Exercise isn't necessarily good for people

There's a recommendation for 150 minutes of exercise/week, but this isn't sound. People who report being active have better health. People who are fitter have better health. These are not evidence that having a person with low activity take up exercise will make them healthier.

I'm not sure where this statement comes from. Googling "exercise experiment health" in google scholar has the first 8 results be experiments, where they took an group of inactive people and made them exercise, and they showed improvement over people who did not. I didn't look beyond the first 8, but I suspect there are many more

Two studies which find that lifestyle intervention has no effect on CVD in diabetics. [11:00] One study which found that lifestyle intervention prevents Type II but doesn't affect microvascular disease (blindness and ulcers). [I'm not sure what this means. Maybe people can have the ill effects of Type II without the disease showing up in their blood sugar levels?] There are no supervised exercise-only intervention studies which show that exercise prevents long term disease progression.

Yes there are. Google "exercise cvd", you'll find several that show improvement.

It looks as though modern hunter gatherers expend about as much energy/mass as Americans on the east coast do.

The only relavent result I could find says the opposite: http://www.nature.com/ijo/journal/v29/n1/abs/0802842a.html

12% of healthy people make their blood pressure higher by exercising 150 minutes a week. 20% get little or no improvement. [42:00] Graphs of low responders for aerobic capacity, muscle mass, and insulin sensitivity.

Mixed results, not enough to show a firm conclusion either way.

Bottom line, the speaker appears to be heavily cherry-picking the studies he shows.

The idea that blood pressure is an adequate proxy for overall health is highly dubious and I wouldn't draw conclusions about longevity from it. Even if the inference was valid blood pressure is notoriously unreliable because it is affected by so many variables.

FWIW, one of my takeaways from taking subjective measurements of my happiness, motivation, etc. everyday was that by far the biggest correlation was that I was happiest when I exercised more. But again, that's not really establishing causation.

Diabetes and Heart Disease.

Type II diabetes predicts a 7 year shorter life, due to cardiovascular disease. No one knows why. It also destroys small blood vessels, leading to blindness and loss of feeling in the extremities (thence falls or infections). This is called microvascular damage and is fairly well-understood as the direct result of blood sugar. The cardiovascular disease is called macrovascular damage to imply it is similar, but it's really a smokescreen.

Timmons cites two studies of diet and exercise improving blood sugar but failing to improve heart disease. One is a small Finnish study. The other is a big American study, Lookahead, but it hasn't published yet; items 88 and 89 in its bibliography sound relevant. As background, there are two large past studies that have conflicting results on whether improving diabetes (mainly via drugs) improves CVD. 15 years ago, the UKPDS study compared aiming for 7% A1c is better than aiming for 8%. It reduced CVD, though not as much as it reduced microvascular outcomes. So 7% became the new baseline and follow-up studies were started that are only just reporting. A couple of years ago, the ACCORD trial finished comparing aiming for 6% to 7%. It found the more aggressive treatment had worse mortality (and worse CVD, though not statistically significantly). The Accord study had lower A1c targets in both arms than UKPDS, but I think it only achieved the same levels, probably because its patients were older and had more advanced diabetes.

One hypothesis that people throw around is that if you are too aggressive with drugs, you cause hypoglycemic events (too low blood sugar), and these are correlated with CVD. But if you lower blood sugar by diet and exercise, you don't expect to cause hypoglycemic events, so there was some hope that this would improve CVD, despite the Accord study. But the recent studies falsify this loophole. (Also, I think it failed to explain the detailed Accord data.)

Still, the UKDPS suggests that for some people reduced blood sugar improves CVD. Maybe microvascular problems are due to very high levels of blood sugar, at the tail end of diabetes, while CVD is due to long exposure to lower blood sugar. Perhaps for the Accord patients it was too late, but starting earlier with the UKDPS patients worked.

Added: In other words, blood sugar might just be a symptom, not a direct cause of heart disease (but definitely a direct cause of diabetic morbidity). This is not too surprising, since the mechanism isn't understood. Experiments in the past had mixed results. What's new is lifestyle experiments, in contrast to drug experiments. It is surprising that they are worse, but type of patients probably matters.

From your summary health appears to mean 'not sick.' If you can clarify what health is rather than what it is not you might be closer to an answer on whether exercise and health are related. Spoiler: yes.

There's the level of physical activity of most of my ancestors, and there's the level of physical activity of my ancestors since the clerical explosion (1800s-present). The former group has a longer track record of success than the later, and for that reason alone I'm guessing they for sure got it right (with a provisional 'not all bad' grade for the inactivity of today). Regular moderate activity of some kind with bursts of heavy activity leads to physical strength and physical grace more often than not.

It seems the results show on that some actually get worse, but I wouldn't say this is a firm conclusion that some should avoid exercise altogether. The problem with most experimental studies on exercise is that many use an across-the-board regimen for all participants that isn't customized to the individual. So, if one participant gets 30 mins a day at 70% of HRmax then all do. It is probable that some who get worse may need less or more exercise, greater or lesser intensity, resistance as opposed to aerobic, etc.

You might want to add an indicator to the title that you're not sure whether this is true or not. I think that people might treat the number of upvotes (not huge, but definitely positive) as an indication of the veracity of the claim in the title when I don't think that they were intended as such.

There's a group of 27 genes which together can 'predict' gains in VO2max.

Hmmm. 27 genes? Assuming this was done as a data mining analysis, you can always find 27 genes to fit any function. I definitely want to see cross validation results before I accept this.

Do you have predictor they're using with those genes? The original paper?

Has anybody looked into sarcopenia and resistance training can slow it's progression?

So, the conclusion here is exercise is 68% likely to do you good, and 88% likely to not harm at least.

Unless you have your relevant genome sequences. :-)

Isn't "exercise" an incredibly broad category? Saying "exercise isn't necessarily good" is a bit like saying "drugs aren't necessarily good". Obviously, there are going to be combinations of exercise and people that don't lead to good outcomes. Broken leg + running a marathon = bad.

It's possible that there are different classes of responders, and it might be possible to detect this from the data they have. I doubt that they've done the right statistical test, though- you'd be looking for a mixture of three Gaussian peaks, rather than one Gaussian which has a large enough standard deviation to be represented both around zero and below zero. (Without a link to the paper, I don't care enough to check.)

It also seems like you could check the test-retest reliability of this- record stats, have people not exercise for X amount of time, then exercise for Y amount of time, then not exercise for X amount of time, then exercise for Y amount of time. Are the people who get worse/better the first time the same as the people who get worse/better the second time? Or do the groups mix like you would expect from it being random noise?

As a general rule taking health advice from youtube video's bad.

I would doubt that the 12% adverse responders is a controlled result.

Another possibility is that the non-responders were on Statins: Can Statins Cut the Benefits of Exercise?

Diabetes in isolation doesn't increase CVD that much for men(2.4X), though the relative CVD risk increase for women are 4.3, (in absolute numbers, CVD risk for diabetic men and women are about the same). Also worth pointing out is that type II correlates to a high degree with other risk factors due to the metabolic disturbance, the cluster is termed metabolic syndrome.

I'm curious how good of a job they've done separating within-person variation from between-person variation in exercise induced changes in risk factors. I would imagine that within-person variation is pretty large, and the sort of hierarchical modeling you would use to tell these sorts of things doesn't seem that common.

I'm also very curious whether response vs. non-response to exercise correlates risk factors. If you don't gain VO2 max from exercise, does that mean you also won't see a drop in blood pressure?