The effect of physical fitness on mortality is overestimated

&gt; Next, the researchers examined how fitness was associated with the risk of dying in random accidents such as car accidents, drownings and homicides. They chose random accidents because they assumed that there ought to be no association between the men’s fitness in late adolescence and the risk of dying in random accidents.<p>Blank slatism is the curse of the sciences. Of course the kind of people who die in car accidents and homicides are not identical to everyone else but for random luck. They&#x27;re less educated[1], they make poor decisions, they have dangerous neighbors, frequently they&#x27;re immigrants from countries with lots of car accidents and homicides. We&#x27;ve known that &quot;everything is correlated&quot; since 2014[2], when will science figure it out?<p>1. <a href="https:&#x2F;&#x2F;www.theverge.com&#x2F;2015&#x2F;10&#x2F;2&#x2F;9438197&#x2F;traffic-accident-study-education-level-deaths" rel="nofollow">https:&#x2F;&#x2F;www.theverge.com&#x2F;2015&#x2F;10&#x2F;2&#x2F;9438197&#x2F;traffic-accident-...</a> 2. <a href="https:&#x2F;&#x2F;gwern.net&#x2F;everything" rel="nofollow">https:&#x2F;&#x2F;gwern.net&#x2F;everything</a>

Like most people I want to live a long time. But more than life span I am interested in <i>health</i> span. I want to feel good and be autonomous as long as possible. Fitness, especially good muscle mass, is an important part of that.

I don&#x27;t think I&#x27;d agree with their hypothesis though that there&#x27;s no connection between dying in a random accident and fitness.<p>Fit people:<p>1. more able to &quot;get out of the way&quot; &#x2F; coordination &#x2F; agility<p>2. faster reaction time<p>3. potentially suffer a reduced injury<p>4. more likely to recover than die from the injury<p>There&#x27;s probably a dozen rational things we could think of to counter that hypothesis.

They appear to have proven that by walking more and driving less, you have a lower chance of dying prematurely in an accident, but for some reason which they have yet to uncover, that effect is not due to the extra fitness you get from walking.

Probability of dying in a random accident is the probability of a random accident occuring times the probability of dying from a random accident conditional on one occurring. I am not convinced that fitness would be entirely unassociated with both of these probabilities, particularly the latter. Meaning that the extent to which this outcome is a good negative control is overestimated.

&gt;&gt;&gt;&gt; n the study, the researchers leveraged data from 1.1 million Swedish men<p>So in other words, light years better shape through out all age ranges compared to your average American.

&gt;Next, the researchers examined how fitness was associated with the risk of dying in random accidents such as car accidents, drownings and homicides. They chose random accidents because they assumed that there ought to be no association between the men’s fitness in late adolescence and the risk of dying in random accidents.<p>This is clearly and obviously false though. Even the assumption is kind of ridiculous.<p>Of course a person with greater general fitness is going to, on average, suffer less severe consequences from a random accident. Including drowning is especially ridiculous, because that is a scenario where greater physical fitness <i>directly</i> contributes to your ability to survive such an accident.<p>The results can just as well be interpreted in a way that the original thesis is correct, but greater physical fitness <i>also</i> helps protect your body against the consequences of random accidents.

This might explain how people who exercise for work do not seem to get the health benefits of people who exercise recreationally.<p>It’s not the exercise, it’s that people who recreationally work out are in a different socioeconomic group.<p>Also, this is consistent with many mouse studies.

&gt; Next, the researchers examined how fitness was associated with the risk of dying in random accidents such as car accidents<p>&gt; The researchers found that men with the highest fitness levels had a 53 per cent lower risk of dying in random accidents. Yet, it is unlikely that the men’s fitness would have such a big effect on their risk of dying in random accidents.<p>Wait, what?<p><a href="https:&#x2F;&#x2F;aaafoundation.org&#x2F;rates-motor-vehicle-crashes-injuries-deaths-relation-driver-age-united-states-2014-2015&#x2F;" rel="nofollow">https:&#x2F;&#x2F;aaafoundation.org&#x2F;rates-motor-vehicle-crashes-injuri...</a><p>The risk of being in a motor vehicle crash increases as one gets older than ~70 years. The risk of dying increases even more dramatically.<p>Now <i>maybe</i> this effect is independent of physical fitness, but that’s quite an assumption. I would guess the contrary: that poor fitness quite dramatically increases one’s risk of a car crash, both due to reduced motor control and increased risk of various neurological issues.<p>Vascular dementia, for example, seems very likely to be correlated and often caused by poor fitness. Various sources seem to think that exercise can quite dramatically reduce Alzheimer’s risk. Alzheimer’s disease is related to PCA, and I suspect that PCA is very much under-diagnosed and that it causes a lot of crashes.

&gt; In the study, the researchers leveraged data from 1.1 million Swedish men who were conscripted for military service between the years 1972 and 1995<p>For anyone from the US reading this just throw it out… we eat significantly less healthy and have significantly more obesity. Sweden as a country is significantly more healthy and active. To everyone reading this and thinking that this applies is sorely mistaken.<p>Fitness might not “extend your life many years” but being morbidly obese will most certainly end it significantly early.

<i>&gt;Next, the researchers examined how fitness was associated with the risk of dying in random accidents such as car accidents, drownings and homicides. They chose random accidents because they assumed that there ought to be no association between the men’s fitness in late adolescence and the risk of dying in random accidents. This method is called negative control outcome analysis and involves testing the validity of your results for a primary outcome by comparing them with an outcome where no association ought to be found. If, however, an association is found, it may indicate that the groups studied are not actually comparable, and that the study suffers from what is typically referred to as confounding. The researchers found that men with the highest fitness levels had a 53 per cent lower risk of dying in random accidents. Yet, it is unlikely that the men’s fitness would have such a big effect on their risk of dying in random accidents.</i><p>I haven&#x27;t read the underlying paper so maybe they addressed this, but: couldn&#x27;t this just be because sedentary&#x2F;unfit people tend to drive everywhere? So they&#x27;re involved in more car accidents than healthier people, who walk places more.<p>Also if you&#x27;re fat and don&#x27;t exercise, you&#x27;ve got a lower chance of surviving emergency surgery after a car crash, or swimming to safety after falling in water, or dodging a knife ... I don&#x27;t think it&#x27;s a given that physical fitness is unrelated to surviving those things.

Finding a random association doesn’t establish causality or de-establish causality on another different association.<p>The causality was originally just assumed. Now with this new association, what changed? Logically nothing has changed right? There is no logical conclusion derivable from this.

There is mortality and there is quality of life and someone who is fit will have a better quality of life even if they don’t necessarily live longer.

Well, it stands to reason that more physically fit people would be better able to leap out of the way of an oncoming train, etc. :-)

Who cares, a long healthspan feels great!

All else being equal a more fit person is more likely to avoid an otherwise fatal accident.

I’m skeptical that it’s worth it to spend too much time working out.<p>If there are three options:<p>1. Sedentary lifestyle (&lt;3 passive or active exercise weekly).<p>2. Moderate (~1 hour passive exercise daily, like walking a dog a few miles daily).<p>3. Active (&gt;1 hr active, like running several miles or lifting).<p>I think there’s huge value in moving out of (1), but am not sure if it’s worth going from (2) to (3) w.r.t longevity

&gt;I believe that every human has a finite number of heartbeats. I don&#x27;t intend to waste any of mine running around doing exercises.<p>—Attributed to Neil Armstrong

I find that a lot of people these days seem to optimize their lifestyle for living up to about 50 years old, up to which point they don’t seem to care about dying off since life after that gets a lot more annoying and less enjoyable due to aging, and mounting debts that go unpaid and have no hope of being paid off. People can envision a good life up to about 50, but they struggle to imagine anything good happening after that since there aren’t many good examples on social media except for ageless rich people with all the time and money in the world.