Completely depends on how you run. The trend I see is that everyone thinks running on hard surfaces incurs more impact, but that isn't necessarily the case.
Dredged that out of my memory from a couple years ago.
Heel strike - Effective mass is approximately the foot plus the lower leg, which equals 6.8% of total body mass.
Forefoot strike - Effective mass is the forefoot and some portion of the rearfoot and leg, which equals 1.7% of total body mass.
"We have found that even on hard surfaces (a steel force plate) runners who forefoot strike have impact forces that are 7 times lower than shod runners who heel strike. Rates of loading are equal to or less than rates of loading for shod runners."
So much nonsense? Where? I agree the "only if forced to" sentiment feels misplaced, but that sentence is in the third paragraph out of more than 15. Did you actually finish reading it or stop there? He didn't conclude that humans are the best runners cause herp derp dogs don't run that far unless they have to.
> ask those guys to run 50km for fun
The Indian tribe in born to run play a game similar to soccer. The course is about 20 miles long and the game lasts upwards of 48 solid hours, with players joining and leaving as they feel. So yes, they do it for fun. And we are still talking about present day Africa, this is not millions of years ago. The persistence hunters there have weapons, they have bows and arrows, they will not starve if they don't hunt this particular way. It's their way of life.
Most of the animals have evolved millions of years...and, humans didn't? I think there is so much nonsense in your comment that I cant believe it was published :p
There is a whole book written about this. There are several conversations in the book with this same professor. I would definitely say this book has changed my life.
In more than a few places, I was pretty sure that book was written specifically for me. My dad was in the process of getting knee surgery right when I picked it up. There was a section that detailed a doctor visit the author had, where the doctor told him his only recourse was to have the same surgery my dad was having. Two years later, the author (who didn't have the surgery) is still running barefoot around central park, yes on asphalt and concrete and any other substrate you can imagine. My dad is not. My dad used to come home and run for hours every day after work. Now he doesn't run at all.
Just thought I'd share some points in the book that I love and find relevant to this discussion so far...
Not mentioned in the article but Lieberman talks about it in the book, is the fact that all four-legged animals can only breath one time per stride. A running cheetah operates like a large bellows. When he extends, his diaphragm (which is attached to the pelvis) pulls back and forces the lungs open, forced inhale. When they stride, all their organs literally slosh forward in their horizontal bodies, compressing the diaphragm, forcing an exhale. Humans standing upright allows us to breath whenever we feel like it while running. No other animal can do that.
Also about the Man vs Horse race. Unless the dude sitting on the horses back is a sumo wrestler, it probably doesn't count for much. A horse that is 1200lbs of muscle has a 150lb man sitting on his back. That's equivalent to wearing a 10lb backpack. I'm not saying you wouldn't notice it, but you can't blame the backpack for losing the race. The real reason is that a horse can only outrun a human for 10-15 miles, at which point the horse has to slow down to a maintainable pace, or die. Humans have no such restriction.
And as for running on asphalt - we have the best shock absorbers science has ever seen...they're called knees. Air cushioned soles and arch support, pronation and supination control, torsion bars, built in computer chips to monitor your (incorrect) foot strike and adjust the shoe on the fly are all awesome - if you won't be needing your feet ankles and knees in old age.
I don't recommend many books, but read this one. Even if you don't run, hate running, have never run in your life. You will love your feet when you're done.
http://www.barefootrunning.fas.harvard.edu/4BiomechanicsofFo...
Dredged that out of my memory from a couple years ago.
Heel strike - Effective mass is approximately the foot plus the lower leg, which equals 6.8% of total body mass.
Forefoot strike - Effective mass is the forefoot and some portion of the rearfoot and leg, which equals 1.7% of total body mass.
"We have found that even on hard surfaces (a steel force plate) runners who forefoot strike have impact forces that are 7 times lower than shod runners who heel strike. Rates of loading are equal to or less than rates of loading for shod runners."