Effect of exercise training for five years on all cause mortality
bmj.com
bmj.com
- The RCT was done only on individuals aged 70-77
- Furthermore the results were not statistically significant at p < 0.05. You can see this in the visual abstract where the 95% CI overlaps with risk ratio = 1.0, where 1.0 means "no difference" between the groups.
Note that the results being non-stat sig does not mean that there was no difference! It means that the difference, if present, was probably too small to detect given the power (number of participants) included in the study. This is important to understand!
Furthermore, in the "Strengths and limitations of this study" they clearly outline some reasons why the results may have been non stat-sig, including:
- "Firstly, participants in the control group had a high level of activity throughout the study, and many exercised using HIIT. This might have affected the study’s ability to detect statistically significant differences between groups."
- "selection bias might have influenced our results, as participants were more active and had better overall health than non-included participants"
Basically, even the "control" group looked like they had a good baseline level of activity, decreasing the activity level difference between that and the two treatment groups.
My takeaway from this study is that in isolation, it doesn't provide much evidence for or against the effect of exercise, but taken together with other studies can be used for evidential value.
The results can also be used to inform future studies. The authors clearly understood this when they stated in the main measure outcome: "An exploratory hypothesis was that HIIT lowers mortality more than MICT."
I absolutely get why they had to use a control group that was decently in shape, otherwise the effect size compared to the sedentary would probably have been so massive as to be comical and uninformative. But…where are they getting 75-year-olds who are doing HIIT? Is Norway full of septuagenarian gym rats and cross-country skiers?
HIIT is relative to your shape, so their workout was not the same as 24 years old dude in shape would have.
And as others pointed out, the baseline group here is probably a force of nature unto themselves. 75-year old Norwegians were born into a poor country just starting to recover from war and occupation, where most people were farmers or fishermen. It was not until these people had been working adults for 10 years that Norway discovered oil and began its rapid economic growth, by that time these people were used to hard work.
Then you take that generation, and select the toughest portion out of those who say they are interested in participating in a scientific study on exercise, so a two stage selection of fit people.
Basically the baseline here consists of people who think hiking in the mountain for several hours is great fun, and that it's been a bad week if they have not done so twice.
Isn't it like, almost everyone? Except possibility to do it twice a week. Most people I know think hiking in the mountain is great way to spend holiday and they are not particularly tough.
Compared to the rest of the Europe, yes.
Article based on Eurostat data: https://qz.com/922865/people-in-nordic-countries-exercise-mo...
Indeed!
In seriousness, Nordic (cross country) skiing is an activity enjoyable well into old age. Having done a couple non-competitive “races”, I’m always amazed at the range of ages.
...Adorable old timers with perfect form just slowly gliding across the snow for hours.
>The numbers of drop-outs after one, three, and five years of follow-up were 76 (19%), 104 (26%), and 132 (33%) in the HIIT group, 58 (15%), 76 (20%) and 101 (26%) in the MICT group, and 61 (8%), 95 (12%), and 156 (20%) in the control group.
In other words, the entire observed effect may be due to HIIT being better at making unhealthy subjects drop out of the study.
> but all participants were included for statistical analysis of the primary outcome (intention-to-treat approach).
I think this study looks rather solid.
- Control: followed the current Norwegian guidelines, which recommend 30 minutes of moderate level physical activity almost every day
- High Intensity Interval Training (HIIT): Generally followed the same program as control, but two of the five sessions were instead a 10 minute warmup, followed by four four-minute intervals, working at 90% max heart rate
- Moderate Intensity Continuous Training (MICT): Generally followed the same program as control, but two of the five sessions were instead a half hour of steady-state exercise, at about 70% max heart rate
Conclusion: There was little to no difference in mortality between the control, HIIT, and MICT groups.
I don't love this study design, because it isn't really testing HIIT (or MICT); it's testing what happens when 40% of your exercise is HIIT (or MICT).
That being said, I think the most important takeaway is that exercise is good for you, and what that exercise looks like is almost completely unimportant. Do what you enjoy and can sustain. If you have ten minutes in the morning, do HIIT. If you have an hour after work and want to get out of the house, go jogging or ride a bike. Anything is better than nothing.
“This study suggests that combined MICT and HIIT has no effect on all cause mortality compared with recommended physical activity levels. However, we observed a lower all cause mortality trend after HIIT compared with controls and MICT.”
This is a scientific study, presumably posted because the poster believes we can read it and understand it. I’m not sure why it needs to have its conclusion rewritten and then some opinion based advice added.
In particular, in the case of HIIT vs MICT they were within a percent or two of that 95% confidence. It is clear that further investigation is necessary, as it is quite a bit more likely than not that a causal relationship will be determined.
It is a good practice for scientists to not draw firm conclusions, nor for policy makers to adjust policy, for results that fail to meet that level of statistical significance. However, trying to shut down discussion and interpretation on that basis is neither helpful, nor productive.
Why on earth would that be?
Most of the evidence came from n95 respirators in hospital settings, while the "normal" medical mask evidence was a lot weaker. Yet their conclusion was to advise mask use for the general public (which is gong to be the normal masks, or cloth masks in the majority of cases) based mainly on n95 evidence.
- https://en.wikipedia.org/wiki/Cherry_picking
- https://www.nature.com/news/scientific-method-statistical-er...
- https://fivethirtyeight.com/features/science-isnt-broken/
- etc...
So, 1.7% vs 1.2% seems just above noise level. The OP is right, the numbers are not that impressive.
We are not talking about reducing overall mortality by double digits...
Summary: looks like exercising is good, and adding HIIT has an increasing effect of reducing mortality, but the overall effect is small.
I can't quite tell by your summary whether you are saying "exercising is good, but the overall effect on mortality is small", or "exercising is good, and the effect of adding HIIT to baseline exercise is small".
You cannot make the former statement from this study as control group were not non-exercisers (and adherence was decent). The latter statement, does seem to be supported.
Regarding exercise in general, the literature shows the mortality gap between exercisers and non-exercisers is absolutely massive.
Those are huge numbers. The problem is that the confidence interval is really wide.
quibble: non significant, wide confidence doesn't mean "small", it means _unknown_. It means the data is too sparse and/or too noisy to tell.
Of course since "everything is correlated" [0] expecting such truly simple signals might be nonsensical/pointless.
I was just lamenting the lack of simple magical treatments basically.
"These differences were not statistically significant" according to the study.
The study itself says that they observed no difference. That is not a strong result. Which is OK.
Focusing on specific kinds of mortality might also give stronger results than measuring "all cause" mortality. I say that because it seems like cancer was the biggest killer in these groups. I am not a doctor, but I wouldn't have thought cancer was causally related to (lack of) exercise, the way cardiovascular diseases are believed to be. I'd be interested to see larger studies with enough non-cancer deaths to say something statistically significant about the effect of exercise on those outcomes.
Additionally, these results could be aggregated with comparable results to yield a stronger result.
I assume the significance problem is inherent to studies looking at mortality as the outcome is very binary and can take a long time to manifest. As an effect on all-cause mortality can be seen as the ultimate metric of how healthy something is, it's probably still worth it to investigate. In this case, they made it quite difficult for themselves by comparing active people to other active people.
It's also possible that they made other observations during the study that are or will be published separately.
The percentage decrease was 37%: Percentage points are not percent!
Assuming healthy / not overweight would be a very big assumption to make for the US (as a Norwegian I went to the the USA, once, in 1999, and what I saw there shocked me), where another study could be to monitor mortality outcome of getting weight under control and exercising vs not.
I'd also love to see impact of weight resistance training added to the mix surveyed.
* The control group wasn't "no exercise." It was "follow national guidelines for physical activity."
* Median age of study participants was 72.8 years.
Because of this, I'm not sure what this study actually means, other than "grandma should get more exercise." I suppose this is a fine study design, if you specifically want to study senior citizens, but it would be nice to have a much longer-term study on younger people.
I'm not sure that's really a control group.
What I wish I'll do: Take above advice.
What I will do actually: file this and never open it again.
But it's the gateway drug to more exercise.
One surprising example would be greyhounds. Yes, they are racing dogs, but, they generally are only interested in running for a couple minutes a day. The rest of the time, they're gentle couch potatoes, who make ideal apartment dogs.
I don't say this to shame you or anyone into getting an animal. My only point is to argue that living in an apartment is not really so bad for an animal. If you're avoiding an animal for your own sanity while living in an apartment, that's fine, I do not fault you for it. If you're avoiding an animal for the animals sake, then I think the animal would prefer an apartment to a cage.
The shelter I adopted from is a no kill shelter, but, keep in mind that "no kill" really means "fixed capacity." If the no kill shelters are full, guess where all the stray animals will go?
Here are some sad statistics from a 1997 survey of 1000 animal shelters by the American Humane Society:
> In 1997, roughly 64 percent of the total number of animals that entered shelters were euthanized — approximately 2.7 million animals in just these 1,000 shelters. These animals may have been euthanized due to overcrowding, but may also have been sick, aggressive, injured or suffering from something else.
> 56 percent of dogs and 71 percent of cats that enter animal shelters are euthanized. More cats are euthanized than dogs because they are more likely to enter a shelter without any owner identification.
> Only 15.8 percent of dogs and 2 percent of cats that enter animal shelters are reunited with their owners. 25 percent of dogs and 24 percent of cats that enter animal shelters are adopted.
See http://americanhumane.org/fact-sheet/animal-shelter-euthanas...
And, as far as anecdata go, when my dog entered the shelter I adopted her from, she was pregnant with 12 puppies that were aborted. While I love puppies, I am glad they did that, for multiple reasons. Most important among them is that when we're destroying millions of animals a year, we don't need 12 more dogs in the shelter. But, secondarily, I am glad they did it, because if she had had the puppies, she would not be leaving that shelter for several weeks, which means I would have had a harder time adopting her. :)
The verbatim conclusion they present is:
"This study suggests that combined MICT and HIIT has no effect on all cause mortality compared with recommended physical activity levels. However, we observed a lower all cause mortality trend after HIIT compared with controls and MICT."
- improved mental state
- protection against covid
- free calories to spend on food or weight loss
- fresh air
- better future health outcomes
- time for podcasts
- new hobby
Overall, I highly recommend trying!
[1] https://archive.org/details/BBCHorizonCollection512Episodes/...
> In line with this, observational studies suggest that exercise has a statistically significant preventive effect on premature all cause mortality with active individuals showing up to a 72% lower risk of premature mortality from all causes compared with inactive individuals
In addition, the mental component continuous summary score was significantly higher in the HIIT group compared with control group (P=0.04) and MICT group (P=0.04) after five years (supplementary table S6).
Exercise helps to keep your body less stressed in many ways during its normal day-to-day life. It's good for your immune system, your circulatory system, your digestive system, and even your brain.
A few extra pounds probably won't cut your life short, but chronic heart disease or blood clots or being bedridden in old age definitely can.
There's a path from falling to bacterial pneumonia that, as one person put it, means that "The death certificate says the cause of death is pneumonia, but the real cause of death was falling."
I'm fuzzy on the degree to which HIIT would contribute to lower incidence of falling injuries. Meanwhile I have a large pool of anecdata about yoga and taichi, some of it first person (I have, in the last five years, tried very hard to break my own ankle on several occasions, but walked away without even a sprain).
This is why the focus on cardio related exercise for the elderly has always confused me. I'd like to see this study done with a basic strength training program instead.
The correct reaction is to take all of the weight off that foot, otherwise once you hit the gutter you’re gonna have a bad time. A young person might solve this by hopping forward, to get your legs in front of your center of gravity. Another option is sinking down on the back leg while you draw the twisted ankle and your CG up and back until you can lift the leg and try to place it a second time.
Most of your time in the gym is either isolating a limb or putting symmetric loads on both. That teaches you nothing about not falling.
One failure mode for old people is having their “knee give out”. Having experienced this myself now, I think it has very little to do with strength and more to do with twitchy motor cortex (in my case, possibly due to a prescription medicine). Highly, highly unpleasant. That same weight shifting trick kept me physically safe if not entirely emotionally so.
Isolation exercises are mostly a waste of time unless you're targeting specific appearance or sports performance goals. The personal trainers at my gym have their clients lying on a bench less than 20% of session time.
> Knees and backs give out because they lack the necessary muscular support and stability.
That is the common way, but not the only way. I was as surprised as anyone. I was literally in a taichi class the first time it happened, and I was nowhere near exhaustion. My knee just went on strike for a 10th of a second. Apparently I'm still mad about it.
Yeah, there's gonna be some things wrong with your body as you get older. Unless you die by misadventure, one of them will very probably get you killed.
'Injured older adult' is a club we all get invited to, and pharmacology so far seems to be a big exercise in replacing one set of symptoms with a less annoying set. Pharmacology adds all sorts of new dimensions to that (since we mostly play a game of symptom substitutions)
The implications of allowing the control group to self-select their activities from the guidelines.
I wonder if they would have biased toward the HIIT activities (perceiving them to be better) simply because they were participating in the study. Would the outcome have been different if they were asked to maintain their existing activity levels or somehow replicate the normal activity mix of people following the guidance. Otherwise, it seems more useful to focus on the difference between the HIIT and MICT groups.
Why do we need this kind of research? Don’t we already have enough to tell us that exercising is good, and that exercising more is probably better?
Ostensibly they were trying to compare the recommended levels of activity with high intensity and medium intensity exercise to see which was better, but would anything really change based on this research? Wouldn’t whatever resources that went toward this research be better put to use by getting more people to exercise instead of studying what’s “best” or whatever this is trying to do?
I understand that doing and publishing research is key to some academic careers (which is questionable in its own right), is that what’s really driving all this? For reference, my view on the role of research in tenured/academic jobs is probably pretty close to the negative viewpoint in this article that was posted on HN a while back:
https://reyammer.io/blog/2020/10/03/the-good-the-bad-and-the...
What am I missing?
Something is better than nothing. More is better than less.
[1] (audio and transcript) https://www.abc.net.au/radionational/programs/healthreport/m...
Other studies show that exercise is better than no exercise for old people.
Obligatory favorite exercise article: https://www.theonion.com/new-study-finds-running-for-20-minu...
The 4x4 protocol btw is a staple in Norwegian training, at all levels. 4x4 and "fartlek" and you are soon an elite athlete is almost the mantra.
Also perhaps some selection bias in that the participants that sign up for an Exercise Study may already be pretty fit. And we see some of that in the baseline characteristics.
If you were to compare these groups to physically inactive groups I'm sure you would have seen quite a big difference.
We (society/physicians/etc) need tools to get people to exercise. This is more a study of how effective one of those tools might be (ie supervised exercise vs recommendations). If supervised exercise is no better than recommendations, I find that pretty disappointing. Because as we all know, recommendations don't work very well, or at least most people don't adhere to them.
One simple thing is making sure our infrastructure makes it safe to do so. Living in the south, I can't tell you how many side walks just end. How many roads have no crosswalks. Don't even get me started on bike infrastructure!
The car is king here, and I sincerely hope that ends some day.
Huh. I would really like to see some sources on that, more than "I remember it being said..."
Edit: actually you need to google it to get to the un-paywalled article.
“Most importantly, men who were highly physically active at age 50 were 32% less likely to die during the study than those who were least active; moderately active men enjoyed a smaller, but still respectable, 13% lower death rate than the least active gents.”
“But the long-term nature of the Swedish study allowed the scientists to follow men who were sedentary at age 50 but who increased their exercise level between ages 50 and 60. For the first five years, the major result was disappointment, since these men continued to die at the same high rate as men who remained inactive. But over the next five years, the benefit kicked in; by 10 years of follow-up, the men who adopted exercise in middle age enjoyed the same low mortality rate as men who began before age 50. All in all, men who adopted exercise after 50 had a 49% lower death rate than the men who remained inactive, a benefit even greater than the 40% risk reduction experienced by men who quit smoking after age 50. And the protective effect of exercise remained significant even after the scientists adjusted their results for the impact of smoking, drinking, obesity, diabetes, cholesterol, blood pressure, and socioeconomic status.”
“According to the Swedish study, men were classified as moderate exercisers if they simply took frequent walks or often went cycling for pleasure. And high-level exercise involved a minimum of just three hours of serious gardening or recreational sports a week. And in case you're tempted to cook up another excuse, you'll soon see that this important study does not stand alone.”
The average age of participants in the study was over 70, so these findings apply only to the elderly. And the conclusion is not that “exercise is good”; the authors were actually trying to figure out if HIIT or moderate exercise was better. TLDR: HIIT is better
Would the intensity of HIIT and endurance of cross-country cardio be useful for significantly increasing aerobic capacity to get to running a mile continuously?
Instead of grinding out a slow 11 minute mile try running at a 9 minute pace for a shorter distance. Then rest for a few minutes and repeat several times. Do that a few times per week and gradually increase the distance you run at the 9 minute per mile pace. Eventually you'll get to a full mile at your target pace.
Also if you're overweight you're going to struggle with running and be at higher risk of injury. If that's your situation then stick to lower impact sports until you drop the extra weight, then ramp up the running.
I'm in the process of losing 40 lbs (17%, cut) and then rebuilding muscle mass.