This shouldn't come as a surprise; "mental" and "physical" aren't distinct entities, our bodies function as a whole. Having to state this is, I think, a reflex of an ever-present dualist view of the body (in the Cartesian sense, i.e., mind vs. matter).
As a rock climber, I can tell you that mental and physical fatigue are very distinct, very real things. But I'd have to say that before I got into climbing, I wouldn't have realized this.
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.
you're right, weight training is 80% mental. on any given day, the work isn't that hard. cumulatively it's just a few minutes of effort and you've done it a hundred times before. you know when you finish you'll feel amazing, and you know in 1 month you'll have more solid results compared to today. you know all this.
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.
Why is this kind of comment (a la "no duh, scientists!") always highly praised on the Internet and in general, even from otherwise intelligent, thinking folks??
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.
I was a scientist until a few months ago (until I finished my PhD, essentially), so - believe me - I know the value of studies which "state the obvious", even when the conclusion seems "small" (which isn't the case, anyway).
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.
For whatever it's worth, I didn't read their post that way. Unsurprising results, validating a null hypothesis, that sort of thing, they're all valuable, but this particular poster seemed to be using the opportunity to bring up their distaste for Cartesian duality and its over-appreciation by society at large. In a sense, "this shouldn't come as a surprise, but it's good they did the study since it stands as another data point in refutation of what's become standard folk dogma about mind/matter duality" -- or something like that.
In any sense, their sentiment didn't seem to be at all opposed to yours, at least to my reading.
> This shouldn't come as a surprise; "mental" and "physical" aren't distinct entities ...
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.
>For the mind, you have to ask the mind's owner what he's experiencing
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.
> 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.
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.
>From a scientific standpoint, yes, it's legitimate
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.
> 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.
I'd say no, but I'm a layman. I think the situation you describe is "just" an interaction between different systems which, together, make the whole open macrosystem which is your body. If I can push myself to go even further, I'm probably triggering something in my nervous system (via a high-level cognitive process - motivating myself, thinking "positive") which will in turn signal other systems which can then provide energy or stimulation to go on.
Some feedback loops between the brain and the rest of the body are more mysterious to me than others. F.e. the placebo effect is something I find hard to rationalize in many cases.
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.
