Squat Every Day, page 8
Until a mouse runs across the trail. In the face of a panicky elephant, the rider’s illusion of control vanishes. The elephant’s going where it wants. A tiny rider just doesn’t have the equipment to strong-arm a two-ton elephant.
This has led psychologists to propose dual-process theories of thought, which very roughly divide into fast but unconscious and slower but deliberative forms of thinking. As Daniel Kahneman writes, the elephant ― which he labels System 1 ― is a fast, intuitive thinker who works in metaphor and associations. System 1 is automatic and quick, but at the cost of accuracy. Our elephant is limited to connections which are immediate in space and time, giving it a considerable set of blind-spots. The rider, System 2, is more deliberative and capable of thinking beyond the here and now but, being newer and comparatively weaker, also slower to act. System 2 demands a cost in both time and energy, and as a result most of our thinking defaults to the lazier, faster options provided by System 1.31
As modern neuroscience continues to discover neurological correlates of behavior, underlying structures and functions of the brain that repeatedly show up with particular thoughts and behaviors, we find more support for the “two minds” view. Our abstract-thinking selves are evolutionary late-comers, a ramshackle network of circuits built around the far more stable and fine-tuned structures of the inner brain ― structures shared with other mammals, birds, and reptiles.
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University of Iowa’s Antonio Damasio spends a lot of time with defective brains. During his career, he’s investigated the origins of consciousness and intelligent decision-making, and has written several books on his findings.32
While it’s long been known that damage to the brain’s frontal lobes – the center of System 2’s reasoning – often leads to behavioral problems, including a profound loss of self-censoring and inappropriate social behavior, Damasio’s work has helped understand why this happens.
His research has included patients with damage to a specific part of the frontal lobes called the ventromedial cortex (VMF). In several studies, Damasio’s team gave VMF-damaged subjects tasks designed to test decision making abilities. They’ve found that, time after time, these subjects simply can’t make good choices. They’re indecisive, and when they do choose, they’re more likely to make bad decisions compared to control groups. This bad decision-making often leads to more high-risk “stupid” behavior, not to mention socially-inappropriate outbursts and violence.
You can’t talk about frontal lobe damage and behavior changes without mentioning the oft-told tale of railroad worker Phineas Gage, who had a three-foot long, one and a quarter inch diameter iron rod rammed through his skull in a blasting accident. Gage, who survived and was even conscious and speaking within a few minutes of his injury, suffered a complete change of personality and temperament. So profound were the changes that Gage’s physician Dr. John Harlow later wrote that “his mind was radically changed, so decidedly that his friends and acquaintances said he was ‘no longer Gage.’”
Damasio’s tests with VMF-damaged patients show that they’ve lost no intelligence. Compared to their lives before injury, IQ tests, factual knowledge, and language skills are all unchanged. On paper, these people are at least as smart as they were before their injury.
But something had changed. In an experiment testing responses to provocative images, two groups with normal and intact brains and the experimental group with damage to the VMF were tested for emotional reactions by skin conductivity. Skin conductivity tests, a measure of involuntary emotional arousal, are very difficult (if not impossible) to fool. Healthy control subjects responded as expected, with a detectable emotional reaction.
The patients with VMF damage? Nothing. While the intellect remained intact, the expression and experience of emotion had been compromised.
How can it be that people who pass all the intelligence tests, and showed none of these defects before their injury, are nevertheless unable to make good decisions or act right when they know better?
Remember that our brains carry around a body map that creates our internal feelings of “bodiness”. Damasio proposes that our emotions are actually changes in that self-image, what he calls the somatic state, and further, these emotional changes guide our decision-making and problem-solving powers.
It happens that the VMF connects with several old-brain regions that handle our response to fear, the sensations of our inner body states, and the connection between the brain and the rest of the body. The network between these regions forms what Damasio calls the “body loop”. It’s the VMF’s job to associate conscious information with our past emotional responses. Damage the VMF and your reasoning abilities are no longer “colored” by emotional intuitions.
It sounds strange that reasoning would be so tied in with emotional reactions, but emotion colors your thinking in profound ways. When you look at that slice of chocolate cake and you know you want it, that’s an obvious emotional response influencing your choice. Or when you see a lion and think, “Holy crap, it’s a lion. I better get out of here”. The feelings are clear.
Have you ever looked at something, or maybe someone, and found what you saw disgusting but had no idea why? You decide you don’t like a pair of shoes, or find yourself really attracted to a potential partner, but can’t quite say why that is. You just know, even if the reasons aren’t clear, and that kind of unconsciously biased thinking drives more of your behavior than you might realize.
Damasio calls this the somatic marker hypothesis. Emotion pares down our options and colors our choices to the point that we aren’t effective decision-makers without those feelings.
Now where this gets interesting is in a second, related circuit which Damasio calls the “as if body” loop. In this circuit, the frontal cortex can avoid the actual sensory input and activate emotional memories “as if” we’d just experienced them. The “as if” feature is why we can imagine movements, or pain, or just about any other sensation and almost feel it happening. It also means that our thoughts and memories can trigger emotions and physical reactions.
Not only are we incredibly sensitive to our body’s state of being, but we can also affect it with our thoughts.
CNS Voodoo
Nervous-system or “CNS” fatigue has become a modern-day buzzword right up there with overtraining. Don’t train too hard or you’ll burn out the nervous system. I’m at least partly to blame for spreading awareness of this phenomenon, and don’t mistake me, it’s a real thing, but the concept has mutated beyond recognition.
Sports science, on the other hand, has a clearer definition. Fatigue is just a fancy way of saying that you’re tired and not operating at peak capacity. The question is, what’s getting tired? Better, is anything tired at all?
Being a body-oriented profession, we naturally focus on the heart and lungs, in endurance athletes, or muscles in the case of more strength-dependent activities. We easily relate to tired muscles, legs made of jelly after a long run, or when you can’t raise your arms after a hard shoulder workout. The muscles themselves have been worked into paste and can no longer sustain the activity. Or, in the case of endurance athletes, you’ve reached your VO2 max and can no longer keep up the pace because your lungs are burning.
When the tiredness happens in the working tissues, we call this peripheral fatigue.
But there’s more. Sports scientists noticed something fishy while playing around with electro-stim devices, which apply an electric current to a muscle and cause it to contract involuntarily. When you do this to a fatigued muscle, the contraction isn’t quite as hard as you’d expect in a fresh counterpart. This makes sense, since the muscle itself is tired and forcing it to contract won’t change that.
Under some circumstances, though, you can apply current to a tired person and the muscle contracts just fine, like it’s not tired at all. Yet when asked to contract the muscle voluntarily, the subjects can’t do it. Researchers labeled this central fatigue, since there’s no obvious cause of tiredness in the muscles. The loss of performance is due to central causes ― that is, happening in the brain or spinal cord, better known as the central nervous system (CNS).
South African sports scientist Timothy Noakes suggested an explanation for this phenomenon, focusing on the brain and its damage-control features. According to Noakes, we experience fatigue as a specific sensation that alters our perception of effort as our bodies do work and grow tired during physical activity, and we can measure this conscious perception of difficulty with the rating of perceived exertion (RPE), a value that rates how hard you’re going compared to your theoretical best-effort. We’ll see a lot more about this later.
Noakes’s central governor hypothesis says that the feeling of difficulty, measured by the RPE, gradually increases during a workout, and in response our neural output ― central drive to the working muscles ― drops off. We’re often physically capable of doing much more work, at a higher effort, than we typically do, but from a survival standpoint, voluntarily working to a point of catastrophic failure isn’t the best idea.33
Noakes suggests that the brain pulls back on the throttle as a protective measure. The sensation of “tiredness” is our psychological experience of this protective mechanism. Our limits, both in endurance and in maximum intensity, are in part physical and in part psychological (although in reality there is no distinction between the two, as I’ve suggested).
The governor isn’t a particular cluster of neurons or any part of the brain that we can point to and say “fatigue happens here”. Like many brain functions, the governor is intended as a shorthand for the behavior of many (many) networks spread throughout the brain acting together. Whatever the governor really is, if Noakes is right it acts like one of Antonio Damasio’s somatic markers, taking feedback from the body ― from muscle tissue and the cardiovascular system in this case ― and integrating it into a bodily sensation.
Fatigue can be triggered by a stunning range of signals, as everything from ammonia and oxygen content in your blood to the availability of neurochemicals in your brain and the feedback from receptors in your muscles and joints works into the calculation of just how tired you are.
This is the kind of fatigue that you can overcome by reaching down and digging in your heels. You can make that last quarter mile; you can grind out that 10kg squat PR if you grit your teeth and keep it moving. Since nothing is actually “tired” in the way we tend to think, you can grunt your way through it with an executive override. It won’t be pleasant, however, because you’re working against the survival instincts built into your brain.
Intriguingly, mental fatigue by itself can trigger the fatigue effect without any need for you to actually do anything. A 2009 paper from Samuele Marcora’s team at Bangor University in Wales tested the effects of mental fatigue on high-intensity cycling. Subjects given a complicated mental task before the cycling test couldn’t keep up the pace compared to the control group.34
Marcora’s team suggests that mentally-demanding tasks fatigue the anterior cingulate cortex (ACC), another part of the brain important for its role as a junction between your body-sense and your conscious perception of effort. During exercise, the autonomic nerves fire on all cylinders to keep heart rate and blood pressure and everything else working in “exercise mode”. The ACC plugs that information in to our conscious minds and we experience it as “hard work”.
When you go exercise after spending half the day studying differential equations, you’ve worn out your ACC and the exercise feels much harder than it should. Marcora argues that the perceived difficulty itself may cause you to cut off a workout before any genuine physical fatigue sets in.35
There’s no “handbrake” in the brain as in Noakes suggests. Instead, as we exercise and gradually tire out, neural output from the brain has to increase to keep up the pace. That increased output translates into feelings of difficulty. Fatigue happens when the feeling out-does your motivation to keep going and to ignore the pain.36
We don’t have to worry over the nuances of the scientific back-and-forth. The competing models differ in detail but agree on the key point: the brain is receptive to physical signs of fatigue as well as being the site of mental fatigue. The two fatigue processes seem to share many of the same circuits, and both involve changes in brain activity that we experience, subjectively, as feelings of difficulty and a loss of performance. Likewise, those same fatigue-induced changes lead directly to “coping behavior”.
Or, more simply: As exercise feels harder, whether from mental or physical tiredness, you’re more likely to stop doing it and it’s more likely to make you feel bad afterwards.
Calling fatigue an altered brain state or an illusion of the senses isn’t meant to discount the feeling. The sensation itself may be “just a feeling”, but the change in brain state, and the reduction of neural output, most assuredly is not. Fatigue markers can impair performance just as sure as any injury.37
Confirming this, Romain Meeusen of Belgium’s Vrije Universiteit has shown that the feeling of fatigue happens as a consequence of altered neurological activity, specifically the behavior of two important neurotransmitters.38
Back in 1987, Eric Newsholme proposed that transmission of serotonin in the brain increases during exercise, leading to feelings of lethargy and contentment as well as a perception of fatigue. Newsholme called this the serotonin hypothesis of fatigue.
Meeusen’s research found that elevated serotonin is only half of the central fatigue equation. Dopamine, another neurotransmitter involved in motivation and motor control, also increases during intense exercise. But Meeusen found that, at the point of exhaustion, dopamine levels drop off sharply. We experience central fatigue after that dopamine crash, while serotonin is still high, and itfs this ratio between dopamine and serotonin that matters in our perception of tiredness.39
Meeusen warns that there is no one pathway that completely governs fatigue. Serotonin and dopamine, while likely an important piece of the puzzle, are only two players in a complex game of arousal and inhibition. He points to the brain’s store of glycogen fuel, which is a paltry 1.5 grams when maxed out, as another factor worth consideration. The brainfs energy usage is so high that even small changes in glycogen make a big difference in our perceived energy levels. Intense focus and concentration depletes brain glycogen, perhaps explaining why studying all night, or spending 10 hours behind the wheel, wears you out.
Thinking and Willing
Modern thinkers haven’t given much credence to free will. The entire concept has been called into question on scientific and philosophical grounds, with many wondering if the idea even makes sense given the cause-and-effect determinism of the physical world. Every effect having a clearly-defined cause seems to rule out the idea of thinking beings able to act of their own volition.
Although the issue is far from settled, we do have some hints that willpower does exist in some sense, insofar as “free will” means that we can make conscious decisions and then act on them (in contrary to more impulsive or emotional desires) ― as in a moral choice or, perhaps closer to home, avoiding the cake while on a diet.
In this sense, willpower does exist, but if the findings of Florida State psychologist Roy Baumeister are any indication, it’s a limited resource. In a series of experiments, Baumeister has repeatedly found that people who exercise their willpower for one thing, say turning down a cookie while hungry, or doing complex math problems before making a decision, are more likely to give in future temptations.
We’ve seen that our brains operate in (roughly) two modes: System 1, the unconscious emotional self, which is impulsive and attracted to shiny things, and then the rational System 2 that keeps the books and turns down beer. Those self-control circuits, remember, are relatively new features of the mammal brain, and they spend much of their time not only doing math or making decisions, but also in choosing which impulses to ignore or restrain.
Resisting temptation, doing complex problem-solving or making a challenging decision wears it out just as if you were standing there flexing your guns. Baumeister calls this ego depletion.40
The ego, in Freudian parlance, is literally the “self”, what you talk about when you say “I”. When you throw your ego’s mental weight around, enforcing your rational edicts over your animal passions, Baumeister argues that you’re draining a reservoir of limited energy. This is no metaphor, as “the self” depends on the brain’s supply of glucose (echoing Meeusen’s earlier point about glucose turnover). When we’re low on energy, willpower is quickly exhausted (and conversely, when we top up our blood sugar, willpower recharges). You literally exhaust your ability to focus and muster up the “oomph” to get anything done.
The will exists, says Baumeister, but it exists by degree. Anything that calls on our self-regulation resources, which includes diets, being nice to obnoxious people, sitting in traffic, doing complex math problems, or driving yourself through intense exercise, depletes that reserve and leaves you vulnerable to temptation.
We’ve already seen the connection between mental exhaustion and exercise performance as a potential candidate for central fatigue. Confirming that the phenomenon isn’t limited to endurance activities, research from Kathleen Martin-Ginis reveals that ego depletion also impairs maximum strength, as measured by the ability to complete a hand-grip test.41
Deplete your supply of willpower, even doing something totally unrelated, and your ability to generate force and push through fatigue signals is equally diminished.
Not only that, but it seems like exhausting your self-regulation powers dials up the intensity on the signals flowing in from the body. The activity of ACC, which you’ll recall as a key junction between conscious mind and unconscious sensation, drops off during intense concentration, leaving you extra sensitive to any and all emotional stimulus. You feel everything, like hunger or the screaming burn in your legs, more profoundly when your willpower is depleted.
