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Mike41

Exercise not too much!

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https://bjsm.bmj.com/content/54/24/1499
 

the above research used accelerometers on a large group over many years. Conclusion not much movement needed to lower mortality. The sweet spot about 35 minutes moderate exercise. That is enough to overcome the downsides of a lot of sedentary time.

 

Conclusion

Higher sedentary time is associated with higher mortality in less active individuals when measured by accelerometry. About 30–40 min of MVPA per day attenuate the association between sedentary time and risk of death, which is lower than previous estimates from self-reported data.

Key messages

What are the findings?

  • Moderate-to-vigorous-intensity physical activity and sedentary time as measured by accelerometry can be combined differently to reduce the risk of premature death.

  • High amounts of sedentary time (>10.7 hours per day) is associated with higher risk of mortality, especially in those with low or very low levels of moderate-to-vigorous intensity physical activity.

  • In active individuals doing about 30–40 min of moderate-to-vigorous-intensity physical activity, the association between high sedentary time and risk of death is not significantly different from those with low amounts sedentary time.

How might it impact on clinical practice in the future?

  • Our work may inform the development of future recommendations for physical activity and sedentary time by WHO and other public health authorities.

  • Individuals who currently must spend large amounts of time sedentary due to work and transportation should aim to achieve the upper recommended level of 150–300 min of moderate-to-vigorous-intensity physical activity per week

 

Edited by Mike41

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Yes, I was surprised too: 

AlPater

  • Posted November 26
  • Joint associations of accelero-meter measured physical activity and sedentary time with all-cause mortality: a harmonised meta-analysis in more than 44 000 middle-aged and older individuals.
    Ekelund U, Tarp J, Fagerland MW, Johannessen JS, Hansen BH, Jefferis BJ, Whincup PH, Diaz KM, Hooker S, Howard VJ, Chernofsky A, Larson MG, Spartano N, Vasan RS, Dohrn IM, Hagströmer M, Edwardson C, Yates T, Shiroma EJ, Dempsey P, Wijndaele K, Anderssen SA, Lee IM.
    Br J Sports Med. 2020 Dec;54(24):1499-1506. doi: 10.1136/bjsports-2020-103270.
    PMID: 33239356
Edited by AlPater

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Contrary to the suggestion of this thread's title, the study Mike references doesn't address the issue of how much exercise may be too much. In fact it doesn't even address the issue of how much exercise is optimal. It simply claims to show that it only takes 30-40 minutes of exercise per day to mostly reverse the deleterious effects of too much sedentary time. From the paper's discussion:

The association between sedentary time and higher risk of death appears attenuated, although not completely eliminated, in those in the highest third of time spent in MVPA. 

The catch is that 30-40 minutes was the maximum level of exercise they binned their study participants into, so it says nothing about whether more exercise than that would have further reduced the mortality rate of their subjects, either those who were sedentary or those who weren't.

Plus, while the authors tried to statistically compensate for underlying health conditions, reverse causality can't be ruled out in this kind of epidemiological study. In other words, people who were sick and likely to die during follow-up were also likely to spend a lot of time being sedentary and less likely to capable of even a small amount of moderate physical activity per day. Those who could must ever a little exercise were the ones where were less sick and therefore less likely to die.

--Dean

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Such studies are very frustrating. As Dean rightly points out, they didn't do much to account for many confounders.

That said, the health impact of sedentary behavior is an extremely important topic - if nothing else, because so many people (including me!) are compelled to work in a sedentary position. Now, there are all sorts of measures one can take - and Dean is a stellar example - of treadmill desks and other solutions, but that is not always possible when you're working at an office or have to go in for the day or whatnot. Even standing vs sitting is controversial, with some researchers claiming that standing (still) has its own set of problems, such as increased blood pressure and on the whole many not be much better if at all than sitting. 

So I am very interested in this topic, unfortunately, this study doesn't tell us much.

 

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2 hours ago, TomBAvoider said:

with some researchers claiming that standing (still) has its own set of problems, such as increased blood pressure and on the whole many not be much better if at all than sitting. 

Where I work, standing still for long times is considered a source of occupational risk for the pathology of varicose veins.

Edited by mccoy

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3 hours ago, Dean Pomerleau said:

Contrary to the suggestion of this thread's title, the study Mike references doesn't address the issue of how much exercise may be too much.

True, although the authors do say this: "Those with as little as 11 min per day of MVPA in combination with ‘low’ sedentary time (ie, <8.5 hours per day) did not differ in risk compared with the referent group (ie, highest third of MVPA in combination with lowest third for sedentary time)."

Then we have this:

Too Much Running Tied to Shorter Life Span

O'Keefe, who reviewed the findings, believes there may simply be "too much wear and tear" on the bodies of high-mileage runners. He has researched the issue and is an advocate of moderate running for the best health benefits. Chronic extreme exercise, O'Keefe said, may induce a "remodeling" of the heart, and that could undermine some of the benefits that moderate activity provides.

In O'Keefe's view, the "sweet spot" for jogging for health benefits is a slow to moderate pace, about two or three times per week, for a total of one to 2.5 hours.

"If you want to run a marathon," he said, "run one and cross it off your bucket list." But as a general rule, O'Keefe advises runners to avoid strenuous exercise for more than an hour at a time.

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17 hours ago, Ron Put said:

True, although the authors do say this: "Those with as little as 11 min per day of MVPA in combination with ‘low’ sedentary time (ie, <8.5 hours per day) did not differ in risk compared with the referent group (ie, highest third of MVPA in combination with lowest third for sedentary time)."

Then we have this:

Too Much Running Tied to Shorter Life Span

O'Keefe, who reviewed the findings, believes there may simply be "too much wear and tear" on the bodies of high-mileage runners. He has researched the issue and is an advocate of moderate running for the best health benefits. Chronic extreme exercise, O'Keefe said, may induce a "remodeling" of the heart, and that could undermine some of the benefits that moderate activity provides.

In O'Keefe's view, the "sweet spot" for jogging for health benefits is a slow to moderate pace, about two or three times per week, for a total of one to 2.5 hours.

"If you want to run a marathon," he said, "run one and cross it off your bucket list." But as a general rule, O'Keefe advises runners to avoid strenuous exercise for more than an hour at a time.

Kenneth Cooper founder of the Cooper institute and so called father of aerobics and who trained astronauts for NASA has said for decades that exercise is a two edged sword. He long ago also said jogging more than 15 -20miles a week is not a good idea for non athletes. And the only reason it may be a good idea for athletes is about performance not long term health.

https://www.cooperinstitute.org/2015/06/how-much-of-a-good-thing-is-too-much/

Edited by Mike41

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