Physically Demanding Work Tied to Male Fertility | Hacker News Reader

Physically Demanding Work Tied to Male Fertility

hms.harvard.edu

101 pointsnradov96 comments

I wonder how much "physically demanding work" is just a surrogate for "not sitting". The article only mentions sitting once (and the press release, not at all)

> Men also reported the level of physical exertion in their current job using the following categories: light (e.g. most time spent sitting, office work)... https://academic.oup.com/humrep/advance-article/doi/10.1093/...

Sitting inherently causes the nerves and blood vessels in the groin to be impinged, so it would not be surprising if that was enough to lower the production of sperm, testosterone, etc.

It would be nice if they could control for sitting, so we could know if lifting heavy objects is causing the increase in sperm count, like the press release suggests.

Also sitting for long periods causes the testes to get warmer, which can damage sperm.

Sure it is. All health outcomes are made up of many causal components with their own coefficient.

Additionally, "physically demanding work" is also a proxy for "low probability of obesity".

> "physically demanding work" is also a proxy for "low probability of obesity".

Me: <laughs in British builders>

This comment was written by someone who was never at a construction site.

As someone from the USA who really only sees road crews from time to time, is the prevalence of obesity in construction really that high? What kinds of construction. I imagine you couldn't replace residential roofs if you were too large, forever if your job consisted of mostly ground based walking tasks like... I have no idea. But maybe some types of construction have more obese than others.

I haven't known many workers in that trade but all my experience is with thin and deceptively strong men who look permanently beat up from years of labor and small accumulated accidents.

I worked in manual labor for 6 years to get myself through college. What is your experience?

Besides, just seek out the data instead of spouting glib anecdotes

Physically demanding work helps the body take out the trash. That's likely a factor.

https://news.ycombinator.com/item?id=25427090

>Sitting inherently causes the nerves and blood vessels in the groin to be impinged

Anyone have a good reco for a chair that doesn't do this? Does it have a hole in the middle or something?

Yes there's one chair James Bond uses in Casino Royale which is like what you're describing.

I feel like there was plenty of impingement though.

The impingement service was an after market addon.

This may seem like a weird question...but what about lying down or reclining as opposed to sitting? Does it have the same disadvantages?

I'm a highly active person with regular exercise (weights, cardio, etc.) but I'm also in sedentary IT and have a setup that allows me to recline/lie down when I'm not standing.

I basically decided years ago when I started having lower back issues (despite the healthy BMI/activity level) to declare war on "sitting" and only do it when I absolutely have to (driving/social functions etc.).

Reclining/lying down while working (coupled w/ standing) at least for me eliminated all of these issues and I'm now curious if it would eliminate the sitting related sperm count issues as well.

What's your reclined setup?

I've had a really hard time finding a comfortable working position over the last 12 months due to back pain. I've tried lap desks on a recliner but they're a pain, especially when I need to get up. I'm trying to avoid the urge to get one of those monstrous, expensive, futuristic reclining workstations.

Honestly just a basic, very comfortable recliner with a lap desk. I'd say 70-80% of the time I'm at my standing desk though...and only use the recliner for when I won't need the keyboard too much because as you say the lap desk isn't that great. I leave the mouse on the recliner arm (it's wooden).

It works for me. Back pain went away in about a week.

Standing desks take some getting used to but they don't cause back pain for me. Only sitting does (prob my posture or something but oh well)

i didn't read the report, but if they had controlled for obesity, would the results be the same?

I specifically have an air cooled chair that keeps my testes at a much lower temperature. I've also rigged a thermocouple harness to monitor temps from time to time as well. It's probably the best way to produce healthy / plentiful sperm if you have to spend hours sitting for work.

I just pictured a dude sitting on a chair, working, wires going to his testicles and a monitor on a side displaying a temperature chart and beeping regularly (for some reason).

Or you could just stand up?

Perhaps it is not even the lifting, but the psychological effect of doing "manly" things.

Lots of "well this is obvious" comments here, but this finding strikes me as a new (haven't seen before) key driver of the global testosterone crisis to which no one has been able to tie a specific cause

I have a friend who puts the blame entirely on microplastics because its been shown microplastics upregulate estrogen (or something to that effect).

Is this accurate? No idea, not a biologist.

That is not accurate. The book of science on the human harm caused by microplastics is thin and still new. There is lots of science on specific plastic chemicals and their estrogenic effects - phthalates is the largest category although there are several - but the classification of "microplastics" is orthogonal to the type of plastic involved

Edit: downvotes why

>Edit: downvotes why

People hate nuance because it doesn't wholly confirm their beliefs

How are "specific plastic chemicals" or "phthalates" orthogonal to "microplastics". They are a subset of microplastics, so of course they cannot be orthogonal.

Are you saying phthalates are not microplastics? It feel likes you are obfuscating the problem by using debate tricks or something and then calling it nuance.

> They are a subset of microplastics

Are they? Not trying to be difficult. Micro plastics are just tiny particles that break off of macroscopic plastic objects. They can be made of any kind of plastic. And phthalates are found in macroscopic plastic objects. Hence, orthogonal

How can you possibly say that? Phthalates break off into tiny particles and become microplastics...how is not completely straightforward? Phthalates are definitely found in microplastics, that's just a fact.

Is there any large scale proof of this testosterone crisis? When I looked into it I found a lot of theories and assumptions but no real evidence for it.

You didn't look far enough. https://pubmed.ncbi.nlm.nih.gov/32081788/#:~:text=There%20ha....

I wouldn't be surprised if testosterone production was lower due to various changes in environment and society, but assuming it's true I don't understand what would make it a crisis.

Maybe because ultimately that means the extinction of the human race ? Dude, not all humans hate themselves to the point of wanting to disappear.

Because testosterone affects fertility, which is very important.

Are people who want to have children having significantly more trouble producing them?

If you're fishing out of a lake and you notice you're catching the fish faster than they are being replaced you may want to note this and keep an eye on what's going on. Especially when fish are your only food source.

Yes.

search for

> site:news.ycombinator.com testosterone

no shortage of discussions here, both recent and old

I don't believe there is a specific cause because there will always be several, measurable, causal factors. But if are going to zoom way out and pick one thing, it's body weight. Increased physical activity is going to increase free Test and reduce the likelihood of being overweight.

Causality is complex here. Obesity reduces testosterone levels, but low-T also causes adipose tissue growth in a positive feedback loop. That's one of the reasons why some obese people have so much trouble losing weight.

Exposure to endocrine disruptor chemicals such as pthalates is also proven to reduce testosterone levels.

There are a lot of obvious things but it looks like the majority of people don't care. Obesity, diabetes, lack of exercise, it kills more than anything in the west yet we address things like car safety with more urgency

> yet we address things like car safety with more urgency

And even then we only focus on the people inside the car.

IIHS car safety ratings now include pedestrian collision prevention.

https://www.iihs.org/ratings/vehicle/acura/integra-4-door-se...

I don't think a majority of people don't care. The causes of obesity and how to un-obese people sustainably and over the long term is still not entirely known. We can cut someone's stomach to a fraction of its size, and the fat person still regains weight after 10 years. The best weight loss drugs that are being researched are actually hormone-based, not fullness-based or some other signaling. There's something fucky going on with the way obesity occurs that doesn't appear to have much to do with how much a fat person "cares" (and in fact, caring too much in the wrong way actually makes it worse-- internalizing fat shaming narratives tends to fatten people regardless of their weight!).

I also think lack of exercise isn't a care thing. The US literally works more hours than other first world countries-- who has the time to hit the gym or go for runs?

It was so weird watching public health messaging during the COVID-19 pandemic. Based on early reports out of China we knew from the beginning that obesity was a key risk factor for severe cases, and yet they hardly mentioned the importance of losing weight. Instead they wasted a lot of effort on other non-pharmaceutical interventions such as face masks, which had never been proven to have any significant benefit for the general public.

https://doi.org/10.14740/cr1118

https://doi.org/10.1002/14651858.CD006207.pub6

Because saying "Oh, lose 100lbs in a month before covid shows up" would have killed ever more people quickly.

In addition to stimulating higher Test, I would go ahead and guess that the cohort had more lean body mass and few overweight individuals. All together, these things make an large difference in male fertility.

Body weight and activity level are enormously significant variables in practically all health outcomes. Easy to understand, but difficult to manage it seems.

Obesity has become a pervasive problem in the U.S (and parts of the rest of the world). The average waistline of American adult males is now 40.5 inches![https://www.cdc.gov/nchs/fastats/body-measurements.htm] That is jaw-dropping to me. I live in a U.S. state that is well-known for being one of the thinnest states in the country, and people don't seem particularly thin to me here - but when I visit other parts of the country, the obesity is pervasive and extreme. (No need to name states - there are numerous maps of obesity rates online.)

There are strong indicators of several causes for this, but America really needs to get serious about health and overall wellness of the population.

but America really needs to get serious about health and overall wellness of the population.

We don't need to fat shame, but also we don't need to accept. To say it is OK. To pretend that in 99.9% of circumstances, people have 0 control over it.

Based off the effectiveness of new anti-diabetes drugs that also help in losing weight I actually think people might have much less control over their obesity than we'd like to believe. Fat people might have some kind of hormonal difference happening that they have to manage in a way thin people don't, in the same way women have to manage their menstrual cycles but it would be weird to say they have control over them. Women who want to take control over their periods usually have to take medication to do so, and it seems fat people respond similarly to thin people once they take medication that adjusts their signaling to that of a thin person's.

That is at least somewhat correct. Obesity causes lower testosterone levels and low-T causes growth of adipose tissue in a positive feedback loop. So I'm general, the fatter someone gets the harder it becomes to lose any fat.

But it's not impossible. It just means they have to shift their energy balance even more negative in order to start losing weight. Some medications such as Semaglutide (Wegovy) can be helpful in starting this process if other approaches have failed.

Yeah, I'm not saying that fat people are hapless victims with no agency, I just think they generally seem to have some phenomenon occurring that is making weight loss way, way harder than society is giving credit for. [Like for example I have some friends that struggle to gain weight and are permanently growth stunted because of misdiagnosed gut issues in their childhood, and its clear to me "just eat more" is an unmedical and kinda dumb approach to managing their weight. I think evidence is pointing that fat people also have systemic problems where "just eat less" might also be an unmedical approach to managing the weight of really fat people.]

> We don't need to fat shame, but also we don't need to accept.

I'd be interested to know how you do the latter without the former.

It's been known for a long time that lifting leads to increased testosterone. This report seems to be mostly that, or did I miss something?

> We already know that exercise is associated with multiple health benefits in humans, including those observed on reproductive health, but few studies have looked at how occupational factors can contribute to these benefits

It seems like a fairly predictable confirmation. It wasn't a given though, exercise tends to improve long-term wellbeing, while lots of people with physically demanding jobs are pretty much destroyed by them.

That checks out: with exercise, you have wide latitude to not do things that hurt (or otherwise suck). With a physically demanding job, you have much less latitude.

There's been a lot of reporting on how testosterone and sperm count levels are decreasing without a clear explanation on why and lots of hypothesis so finding clear links between sedentary jobs and fertility is interesting.

This study shows that occupational lifting (moving heavy things as part of a job) increases testosterone and sperm counts, while previous studies were looking at lifting weights in a gym.

Yes, the earlier studies would certainly imply the later results were most likely true, but that's how science works. And this in turn lends higher credence to those earlier studies.

That's fair.

I would be interested in knowing:

- What is the magnitude of the change in testosterone? Are we talking 5-10% or more like 60-90%?

- How long does it take to happen? Are we talking 2 weeks or 6 months?

- How quickly do testosterone levels decline to baseline levels after someone stops performing physically demanding work?

Other unrelated studies on weight lifting and high intensity training put the differences at around 20%. I'd consider weight lifting and HIT/HIIT 3-5 times a week to probably be more effective at producing these results than a job, obviously depending on the job, so likely an upper bound of 20%. Obviously a big conjecture here.

Other interesting results from various studies on improving testosterone also show around a 10-20% change in testosterone due to various stresses on the body:

  - higher carb diets (200+ grams carbs per day) produce ~20% more testosterone
  - vitamin D deficiency linked to ~20% reduction in testosterone
  - 5 hours sleep per night over 10 days linked to ~20% lower testosterone
  - excess cortisol due to stress linked to ~ 10% lower testosterone

I got interested in this due to finding out I had pretty low testosterone levels. I am a chronically sleep deprived dad of 3 with a stressful job, so it wasn't a surprise. Working through that list myself and running some experiments to see if I can improve levels naturally, and if so, if the above list has any stacking effect, or if there's maybe just a 20% hit due to body stressors, regardless of the stressor.

Dang. That actually explains a lot about why I feel good when I feel good.

It's amazing that just doing what feels good and ignoring all advice - whether from online / media / friends - often leads to a better end result than studying up on everything. Can certainly land you in trouble too, but largely, the body's built-in feedback systems are better at telling me what I should do than the words other people create to explain how their body's feedback systems have worked.

I will also say that getting your own labs done, even if you are footing the bill, is relatively cheap. You don't need to go to the doctor and have them refer you.

Check out ulta labs (obtuse, some learning curve) if you want to DIY, otherwise there's a couple services out there that make the learning curve shorter. One I see come up a bunch is Inside Tracker.

Health and fitness is a fun little side hobby that you can turn into a fairly intellectual exercise. Get hooked on Peter Attia's podcast, read a bunch of studies, get labs done, put together an exercise and nutrition plan and then get DXA scans to watch body composition change. It can easily replace other intellectual hobbies :)

Absolutely! I came out of a long period of depression / anxiety (triggered by a specific event, not just chemical imbalance) by starting to go for walks a few years ago. That turned into more and more intense hikes (doing 10-20 miles in a single day). The difference of being indoors and sedentary vs outdoors and active was night and day.

Recently moved into an apartment with a 24 hour gym and started doing basic strength training with weights as well - quickly learned that my body prefers that to cardio, and now I do 2-4 miles of walking a day and 20-40 minutes in the gym. It's amazing. Wish I'd been doing it for years.

I'll give that podcast a look

Good to see a study on it.

Bodybuilders or powerlifters can feel the changes it creates in T levels almost intuitively. I still believe that as men age, with many (most?) becoming out of shape - their T level changes due to lack of vigorous exercise.

Does this explain falling testosterone levels worldwide, as men become increasingly sedentary - desk jobs, video games for entertainment, etc?

One factor out of many, such as xenoestrogens in diet and environmental pollution, sleep disorders, weight issues..

My unpopular opinion 5cents is that this is the cause of (skyrocketing rates of) transexualism in men, with social contagion being the cause of (skyrocketing rates of) transexualism in women

> skyrocketing rates of

You have some evidence for that? Or is it just that you see lots of stories in the popular press?

https://www.ny1.com/nyc/all-boroughs/news/2022/06/10/study-e...

Here ya go. And theres plenty of other studies out there. We only started keeping track of this kind of thing recently so its hard to gi very far back.

But I mean come on, anecdotally, you can see how this is true right?

I knew 1 transgender person over my whole life, until like 2016. Now I know 6. Half of those 6 are people I knew back when I only knew 1 transgender person.

Its clear that at the very least, more peoppe are openly trans, but I think the rate in general has increased, open or not.

The linked article gives a reasonable possibility:

  Jody Herman, the paper’s lead author, told Spectrum News there are several reasons for the jump in the youth transgender population estimate, including that the CDC’s Youth Risk Behavior Survey began asking high school students in 2017 if they are transgender, giving researchers a clearer picture.

 Herman, a senior scholar of public policy, said other factors likely include shifting populations, greater awareness and education about trans people and gender identities, and increased social media that allows young people to connect with people they relate to.

  “I think it's a combination of things,” she said. “And we should be suspect of pointing at one thing.”

The health and wellness gym rat community are the most cargo cult, anti-science wingnuts with their magnetic copper bands, kino tape, fad diets, and cleanses. And there's plenty of those who juice and deny the reality of consequences like a smoker.

TRT is usually a terrible idea for a biological male due to the various risks like shrinking testicular volume, fertility impairment, cardio risks, and roid rage.

IANAD: Clomifene can help in the short term, but solving underlying concerns is likely more important.

The natural (and probably correct) assumption is that physically demanding work causes higher fertility. While "having lots of children leads to physically demanding work" is super unlikely, it's worth considering whether there's some third factor that leads to both high fertility and a preference for physically demanding work.

My first thought is that people with naturally higher testosterone -- and thus more muscle mass -- are more likely to end up in physically demanding jobs.

> While "having lots of children leads to physically demanding work" is super unlikely

I don't think I'd toss that theory out entirely. Having lots of children is usually tightly correlated with having children early, and this absolutely makes gaining post-secondary education far more difficult. Which then correlates pretty nicely with being stuck with physically demanding jobs.

Interesting, I wonder if this correlates to falling birthrates in Advanced Economies ?

And maybe how this worked in the old days when many kings blamed their wives with issues in producing children.

Yes.

But it doesn't necessarily mean that the reduction in male fertility is the cause of a reduction in birth rates.

Birth rates are falling all over the world. People aren't childless despite trying. They're just not trying, for the most part.

>People aren't childless despite trying

That's simply not true. Worldwide, sperm counts have dropped by 50-60% over the last 50 years (and the decline is accelerating). Sperm motility has been declining as well. These factors have a direct impact on fertility despite trying

Divisive politics, social media, many things have an impact on fertility which can individually have more impact than even dropping sperm count by 50%.

1/3 of one household for a 2bedroom flat would kill any fertility rates.

> sperm counts have dropped by 50-60% over the last 50 years

Still more than enough to get a kid unless you have other issues, biology might play a role but it isn't the main factor here. Plenty of country with massive baby booms right now

Probably because many advanced countries can’t thrive financially with only one spouse working. In many countries it takes but people working in order to afford things like a house in a safe enough neighborhood to want to think about kids.

All guys should start lifting weights now: 'Fertility crossfit' every corner.

> All guys should start lifting weights now

Everyone should no matter their sex, literally no drawbacks and unlimited benefits

Of course there are drawbacks :

1. It takes time

2. It costs money

3. It can lead to injuries.

4. Apparently now, it leads to babies too.

> It can lead to injuries.

Not exercising 100% leads to bad health, exercising only lead to injury when you have underlying conditions or poor form

> It takes time

When the average social media usage per day is 2.5 hours this is no excuse, we have the time we just don't use it

> It costs money

Obesity is more expensive, my 24/7 gym is 15$ a month, in a major western capital

I didn't say people don't have the time and money. I said it costs time and money.

Just because you don't like people spending 2.5 hours on TikTok everyday, doesn't mean they're not using their time. They're using it on what they want : TikTok.

I would also be surprised if most people walked to the gym. You have to pay for transport. That's car wear, gas expenses, possibly higher insurance cost.

You're also using a false dichotomy : go to the gym or be obese. You can be obese while going to the gym and you can be a healthy weight while not going to the gym. Controlling what you eat is way more important for weight control than exercise. "You can't outrun your fork."

Is it possible that the causality goes in the opposite direction - hormonal levels affect job selection?

Could this be a self-selecting group? Guys with higher testosterone can't stand the idea of sitting at a desk all day?

Am I an outlier as I had three kids when I was a sedentary fatty?

Got super fit and healthy now and have no desire or interest in that sort of stuff!

iFootball coming in 3…2…1…

this is all explained in idiocracy

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