It is not clear that running is bad for the knees. Recent studies ([1], [2]) find no evidence of any adverse effects, rather the contrary (lower incidence of knee osteoarthritis in the running group). One possible explanation is that the runners were less likely to put on weight over the years, leading to lower day-to-day stresses on the knees.

[1] Eliza Chakravarty et al. "Long distance running and knee osteoarthritis: A prospective study," American Journal of Preventive Medicine, 2008, 35(2), 133-138

[2] David Felson et al., "Effects of recreational physical activities on the development of knee osteoarthritis in older adults of different weights: The Framingham Study," Arthritis & Rheumatism, 2007, 57(1), 6-12

> It is not clear that running is bad for the knees

I wrote 'extensive running'

You didn't define 'extensive'.

Is it 20-30 miles/week over a long period, which you claim is already way too much for the majority? If I read study [1] correctly the runners were running 3.5 hours a week at the beginning of the study, which would be around 20 miles/week. That same group had a lower incidence of osteoarthritis than the control group.

Do you have any evidence to back up your claim?

its far from crystal clear - each body is different, what builds one breaks another one (even if fitness levels are similar). genetics is not fair.

our bodies require challenge, otherwise they get weak and fragile. challenge too much, it will break. this point of diminished return is again different for each of us, and varies over time for same person.

BUT - if you give it enough time to fortify itself - I don't mean muscles, they grow faster than rest of the body. I mean when bones, tendons, ligaments and generally joints catch up (ie for climbing it takes years of gradual progression to train your fingers), they hold the body together better (knees, feet, spine etc.) and can manage stress put on it, even till high age. I have a friend who is 80 year old mountain guide and he still climbs easier stuff.

But to find the balance, the edge of benefits vs losses that is never stable and unique to each of us is very hard

Where is the research you are citing? Running is not bad for the knees period. You do not define extensive or what you are basing your opinions on.

Bad knees can be the result of many, many things, including an injury which may have been the result of twisting your knee rising from a chair.

Or shoes with shock absorption are more prevalent now

I don't think you know anything about the cause and effect relationship considering you have no idea who I am let alone what is wrong with me knee.

I haven't been running like that since I was in college. I wore down cartilage in my knee while running through pain I had been having for a while. I wasn't taking care of myself the way I should have been. If you take the time and care to make sure you stay healthy, 20-30 miles a week is nothing. If your logic held than 'pay back time' should have happened for my peers a long time ago, they all ran more mileage than I did and some still run 100 plus miles per week. If there is some magic number of miles knees get, they would have hit it a long time ago. That is not how it works. People are different, bodies are different, you just need to make sure you take care of yourself and don't ignore the maintenance.

With only that tid bit of information you have about him, there is nothing crystal clear. There is not a single individual build the same way. Some people can run 7 marathon in 7 days, and they have been doing that for 20 years, others are going to have knee injury after a couple years of running. Some of it might be technique, but it is likely combined with different bone/joint/muscle architecture.

> I don't think you know anything about the cause and effect relationship considering you have no idea who I am let alone what is wrong with me knee.

Why are you getting aggressive? You have your opinion, I have my opinion, no need to snap.

> People are different, bodies are different

Ok, I agree. But why do you then generalize yourself few sentences before and tell us that '20-30 miles a week is nothing' and treating everybody the same? I think, I was more differentiating, I said 20-30 miles/week for a long period is already too much for the majority—not for all.

> I wore down cartilage in my knee while running through pain I had been having for a while

Ok, doesn't really make your stance better. Who says that every other runner is so wise and stops running while having a pain? Maybe most of them do the same mistake like you did? Maybe they just want to win, just want to outperform other runners, just fear loosing or just want to prove themselves that they can run more than last week—all while slowly crushing their knees. And maybe it's the dynamics or game mechanics of running itself—it's not that easy to stop.

Sorry, but the cause-effect-relationship is getting even clearer with your last comment. Extensive running can get quickly dangerous and the problem is that the runner might realize this too late.

> Why are you getting aggressive? You have your opinion, I have my opinion, no need to snap.

I hope you don't think that counts as aggression, hardly. And while you are certainly entitled to your opinion, considering you know nothing about me, my running history, or my medical history, it's pertinent that people know your opinion is based on zero knowledge of the situation.

> Ok, I agree. But why do you then generalize yourself...

I was not generalizing. The conversation is about distance running. For a distance runner, 20-30 miles per week would be nothing, considering the shortest distance race is 5 miles long.

I honestly don't know how to address your last comment. You jump wildly from conclusion to conclusion and then just dismiss everything outright. And your argument isn't based on anything other than the fact that I personally got hurt, which is a dumb reason for others not to run. I don't have a great singing voice, but just because my singing hurts my ears, it doesn't mean others shouldn't sing to their hearts content. Really, the only cause-effect relationship that is clear is -> cause: be nbschulze for 25 years effect: need knee surgery. Which people can take with and do what they want. Yeah, knee surgery is a bummer, but I've enjoyed my life other than that and will continue to enjoy it.

The only stance I've taken is 'If you're going to run, make sure you take care of yourself'. I was trying to help others learn from my mistakes. If you want to argue with that, feel free. We don't caution people from buying cars just because a select few choose not to get the oil changed and ruin their cars. And you should not be caution people from running just because I personally ignored persistent and intense knee pain and damaged my knee.

It's worth adding that some people are able to continue running after knee surgery. And many non-runners have to have knee surgery too.

Except you still don't know what's the matter with his knee, and you definitely don't know what caused it. It seems a bit premature to assume that overtraining was the cause, and it's pretty ridiculous to imply that because some runners have hurt their knees, it is unsafe, or pointless.

> ... the cause-effect-relationship is crystal clear.

That must have been one of the most ignorant statements I read on HN.

> Just wait till you're older and then it's pay back time.

Well guess what, I know 70-year-olds still running a sub 3h marathon.

Please avoid a harmful tone when replying here, there's no need for that :)

As for the 70 year-olds still running marathons, I've heard of plenty more 25 year-olds dying of heart attacks. Anecdotes are not enough here it seems.

I've managed to avoid injury by being paranoid. Whenever my knees start bothering me, I reduce milage for a while until they feel 100% normal.

The trouble is, when someone signs up for a big race, they feel pressured to stick with their training plan in spite of any discomforts.

Actually there is some evidence that running is good for your knees.

Either way I think the health benefits of running clearly outweight any damage they do to your knees.

In my experience the untrained people are the ones that gets problems early when they age. If you can't run when you are 50, don't expect to walk without problems when you are 70. If you are a decent runner when you are 60, you have a good chance of being in quite good shape when you are 85.

> Just wait till you're older and then it's pay back time.

Of course, the cardiovascular benefits of running mean you're a lot more likely to live long enough for pay back time.