youzicha:

nostalgebraist:

youzicha

replied to your post

“bartlebyshop replied to your post “Question: are there any tests of…”

I mean, we *do* say e.g. “yes, he is very fit”. This is only informative because there is a positive correlation between many/all kinds of fitness. Doesn’t this mean that we already use the concept of a “general fitness factor”, similar to how we talk about intelligence?

Yeah, that is definitely true – but I think the way in which we talk and think about these two “general factors” is still very different.

In the fitness case, we see statements like "yes, he is very fit" as casual shorthands, and when we think of what it means to have a scientific understanding of fitness, we think of finer- and finer-grained breakdowns of the different dimensions and systems that are bundled together in the world “fit.”  For example, “he’s aerobically fit” is more multi-dimensional and more “sciencey” than just “he’s fit,” and if you want to get really sciencey, you break that down into even more dimensions by talking about, say, his VO2 max and vVO2max.

In the case of intelligence, we are told that the “sciencey” way to think about things is to focus on the coarse-grained, one-dimensional thing.  Books are written about how, even though the general public doesn’t but much stock in the one-dimensional thing, scientists think it’s really important and well-founded.  If exercise physiology were like intelligence research, it’d be all about one-dimensional fitness and what it correlates with, how it varies between groups and over one’s lifetime, etc.  (Try paging through some paper titles from the scientific journal Intelligence and mentally replacing “intelligence” and the like with “fitness.”  A strange scientific field from an alternate universe!)

I guess my impression of what “we are told”, and generally where the fault lines are in this debate, is a bit different from yours.

I would say IQ fans are generally interested in the details of how intelligence arises. Earlier today someone linked to a paper that claims they can decompose g into separate ‘reasoning’, ‘short term memory’, and ‘verbal’ components, but I’d expect everyone to agree that, if that holds up, it’s a more “sciencey” model than the one-dimensional one. Similarly, some of the early intelligence researchers tried to correlate IQ with nerve transmission speed, which shows that they were trying to isolate the causal mechanisms behind the statistical phenomenon. And finally, when I see people blog about IQ, they also seem interested in e.g. comparing verbal and quantitative SAT scores for different populations; i.e. even when they talk about descriptive statistics they seem interested in more than one dimension.

At the same time I think it is also possible to find situations where a one-dimensional measure of fitness is seen as “more sciencey”. It’s certainly possible to find papers with “fitness” in the title, but what comes to mind for me is epidemiological studies about BMI. There are lots of studies about obesity epidemics, comparisons of BMI distributions of different countries and how it correlates with various diseases, how that should influence health advice, and so on. It’s clear to everyone that a single number is not a perfect measure of anything, but the style is very “scientific”.

Instead, I think the key disputed part seems to be whether to use descriptive statistics at all. For example, the Amazon book blurb you link to states,

Just mention IQ testing in polite company, and you’ll sternly be informed that IQ tests don’t measure anything “real” and only reflect how good you are at doing IQ tests; that they ignore important traits like “emotional intelligence” and “multiple intelligences”; and that those who are interested in IQ testing must be elitists, or maybe something more sinister.

Yet the scientific evidence is clear: IQ tests are extraordinarily useful. IQ scores are related to a huge variety of important life outcomes like educational success, income, and even life expectancy, and biological studies have shown they are genetically influenced and linked to measures of the brain.

I haven’t read the book, but from the description, I would expect he is not arguing against things like the Hampshire et al. 3-factor model, but against people who claim this sort of thing cannot be quantitatively measured at all.

Similarly, there is a split about whether BMI guidelines are useful advice (“look at these correlations”), or despicable body-shaming (“one can be healthy at any weight”).

I’m in a bit of a rush but I thought about this stuff on the bus, so I will write something quick and I hope it makes sense –

Keep reading

(via youzicha)

exercise →

exercise

perversesheaf:

nostalgebraist:

On the other hand, changing the amount of fat in your body is famously difficult.  It’s hard to get people to lose nontrivial amounts of weight (or gain nontrivial amounts of weight, through methods other than muscle-building exercises) even if you’re running a study and can order them to do extreme things because they signed a consent form.  Losing weight through exercise isn’t impossible, at least not for everyone, but describing it as “low-hanging fruit” seems very inaccurate.  It’s a strategy that many, many people have put large amounts of time into for, in most cases, remarkably little effect.

I thought it was fairly well known that weight and body fat is most a function of diet, not exercise? E.g. you can lift as many weights as you want, but if you aren’t eating more than your base metabolic rate, you aren’t going to gain weight. 

This is a really complicated and controversial area, which I don’t want to pretend to be any kind of expert in.  Certainly you can’t gain muscle if you eat too little (or get too little protein).  Beyond that, though, my impression is that aside from strength training, which actually works, weight and body fat aren’t functions of much of anything.  People have weight set points, and the body will work very hard to keep you near yours.  (Obviously this is not true in literally every case, as there are examples of people who have lost large amounts of weight and kept it off, etc.)

There are all kinds of other ideas out there, like the idea that carbohydrates make the body gain weight (advocated by Gary Taubes among others) and Seth Roberts’ idea about changing your set point by eating flavorless food at certain times.  I get the sense that none of these work all that well for your average person, or else the numerous people out there who want to lose weight and are willing to try anything once would have converged on the really effective one.

(via perversesheaf-deactivated201508)

exercise

People have been talking about exercise as a possibly quick and easy route to improve one’s physical attractiveness.

It seems to me like this could mean two very different things.  If you have enough androgens in your system, it is pretty easy to build some muscle if you don’t have any.  Strength training doesn’t take much time per session, and it’ll have amazing marginal effects if you go from not doing it to doing a bit of it.  Telling guys who don’t work out to do some pushups regularly, or the like, certainly sounds like “low-hanging fruit” and good advice.

On the other hand, changing the amount of fat in your body is famously difficult.  It’s hard to get people to lose nontrivial amounts of weight (or gain nontrivial amounts of weight, through methods other than muscle-building exercises) even if you’re running a study and can order them to do extreme things because they signed a consent form.  Losing weight through exercise isn’t impossible, at least not for everyone, but describing it as “low-hanging fruit” seems very inaccurate.  It’s a strategy that many, many people have put large amounts of time into for, in most cases, remarkably little effect.

I get the sense that when people say things like “you can improve your appearance very easily with a little exercise,” they mean something like the “do some basic strength training regularly” idea, but it makes many people think of their struggles to lose weight, and seems totally wrong if you interpret it in the latter way.