At the risk of opening another can of worms from my mysterious friend who claimed he has provided scientific data on why running is bad and I have not; here goes:
..... Dr Bonnie Bruce, the study author, followed more than 500 runners from a local club (called “ever runners” in the study) and 300 inactive people (“never runners”, but not necessarily sedentary) in their 50s and 60s for 14 years. When results from an annual health questionnaire were analysed, Bruce and her colleagues found that the “ever runners”, who ran at least six hours a week on average, experienced less joint pain by their 60s and 70s and only 35% of the joggers got arthritis (compared with 43% of non-runners)......Myth: Running is bad for your knees
....The belief that running is bad for your knees is a myth. In fact, the only runners who ever have bad knees are those who already had knee problems before they started running, have a knee condition they didn’t previously know about, or are using incorrect form when they run..... Why should you run?
.....This research also allows runners to be a little smug, because we now know that despite what scientists and the cynical suggest, running is far from bad for you. The only difference between what our ancestors did and modern man does is that most of us have become a little soft.....Running Evolution
...However, it is also worth noting that because running is a weight bearing exercise, it also stresses the bones of the lower body in a positive way. Weight bearing exercise causes the bones to retain minerals and thus supports the rebuilding/maintenance of strong bones....Running: Advantages & Disadvantages
......There are many factors that cause pain in the knees. The most common cause of knee pain is a muscle imbalance in the quadriceps. This imbalance causes the knee joint to be pulled in a direction in which it isn’t designed to be pulled.....Running is bad for your knees
And I can go on and on but I suspect somebody else will dig out even more anti-running stuff to support his case.
I will end with these posts from a forum (no offence but this is exactly how I feel most time with the 'expert' opinion:
"Exercise and nutrition seem to be two of those areas everyone has an opinion on. Who knows why... Some of the crappy advice never seems to die either. It just spreads like a disease or something... Blah. I always love the "running is bad for you (r knees)". WTF?"
"In every instance where someone has told me that running is bad for me-that person is on medication for at least one of the above mentioned issues. Go figure!!"
"Those who CAN'T (or won't) teach, those who can DO!
"I think they are just another case of people who think they are always right.
They don't run...so it must be bad for you, right? Otherwise they'd be out there doing it too. Or feeling guilty that they're fat and lazy"
All quotes from Runner's World Forum