Mental fatigue impairs physical performance in humans (2009)
jap.physiology.org
jap.physiology.org
In one critical sense, the mind and body are distinct. The body can be scientifically investigated because it yields objective, empirical evidence. For the mind, you have to ask the mind's owner what he's experiencing, and that leads to all sort of well-documented distortions.
> ... our bodies function as a whole.
Most of the time, yes.
This isn't really a legit distinction. Describing "the mind" as separate from the body because we don't know how it works is like describing cancer or AIDS as separate from the body because we don't know precisely how they work. All of cancer, HIV, and thought stem from biological processes that we don't fully understand. That doesn't mean they are somehow not the body, it just means we don't understand the body.
From a scientific standpoint, yes, it's legitimate. We can gather unambiguous empirical data about the brain and the body, the meaning of which different observers will accept, but we cannot do that for the mind.
> All of cancer, HIV, and thought stem from biological processes that we don't fully understand.
Yes, but we can diagnose the first two objectively, so they're much more objective and scientific than what people choose to report about their minds. A microscope image of a pathogen has it all over someone's verbal report that he's sick.
Consider this example -- a trained actor can simulate all the symptoms of Alzheimer's, such that a psychologist will provide the diagnosis (as they regularly do), but that same actor will not get the diagnosis from a neuroscientist using an MRI scanner, because the latter method can produce an objective diagnosis that the former cannot.
> That doesn't mean they are somehow not the body, it just means we don't understand the body.
It's all relative. We may not fully understand the body, but we understand it much better than the mind. This is why psychologists have had to abandon promising diagnoses repeatedly over the decades -- such diagnoses often create a huge public uproar, then they're discredited, then they're abandoned. Psychologists can make a popular diagnosis like Asperger's disappear by removing it from their diagnostic manual (as they recently did), but that doesn't work for cancer and heart disease, because the latter conditions are real.
No, sorry, it isn't. You can't gather empirical data about 'the mind' because it is a category you made up to describe a set of symptoms but which you are confusing for an entity.
No, I'm not doing that, psychologists are. And psychologists insist that the mind is a suitable topic for scientific investigation. You've managed to confuse me with a group that I spend much of my time criticizing for their scientific pretensions.
This particular connection really seems kind of obvious. My amateurish explanation would be that every voluntary muscle movement has to be actuated by brain activity, and hard workouts require a lot of muscle steering. If the brain is tired (which means its stores of energy or some other chemicals/transmitters are lowered/exhausted) it becomes harder for it to induce muscle activity.
Since when have we been okay with "no duh" being our source of information? Come on guys, we have to figure shit out before we get to say "no duh", and then instead of saying "no duh" (which is another word for "common sense", which we all laugh heartily about in other contexts) we get to cite the studies and the research that provides a strong correlation.
In any sense, their sentiment didn't seem to be at all opposed to yours, at least to my reading.
My previous comment wasn't meant as a "no, duh", really. I'm sorry it came out that way. I'm highly favourable to studies which prove "common sense" (or disprove: those I live even better!). The comment was just to share my opinion: the fact that this kind of studied is shared (here, and in other media) highlights how dualism is still basically the common sense view.
There are times when you are physically capable of completing a climb, but your mental tiredness prohibits you from doing so. The very nature of climbing is scary, and your brain knows this. It's not just fear of heights, but fear of falling, and even failing. Every move you make is a little fatigue on your mind. You have to calculate it out, make the move, and beat all your fears at the same time.
Over the course of a climbing session, your mind wears down. You may be physically able to complete a climb, but your mind is just giving up. The stress overwhelms you. You give up.
There is another non-rock-climbing example. In Arnold's bodybuilding book, he talks about the mental aspect of bodybuilding. Not just in competition, but also in training. He gave an example of some famous bodybuilder who was having a bad day. He couldn't do some deadlifts (I think) that he was totally capable of doing, even with Arnie cheering him on. The guy was about to give up. Then a bunch of his fans showed up, and he wasn't about to disappoint them. He completed his set with ease.
but damn, sometimes you just want to quit for no reason at all. i've come so close to just walking out in the middle of my workout for absolutely no reason whatsoever. this is even after you've gone to the actual gym, which is a whole 'nother story.
it's really fascinating.
See: https://en.wikipedia.org/wiki/Golgi_tendon_reflex and http://www.wisegeek.com/what-is-the-golgi-tendon-reflex.htm
What's interesting is that I usually hit PRs immediately after a mental fatigue, but a week or so afterwards it catches up with me and my performance in the wightlifting hall goes down.
If you feel like you're not improving, change something.
Weightlifting is mostly mental discipline, acquired via training. A very large percentage of the increased weight you can move is due to improved form and increased recruitment of the existing muscle tissue. (This is why newcomer gains are so large.)
Just make sure you give it enough time to make sure it's truly a plateau (measured in weeks or months depending on how long you've been training). Bouncing around to a new barbell program every 2 weeks will do you little to no good.
Two things about the methodology leave me wondering. They gave a 50-pound prize to the top performer on the mental fatigue tests. Couldn't this work against the study as a demotivator? I'm thinking in particular of the other studies showing monetary rewards have a negative performance effect on demanding cognitive tasks.
Second, why neutral mood documentaries? Neutral mood doesn't to me make something obviously not mentally demanding. It does sound relatively lower mental effort, but as a research paper methodology, it doesn't seem to prove it, and I feel like there are better options. Why not meditate, for example, or just lie down for an hour listening to soothing beach sounds or something like that?
Here, the test subjects were simply subject to some cognitive loading.
Nothing "doh, obvious" about this.
We know that there is a connection between mental alertness and muscle coordination and drive, but it's not obvious that these can be eroded simply by cognitive activity; essentially a "software" problem.
I wonder if this extends into the positive as well, do cognitive boosting drugs (nootropics?) enhance your performance.
Yes. Dextroamphetamine is considered a PED and is banned in (some? all?) professional sports. The Orioles' slugger Chris Davis was suspended a couple years ago for using it. But it is a CNS drug; I believe it is most commonly prescribed to people with ADHD, to improve their focus.
From the conclusion at the end: "... mental fatigue limits exercise tolerance in humans through higher perception of effort ..."
So, according to them, it's the perception that changes with mental fatigue, not because there is any physiological reason to be tired.
When you exercise, the increase in cortisol results in a 50% increase in endurance compared to if there was no cortisol increase, at least in rat experiments [1].
Given that cortisol is involved in both mental alertness and physical endurance, it seems like it could be a plausible reason for this finding.
1. https://www.researchgate.net/profile/Mehis_Viru/publication/...
Even if the overall idea is obvious, these effects are good to validate and quantify.
For instance, this is a bit less obvious: “[...] physiological responses to intense exercise remained largely unaffected. Self-reported success and intrinsic motivation related to the physical task were also unaffected by prior cognitive activity. [...] our study provides experimental evidence that mental fatigue limits exercise tolerance in humans through higher perception of effort rather than cardiorespiratory and musculoenergetic mechanisms.”
It would be interesting to do follow-up studies with larger groups of participants to figure out how much variation there is in the effect between different people, or whether there are any ways to reduce the subjective impression of effort to mitigate the apparent throttling effect of mental fatigue.
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The paper has been cited nearly 300 times in the past 6 years, so it’s probably not completely useless. https://scholar.google.com/scholar?cites=957481530281065221&...
In such a case, please either flag the article and move on, or post something substantive about its specifics.