Induced boredom? NO WAY. Finally something from this thread worth saving.
Thank you.
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]]On Behalf Of Elliott Oti
> Sent: Thursday, March 22, 2001 5:04 AM
> To: T-and-F; Ed Prytherch
> Subject: Re: t-and-f: absolute limit of reaction time
>
>
> [Warning: this may induce boredom]
>
> There are some major differences between muscle stretches during a stride,
> and starting out of start blocks:
>
> 1. During sprinting strides. neural signals do not go to the
> brain, they go
> to the lower lumbal spinal cord and back. This is why damage to
> this region
> leads to the inability to walk. (Conversely beheaded chickens can
> still run
> around). Going to the brain would take approximately twice as long. Take
> your hypothetical figure of ~0.04 seconds; based on that the round trip to
> the brain would take 0.08 seconds, or almost 0.1sec. This is exclusive any
> cognitive and processing time to filter out the start shot from ambient
> noise levels. Actually this figure (0.08) is pretty close to
> reality, as far
> as I can determine.
>
> 2. Sprinting strides are plyometric in nature; pre-stretched muscles
> contract faster than static muscles. Starting out of the blocks, in
> contrast, involves contracting muscles that have been held in a static
> position for some time. This leads to contraction times between 3 to 10
> times slower than plyometric stretches.
>
> 3. There's the complexity aspect: regardless of the transmission speed of
> any particular signal, axons do not transmit more than about 200
> pulses per
> second; that is they have a bandwith of 200 Hz. Striding is less complex
> than starting (which is why the spinal cord can handle it alone).
> This means
> that there is a 0.05sec lag between individual signals sent to
> the trunk or
> legs from the brain. (The total delay is not going to be much
> more than this
> though, because the nervous system is massively parallel, but I digress).
>
> 4. Then there's the cognitive aspect. There have been numerous experiments
> performed to see how fast humans can respond cognitively to unexpected
> signals. A quick search of the available literature on the Web
> (Google does
> wonders) reveals no faster reaction to sound signals than 0.125 sec.
> Reactions to visible signals are 50% to 100% slower. (Loud sudden noises
> startle us reflexively. Lights have much less effect). In fact, our eyes
> process visible information so slowly that we are unable to distinguish
> individual frames in a movie run at 10 frames per second (i.e.
> each frame is
> shown for 0.100 sec).
>
> Finally, some hard figures from the trenches. In Seoul the reaction times
> were:
>
> Ben Johnson: 0.132s
> Carl Lewis: 0.136s
> Linford Christie: 0.138s
> Desai Williams: 0.149s
> Robson da Silva: 0.155s
> Ray Stewart: 0.159s
> Calvin Smith: 0.176s
> Dennis Mitchell: 0.186s
>
> Rest assured that none of these gentlemen stayed longer in the blocks than
> was absolutely necessary. Also, don't make the mistake of looking at the
> fastest reaction time -- look at the slowest.
>
> More trivia: in Rome '87 Carl Lewis's reaction time was 0.197s;
> in Seoul '88
> it was 0.136s. Dennis Mitchell had a reaction time in Seoul of 0.186s; in
> Tokyo '91 that was 0.090s. This is not a matter of their bodies undergoing
> great physiological changes. Their muscles still contracted at the same
> rate; their nerves still conducted signals at the same speed. They simply
> learned to anticipate the starter better.
>
> Cheers, Elliott
>
> From: "Ed Prytherch" <[EMAIL PROTECTED]>
>
>
> > When Lauren Seagrave explained muscle stretch reflex in a clinic that I
> > attended, he said that when the sprinters foot touches down the
> stretch in
> > the calf muscle fibers sends a signal to the base of the spine. A signal
> > returns to the muscle and causes the muscle to contract. The
> contact time
> > for a top sprinter is about .09 seconds. So within that 0.09
> sec you have
> a
> > muscle stretch, a signal out from the muscle, an interpretation of that
> > signal in the central nervous system, a signal back to the muscle, and a
> > powerful muscle contraction which starts about .05 second
> before the foot
> > breaks contact. The time for transmission of the signals in both
> directions
> > must be less than .04 second. How does this physiology limit start
> reaction
> > time to 0.1 second?
> > Ed.
> >
> >
>
>
