3 ms·

19 subjects, assigned sedentary or active based on habitual physical activity levels. Subjects were screened on basic health measures. The problem with this is

by jsw97 3mo ago

19 subjects, assigned sedentary or active based on habitual physical activity levels. Subjects were screened on basic health measures. The problem with this is that people are sedentary or active for a variety of health-related reasons that are not captured in any screen (esp. the crude one used in this study). As a predictive study, this is fine, sedentarism predicts a lot of bad things. But it doesn't, on its own, suggest that becoming active is helpful. See also grip strength and mortality.

adam_arthur 3mo ago
The principle of what you're stating is true, it could be correlational. But there's an enormous volume of evidence that exercise, especially intense exercise, is better for health than any other intervention, including more sleep, quality of diet, pills+supplements (except those that treat an active illness/disease of course). There's even compelling data showing that moderate drinkers who exercise live longer than non-drinkers who don't exercise. Even given that Alcohol is a powerful carcinogen. The only thing proven more effective than exercise is weight loss really, if starting from high bodyfat levels. (Anything above ~15% bodyfat in men seems to have negative implications for lifespan, and ~30% for women)
- makeitdouble 3mo ago
  > specially intense exercise That sounds like a study that is pretty tough to control for, especially long term and at scale. You'd need to find subjects that are provably capable of sustaining intense exercise as a habit if they wanted to but never did, and won't either for the years you'll be following them. That won't work in the reverse, as people can be consciously or not self adjusting based on the health conditions you're trying to check. PS: I'm remembering a friend who never liked running, but tried pretty hard after being pestered by their doctor and family, to discover that their knees are just not good and their whole lineage hated running for a reason. Intense exercise can be anything else, but people won't know their real health limitations until they actually do it for a while.
  - adam_arthur 3mo ago
    A large volume of studies already exist. That intense exercise is good, and even very good for you, is proven as far as reasonably possible given that we can't run deterministically controlled experiments. More evidence may come out that adds nuance, but the effect size is so large that it becomes obvious in the data just from observation. You can cycle or stationary bike if you have bad knees. There are plenty of exercises that are intense but easy on the joints.
    - makeitdouble 3mo ago
      I am aware of that for exercising, but was ignorant of what "intense" actually means in this context. And you're right. Looking around, the simplest wording I get: > the intensity must be high. This means that you need to really exert yourself so you get out of breath. [https://norwegianscitechnews.com/2026/05/exercise-a-very-little-goes-a-long-way/ https://norwegianscitechnews.com/2026/05/exercise-a-very-lit...] So if climbing the stairs gets someone out of breath it's intense (and I also see how getting to your limits, whatever they are, can help)
      - adam_arthur 3mo ago
        Yeah, typically "intense exercise" is implying HIIT style cardio. More and more studies have been indicating that even just a few minutes of intense exercise can outperform long/slow LISS type cardios. E.g. 5m all out effort is probably better, or at least equivalent, for health than a 30m moderate effort. The average person can likely hit the 80/20 benefit threshold at less than 30m/week.
        Swizec 3mo ago
        > More and more studies have been indicating that even just a few minutes of intense exercise can outperform long/slow LISS type cardios. For best results run fast and far. During my personal best marathon (3h 15min) my heart rate averaged in the 170 range
- faangguyindia 3mo ago
  >(Anything above ~15% bodyfat in men has negative implications for lifespan, and ~30% for women; when reviewed at scale) Can you link evidence for this? I stay at 12% year around as male (confirmed via DEXA)
  - adam_arthur 3mo ago
    The claim comes from this study: https://www.acpjournals.org/doi/pdf/10.7326/M15-1181 https://www.acpjournals.org/doi/pdf/10.7326/M15-1181 Though to be clear, there aren't a ton of studies that look at bodyfat percentage. Most use BMI and similar measures. Likely overall fat levels matter more than %, I'd guess. E.g. I'd presume being 15% at very muscular levels is less healthy than 15% at moderate. (Because absolute fat mass plus visceral fat would be higher)
  - Jweb_Guru 3mo ago
    Sounds like absolute BS to me. Even in very large scale studies specifically designed for studying mortality, only morbid obesity has been negatively correlated with lifespan. There is even some evidence that being a little overweight is actually helpful for the very old (essentially, because it gives them more buffer if they get sick enough that they stop eating for a while). A lot of this is because modern medicine has gotten very good at treating stuff like diabetes and other stuff caused by obesity. Your quality of life will undoubtedly improve if you are thinner, but that's not the same thing.
    - andsoitis 3mo ago
      [dead]
    - adam_arthur 3mo ago
      https://pubmed.ncbi.nlm.nih.gov/36756765/ https://pubmed.ncbi.nlm.nih.gov/36756765/ Lowest risk is around 18-20 BMI in this recent study, which controls for many confounding factors not controlled for in other studies. Other studies show slightly higher troughs, but often don't sufficiently control for correlation of weight with health in elderly people. From this study: Estimates of mortality differences by body mass index (BMI) are likely biased by: (1) confounding bias from heterogeneity in body shape; (2) positive survival bias in high-BMI samples due to recent weight gain; and (3) negative survival bias in low-BMI samples due to recent weight loss And if you follow the longevity/health space and studies as they come out, it's becoming pretty clear that bodyfat is objectively bad for you above a pretty low baseline. It shows up in insulin resistance, heart markers, inflammation, and once you control for confounding factors sufficiently, mortality. You likely won't become diabetic with a bodyfat of 25%, but all your health markers will be worse than somebody at 15%. This is measurable and clear.
- strbean 3mo ago
  I'd love to find out if electrical muscle stimulation while sleeping could effectively provide exercise without causing excessive sleep disruption. Could be a zero-effort supplemental form of exercise for sedentary people.
  - Schiendelman 3mo ago
    It can't, because it isn't training your heart and cardiovascular system.
    - strbean 3mo ago
      Well, it's causing muscle contractions. At high enough intensity, it should raise your heart rate. It's just a matter of what intensity level is tolerable during sleep (and the effect on sleep quality), no?
      - Schiendelman 3mo ago
        No, that would wake you up long before it had cardiovascular benefit. You need your heart rate up into zone 2 to 5 to really have a positive impact. That's 120 BPM plus for most people. Once you're around 80 it'll wake up anyone, even someone with very low cardiovascular fitness.
        strbean 3mo ago
        > Once you're around 80 it'll wake up anyone Source? I haven't been able to find info on this. I get resuls on nocturnal tachycardia and such. Nothing on elevating a sleeping person's heart rate and observing the result, though.
        Schiendelman 3mo ago
        To be clear, if you implanted a lead, you might not wake them up. It's the mechanism by which you would raise their heartrate that would wake them - the same things that elevate heartrate from external stimulation would also cause cortical arousal.

by jsw97 3mo ago

adam_arthur 3mo ago

The principle of what you're stating is true, it could be correlational. But there's an enormous volume of evidence that exercise, especially intense exercise, is better for health than any other intervention, including more sleep, quality of diet, pills+supplements (except those that treat an active illness/disease of course). There's even compelling data showing that moderate drinkers who exercise live longer than non-drinkers who don't exercise. Even given that Alcohol is a powerful carcinogen. The only thing proven more effective than exercise is weight loss really, if starting from high bodyfat levels. (Anything above ~15% bodyfat in men seems to have negative implications for lifespan, and ~30% for women)

makeitdouble 3mo ago
> specially intense exercise That sounds like a study that is pretty tough to control for, especially long term and at scale. You'd need to find subjects that are provably capable of sustaining intense exercise as a habit if they wanted to but never did, and won't either for the years you'll be following them. That won't work in the reverse, as people can be consciously or not self adjusting based on the health conditions you're trying to check. PS: I'm remembering a friend who never liked running, but tried pretty hard after being pestered by their doctor and family, to discover that their knees are just not good and their whole lineage hated running for a reason. Intense exercise can be anything else, but people won't know their real health limitations until they actually do it for a while.
- adam_arthur 3mo ago
  A large volume of studies already exist. That intense exercise is good, and even very good for you, is proven as far as reasonably possible given that we can't run deterministically controlled experiments. More evidence may come out that adds nuance, but the effect size is so large that it becomes obvious in the data just from observation. You can cycle or stationary bike if you have bad knees. There are plenty of exercises that are intense but easy on the joints.
  - makeitdouble 3mo ago
    I am aware of that for exercising, but was ignorant of what "intense" actually means in this context. And you're right. Looking around, the simplest wording I get: > the intensity must be high. This means that you need to really exert yourself so you get out of breath. [https://norwegianscitechnews.com/2026/05/exercise-a-very-little-goes-a-long-way/ https://norwegianscitechnews.com/2026/05/exercise-a-very-lit...] So if climbing the stairs gets someone out of breath it's intense (and I also see how getting to your limits, whatever they are, can help)
    - adam_arthur 3mo ago
      Yeah, typically "intense exercise" is implying HIIT style cardio. More and more studies have been indicating that even just a few minutes of intense exercise can outperform long/slow LISS type cardios. E.g. 5m all out effort is probably better, or at least equivalent, for health than a 30m moderate effort. The average person can likely hit the 80/20 benefit threshold at less than 30m/week.
      - Swizec 3mo ago
        > More and more studies have been indicating that even just a few minutes of intense exercise can outperform long/slow LISS type cardios. For best results run fast and far. During my personal best marathon (3h 15min) my heart rate averaged in the 170 range
faangguyindia 3mo ago
>(Anything above ~15% bodyfat in men has negative implications for lifespan, and ~30% for women; when reviewed at scale) Can you link evidence for this? I stay at 12% year around as male (confirmed via DEXA)
- adam_arthur 3mo ago
  The claim comes from this study: https://www.acpjournals.org/doi/pdf/10.7326/M15-1181 https://www.acpjournals.org/doi/pdf/10.7326/M15-1181 Though to be clear, there aren't a ton of studies that look at bodyfat percentage. Most use BMI and similar measures. Likely overall fat levels matter more than %, I'd guess. E.g. I'd presume being 15% at very muscular levels is less healthy than 15% at moderate. (Because absolute fat mass plus visceral fat would be higher)
- Jweb_Guru 3mo ago
  Sounds like absolute BS to me. Even in very large scale studies specifically designed for studying mortality, only morbid obesity has been negatively correlated with lifespan. There is even some evidence that being a little overweight is actually helpful for the very old (essentially, because it gives them more buffer if they get sick enough that they stop eating for a while). A lot of this is because modern medicine has gotten very good at treating stuff like diabetes and other stuff caused by obesity. Your quality of life will undoubtedly improve if you are thinner, but that's not the same thing.
  - andsoitis 3mo ago
    [dead]
  - adam_arthur 3mo ago
    https://pubmed.ncbi.nlm.nih.gov/36756765/ https://pubmed.ncbi.nlm.nih.gov/36756765/ Lowest risk is around 18-20 BMI in this recent study, which controls for many confounding factors not controlled for in other studies. Other studies show slightly higher troughs, but often don't sufficiently control for correlation of weight with health in elderly people. From this study: Estimates of mortality differences by body mass index (BMI) are likely biased by: (1) confounding bias from heterogeneity in body shape; (2) positive survival bias in high-BMI samples due to recent weight gain; and (3) negative survival bias in low-BMI samples due to recent weight loss And if you follow the longevity/health space and studies as they come out, it's becoming pretty clear that bodyfat is objectively bad for you above a pretty low baseline. It shows up in insulin resistance, heart markers, inflammation, and once you control for confounding factors sufficiently, mortality. You likely won't become diabetic with a bodyfat of 25%, but all your health markers will be worse than somebody at 15%. This is measurable and clear.
strbean 3mo ago
I'd love to find out if electrical muscle stimulation while sleeping could effectively provide exercise without causing excessive sleep disruption. Could be a zero-effort supplemental form of exercise for sedentary people.
- Schiendelman 3mo ago
  It can't, because it isn't training your heart and cardiovascular system.
  - strbean 3mo ago
    Well, it's causing muscle contractions. At high enough intensity, it should raise your heart rate. It's just a matter of what intensity level is tolerable during sleep (and the effect on sleep quality), no?
    - Schiendelman 3mo ago
      No, that would wake you up long before it had cardiovascular benefit. You need your heart rate up into zone 2 to 5 to really have a positive impact. That's 120 BPM plus for most people. Once you're around 80 it'll wake up anyone, even someone with very low cardiovascular fitness.
      - strbean 3mo ago
        > Once you're around 80 it'll wake up anyone Source? I haven't been able to find info on this. I get resuls on nocturnal tachycardia and such. Nothing on elevating a sleeping person's heart rate and observing the result, though.
        Schiendelman 3mo ago
        To be clear, if you implanted a lead, you might not wake them up. It's the mechanism by which you would raise their heartrate that would wake them - the same things that elevate heartrate from external stimulation would also cause cortical arousal.