More exercise = more I.Q.?

By Razib Khan | September 16, 2010 9:54 am

Uni_Freiburg_-_Philosophen_Interesting post by Gretchen Reynolds reviewing the evidence on exercise and intelligence. The title is “Phys Ed: Can Exercise Make Kids Smarter?”, so this is definitely seen as something which is “actionable” in a public policy sense, especially in light of the increases in obesity among young people. Intuitively I think most people are going to agree with this in the United States. In fact, when you’re down with the flu or some other illness you are generally less productive (most of the films I’ve watched over the past three years have been when I’m ill since I can’t focus on difficult material), so there’s probably going to be a natural connection made between greater cognitive function with greater health.

First, Reynolds points to a study which shows that:

1) The most fit children are more intelligent than the least fit as adduced from psychometric tests

2) The most fit children ‘had significantly larger basal ganglia, a key part of the brain that aids in maintaining attention and “executive control,” or the ability to coordinate actions and thoughts crisply.’ The researchers controlled for socioeconomic status and body mass index,

A second study indicated that the fit children had better working memory and greater hippocampal volume. Finally, an earlier study using data from Swedish conscripts showed that even among identical twins the fitter ones were more intelligent. Note that the primary author was the same on the first two studies. Before commenting further how about looking at some tables and/or figures from the papers?


The first image has two tables from the first paper, the second two images are from the second paper, and finally, the last is from the last paper.

no images were found

As most of you know just because papers make it through peer review doesn’t imply that they’re going to stand the test of time. Over the years I’ve also gotten more and more skeptical of neuroimaging results, primarily because there’s now psychological evidence that images of brains add to the credibility of research in a very irrational fashion. To really understand the first two studies you probably have to be a cognitive neuroscientist, in particular, one with some background in psychometrics. The last study is more straightforward as you’re comparing dizygotic and monozygotic twins, and seeing the correlations between traits as a function of genetic relatedness. The latter are genetically identical, in theory if not totally in practice, so one presumes that the differences may be environmental.

Perhaps, but it depends on what you label “environment.” We may be seeing differences which derive from random events in the fetal environment, or during early stages of development. Aspects of fitness are often correlated. If athletic and intellectual prowess are both embedded in numerous genetic and physiological pathways, which seem likely, then variations due to stochastic aspects of development may affect both trait clusters in the same fashion.

In other words I’d say to make a strong case for the efficacy of exercise and aerobic health as a driver of higher intelligence we should wait for more research. On the other hand there are plenty of data on the value of aerobic health more generally, and the downsides of obesity, so there are other grounds on which to move forward. I suspect if these sorts of studies get into the Zeitgeist you’ll have pretty dumb books published soon with titles like “How 1 hour of exercise a day can give you 10 I.Q. points! (as shown by studies!)”.

Note: A quick lit search yields papers like this, so I’m not totally clear that there are robust long term cognitive benefits to exercise, though in some cases there seems to be.

Image Credit: Michael Schmalenstroer

CATEGORIZED UNDER: Health, Select, Social Science
  • Chris T

    I wouldn’t be surprised if there was some link between staying in shape and better mental function (better metabolism and more efficient oxygen transport for starters), but papers that make these types of logical leaps get kind of annoying and really mislead the general population. It seems genetics is far more complex than most psychologists realize.

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  • Georg

    Publius Ovidius Naso
    exclamated “orandum est , ut sit mens sana in corpore sano.”
    when he got sight of the athletes in Olympia.
    Georg

  • Ali

    but how does this explain Steven Hawkings , he has a great IQ and is on a wheelchair!

  • joek

    maybe it’s the computer hawkings speaks through who says things that are smart.

  • llortenstein

    “but how does this explain Steven Hawkings , he has a great IQ and is on a wheelchair!”

    Yeah. I know a few sickly people who are really smart too. Statistics don’t explain them either. One of them is even black! Take that, “psychometrics”.

    And IQ doesn’t even measure intelligence anyway, it’s just a test. People who like test-taking will always score higher. I’d guess people like me and Ali who prefer to excercise outside, shooting hoops and such, are actually disadvantaged on these “IQ tests”.

    So, this study is B.S.

  • http://Untitledvanityproject.blogspot.com Rhacodactylus

    First off, to Ali (who I think was kidding) and llortenstein (who I don’t think was), statistics is actually about predicting trends, outliers do not in any way invalidate a general trend, we all know men who are short and women who are tall, but that doesn’t change the fact that women are in general shorter than men, it’s a straw-man to imply that Razib or the study was saying that there is an infallible 1 to 1 relationship between physical health and intelligence, and I don’t know where your racial angle came from.

    Secondly, you just claiming that people who play basketball are at a disadvantage on tests, or putting “IQ Test” in quotes aren’t real arguments . . . they are at best flawed rhetoric.

  • Chris T

    IQ is a rough measure of the current operating definition of intelligence. It does an excellent job predicting life outcomes and is very stable across a person’s lifetime. Furthermore, a number of physical correlates have been found over the last couple of decades suggesting that it does in fact have some physical basis. So your contention that it is ‘just a test’ is belied by how useful it is.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    no idea who was joking or not :-)

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  • Matthew

    they would need to do a “training” study to see if intelligence is improved in individuals who go from being unfit to fit via aerobic training

    i have also come across some research that indicates that exercise activity levels are to some extent inherited (in mice it is pretty clear that spontaneous activity level has a genetic basis), so it remains to be seen whether the increased activity causes the higher intelligence or is something that goes along with it

  • huh

    Looks like some just can’t grow out of the pick on the fat kid phase.

  • Miguel Madeira

    Reading the article, these seem more a correlation between “fitness” and “executive function” than a correlation between “fitness” and “IQ”.

  • Katharine

    4 and 6:

    It’s ‘average’, not ‘every’.

  • Katharine

    Are you sure they were joking, Razib?

  • Katharine

    Hey! Even we smart and nerdy types with IQs quite a bit above the 1-standard-deviation range can be fit too!

    I’m not so bad off myself fitness-wise and I also have a professor who runs 100-milers in her free time.

    (I think 100-miler runners are a little nuts, but.)

  • llortenstein

    “I don’t know where your racial angle came from.”

    I was just pointing out why IQ tests and statistics (lies damned lies and statistics) can’t be used to judge human worth. IQ tests purportedly show blacks are not as smart as many other people. So, since I know some really smart blacks, that invalidates the legitimacy of gathered statistics on IQ, just like how Ali pointed out that the theory highlighted in this post would dictate Stephen Hawking can’t have a high IQ, since he is very sickly, god bless his soul. In short, the exceptions invalidate whatever “trend” these soothsayers are projecting on their crystal ball.

    Another point against this study is that black people love basketball, so since they do not get a benefit on the IQ tests from said physical exertions, this study is B.S., like all “psychometricks”. Just hand-waving nonsense used as an excuse to talk down to people who are not like them.

    The Nazis used similar theories as an excuse to exterminate people, we must never ever ever forget.

  • Chris T

    Katherine – It’s funny, but I’ve known and worked with scientists for my entire life (my dad is a geologist and I work in a biology lab) and the stereotype of the non-physical intellectual is completely wrong in my experience. It’s impressive how athletic and active many scientists are; dare I say well above the general population. I’ve known the opposite too, but way more of the former.

    llortenstein – No one here has said anything about the moral worth of people being dependent on IQ and you may want to read up on what an average is. You can’t use individual examples to contradict aggregated data unless someone is making an absolute claim – which no one is.

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  • http://Untitledvanityproject.blogspot.com Rhacodactylus

    Haha, ok first I’m not sure you know what “invalidate” or “trend” mean since you are using both incorrectly, and I’m pretty sure you affirmed my fears that you weren’t joking. Outliers do not invalidate a trend, there will always be exceptions in any basic bell curve, they don’t eliminate the underpinning correlation.

    And second, I call a Godwin’s Law foul – first to mention Hitler or the Nazis = loser of the discussion =)

    Razib, a basic statistics lesson may be in order ;-)

  • Chuck

    llortenstein Says…

    “I was just pointing out why IQ tests and statistics”

    I’m having trouble telling whether or not llortenstein is being facetious. Either way, he presents a good caricature of the product of liberal education.

    We have the reflexive IQ-race connection and dogmatic antiracism. (“One of them is even black! Take that, “psychometrics”.”…”Just hand-waving nonsense used as an excuse to talk down to people who are not like them”)

    We have the typically presumption that intelligence defines worth — and the absurd reversed naturalistic fallacy that, since humans are equally worthy, everyone, therefore, must be equally intelligent.

    We are presented with categorical thinking instead of statistical thinking. We are told, for example, that deviations disprove the case, which makes no sense when talking about mean averages. (“Stephen Hawking can’t have a high IQ, since he is very sickly”)

    We have the typical selective anti-empiricism. (“And IQ doesn’t even measure intelligence anyway, it’s just a test.”)

    We even have argumentum ad Hitlerium. And the fallacious conclusion that since ideologically loaded science was misused, the problem is the science, not the interpretive frames used (above)

  • Chris T

    I’m having trouble telling whether or not llortenstein is being facetious. Either way, he presents a good caricature of the product of liberal education.

    I think we’ve entered ‘satire indistinguishable from reality’ territory.

  • Miguel Madeira

    The second image goes against the conclusions – according to that, the low-fit group have higher iQ than high-fit group.

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This blog is about evolution, genetics, genomics and their interstices. Please beware that comments are aggressively moderated. Uncivil or churlish comments will likely get you banned immediately, so make any contribution count!

About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at http://www.razib.com

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