I don't know who considers 5 or 6 miles of running unhealthy. I reckon that if you couldn't run 5 or 6 miles at a time back in the day you'd be very hungry and/or very dead. Hunters in the Kalahari run down big game in the desert running up 20 miles in a day. Me, I absolutely hate running, I'd be an ambush hunter (I'm good on a sprint)...but the notion that we're ill adapted for running long distances seems odd to me.

As for the notion that you need a lot of carbs for running...why? The bushman in the Kalahari running in the desert sun for 8 hours is probably doing it while IFing. He's gonna run down that kudu and gorge on meat after the kill. You think he's going to sit down to a nice big bowl of carbs after a marathon hunt? No way. Dude is going to drink some blood, eat some brain and suck some marrow.

Five or six miles? It's cake. You'll be fine.

I've done a half-marathon, a sprint triathlon, and a full marathon. I plan to stick with triathlons and half-marathons in the future. Okay, maybe one or two more marathons...

I think anyone can train and run for any distance up to a half-marathon without deleterious effects. Once a person goes past 13.1 miles, I think he or she will find their "point of diminishing returns" rather quickly.

5-6 miles is not excessive at all. Our ancestors must have done a lot of running and walking in search of food.

Distance running is great. Watch this video. The ancients probably had to do a lot of running to get food. Not only chasing down animals (which we're great at apparently!), but also simply searching for sources of water, places where there's a lot of some kind of plant, etc.

If everything you needed was concentrated somewhere, of course you'd just move there. But what if most of what you need to concentrated somewhere, but there's 1-2 things that you need to go far for? Set up home base where everything else is, and run back and forth to get to the few things that aren't around!

Not that I have any idea what I'm talking about or anything. Perhaps they were already running or walking from one place to next, never setting up a home base. But then that would simply support long distance EVEN MORE. Either way, seems like we're good at running long distance... If you wanna be healthy, do what we're good at!

I love a good run and have done up to 10 miles without needing to make any significant changes to my food intake before hand (no carbo-loading, or the like). Have a blast. I think all healthy humans should be able to handle a 5-6 mile spontaneous run.

As a follow up to Dr. K's telemere comments.

Take a look at these postings back a year ago when Paleohacks was in its infancy regarding CVD and running: http://paleohacks.com/questions/2469/long-distance-running-and-heart-disease#axzz1JisHsczX

http://paleohacks.com/questions/3429/long-distance-running-and-paleo#axzz1JisHsczX

And we have these records of history of death by running...maybe legend or some truth:

According to the legend, a Greek runner by the name of Pheidippides ran in excess of 145 miles from Athens to Sparta in roughly 24 hours, which was quite a display of ultraendurance athleticism. Pheidippides followed up on this feat by running an additional 26 miles from Marathon to Athens to announce a great Greek victory. When he reached Athens he proclaimed either "Nike" (Victory) or "Be Happy! We have won!" Pheidippides then fell to the ground---dead. Recall the fate of famed long distance runner, Jim Fixx, who died of a massive heart attack at age 52 after going for his routine morning run.

All his family had heart disease and all were carb loaders. Chronic long distance was the cure for heart diesease. Not when carb loading is involved....and probably never.

The scientific literature is filled with data that strongly make the case that long-distance runners are much more likely to develop cardiovascular disease, atrial fibrillation, cancer, liver and gallbladder disorders, muscle damage, kidney dysfunction, (renal abnormalities), acute microthrombosis in the vascular system, brain damage, spinal degeneration, and germ-cell cancers than are their less active counterparts.

Taken from Body by Science, Authors Doug McGuff, MD & John Little, Page 6

Not elite or anything, but I completed the Shamrock Marathon recently after 60 days of straight Paleo. I 'carb-loaded' on sweet potatos and plantains 1-2 days before and kept almond butter squeeze gels on me for fuel during the race. It took 6 hours, not much different than when I ran a marathon on SAD a decade ago. I also ran the whole thing in Vibram Five Fingers. Felt primal, and felt good..

When I was in high school I was on sprint team, but we had regular long-distance (for a sprinter, about 3-6miles) runs incorporated. The good thing was, that it wasn't on a flat boring track, but through small forest, dirty paths and occasional mud and dirt. Now that was FUN! I still can't think of long running, so boring... but when I am on a hike, I often just want to run through the woods, with total euphoria and joy. For the sake of running.

Do what's fun, what makes you feel good and what you feel you are good at. The moment you feel it's painful, boring or too stressful on your body - try something different.

I am an endurance athlete (cyclist) and I am able to ride at heart rates of 160s being fueled completely by fat and I even get about 80% of my fuel from fat in the 170s.

Do what you enjoy doing, and you'll see that a high fat/high protein diet will serve you well running long distances.

Also you should check out the crossfit endurance website. Im sure your workouts are already set for the team, but these guys are really onto something great. One of the founders (Brian) has run a couple of 100 mile runs and I asked him what the longest training run he did leading up to it and he said 15 miles.

Good luck and have fun!