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M_Tyson
August 11th, 2008, 08:37 AM
We've been treated to a number of close races in the Olympics, along with a number of underwater shots of swimmers finishing their races.

What I've been surprised at are the number of swimmers who put their hand into a "Halt!" position as they come to the wall. While the added resistance of that position is probably not going to hurt more than 0.01 seconds, the fact that the touch is delayed by about 6 inches of arm movement (your arm+hand is about 6 inches shorter in this position than if the fingers are pointed). That's at least 0.07 seconds (for 100m in 50sec).

For instance, see the finish of the men's 4x100 Free Relay (in this case, the position of the hand loses only 2 or 3 inches), or more dramatically, Hoff's finish in the W400Free where the touch technique may have cost her the gold.

Is there some reason that swimmers are finishing this way? Why not drive your fingertips into the touchpad?



Related to this, can anyone point me at documentation that shows that touchpads accurately record touches to at least 0.005sec, no matter where on a touchpad it is touched, by a sharp jab or a soft, flat hand, and that any two touchpads have the same latency. I've seen what appeared to be discrepancies between recorded time differences and what video shows as the difference in two touches.

I did find it interesting that at the World Masters meet at Stanford, relay starts that had a reaction time of -0.04 were considered not a false start, but -0.05 were a false start. If these were perfectly accurate, why isn't -0.01 a false start? Any documentation on this?

Redbird Alum
August 11th, 2008, 09:08 AM
I totally agree with your assessment of Hoff's finish in the 400. She should have had that race, even with the close of the English.

osterber
August 11th, 2008, 09:55 AM
I did find it interesting that at the World Masters meet at Stanford, relay starts that had a reaction time of -0.04 were considered not a false start, but -0.05 were a false start. If these were perfectly accurate, why isn't -0.01 a false start? Any documentation on this?

Not sure what relay pads were being used... when we use our Daktronics relay pads, 0.00 is a safe start, and -0.01 is an early start.

-Rick

hofffam
August 11th, 2008, 11:34 AM
We've been treated to a number of close races in the Olympics, along with a number of underwater shots of swimmers finishing their races.

What I've been surprised at are the number of swimmers who put their hand into a "Halt!" position as they come to the wall. While the added resistance of that position is probably not going to hurt more than 0.01 seconds, the fact that the touch is delayed by about 6 inches of arm movement (your arm+hand is about 6 inches shorter in this position than if the fingers are pointed). That's at least 0.07 seconds (for 100m in 50sec).

For instance, see the finish of the men's 4x100 Free Relay (in this case, the position of the hand loses only 2 or 3 inches), or more dramatically, Hoff's finish in the W400Free where the touch technique may have cost her the gold.

Is there some reason that swimmers are finishing this way? Why not drive your fingertips into the touchpad?



Related to this, can anyone point me at documentation that shows that touchpads accurately record touches to at least 0.005sec, no matter where on a touchpad it is touched, by a sharp jab or a soft, flat hand, and that any two touchpads have the same latency. I've seen what appeared to be discrepancies between recorded time differences and what video shows as the difference in two touches.

I did find it interesting that at the World Masters meet at Stanford, relay starts that had a reaction time of -0.04 were considered not a false start, but -0.05 were a false start. If these were perfectly accurate, why isn't -0.01 a false start? Any documentation on this?

Do you doubt the accuracy of touchpads? I trust them more than my own eyes watching underwater cameras.

Omega was issued a patent in 1973 for their touchpad. See more here (http://www.freepatentsonline.com/3745275.html).

As for touching in the halt hand position - I'm sure many here have jammed their fingers or thumb in a too hard touch. I have. Emily Silver has twice broken her hand/wrist on finishes. So I trust the elite swimmers of the world to touch in the very fastest way possible without unreasonable risk of injury. The velocity of the hand at the wall may be much higher than the speed of the body moving through the water so the time difference of 6 inches might be less than you estimate.

Frosty
August 14th, 2008, 01:29 PM
I did find it interesting that at the World Masters meet at Stanford, relay starts that had a reaction time of -0.04 were considered not a false start, but -0.05 were a false start. If these were perfectly accurate, why isn't -0.01 a false start? Any documentation on this?

The documentation is here: http://www.swisstiming.us/content1_files/DOCU_SW_RELAYBR_E.pdf

The sensor on the starting block detects the force that the swimmer exerts. On a relay exchange, the outgoing swimmer only needs to be in contact with the block when the arriving swimmer touches the wall. For a very brief moment, the outgoing swimmer could be completely horizontal, not exerting force upon the sensor, and still have a toe touching the block. Research determined that this brief moment was consistently 0.024-0.027 seconds. Thus, after discussions between Omega and FINA, FINA decided that it would give the swimmers -0.03 seconds of benefit on a relay exchange.