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Comment by wslh | Hacker News Reader

How much exercise this should be in humans?

This study is looking at one specific mechanism by which exercise may be helpful in improving some aspect of your health. It's not especially useful to look at just this study though, as it doesn't actually link to any outcomes (the telomere protective expression may or may not actually reduce your risk for cardiovascular disease).

It's more useful to look at studies that have looked at actual outcomes (e.g. reducing the incidence of heart attack or stroke, etc). In those cases, the bulk of the evidence points to 30 minutes a day, 5 days a week of moderate exercise (e.g. a brisk walk or jog) being the best 'bang for your buck'. There are certainly gains to be made by going beyond that, but the curve falls off pretty sharply, and you can get almost all the (proven) benefits of exercise at that level.

EDIT: I would suggest this YouTube video from Healthcare Triage on the benefits of exercise that are supported by good research: https://www.youtube.com/watch?v=SFBBjynBpSw

Do you happen to know if the crucial thing here is "regular" excercise? As in, is it in important to spread out the excercise over the 5 days?

Would doing the 2h30 min excercise over say, 2 or 3 days per week, amount to the same benefit?

from what i understand (not being in any way a professional in any related field), its best to even split it up during the day. 15min early, 15min late is better than 30min in a block?

so i'd assume that short times more often is better

> so i'd assume that short times more often is better

I wouldn't assume this. The logical end of this is to split your exercise into many tiny bursts throughout the day. But it's likely that sustained output is an important part of exercising. The shorter your exercise, the less likely you are to get your heart into an elevated range, the less likely you are to cause an oxygen-depleted state (which encourages vascular growth), the less likely you are to use a significant portion of your free glucose (which is important for insulin sensitivity), etc.

I don't know where the threshold is, but it seems like a bad idea to assume that shorter, more often is better. It likewise seems like a bad idea to assume that longer blocks are better (or just as good). Any exercise is far better than none, but there is a lot of support for ~30 minutes ~daily being extremely valuable. Absent evidence, I'd be hesitant to assume that some other arbitrary division of exercise would yield the same results.

> the less likely you are to cause an oxygen-depleted state

I don't know if this is a safe assumption either. What makes you think it would take more than a few minutes of acute exercise to reach an oxygen depleted state?

Basic physics. Assuming you are generally healthy, your body is not usually in an oxygen-depleted state. Therefore it will take some amount of time in a state of increased oxygen use to cause oxygen depletion. Therefore, "the shorter your exercise, ... the less likely you are to cause an oxygen-depleted state".

Depending on your fitness level and exercise level, it will take more or less time to put you into this state. An overweight, sedentary person sprinting will be there pretty much instantly. A marathon runner walking briskly won't get there in any amount of time. But all things being equal, more time exercising will be more likely to put you into an oxygen-depleted state (and glucose depleted state, and elevated heart rate).

For endurance athletes like your marathon runner, this is certainly the case. Strength and power athletes can certainly expend far more energy in a shorter time than someone who is less fit. It's a bit of a paradox where the better shape you are in, the sooner you can tire yourself out. From everything I've read, it certainly seems possible to reach oxygen depletion in a very short period of time.

https://mobile.nytimes.com/blogs/well/2016/04/27/1-minute-of...

There's not much evidence for that, and some evidence that heart health is improved by sustained submaximal exercise. In my experience the best improvements I have sustained in overall fitness have been from either very short, very brutal exercise (NOT just splitting up a dose of 30 minutes into easy sections) or from chilling out for 40-60 minutes at comparatively easy pace. The latter has been something that you can do all the time; the harsh interval training is something that seems to work in 2-3 week bursts with time off afterwards.

Anything is a lot better than nothing, but there is some evidence that there are all sorts of good effects from a longer session once in a while.

The other thing about phasing in short brutal intervals for a few weeks and mostly doing Long Slow Distance ("LSD") is that it's either over quickly or it's quite pleasant. I get most of the exercise in the more painful 'middle' of this continuum from sport.

EDIT: here's the article that got me interested in LSD style training. https://www.elitefts.com/education/training/echocardiography...

Thank you for the link! Anything sure is bound to be better than nothing, I limit my sessions to 1 hour but alternate between doing an hour of constant excercise at a slower speed (I'm a swimmer), and doing shorter burts of intensive excercise but then taking a minute or two break after 2 lanes.

Either way, I think it's easier to go for an hour 3 times a week, than doing half an hour each day. (would become a bit more pricey, and I'd lose the time of going to the pool and back each day. Not as easy to combine with other responsibilities imo)

The study says that the effect wore off in less than an hour. I suspect (though they couldn't test this) that the effect lasts as long as your are exercising and stops quickly when you stop.

At least when trying to increase muscle mass, you'd want to do short periods of intense exercise, rather than a longer period with lower intensity.

Thanks a lot for the Healthcare Triage link!

Not yet known; this research was only performed on mice so far.

Literally no way of knowing since they studied MICE not HUMANS. If you want to exercise your mouse though it might be useful...

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