Do these studies control for people who quit running due to an injury? It doesn't appear that they do. They look only at "healthy long distance runners." Sorry, but that is not very compelling. It's like studying 90-year old chess grandmasters and concluding that chess prevents Alzheimer's.

You have to control for all the people who don't do an activity because they're too unhealthy to continue. And there is no obvious way to do that.

It says they followed runners and non-runners for 18 years. Presumably, that means they monitored the same bunch of people over the 18 years and the effect you mention would have been noticed, if it existed.

The question is: did they only count someone as a runner if they were still a runner at the end of 18 years? Or if someone was running for 1 year, got injured and then quit running, did they get dropped from the study or even grouped with the non-runners?

Well, I don't have the time to go through the whole thing but on a first glance:

1. Seems like they identify someone as runner or walker based on a questionnaire filled. After X years those people fill another questionnaire to indicate whether they had OA or hip replacement. I would think that at the time of the second questionnaire a runner will still be assumed a runner, even if he doesn't run anymore.

2. Exercise other than running increased rates of OA and hip replacement.

That's not a very good study then. They should be taking a group of people, none of whom are runners, and randomly assign them to runner or non-runner groups, and then follow them for 18 years. The activity levels of all participants should be tracked at all times by GPS devices with heart rate monitors. Their health should be monitored by professionals, though they should not be given any instruction in proper running techniques. At the end of the study they should give everyone a full examination to determine the outcomes for each group.

Of course, I'm being facetious. Such a study would never be done because it's completely unethical. But the point is that you can't determine an intervention (running) is safe and effective without a proper trial like that. A survey that asks people whether they're a runner or not, before even beginning, has a problem with selection bias.

I skimmed the report, they break down the % of people still running. They took x-rays and measured the space between the joints amongst other tests to see how much wear/damage occurred in the 18 year period. In both the control, and the runners group there were runners (17% vs 97.8%). By the end the runners group still had 55.6% running vs 3.8%.

Unfortunately they didn't break down the km's ran to classify the individuals. Also The runners group was almost more likely to do 'vigorous exercise'.

To answer your question, they did continue to classify as runners even if they stopped (and almost half did stop).

I'd suggest you read the actual study. It's way more nuanced and detailed than the 2 sentence summary I provided. And no, I don't think it provides a 100% guarantee that running is safe but that's not what I'm expecting from a study. It's just one more data point in the ever growing body of evidence that active lifestyle is better than sedentary lifestyle.

The problem is not that you're being facetious, the problem is that if you insist on a single study proving something with a 100% certainty, we shouldn't be doing any science. For example, I can find numerous holes in your supposedly perfect study design. It turns out that active runners have less joint issues indeed? How can you be sure that it's due to running and not due to increased exposure to sunlight? Why aren't you testing different exercises? What if the benefits of running are solely due to improved cardiovascular performance but running specifically is actually bad on the joints bearing the heaviest load? If you dig deep enough, we can go on and on.

If you go back to the beginning of the discussion, the person I was replying to was citing these studies to claim that running is perfectly safe. My reply was intended to raise doubts about that claim.

The burden of proof is on running advocates to show that running is safe and to clearly lay out the conditions for safety. As a former runner (who quit after breaking an ankle and speaking to an orthopedic surgeon who saw runners all the time), my strong suspicion is that running is only safe for those who:

a) run with perfect form

b) have perfect-fitting shoes

c) eat a well-balanced athletic diet

d) are already slim and fit before they begin running

I feel like that last one is the real key. If you're massively overweight and someone tells you to just go for a run, you're going to get hurt. To be a runner you need to get in shape first and have someone help you buy proper shoes and teach you proper form. Anything other than that is bad advice.

You are questioning the study methodology without bothering to read it. The burden is on you to actually understand what you are talking about.

>> If you go back to the beginning of the discussion, the person I was replying to was citing these studies to claim that running is perfectly safe.

I'm mystified at why you'd say he was trying to "claim that running is perfectly safe" when his first sentence was, "Like all repetitive activities, runners are prone to overuse injuries and the most common is to the knee." Maybe you should go back and get a grip on precisely what point he was trying to make. It was _not_ that running is perfectly safe.

People who run are prone to overuse injuries, no doubt about it. People who are long-term runners tend to learn how to manage injuries and keep them minor. Some people never learn.

I've discussed with running friends that in a way it seems odd that medical insurance covers treatment for our running injuries, when they are injuries that are in a sense "chosen"; we could certainly have avoided them if we didn't run at all. Yet, still, a runner's visits to physical therapist, orthopedist, or sports medicine doctor are covered. The answer we come up with, and it seems correct to me, is that covering runners for their "chosen", "elective" injuries is over the long term still much cheaper than covering non-runners for the much more expensive health problems they will have over the course of their life.

> If you're massively overweight and someone tells you to just go for a run, you're going to get hurt

Massively overweight people can't run, even if they wanted to. Their "run" speed is slower than my "walk" speed.

Thanks for mentioning that, this is something I often wonder about, as this is at least often left out of the press. I don't know how/if the underlying research accounts for it, but I'd be very happy if such statistical complications were mentioned more often to show hard it is to get the science right.

Right now I weigh a little more than 100kg and am currently trying to better my life to live healthier and be more active.

I can run pretty well, currently about 10km with a heart rate monitor to not exceed my limits. I've tried swimming as well but for some reason I get knee pain during swimming, it's probably just bad technique but it feels so stupid to have to get out of the water because of knee pain.

At my max I weighed 115-120kg and I'm pretty sad that I didn't start doing all this stuff earlier.

How tall are you?

Also, the article briefly mentioned rowing. I didn't enjoy it as much when I was competing when younger, but it's a brilliant exercise if you have access to even (or can afford) an ergometer (indoor rowing machine).

As long as you study form and adhere to that principally before exerting yourself, it's a great aerobic exercise that also helps build and maintain muscle mass (arms, back, and legs mainly). It's easier on the joints as well—again, and I must stress, as long as you maintain proper form. I see so many "cross-fitters" yanking and janking their arms and back and shooting their butts around it makes me cringe knowing what kind of hell it's going to render to their bodies. With proper form, it's one of the best compound exercises. I wish I had access to an erg these days, but I'm trying to keep my own costs down by using the limited gym in my building.

Also if you're in a town with a rowing club, they often host "learn to row" sessions that will guide you through a lot of it—and get you out on the water as well, if you're not averse.

> (...) it's probably just bad technique but it feels so stupid to have to get out of the water because of knee pain.

Get one-on-one classes! A teacher can correct most of your errors in a couple of hours, and will make a decent swimmer out of anyone in ten hours[¹]. It's a very small investment for a very large gain.

[¹] Assuming there's no fear of water involved, you can go from "I can't do one lap without stopping for air at the wall" to "I can swim 1km continuous" with 10h of classes.

Maybe try ellipticals instead of swimming if you are bored of running? They should be easy on the knees.

Anecdotes follow:

As a lifelong soccer player, my knees are in terrible shape. I have multiple meniscus tears in each, and I've also had catastrophic injuries in both ankles. Despite that, I keep playing. The most useful teammates I have are those players who are also running fanatics. They put a lot of effort into gear, technique, and ritual that helps prevent and repair knee and foot damage. I've not encountered this much devotion to bodily integrity in any other sort of athlete.

Soccer is a totally different game than running - it's basically a game of "how to best apply extreme forces to your lower body in unstable positions". You're twisting and turning and applying force in ways the body wasn't meant to handle in any sort of repeated manner. I can definitely see how running would help - it'll help build up the muscles and surrounding tissue, but really, when it comes to longevity of the joints, soccer is just bad news.

> Also, knee pain is almost always due to a biomechanical or strength issue.

If you have a recurring running issue it’s one of those. I got shin splints every month. Then I stopped running for six months and started weightlifting. No one who squats is going to get shin splints.

Shin splints is the classic injury for enthusiastic people who see aerobic improvements that outpace the strengthening of muscle, tendon and bone. Shin splints is almost unheard of amongst experienced runners.

It's fantastic that squats helped you, but if you are primarily looking to improve your running then months of training at a lower intensity, to avoid the shin splints, is much more productive than stop-start training resulting from the need to let your injury heal.

I got shin splints because my calves were too strong, so I worked on that issue of strengthening the front, and flexibility.

This is why I bike rather than run. Crashing is your primary risk there but otherwise, it's stupendously hard+ to hurt yourself unknowingly.

I'm not fully aware of all of the possible long term risks to cycling but I know pollution from cars comes up a lot. I believe the prevailing consensus is that the benefits still outweigh the harm done.

+: May be overstating it. You can hurt your wrists through a bad fit and your knees through using too high a gear. In both cases, your body will probably let you know about it soon though.

I bike and run, and like you appreciate how gentle cycling is on one's body. With that said, I don't worry about getting killed while running the way I do while cycling (i.e. by cars).

Swimmers get shoulder problems.

That is a very general statement. It really depends on the type of swimming and intensity.

I have a bad shoulder (pain) from having it dislocated several times over the years.

When I first started swimming (only breaststroke), I felt tingles of pain pretty quickly. Outside of swimming, I would feel it if I raised my arm over my head in certain angles.

After about 6 months of regular swimming, literally all the pain went away. Clearly my body developed strength around the injury. My shoulders feel better because of swimming.

In a similar vein... I used to have terrible RSI from typing. I randomly started rock climbing. After a while, my hands strengthened and the RSI pain went away. I climbed actively for about 8 years. I stopped climbing years ago (kept typing) and the pain never returned to the same degree as before. When I started swimming more recently, the current hand pain went away again as well.