Author Topic: Biomechanics in Parkour  (Read 25297 times)

Offline Sat Santokh

  • Hirundo Rustica
  • *****
  • Posts: 1825
  • Karma: +132/-32
  • Don't think with your balls, think with your brain
    • View Profile
Re: Biomechanics in Parkour
« Reply #60 on: June 27, 2007, 10:53:11 PM »
Steve to answer your question (I was there).  Everybody is pretty much the same however the peak impact by a traceur is much lower.  I am fairly new to this stuff so I'm sure Ryan can clarify later.  Another interesting discovery/theory is that flexibility plays a fairly large role in absorbing impact.  We also pretty much got rid of the 90 degree rule to an extent.  You try and stop at 90 and your peak impact will be about twice as much.  However that is strain on your quads which is better than strain on your tendons and ligaments if you go past 90.  So yeah we'll see how everything plays out.

Offline Alissa J. Bratz

  • Hirundo Rustica
  • *****
  • Posts: 2300
  • Karma: +525/-42
  • middle-aged man in mom's basement eating Fritos
    • View Profile
    • wisconsinparkour.com
Re: Biomechanics in Parkour
« Reply #61 on: June 28, 2007, 08:02:31 AM »
Another interesting discovery/theory is that flexibility plays a fairly large role in absorbing impact. 

That *is* interesting. When can we see the results?

*does the ants-in-the-pants dance*
She followed slowly, taking a long time,
as though there were some obstacle in the way;
and yet: as though, once it was overcome,
she would be beyond all walking, and would fly.
--excerpt from Going Blind, Rainer Maria Rilke

www.madisonparkour.com

Offline Sat Santokh

  • Hirundo Rustica
  • *****
  • Posts: 1825
  • Karma: +132/-32
  • Don't think with your balls, think with your brain
    • View Profile
Re: Biomechanics in Parkour
« Reply #62 on: June 28, 2007, 09:39:20 AM »
Haha we did a very impromptu study of that.  We don't really know how much yet.

Offline Colorado Kong

  • Oryctolagus Cuniculus
  • *
  • Posts: 40
  • Karma: +0/-8
  • Unleash your inner monkey!!!
    • View Profile
    • Best Pk website (for vids)
Re: Biomechanics in Parkour
« Reply #63 on: June 28, 2007, 10:35:03 AM »
Sat this is Patrick by the way, from the spot.  And what all were you guys testing just impact resistance or more and how did you measure it.
"In primary freedom, one utilizes all ways and is bound by none, and likewise uses any techniques or means which serves one's end. Efficiency is the key."

-Bruce Lee

Offline Andy Animus Tran

  • Hirundo Rustica
  • *****
  • Posts: 2980
  • Karma: +146/-44
  • The Invisible Man
    • View Profile
Re: Biomechanics in Parkour
« Reply #64 on: June 28, 2007, 11:06:40 AM »
Steve to answer your question (I was there).  Everybody is pretty much the same however the peak impact by a traceur is much lower.  I am fairly new to this stuff so I'm sure Ryan can clarify later.  Another interesting discovery/theory is that flexibility plays a fairly large role in absorbing impact.  We also pretty much got rid of the 90 degree rule to an extent.  You try and stop at 90 and your peak impact will be about twice as much.  However that is strain on your quads which is better than strain on your tendons and ligaments if you go past 90.  So yeah we'll see how everything plays out.

The 90-degree rule never says to stop at 90.  It says stop before then, lean forward, place your hands down, and push off to preserve momentum.
Andy Tran, C.S.C.S.
Lead Parkour Instructor
Urban Evolution
Parkour Virginia

Offline Ryan Ford

  • Hirundo Rustica
  • *****
  • Posts: 2423
  • Karma: +3/-1
    • View Profile
    • APEX Movement
Re: Biomechanics in Parkour
« Reply #65 on: June 28, 2007, 11:44:41 AM »
The "90 degree rule" has about 50 different descriptions depending on who you ask. One of the goals of this project is to put to rest most (hopefully all) of the confusion and inconsistency surrounding this rumor.

Offline Andy Animus Tran

  • Hirundo Rustica
  • *****
  • Posts: 2980
  • Karma: +146/-44
  • The Invisible Man
    • View Profile
Re: Biomechanics in Parkour
« Reply #66 on: June 28, 2007, 12:04:33 PM »
The "90 degree rule" has about 50 different descriptions depending on who you ask. One of the goals of this project is to put to rest most (hopefully all) of the confusion and inconsistency surrounding this rumor.

That would be good.  Hopefully, you will be able to test the effectiveness of most versions of the myth.
Andy Tran, C.S.C.S.
Lead Parkour Instructor
Urban Evolution
Parkour Virginia

Moa

  • Guest
Re: Biomechanics in Parkour
« Reply #67 on: September 20, 2007, 04:18:29 PM »
demon any more updates i havent seen much action on this thread recentley

Offline wingz

  • Oryctolagus Cuniculus
  • *
  • Posts: 28
  • Karma: +3/-0
    • View Profile
Re: Biomechanics in Parkour
« Reply #68 on: September 20, 2007, 06:17:19 PM »
I'm late to this party...but in case studies are still going on, it would be very interesting to see the "force vs. time" profile with multiple trials of an experienced traceur doing 1) silent straight drop (no roll), and 2) drop and roll.  I can see a possibility (needing experimental validation) that the roll lowers the effective center of gravity somewhat more than just a bent-leg landing, allowing more time to dissipate the vertical component of landing force -- irrespective of forward momentum (though forward momentum certainly may make it easier to initiate the roll).

Also would be interested in the relationship between typical peak G-force and jump height, for skilled traceurs and for non-traceurs.  Based on some basic physics calculations in another thread I'm guessing peak force is roughly 2Gs per meter of drop, presuming landing on a nonyielding surface.

The preliminary measurements suggesting that "silent landings reduce peak force" make intuitive sense, in that highest velocity (and therefore kinetic energy: 0.5 mv*v) occurs at the start of the landing, so the smooth transition to resistance (instead of a shock wave) should spread out the force over time better...(similar to proper technique of the "egg toss" game).

Definitely interested in the full study details when available.



Offline Sat Santokh

  • Hirundo Rustica
  • *****
  • Posts: 1825
  • Karma: +132/-32
  • Don't think with your balls, think with your brain
    • View Profile
Re: Biomechanics in Parkour
« Reply #69 on: September 21, 2007, 02:33:46 PM »
I'm late to this party...but in case studies are still going on, it would be very interesting to see the "force vs. time" profile with multiple trials of an experienced traceur doing 1) silent straight drop (no roll), and 2) drop and roll.  I can see a possibility (needing experimental validation) that the roll lowers the effective center of gravity somewhat more than just a bent-leg landing, allowing more time to dissipate the vertical component of landing force -- irrespective of forward momentum (though forward momentum certainly may make it easier to initiate the roll).

Also would be interested in the relationship between typical peak G-force and jump height, for skilled traceurs and for non-traceurs.  Based on some basic physics calculations in another thread I'm guessing peak force is roughly 2Gs per meter of drop, presuming landing on a nonyielding surface.

The preliminary measurements suggesting that "silent landings reduce peak force" make intuitive sense, in that highest velocity (and therefore kinetic energy: 0.5 mv*v) occurs at the start of the landing, so the smooth transition to resistance (instead of a shock wave) should spread out the force over time better...(similar to proper technique of the "egg toss" game).

Definitely interested in the full study details when available.




The force plate isn't big enough to roll on.

Moa

  • Guest
Re: Biomechanics in Parkour
« Reply #70 on: September 21, 2007, 04:05:04 PM »
Woah so demons results are from just doing a proper landing and not a roll, amazing how much it does

Offline wingz

  • Oryctolagus Cuniculus
  • *
  • Posts: 28
  • Karma: +3/-0
    • View Profile
Re: Biomechanics in Parkour
« Reply #71 on: September 22, 2007, 07:22:54 AM »
Thanks for the clarification Sat Santokh.

Good point - in a commercial catalog the largest force plate I saw was 4' x 2', and maybe the lab has a 2' x 2' model.

It would be possible to build a much larger plate (like 4' x 8') using commercially available parts, but would cost at least several thousand dollars just for vertical-axis measurement...so someone would have to be reeeealy interested in the answer to that question, to invest that money and time.

On the other hand, if I recall, the force plate at University of Colorado is part of a walkway and can be repositioned within the walkway.  So they still could measure at least the vertical landing in what becomes a roll-out.  And perhaps could separately measure the rolling force right after the landing.  This isn't as clean an experiment as gathering the data from a single event (the drop AND the roll, together) but by combining a number of trials one might get some statistically useful data out of it.

Offline Sat Santokh

  • Hirundo Rustica
  • *****
  • Posts: 1825
  • Karma: +132/-32
  • Don't think with your balls, think with your brain
    • View Profile
Re: Biomechanics in Parkour
« Reply #72 on: September 22, 2007, 03:43:04 PM »
Thanks for the clarification Sat Santokh.

Good point - in a commercial catalog the largest force plate I saw was 4' x 2', and maybe the lab has a 2' x 2' model.

It would be possible to build a much larger plate (like 4' x 8') using commercially available parts, but would cost at least several thousand dollars just for vertical-axis measurement...so someone would have to be reeeealy interested in the answer to that question, to invest that money and time.

On the other hand, if I recall, the force plate at University of Colorado is part of a walkway and can be repositioned within the walkway.  So they still could measure at least the vertical landing in what becomes a roll-out.  And perhaps could separately measure the rolling force right after the landing.  This isn't as clean an experiment as gathering the data from a single event (the drop AND the roll, together) but by combining a number of trials one might get some statistically useful data out of it.

I don't think its 4X2 but I might be wrong, but yeah it can be repositioned as part of the walkway. 

Offline Phytolith

  • Mangabey
  • ****
  • Posts: 260
  • Karma: +27/-18
  • Phytolith
    • View Profile
    • APK Alliance Blog
Re: Biomechanics in Parkour
« Reply #73 on: September 24, 2007, 08:13:03 AM »
Sorry to step in so late, only found this thread recently.

I work with a bunch of people who do biomechanics, talked with them a bit about this, they were intrigued.  You wouldn't necessarily need a bigger forceplate to measure drop vs. drop and roll.  If you assume that in either case you're dissipating the same forces, you can measure the drop in both cases, and assume that whatever the difference is between the two is the force dissipated by the roll. It'd be really interesting to see how much a roll really helps. . . 

Offline wingz

  • Oryctolagus Cuniculus
  • *
  • Posts: 28
  • Karma: +3/-0
    • View Profile
Re: Biomechanics in Parkour
« Reply #74 on: September 24, 2007, 09:12:58 AM »
Phytolith, while that certainly would give us more data than we have at present, I would be interested in the vertical force vs. time curve for the entire movement if it were feasible to obtain.  In particular, the concentration of the various force peaks, and what part of the body is bearing the forces, for what amount of time.  Materials behave as if stiffer and more brittle during momentary impact shock than they do at normal timescales, so knowing instantaneous force versus time could be useful in optimizing technique for minimum tissue damage.  Of course there is a time resolution limit in standard force plates of the "natural frequency" of the plate (where it "rings" if tapped) since the resonance tends to mask superfine-timescale detail.

That said, I hope they try, as you suggested, the drop vs. drop and roll, in that the greatest forces are likely near the beginning of the landing.

In some other APK thread, an experienced traceur stated that greater forward velocity dramatically decreases the perceived force of a ten-foot-drop landing versus a straight drop.  Perhaps that's because the forward velocity propels you into a roll faster, and a larger area of the body takes the deceleration...

So if they do the drop vs. drop-and-roll, the experiment should also be conducted with a representative set of forward velocities.  This might require rebuilding the jump "staircase" to have more run-depth, moving the force plate further from the jump staircase, and probably would require either a means of 'liftoff' velocity sensing or a means to record exact landing location (knowing the drop height you can compute likely horizontal velocity by distance traveled).

Offline like_a_child

  • Patas
  • ***
  • Posts: 211
  • Karma: +8/-8
    • View Profile
Re: Biomechanics in Parkour
« Reply #75 on: September 26, 2007, 01:53:07 PM »
In some other APK thread, an experienced traceur stated that greater forward velocity dramatically decreases the perceived force of a ten-foot-drop landing versus a straight drop.  Perhaps that's because the forward velocity propels you into a roll faster, and a larger area of the body takes the deceleration...

When you jump off a horizontal surface and jump horizontally away from it, does the curve describing your movement grow steeper over time? In other words, do you start to fall more down per second than across?

If that's the case, it might be worthwhile to do a straight-down vertical jump and then use the side of that wall to propel yourself sideways using your legs, to create a sideways motion that is fresh and strong when it's most needed.
I give you this:
I will never view my fellow traceurs as a springboard.

Offline wingz

  • Oryctolagus Cuniculus
  • *
  • Posts: 28
  • Karma: +3/-0
    • View Profile
Re: Biomechanics in Parkour
« Reply #76 on: September 26, 2007, 03:32:24 PM »
In some other APK thread, an experienced traceur stated that greater forward velocity dramatically decreases the perceived force of a ten-foot-drop landing versus a straight drop.  Perhaps that's because the forward velocity propels you into a roll faster, and a larger area of the body takes the deceleration...

When you jump off a horizontal surface and jump horizontally away from it, does the curve describing your movement grow steeper over time? In other words, do you start to fall more down per second than across?

If that's the case, it might be worthwhile to do a straight-down vertical jump and then use the side of that wall to propel yourself sideways using your legs, to create a sideways motion that is fresh and strong when it's most needed.

If we ignore wind drag and "terminal velocity" effects (which become pronounced at higher velocities than parkour, like skydiving), then your horizontal velocity remains unchanged after the jump until you hit something or land on something.  Kind of like being in space...you keep moving with the same horizontal velocity.

However, vertical is a whole different ballgame because near the surface the Earth is gravitationally accelerating you at about 9.81 meters per second, every second, so you go faster and faster and faster until landing.  There IS a limit where the force of air drag counterbalances gravitational acceleration, typically quoted as 120mph for a normal skydiving position, but as a traceur you should never encounter such airspeed.

So yes, the curve describing your movement indeed grows vertically steeper over time, and you do start to fall more down per second than across -- if you're falling far enough.

Keep in mind that your horizontal velocity doesn't really degrade with time (unless you're jumping into a strong headwind, I suppose), so since you can probably attain greater horizontal velocity in the run up to the edge than in a push-off of the building, the run should give you a lot more advantage.

Also, to push off the building you kind of need to be sideways in the fraction of a second of the drop, and then somehow get back vertical for the initial landing, or risk bellyflopping/diving onto a hard surface (severe injury alert).  And if there is just a little residual horizontal velocity in an "intended push-off" jump, you may end up too far from the building to push, anyway.  Similarly if you jump from an overhang, can't reach the wall.  And it would be too easy to miscalculate/misperform the precise amount of rotation speed necessary to put you in position within the drop time.

So I'd warn against trying the pushoff-midway-down-the-building approach for an actual drop.  It sounds cool in theory but could go terribly wrong...I'd leave that one to the movie ninjas filmed in front of greenscreen...

Offline dandaman208

  • Oryctolagus Cuniculus
  • *
  • Posts: 21
  • Karma: +1/-0
    • View Profile
Re: Biomechanics in Parkour
« Reply #77 on: November 30, 2007, 03:06:18 PM »
Where are you going to post your results? Have they already been posted?

Offline Samuel96

  • Hirundo Rustica
  • *****
  • Posts: 593
  • Karma: +59/-348
  • Bear hunter-3rd in command
    • View Profile
Re: Biomechanics in Parkour
« Reply #78 on: November 30, 2007, 05:10:11 PM »
Heres proof: in this boy scout camp (where we made platforms in trees to sleep on. one that we toured in the morning was 10 feet up that had supportes for what could be another platform 4 feet up) we one of the supportes on the 10 foot platform snapped so I took a direct fall. While I was falling I grabbed onto one of the lower supportes and swung forward. Kinda like prince of persia, exept without the gainer. the shocking thing is that I trained my self to roll naturally from any drop from 3 feet up.............

Offline KC Parsons

  • Hirundo Rustica
  • *****
  • Posts: 1414
  • Karma: +82/-13
    • View Profile
    • Eat. Move. Improve.
Re: Biomechanics in Parkour
« Reply #79 on: November 30, 2007, 05:57:11 PM »
Here'd be a good suggestion:
Since monkey vaults are used so much in parkour,
It'd be nice to know just exactly what your body's doing. All it would take is a rail/platform to vault over, plus the high speed camera so you can analyze what exactly your body is doing.

If you can do it with the pressure sensitive device, then you can see how much impact you're hitting the rail/platform with your hands.

Even if not, though, just the high speed camera capturing everything your body does frame by frame would be AMAZING insight.

Thanks =D