I hear this all the time and I don't think it is any coincidence that mostly this nonsense is spouted forth by people who are not in good shape - as if they were trying to justify the fact that they don't exercise not because they are lazy, but because they have a heightened concern for their joints and know that exercising will cause them to have problems later in life.
oooh, that hurts a little bit... maybe it would be better if I sat on the sofa and ate donuts!
Everyone always knows a guy who knows a guy who has knee problems but he used to run marathons every day or some ridiculous story like that. There is no medical information to indicate that any of this myth is in any way true. In fact the evidence all points to the opposite.
Just like any other part of your body, the more you use it, the stronger it gets. This is the reason why people in the gym tend to be more "ripped" than someone who doesn't do that sort of thing. The same is true for your joints.
Let's start with the experts
A recent article in the journal Arthritis and Rheumatism came to the conclusion of "far from increasing the risk of joint problems, running can protect against osteoarthritis by keeping joints and tissue strong, mobile and topped up with nutrients."
A further study published in Journal of Rheumatology found that there was no difference in the rate of deterioration of knee (and hip) tissue based on increased running activity and both groups deteriorated with age.
Let's move on to my own personal group
This happened yesterday. A group of us, mostly men between the ages of 40 and 70 meet at a local pub for a few beers every Sunday afternoon and this very topic came up. At the table there were two groups of thought, one was the very vocal opinion of "running causes bad knees" and then the other side (mine) of "running is good for you."
The people who were really opposed to running (because of the perceived damage to joints) were all overweight, and many of them smoked. The two people at the table that were in the other camp were me (I run 5k at least 3 times a week, sometimes competitively) and an ex S.A.S. soldier who runs 5 miles every morning. I am in relatively good shape and my S.A.S. pal "Bob" is 70 years old and extremely fit.
So who are you going to trust? A myth predicated on non-science and laziness or the testimony of medical experts who stand to gain nothing financially if they were lying in a peer-reviewed academic journal and the two most fit people at the pub during the conversation?
I am not a professional trainer nor a dietitian. I am merely recounting what I did in order to lose over 50 lbs and gain muscle mass while still living a fun life and I think it can work for other people as well