Exercise is good for you.
Exercise is bad for you.
Running makes you smarter.
Running shrinks your brain.
Scientific news at best has it's limits and is at worst completely frustrating. Reading through the sources of scientific journals where these sound bites are derived may seem pointless for the layman. If you have the patience to bore through the terminology keeping an eye out for the broad strokes you generally find that the science often proves a single common sense principle... moderation and balance. There are far fewer good things and bad things than we tend to perceive. Just because a particular vitamin is essential for life doesn't mean that taking (ample) amounts of it extracted into a pill will be better for the body. Timothy Ferris followed a similar principle in his 4 hour body self experiments attempting to find just the right amount of input to get the desired results from his body, believing that any more was unnecessary and potentially harmful. In this article about free radicals and antioxidants it mentions both the purpose of free radicals and the damage they can do when out of control. So there is a benefit to taking antioxidants but you don't want your body to stop producing them. The same way you don't want to completely wipe out your gut microbes with antibiotics if you can help it. They are there for a reason.
A running injury that has plagued me for the last year+ seems to be a similar imbalance. Friends and family shrug and nod as if to say yea of course every runner gets injured cause it's hard on your body and that's what the doctors have said all along. I was admittedly one of those Born to Run folks who believe that we are all natural runners, and injury is just us not taking care of our bodies. Running on pavement in 'technologically' advanced shoes that are supposed to make you a better runner, whatever that means. Maybe everyone else was right and I should go back to eating spaghetti and hitting the gym when I can bear it. Start complaining about my age and lack of time over my third beer. There's still this breeze that beckons me to start over. While I have a bent towards the extreme and am attracted to purism there's work to be done to fix the imbalance that's hurting my foot and get back to doing what makes me the happiest - moving over the land. All the time remembering to care for my body as much as I enjoy forgetting that it's there.
The Transeurope Footrace Project
Long Distance Running and Knee Osteoarthritis
Adverse Cardiovascular Effects from Excessive Endurance Exercise