Perhaps we need to distinguish running from runners. Most runners are basically SAD eaters who burn off the calories so they aren't overtly obese, but that crap food still affects them. To me the lesson is that you can't burn away excessive PUFA, the pathogenic effects of grains and sugars, and poor nutrition in general.

Most endurance runners are the epitomy of skinny fats. They are skinny, but skinny in a rather unattractive way which reveals the nutritional deficient underneath.

The San bushman persistence hunting and the Tarahumara in Born To Run don't have these problems.

Art De Vany has long sounded the alarm on this.

And my personal experience rings true as well. As a child, a neighbor's father died from a heart-attack after jogging. He had the classic, "skinny-fat", muscle-less jogger body and never appeared to actually enjoy his jogging.

The word around the neighborhood went around, "But how could that be? He was so fit and was always jogging".

I sincerely believe jogging assisted in bringing this poor man to an early end.

I got a whiff of this from Mark Sisson when he was first interviewed in a cycling 'zine, The Rivendell Reader:

http://www.marksdailyapple.com/mark-sisson-interview-rivendell-reader/

You can follow the links to a PDF of the whole article. In that, Sisson names off a good handful of cardiac damaged elite endurance athletes. These runners/triathletes/cyclists have years of sugar-burning behind them as well. But chronic cardio is associated with heart/vasculature issues and I think more will come to light.

I've shaped my activity to mimic our paleolithic past, trying to avoid blind or pointless re-enactment. So that means lifting heavy stuff, climbing/gymnastic motions, compound movements, sprinting, naps, leisure, competitive fun, some long slow walks or bike rides that avoid upper level "training" heart rates, fasting, etc.

My heart rate monitor is useful to be certain I stay UNDER 70% of my max heart rate during longer hikes/walks/rides! I certainly wince when I see the runners and riders out to pre-maturely age themselves and compromising longevity.....tsk tsk.

I certainly did not know this, Dexter! I know many vegetarians and SAD eaters who are long distance runners/swimmers/cyclists and they are so healthy looking. It never even crossed my mind that these guys are 'over-doing' it, or that they are more susceptible to heart attacks - they are like, the epitome of 'fit'. They garner great respect amongst my friends and I often think about them working so hard to maintain their slim physiques. It came as quite a surprise to me when I first switched to paleo and my body started to look like theirs, but I ran not a mile.

I think that the indoctrination we are exposed to nowadays about saturated fat being bad, aerobic exercise being good is pretty much ingrained into almost all of our brains. Where have these ideas come from and how come they are so persuasive? As Mark Sisson says in the article you cite: "But itʼs not a matter of being stupid. Unlike other animals, we have advertisements and testimonials and hype to deal with, and our tendency is to believe, not to doubt, so we are more susceptible." There certainly is pressure to get out there and do it, absolutely - thankfully, I enjoy walking more than long-distance running and have always preferred 'all-round' exercise like gardening, housekeeping and looking after small children, which involves nearly all of the motions Tim describes (esp. the naps).

Since reading your quote on Tim's question yesterday, about the Greek runner Pheidippides, I have been feeling less guilty that I am not out running every evening like I see so many of my friends doing. I still think I must be labelled as 'lazy' by my friends though - perhaps all this has something to do with some kind of work ethic we are supposed to be subscribing to?

A question I would like to ask is: some races must be more predisposed to long distance running than others, like Ethiopians such as Haile Gebre Selassie for example, do you think this is the case?