stop when your mind wanted it to go on.
This is what Meltzer seemed to be up against on his 33rd morning on the AT. Although he’d won more 160km trail races than any other runner in the world, he couldn’t outrun the laws of chemistry. After thousands of kilometres without a day off, his muscles must have been acidic jelly. It’s no wonder he found himself napping in the dirt.
But here’s the thing: Karl Meltzer didn’t stop. He didn’t care about a hard chemical cap. He just kept going.
IFIRST MET DR HOLDEN MACRAE, A PROFESSOR of sports medicine at Pepperdine University, at a shopping mall in Malibu, California. MacRae is 61, but his sinewy body is testament to his lifelong interest in athletic performance. When MacRae talks about his research, which has transformed the science of energy, he inevitably brings it back to his own mountain biking. “That’s part of the test,” he says. “Can I use these ideas to understand and maybe improve my own performance?”
When MacRae started out as a scientist, conducting experiments on athletes in the lab of Professor Tim Noakes at the University of Cape Town, the science of human energy seemed mostly settled. Peak performance was about staving off inadequate oxygen delivery and avoiding the build-up of acid for as long as possible. That’s why trainers were obsessed with such stats as VO2 max, a measure of the maximum amount of oxygen that can be consumed and utilised by an athlete. According to this model, endurance freaks like Lance Armstrong – with his VO2 max of 84, about 46% higher than normal – owed their success to their highly efficient cardiovascular systems. They didn’t run out of energy, because their muscles didn’t run out of oxygen.
It didn’t take long for MacRae to realize that the existing paradigm was terribly oversimplified. Take the so-called lactate threshold, that chemical point past which lactic acid levels increase rapidly and muscles shut down. MacRae concluded that the threshold was largely a statistical illusion, a byproduct of scientists failing to collect enough blood samples during difficult workouts. “The theory had been that once you get past 2 to 4 millimoles of lactate, you’re going to feel really fatigued,” he says, citing a standard blood measure of lactic acid. “But what we found is that if you actually measure lactate levels in people competing in half marathons or long bike races, their lactate levels can get up around 6 or 7 millimoles and their performance is not degraded. If you’re saying that they’re stopping due to the lactate accumulation, then those levels should lead to contractile failure [in the muscles]. But that’s not what we saw at all. They were still going strong.”
How was this possible? One of the first clues came from the research of Håkan Westerblad at Sweden’s Karolinska Institute. In the mid-1990s, Westerblad began using mouse muscle to replicate those frog-leg studies that led Hopkins and Hill to blame lactic acid for muscle failure. Westerblad made one other crucial change to the protocol. Instead of doing the studies at room temperature, he conducted them at the rodents’ body temperature, which is about 25 degrees higher. This change made all the difference: The muscles now continued to function even when they were saturated with acid. More recently, scientists have shown that lactic acid can actually benefit fatigued muscles, making it easier for cells to contract. The chemical that once stole our energy is now being described in scientific literature as a performance-enhancing drug.
Perhaps the greatest refutation of Hill’s chemical model didn’t even require a lab. In many competitions, athletes often experience a phenomenon known as the end spurt, a speed burst near the finish line when they’re most fatigued. Such spurts are a defining feature of many great performances, whether it’s LeBron James chasing down Andre Iguodala in game 7 of the NBA Finals, or Mo Farah, whose last 100-metre push in the 10 000-metre final at the Rio Olympics was four-and-a-bit seconds faster than his first 100. For the chemical model, these spurts are a paradox,
since fatigued athletes should have little energy left. The body should be falling apart, not speeding up.
These phenomena led MacRae and Dr Noakes and their fellow renegades to conclude that the science of athletic performance was all wrong. “For nearly 100 years, people have been told that they get tired because their muscles get tired,” Dr Noakes wrote. “That’s in all the textbooks on exercise physiology and athletic coaching. Students everywhere around the world are still being taught this. But it’s not true.” This raises the obvious question: if the acid in your muscles isn’t slowing you down, then why do you think you’ve run out of energy? What’s holding you back?
For MacRae, the answer is simple. “What stops you is up here,” he says as he taps his head. “It’s all between the ears.” Take the end spurt: according to MacRae, this is proof that athletes have a tremendous reserve capacity. “Most of the time, people don’t tap into this reserve,” he says. “We’re scared of the challenge. If you really want to understand top athletes, you have to study that reserve. You have to ask yourself: how do I tap into that? How do I hack my brain so I can perform at the highest level?”
This is the dilemma Karl Meltzer was wrestling with in that Virginia forest. It didn’t matter how many kilojoules he consumed or how much Red Bull he chugged; he still had no energy. But then he started thinking about his family, how his wife and his father had been supporting him on the trail, and he realized that he needed to change his attitude. “I just told myself, ‘Karl, you’ve got to turn off that negativity switch,’” he says. “‘You came out here to be successful. Shut up and do it.’ That was what I needed to hear. I knew then that I didn’t need to stop.” Meltzer ended up running more than 80 kilometres that day, finishing the last kays in the dark, the bobbing light of his headlamp showing the way.
TIMOTHY NOAKES, NOW AN EMERITUS professor at the University of Cape Town, became curious about human energy during medical school, when he decided to run the 86km Comrades Marathon. On his third attempt, Dr. Noakes ran into a physiological wall: he was 21km from the finish when his muscles rebelled, utterly “depleted of energy, their connective tissues coming apart.” He assumed he would drop out of the race. But then something strange happened: he kept running, energised by the spectators along the road. Their cheers pulled him through.
This experience led Dr Noakes to become interested in the psychological side of energy. When he was suffering through those last kilometres, it wasn’t a sugary drink that saved him, or a brief rest to suck up some oxygen. Rather, it was the sight of those other people. This was a run that chemistry could not explain.
It took decades of research, but Dr Noakes would eventually develop a theory of energy regulation that he calls the “central governor”. In essence, the central governor is a software script in your brain that controls your physical performance, generating a feeling of fatigue to preserve your body. While Hill thought human energy levels were reducible to the laws of chemistry, Dr Noakes argued that the reality is more complicated; and that your sense of energy is a subjective mental construct based on countless variables, from skin temperature to the cheers of the crowd. “I am not saying that what takes place physiologically in the muscles is irrelevant,” Dr Noakes wrote. “What I am saying is that what takes place physiologically in the muscles is not what causes fatigue.”
As evidence, Dr Noakes cites his studies of cyclists during a 100-kilometre time trial. When the cyclists were in the midst of a sprint, Dr Noakes found a steady decrease in electrical activity in their quadriceps muscles. This suggests that the brain was reducing the overall number of muscle fibres it was trying to activate; the central governor was systematically shutting down the body. While the cyclists thought their legs were running out of energy, the reality was that they had stopped asking their quads to contract.
The big challenge for an athlete, then, is to reprogram the central governor, to train the mind to get more out of the body. As Dr Noakes points out, in the final stages of a marathon only a third of muscle fibres in the leg are active. Plus, levels of ATP – the molecule used to transport energy within cells – almost never fall below 60 to 80% of their resting value. This suggests that we still have plenty of energy left. The central governor is just too clever to use it.
The good news is that scientists have come up with tricks and treatments you can use to reliably increase your sense of energy and perform at higher levels. Some are simple, such as cooling your skin during exercise. (Your brain measures exertion by monitoring changes in body temperature, so a cooler body leads to lower levels of perceived effort.) Others are mischievous, and involve giving athletes false information about their performance by slowing down the clock, doctoring the odometer, or getting them to compete against a “previous” performance that was subtly improved.
Your brain can also be influenced by motivational cues. In one recent study, researchers at Bangor University asked people to pedal to exhaustion, going at 65% of peak power for as long as they could. While the study participants were sweating, the scientists exposed them to either a smiling face or a frowning face for 16 milliseconds – far too brief for conscious awareness. Despite the fact that the cyclists couldn’t discern the face – let alone its expression – the ones exposed to the smile stayed on the bike for 178 seconds longer, or 12% of the total time. The smiling face made exercise feel easier, so those cyclists were able to go a few extra laps.
And then there are the chemical fixes. Giving athletes acetaminophen before a race makes them go faster – this mild pain reliever numbs the central governor. A variety of stimulants, from amphetamine to caffeine, have a similar effect. Because energy is a state of mind, waking up your brain can make you less sensitive to the tired state of your body. (Unfortunately, the opposite is also true: doing a tedious cognitive task before a workout can dramatically impair endurance.)
Interestingly, many of these treatments also work as placebos. In other words, coaches don’t need to dose athletes with stimulants or painkillers to improve their performance; merely convincing them that they did so is enough. In one study, rinsing endurance cyclists’ mouths with a sugary beverage helped them go faster during a time trial, even though they didn’t swallow any. Subsequent research showed that the rinse turned on the brain’s reward regions, thus tricking it into believing that kilojoules had been ingested.
The question, of course, is how you can translate this
research into performance. It’s one thing to know that energy is largely a state of mind. It’s something else entirely to not feel so tired you need to stop. Karl Meltzer doesn’t have all the answers. “I’ve been saying it’s all in your head for 20 years,” he says. “Doesn’t mean I understand it, though.”
THEY CALL IT THE BEAST. FOR NEW CADETS at West Point Military Academy, the Beast is basic training, that arduous introduction to military life. A typical day during the Beast begins in the dark, with a zero dark thirty wake-up, followed by 90 minutes of running and calisthenics. Then it’s a shower and a quick breakfast followed by a morning of classroom lectures. After lunch it’s training time, when cadets learn to assemble and fire their M4s, march in formation, and complete difficult obstacle courses. Evening is for homework, and something called “mass athletics”. It’s lights out around midnight.
This challenging routine goes on for six weeks, culminating in what’s known as the Graduate March Back, a 19km slog in the August heat with a heavy pack. “Basic training is designed to stress the cadets,” says West Point’s Mike Matthews, a professor of engineering psychology. “We have six weeks to turn them into soldiers. That means teaching them that they’re tougher than they think.”
It’s easy to overlook the remarkable nature of this transformation. Before these cadets showed up at West Point, they were typical American teenagers. They slept in, played video games, and struggled to do 50 push-ups. But in just over a month, the academy resets their central governors. The cadets are able to handle tests of endurance that only a few weeks before would have been unimaginable.
The Army does this by consistently emphasising the mental side of performance. The hardest parts of the Beast – like the long marches, or sleeping alone in the woods in a wet uniform – are framed as tests of will and grit. Nate Zinsser, director of West Point’s performance psychology programme, is tasked with training cadets in the psychological principles of elite performance. “People think it’s all about doing more at the gym,” Zinsser says. “But the hardest part is often changing the way you think about yourself. When the crap hits the fan, what ends up limiting you is usually not your body. It’s that voice in your head telling you that you can’t do it.”
Zinsser tells the story of Dan Browne, the first West Point cadet to run a sub-four-minute mile. To prepare for the race, Zinsser got Browne to do a relaxation exercise, followed by a guided visualisation in which he ran the entire mile in his head. “I wanted him to think about how he would react when his legs got heavy and fatigue set in,” Zinsser says. “Is he going to tell himself he’s in trouble? Or is he going to say, ‘I can do this, I can do this, I just need to hang on.’” In the imagination exercise, Browne ran a 3:58 mile. Two days later, when he stepped onto the actual track, he ran the exact same time.
What can the rest of us learn from West Point? First off is the importance of making exercise social. It doesn’t matter if it’s CrossFit or a running club – you’re much more likely to push your limits when you’re surrounded by other sweaty people. That’s because your central governor isn’t just monitoring the chemistry and mechanics of the muscles – it’s also keeping track of the athletes around you.
The second lesson involves changing the way cadets think about fatigue. “If these cadets get six hours of sleep, that’s a miraculous accomplishment,” Zinsser says. “And it’s easy to feel that exhaustion and just say, ‘I’m done.’” But West Point teaches cadets how to push past the exhaustion and thus wring more out of their bodies. “I can lecture them about the psychology, how their thoughts determine what their muscles are capable of,” he says. “But it’s better for them to experience it for themselves. They need their own narrative of, ‘I went through hell but I made it.’”
MELTZER’S LAST DAY ON THE TRAIL BEGAN as usual, with a mug of coffee and cream, chugged in the dark. He’d already been on the trail for 45 days; he didn’t want to sleep in his van again. The only problem was that the finish line was 136km away. It took him 23 hours of straight trail running, but he ran those last kilometres in an end spurt for the ages, coming down Springer Mountain at 3:38am. He broke the record set by Scott Jurek by nearly half a day. Meltzer celebrated with a cold pizza and a warm beer. When I ask him why he wanted to run the trail faster than anyone else, I was hoping for some thoughts on the nature of human possibility. But Meltzer is no philosopher. “The bottom line is, I do these things because I want to talk about them later,” he says. “The faster you go, the sooner it’s all over.”