Exercise Tied to Lower Risk for Some Types of Cancer

It's an interesting idea, but it would really need to be explored further. There's many things I see as variables that could cause the effect with the house maids, like an overly broad definition of house maids, or wrong assumptions about the type of exercise they get.

That's a very interesting experiment, however, at least from how it's described in that article, I don't think it's anywhere rigiorus enough to draw any conclusions from.

> One possible explanation is that the process of learning about the amount of exercise they were already getting somehow changed the maids' behavior. But Langer says that her team surveyed both the women and their managers and found no indication that the maids had altered their routines in any way. She believes that the change can be explained only by the change in the women's mindset.

I think that they're too quick to dismiss a change in behavior. Simply asking someone (and their managers‽) if they did anything different this month than they did last month isn't a very reliable way to figure out if there were any subtle changes in behavior.

I don't know if they were expecting massive conscious changes, but I would be shocked if suddenly knowing that their daily routine is good for them didn't change some of the subconscious decisions they were making. Even just simple things like taking the stairs 10% more than they did before or how they decide when and how much to eat based on a certain level of hunger. You're still going to think "I took the stairs sometimes, but took the elevator when I needed it." or "I ate the same foods that I did before." but maybe you were taking smaller portions.

Basically what I'm trying to say is that it's very hard to draw hard quantitative conclusions from vague qualitative assessments.

Not all physically active careers are dangerous. Off the top of my head I can think of mail carrier, garbage collector, movers.

This is directly related to a comment I posted on another article two days ago[0].

This may seem more surprising than it actually is, because by "overweight" and "obese" they are referring to BMI categories, according to the abstract. The overweight BMI category contains people who range from healthy, lean and muscular (think muscular gym goer) to people who have little muscle mass and high body fat percentage (think large beer belly). The fact that you can decrease cancer risk by gaining muscle (usually from increased exercise, precisely the thing being studied) and losing fat while maintaining the same physical mass and thus the same BMI, is not shocking.

Once you control for body fat, having additional muscle mass (thus higher BMI) probably decreases all-cause mortality.[1]

Unfortunately, I don't think this has much bearing on azdle's questions, since people can be fit for many reasons, either by intent or by necessity.

0: https://news.ycombinator.com/item?id=11714249 1: http://annals.org/article.aspx?articleid=2499472

I'd guess it doesn't really prevent cancer so much as boost your immune system so it can eliminate early tumors.

>Phew, 186 thousand cancers included out of 1.4 million participants? I knew cancer was not entirely uncommon but... man. That's a lot of unhappy news. Feels bad to think about.

2 out of 5 will get cancer during their lifetime.

http://www.cancer.gov/about-cancer/what-is-cancer/statistics

Doesn't that just mean that people who have cancer (and maybe don't know it) don't really feel like exercising?

It's conjectured that fasting kills (pre)cancerous cells by basically starving them when they fail to downregulate their metabolism under a calorie deficit. Perhaps exercise could have a similar effect in diverting energy from higher-cancer-rate cells (skin, digestive tract linings, endometrium, etc.) to lower-cancer-rate cells (muscle cells)?

I remember as a kid I used to play soccer 1 hour bike away from home. One week I had a bad flu, but I decided to go anyway. The next day I felt mostly cured. I expected that exhaustion (2 hours biking + 2 hours somehow intensive soccer amongst PE teachers .. really exhausting) would worsen the disease but it did not.

Few times since I could notice that in lesser scales.

Maybe increase blood flow, increased metabolism, endorphins, etc do help keeping your system active instead of going in suspend mode while the immune system reacts alone.

Just yesterday I had this metaphor of biology being a gyroscope, the more it spins the more it can dodge.

HR stands for Hazard Ratio. 0.5 would mean something is half as likely as for the control group, while 2 would mean twice as likely.

0.37-0.89 is the confidence interval at 95% confidence. So it's expected that if the study were repeated many times, the HR would appear to be within that (rather wide) range 95% of the time. This time it's 0.58.

The main thing is that the upper bound 0.89 is quite a bit less than 1, so you could pretty confidently say there's a reduced risk, even if the amount is uncertain.

John Oliver pointed out that the media usually distorts what the studies say. He failed to flag the problem of junk science in high-prestige journals.

(Edit: I just re-watched his segment. He does talk about P-hacking and perverse incentives, which is at least a reasonable-size chunk of the problem, just not the failure mode for this particular study.)

I haven't read the paper itself, but even if it didn't explicitly note these caveats, it would be assumed by any reader in its intended audience.

The problem is the press representation of the papers as something they're not.

These types of papers should be published, because they are necessary to decide which hypotheses to test with interventional studies.

the problem is that on noisy data, that adjustment of the variables isn't really as statistically clean as maths would say.

it's the same with red meat causes cancer studies. they say they remove smoking and lack of exercise and still wave the statistical significance.

it's very questionable how they removed the influence of these variables, since meat eaters do smoke way more, and do not exercise, and care about their health less.

The correct study is one where some participants get an intervention to make them exercise more, and some are left alone. There's no ethical issue, but running such a study would be difficult and expensive.

Adjusting for BMI does not solve the problem, because there are many things besides BMI (unmeasured confounders) which affect both cancer risk and willingness to exercise.

Statistically significant does not prove anything, and it does not mean the difference would be large either.

Healthy for the mind, sure. For you cardiovascular system? I doubt it.

you want a randomized study? :D

This depends greatly on what type of sport was practiced for 20 years.

I'm talking about a healthy athlete, not one that it's into professional sports and actually destroys his body or hearth with substance abuse.

> I read that cold water burns some calories as well?

Not very many. An 8oz cup of water at 40F burns 2.1 calories to warm up to body temperature.

Yeah, compelling is what I meant.