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A study of the double dyno 24-Jan-2011 At 9:40:08 AM Tino

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On 18/01/2011 patto wrote:
>They needed a 'study' to come to that conclusion!? Oh dear.
>
>Anyone with a decent high school knowledge of physics should be able to
>come to those conclusions without calculations or testing.

True, yet which kind of recommendation would you be inclined to accept, especially when written in a climbing book:
a) simple high school physics tells you: don’t deadpoint!
b) an engineering investigation proves that classical deadpointing, compared to overshooting, has a smaller chance of performing a successful jump, and results in a higher finger force, thereby increasing the risk of finger injuries.

Still, the basic recommendation in the climbing literature is related to the deadpoint (and unfortunately not to high school physics principles…), e.g.

It’s best to hit the hold at the deadpoint – the top of your arc, when your body is essentially weightless. If you overshoot the hold, you will have to catch more weight as your body falls back down onto it” [Luebben C 2004 Rock Climbing: Mastering Basic Skills. Mountaineers Books, Seattle WA].
INCORRECT! – and this is why you need a ‘study’ in order to prove that:
At the deadpoint, you have to hit the hold in a split second, which produces a high shock spike on your fingers.
If you overshoot, you have more time to dampen the fall and thus experience less force.
Again, simple high school physics gives the clue: increase the exposure time of the force and the magnitude of the force will drop – e.g., the impact on a softer spring: same impulse, less force, longer time; that how any decent sports shoe should work

“Another important aspect of any type of dyno is the ‘dead point’. This is the point at which your body ceases its upward motion and loses momentum, pauses for the briefest of moments before gravity start pulling it down again. The trick is to be able to grip the hold when you are at the dead point; this will make holding onto it successfully a lot easier and also goes a long way towards preventing soft tissue injury. To grab for a hold as you are descending past it, with your body accelerating, is asking to pull a tendon or cause similar damage.” [Hill P 2007 Rock Climbing – Instructional Guidebook. Cicerone Press, Milnthorpe UK].
INCORRECT!
It’s the opposite: less successful and more injury risk!
However, the following sentence is correct: “To grab for a hold as you are descending past it, with your body accelerating, is asking to pull a tendon or cause similar damage”. And this is what you should NOT do – “grab for a hold as you are descending past it”! You should rather grab the hold as you are ASCENDING past it, i.e. well before the deadpoint, which is only possible if you overshoot.