Why do distance runners typically look older than non runners their age?

Disagree with the premise. Show me the data.

And, there is at least one meta-analysis I just easily found with a quick Google that finds exercise, including aerobic exercise, slows telomere attrition. The rate of telomere length decrease, somewhat obviously, is not only dependent upon number of cell divisions but many factors and it appears exercise is protective against it.

Biology is messy and it’s usually not a good bet to apply very simple models to complex phenomena

Just to add some more anecdotal yet relevant evidence here as a few folk are talking about running being linked with balding. I recently had a reunion with high school folks and loads of the guys there were either bald or severely balding and going by their bellies, they certainly do NOT run (mid 30s). Meanwhile I have a full head of hair. It's genetic.

As others have pointed out, it's not the years but the miles.

Seems to me that you would get different results from a study depending on whether you looked at face-only photos (runners might look older), full-body photos (not sure), or videos showing movement (I expect sedentary people would look older). Once you get past about age 60, you'd also have to take into account all the people (I assume disproportionately nonrunners) who have already died, I suppose by saying they look worse than anyone else.

The hair thing is definitely genetic. My dad lived the most stressful life ever. Drank, used heavy pills all day until his death, was broke and depressed all the time. He eventually got cancer, still drank and drugged through the whole thing, lasted another 8 years, finally his liver and pancreas gave up at 46. Had the most beautiful head of silky black hair at the end though. I remember stroking his right after he passed away and it was a head and shoulders commercial.

Some of my favorite, comically false myths people like to repeat:

"I saw one runner who looks older than I think he should, therefore running makes everyone who does it look old."

"I saw one runner had a heart while running, therefore you shouldn't run because running is bad for your heart."

"I read that one guy died 'because of' his seatbelt, therefore wearing a seatbelt is dangerous."

"I read about a guy who smoked, drank whiskey and ate bacon daily but lived to 100, therefore smoking, drinking and eating bacon daily will make you live longer."

Not all. Look at Dean Karnazes. He looks 40, tops 42.

But, guess what?! He's 60!

Just incredible.

When you get really lean from running a ton of miles, you have less fat in your face, which makes you look older. Most runners don't get this way. Just the ones who are really cranking out high mileage.

Some runners don't take care of their skin and get pretty leathery by their 40s.

But, in general, being lean makes you look a lot younger. Every time I have been around normies who do not run and meet some of my older running group members, I do the "guess how old" and the normies regularly miss by 5-10 years (guessing too young). Especially when you look at people in their 50s who are overweight, they look like hell compared to lean runners.

One thing I've wondered about with regard to professional runners and balding is whether or not typical hair loss remedies are allowed under anti-doping protocol. Could a pro runner in the WADA/AIU/USADA/etc. pools take oral minoxidil or topical finasteride? Or would those come with risks of messing up their testable hormone levels? I'm not in the healthcare field and don't know the science behind those drugs or all the specific things anti-doping bodies test for, but perhaps it seems like more pro runners bald prematurely because they can't partake in the common remedies that a lay person may use.

Another angle to this conversation is that the majority of distance runners in the US tend to be white, and I believe that white men have higher rates of balding than other races. It's not that other races never experience male-pattern hair loss, but I believe that the rates are higher in white populations. As an example, I don't think there's the same prevalence of receding hairlines amongst male Japanese distance runners as there is among white Americans, which would be due to genetics, not running.

This...this is why I come here. Thank you Bad Wigins for making me laugh.

Bro, that guy looks like he is at least 40,000 years old, straight up that guy got thawed out from the ice age.

I have had this same observation. When I attended my high school 30 year class reunion almost the whole XC team was there. Most of us still kept physically active doing something whether it was running, cycling, hiking, etc. I think it was noticeable that all of us looked much younger than the rest of our classmates.

I'm not sure this is really a thing...

If I'm mistaken, it's probably sun exposure.

YES

DUH! Of course, those that exercise look younger.

Truck drivers may not always look older, but they definitely do not look as fit. (ON AVERAGE)

There might be some that run too many miles for too many years. That might make a few look older, but I'm not speaking from experience as I have cut way back on my mileage as I've gotten older. But I have always looked young for my age, even when I was in elementary school. How old you look depends on many factors, including WHO is looing at you and WHEN!