Something I posted a few days ago bears repeating: Running trails and running clubs are disproportionately populated with people who are more resistant to inju

Something I posted a few days ago bears repeating: Running trails and running clubs are disproportionately populated with people who are more resistant to injury. Lots of people quit running out of frustration with injuries. I had a two-year love affair with running that kept getting interrupted by shin splints and sore knees. (Cue the "you're doing it wrong" folks. I paid careful attention to my form and did my best to learn from, to choose one example from many, Evolution Running.) There's no way you can create an adequate control group for middle-aged long distance runners. You'd have to find people who had proved their ability to withstand high mileage running in their middle age and then quit for reasons unrelated to injury. These days running is still my favorite form of exercise, and I no longer have problems with injury, but that's because I gave up running long distances at a steady pace. I'm either run/walking with my girlfriend or doing solo fartlek sessions of no more than five miles total. I could certainly achieve higher mileage, but pushing the injury envelope longer seems worth it. When your study group is middle-aged long distance runners, you are perforce excluding people like me. How do you exclude people like me from the control group?