The first couple of minutes here is warm ups... and a little part where the camera gets all screwy for a second, but after that... this guy does some pretty cool ****.

http://www.metacafe.com/watch/726552/russian_climbing_le_parkour/

I thought everybody on the internet saw that by now. Twice. But good video, yes.

Baggy jeans + no shirt + trip hop soundtrack + flips and jumps = *yawn*

Augh. The Russian Climbing video.

Cool? Yes.
Parkour? No.
Extremely dangerous and unhealthy: Yes.

If memory serves, he currently has a somewhat significant amount of joint problems from doing such extreme drops. This video is not what Parkour is all about, although it is very impressive.

For those of you who don't know/might be interested: When training Parkour, most people train at ground levels, taking very small drops. Certainly nothing about your own height, and certainly not from multiple stories up. People who can do this (David Belle, Sebastian Foucan, etc) have been training for 20+ years. They started small, and over the course of two decades have been able to increase the distances of drops, among other techniques, safely, because their body and their joints have been conditioned to be able to take it.

So people see their videos, and immediately assume they can just go out right now and bust out a two story drop (ex: Manpower gap: http://video.google.com/videoplay?docid=-1384889833664818323&q=manpower+gap&total=7&start=0&num=10&so=0&type=search&plindex=1 ). What people don't realize is that that is David Belle, and like I said before, he's been training for 20 years. So people see this video, and then they go jump off their roof, and they might even be okay! But after repeated drops like that, they wreck their knees, ankles, feet, legs, entire bodies.

So long story short: It's a cool video. It's impressive. It's not what Parkour and Freerunning is about. Just a PSA from your friendly neighborhood Traceur, concerned about safety.

I know next to nothing about Parkour, but I'd say happydud is right just from looking at the physics of it. The Russian guy seems to be trying for whatever looks more impressive, where David Belle is a lot more efficient. And I'm not even talking about doing flips or anything; you can really see it in the final landing he (David) does where his legs look like they might as well be springs, and gives him less stress on his joints than anything. Really I'd think that rolling when you hit the ground, as well as being hazardous if you don't know what's there, isn't any better as far as forces are concerned because the center of gravity of the body doesn't really end up any lower.

Actually, rolling is key. From a basic physics perspective: The time it takes to decelerate from not rolling vs the time from rolling is a whole second or two different. That's a lot more time for the force to be absorbed over your body.

F=ma. So if A is .25 seconds (as it would be, roughly, if you just took the drop), versus 1.5 seconds... that's a HUGE difference.

The force is also displaced over your entire body with the roll, not just your feet/ankles/knees. This is KEY.

Also, rolling transfers a lot of momentum, so it isn't being absorbed by your body, it's being converted into forward momentum that you use to help get yourself back on your feet and continue running.

I prefer the 'run-jump-break my leg' style of parkour. It makes the experience that much more intense.

I like watching these guys on the buildings.

It's like nascar. The only reason people watch is for the possibility of a career ending crash.

I guess I see what you're saying, but it's only vertical acceleration that matters as far as stresses go. I hadn't thought about how it converts to forward momentum though; that's a good point.

(Someone call the Mythbusters, get them to mount accelerometers on some people and test different landing techniques)

Or just jump off something high and roll into it and you'll see for yourself.

I remember seeing this when I was big into parkour. It made me feel retarded-er.

They've actually done scientific studies.

This, while no scientific study, explains it better than I can:

By the way, shameless plug: If you're interested in Parkour, check out my blog at Zaccohn.com. I post all sorts of things there, from articles to events to parkour training.