Epistemic Spot Check: Fatigue and the Central Governor Module

Epistemic spot checks used to be a series in which I read papers/books and investigated their claims with an eye towards assessing the work’s credibility. I became unhappy with the limitations of this process and am working on creating something better. This post about both the results of applying the in-development process to a particular work, and observations on the process. As is my new custom, this discussion of the paper will be mostly my conclusions. The actual research is available in my Roam database (a workflowy/wiki hybrid), which I will link to as appropriate.

This post started off as an epistemic spot check of Fatigue is a brain-derived emotion that regulates the exercise behavior to ensure the protection of whole body homeostasis, a scientific article by Timothy David Noakes. I don’t trust myself to summarize it fairly (we’ll get to that in a minute), so here is the abstract:

An influential book written by A. Mosso in the late nineteenth century proposed that fatigue that “at first sight might appear an imperfection of our body, is on the contrary one of its most marvelous perfections. The fatigue increasing more rapidly than the amount of work done saves us from the injury which lesser sensibility would involve for the organism” so that “muscular fatigue also is at bottom an exhaustion of the nervous system.” It has taken more than a century to confirm Mosso’s idea that both the brain and the muscles alter their function during exercise and that fatigue is predominantly an emotion, part of a complex regulation, the goal of which is to protect the body from harm. Mosso’s ideas were supplanted in the English literature by those of A. V. Hill who believed that fatigue was the result of biochemical changes in the exercising limb muscles – “peripheral fatigue” – to which the central nervous system makes no contribution. The past decade has witnessed the growing realization that this brainless model cannot explain exercise performance.This article traces the evolution of our modern understanding of how the CNS regulates exercise specifically to insure that each exercise bout terminates whilst homeostasis is retained in all bodily systems. The brain uses the symptoms of fatigue as key regulators to insure that the exercise is completed before harm develops.These sensations of fatigue are unique to each individual and are illusionary since their generation is largely independent of the real biological state of the athlete at the time they develop.The model predicts that attempts to understand fatigue and to explain superior human athletic performance purely on the basis of the body’s known physiological and metabolic responses to exercise must fail since subconscious and conscious mental decisions made by winners and losers, in both training and competition, are the ultimate determinants of both fatigue and athletic performance

The easily defensible version of this claim is that fatigue is a feeling in the brain. The most out there version of the claim is that humans are capable of unlimited physical feats, held back only by their own mind, and the results of sporting events are determined beforehand through psychic dominance competitions. That sounds like I’m being unfair, so let me quote the relevant portion

[A]thletes who finish behind the winner may make the conscious decision not to win, perhaps even before the race begins. Their deceptive symptoms of “fatigue” may then be used to justify that decision. So the winner is the athlete for whom defeat is the least acceptable rationalization

(He doesn’t mention psychic dominance competitions explicitly, but it’s the only way I see to get exactly one person deciding to win each race).

This paper generated a lot of ESC-able claims, which you can see here. These were unusually crisp claims that he provided citations for: absolutely the easiest thing to ESC (having your own citations agree with your summary of them is not sufficient to prove correctness, but lack of it takes a lot works out). But I found myself unenthused about doing so. I eventually realized that I wanted to read a competing explanation instead. Luckily Noakes provided a citation to one, and it was even more antagonistic to him than he claimed.

VO2,max: what do we know, and what do we still need to know?, by Benjamin D. Levine takes several direct shots at Noakes, including:

For the purposes of framing the debate, Dr Noakes frequently likes to place investigators into two camps: those who believe the brain plays a role in exercise performance, and those who do not (Noakes et al. 2004b). However this straw man is specious. No one disputes that ‘the brain’ is required to recruit motor units – for example, spinal cord-injured patients can’t run. There is no doubt that motivation is necessary to achieve VO2,max. A subject can elect to simply stop exercising on the treadmill while walking slowly because they don’t want to continue; no mystical ‘central governor’ is required to hypothesize or predict a VO2 below maximal achievable oxygen transport in this case.

Which I would summarize as “of course fatigue is a brain-mediated feeling: you feel it.” 

I stopped reading at this point, because I could no longer tell what the difference between the hypotheses was. What are the actual differences in predictions between “your muscles are physically unable to contract?” and “your brain tells you your muscles are unable to contract”? After thinking about it for a while, I came up with a few:

  1. The former suggests that there’s no intermediate between “safely working” and “incapacitation”.
  2. The latter suggestions that you can get physical gains through mental changes alone.
  3. And that this might lead to tissue damage as you push yourself beyond safe limits.

Without looking at any evidence, #1 seems unlikely to be true. Things rarely work that way in general, much less in bodies.

The strongest pieces of evidence for #2 and #3 isn’t addressed by either paper: cases when mental changes have caused/allowed people to inflict serious injuries or even death to themselves.

  1. Hysterical strength (aka mom lifts car off baby)
  2. Involuntary muscle spasms (from e.g., seizures or old-school ECT)
  3. Stiff-man syndrome.

So I checked these out.

Hysterical strength has not been studied much, probably because IRBs are touchy about trapping babies under cars (with an option on “I was unable to find the medical term for it). There are enough anecdotes that it seems likely to exist, although it may not be common. And it can cause muscle tears, according to several sourceless citations. This is suggestive, but if I was on Levine’s team I’d definitely find it insufficient.

Most injuries from seizures are from falling or hitting something, but it appears possible for injuries to result from overactive muscles themselves. This is complicated by the fact that anti-convulsant medications can cause bone thinning, and by the fact that some unknown percentage of all people are walking around with fractures they don’t know about.

Unmodified electro-convulsive therapy had a small but persistent risk of bone fractures, muscle tears, and join dislocation. Newer forms of ECT use muscle relaxants specifically to prevent this.

Stiff-man Syndrome: Wikipedia says that 10% of stiff-man syndrome patients die from acidosis or autonomic dysfunction. Acidosis would be really exciting- evidence that overexertion of muscles will actually kill you. Unfortunately when I tried to track down the citation, it went nowhere (with one paper inaccessible). Additionally, one can come up with other explanations for the acidosis than muscle exertion. So that’s not compelling.

Overall it does seem clear that (some) people’s muscles are strong enough to break their bones, but are stopped from doing so under normal circumstances. You could call this vindication for Noake’s Central Governor Model, but I’m hesitant. It doesn’t prove you can safely get gains by changing your mindset alone.  It doesn’t prove all races are determined by psychic dominance fights. Yes, Noakes was speculating when he postulated that, but without it his theory is something like “you notice when your muscles reach their limits”. When you can safely push what feel like physical limits on the margin feels like a question that will vary a lot by individual and that neither paper tried to answer.

Overall, Fatigue is a brain-derived emotion that regulates the exercise behavior to ensure the protection of whole body homeostasis neither passed nor failed epistemic spot checks as originally conceived, because I didn’t check its specific claims. Instead I thought through its implications and investigated those, which supported the weak but not strong form of Noake’s argument.

In terms of process, the key here was feeling and recognizing the feeling that investigating forward (evaluating the implications of Noake’s arguments) was more important than investigating backwards (the evidence Noake provided for his hypothesis). I don’t have a good explanation for why that felt right at this time, but I want to track it.

Roam

For the last few epistemic spot check posts I’ve been sharing my evidence via Roam, rather than typing it up in the post itself. Longtime readers: How is that working out for you, relative to the old system?

Epistemic Spot Check: Unconditional Parenting

Epistemic spot checks started as a process in which I investigate a few of a book’s claims to see if it is trustworthy before continuing to read it. This had a number of problems, such as emphasizing a trust/don’t trust binary over model building, and emphasizing provability over importance. I’m in the middle of revamping ESCs to become something better. This post is both a ~ESC of a particular book and a reflection on the process of doing ESCs and what I have and should improve(d).

As is my new custom, I took my notes in Roam, a workflowy/wiki hybrid. Roam is so magic that my raw notes are better formatted there than I could ever hope to make them in a linear document like this, so I’m just going to share my conclusions here, and if you’re interested in the process, follow the links to Roam. Notes are formatted as follows:

  • The target source gets its own page
  • On this page I list some details about the book and claims it makes. If the claim is citing another source, I may include a link to the source.
  • If I investigate a claim or have an opinion so strong it doesn’t seem worth verifying (“Parenting is hard”), I’ll mark it with a credence slider. The meaning of each credence will eventually be explained here, although I’m still working out the system.
    • Then I’ll hand-type a number for the credence in a bullet point, because sliders are changeable even by people who otherwise have only read privileges.
  • You can see my notes on the source for a claim by clicking on the source in the claim
  • You may see a number to the side of a claim. That means it’s been cited by another page. It is likely a synthesis page, where I have drawn a conclusion from a variety of sources.

This post’s topic is Unconditional Parenting (Alfie Kohn) (affiliate link), which has the thesis that even positive reinforcement is treating your kid like a dog and hinders their emotional and moral development.

Unconditional Parenting failed its spot check pretty hard. Of three citations I actually researched (as opposed to agreed with without investigation, such as “Parenting is hard”), two barely mentioned the thing they were cited for as an evidence-free aside, and one reported exactly what UP claimed but was too small and subdivided to prove anything. 

Nonetheless, I thought UP might have good ideas kept reading it. One of the things Epistemic Spot Checks were designed to detect was “science washing”- the process of taking the thing you already believe and hunting for things to cite that could plausibly support it to make your process look more rigorous. And they do pretty well at that. The problem is that science washing doesn’t prove an idea is wrong, merely that it hasn’t presented a particular form of proof. It could still be true or useful- in fact when I dug into a series of self-help books, rigor didn’t seem to have any correlation with how useful they were. And with something like child-rearing, where I dismiss almost all studies as “too small, too limited”, saying everything needs rigorous peer-reviewed backing is the same as refusing to learn. So I continued with Unconditional Parenting to absorb its models, with the understanding that I would be evaluating its models for myself.

Unconditional Parenting is a principle based book, and its principles are:

  • It is not enough for you to love your children; they must feel loved unconditionally. 
  • Any punishment or conditionality of rewards endangers that feeling of being loved unconditionally.
  • Children should be respected as autonomous beings.
  • Obedience is often a sign of insecurity.
  • The way kids learn to make good decisions is by making decisions, not by following directions.

These seem like plausible principles to me, especially the first and last ones. They are, however, costly principles to implement. And I’m not even talking about things where you absolutely have to override their autonomy like vaccines. I’m talking about when your two children’s autonomies lead them in opposite directions at the beach, or you will lose your job if you don’t keep them on a certain schedule in the morning and their intrinsic desire is to watch the water drip from the faucet for 10 minutes. 

What I would really have liked is for this book to spend less time on its principles and bullshit scientific citations, and more time going through concrete real world examples where multiple principles are competing. Kohn explicitly declines to do this, saying specifics are too hard and scripts embody the rigid, unresponsive parenting he’s railing against, but I think that’s a cop out. Teaching principles in isolation is easy and pointless: the meaningful part is what you do when they’re difficult and in conflict with other things you value.

So overall, Unconditional Parenting:

  • Should be evaluated as one dude’s opinion, not the outcome of a scientific process
  • Is a useful set of opinions that I find plausible and intend to apply with modifications to my potential kids.
  • Failed to do the hard work of demonstrating implementation of its principles.
  • Is a very light read once you ignore all the science-washing.

 

 

As always, tremendous thanks to my Patreon patrons for their support.