all hypo aside…asafa is the making of his own problems, provided nobody gives him chase he runs relaxed but put a descent runner beside him, he tightens like a dry canabis rope…
BEN JOHNSON IS A MONSTER, TO GOOD !!!
CIAO … VIVA FERRARI
yes, exactly right!
That picture shows the the support leg just prior to toe off. Pictures of the support leg during mid-support will show the knee bent. I suggest the methods used in the study are significantly more accurate.
The two cameras were synchronized and captured images at 100 Hz. Using motion analysis software (DKH, Tokyo, Japan),the two-dimensional coordinates of 24 body points were scanned at 100 fps, and the direct lineartransformation method (DLT) was used to calculate three-dimensional coordinates where the x-axis was the direction of sprinting, the y-axis the vertical direction perpendicular to the ground, and thez-axis was the horizontal line parallel to the starting line.
Not really, your definition is not correct, i can reach stride frequency over 5/sec with minimal ground time, but running on spot.
not sure about that. (GCT). Has anyone ever measured that?
No you can’t.
You think your horizontal velocity will be 0 with stride freq of 5/sec with minimal contact time & high rate of force development on ground. Proof it!
Remember my definition involves
1- Higher stride freq
2- Shorter contact time
3- High rate of force development
Tap Dancers reach step freq of 5/sec with minimal contact time. But they don’t elicit any significant rate of force development from the ground.
I take an example of a Japanese sprinter, whose frequency was recorded as 4.85hz (highest of race), and contact time 0.083sec (shortest of the race). He was actually one of the slowest (10.19m/s) due to a 2.10m stride length. In that race Carl Lewis won and his data was 4.45hz, contact time 0.099, stride length 2.55 and speed measured as 11.45m/s.
So, according to Sharmer definition (What determines faster stride freq shorter contacts times achieved is the rate at which forces are applied on the ground.), who is applying more forces on the ground, Japanese or Lewis?
The studies would of also showed that Carl exhibited the greatest RFD from the ground.
Combine High freq+ shorter contacts+ RFD =9.7 Asafa, Ben, Maurice, Tim. All these guys have step freq of 5/sec but also had excellent RFD.
contact time and step frequency
Japanese 0.083 4.85
Lewis 0.099 4.45
Who has the highest RFD?
My point is that your definition is not correct, you need to formulate better.
That depends on your definition of RFD. Contact times + stride freq don’t determine RFD.
RFD is determined by vertical and horizontal components of force during contact time.
divided by limb length to account for effectiveness maybe??
I love and often use that quote and when talking to students ask them which exams do you feel most nervous about? Answer The ones you don’t prepare for and you know you aren’t ready. Now think about when you have done plenty of study, yes you are nervous but expectant which is completely different. Its the same with competition
It all comes down to quality of contact which will determine quality of impulse. And quality of contact is something coaches and athletes can actually work on to improve. Everything else is just measurement after the fact …
The Harvard team used the following equation.
speed= Step L x Step Freq
speed = Freq step x force average/ body weight x contact length
They rearranged the equations so stride length is expressed contact length x average vertical force during contact time. According to the them effectiveness is determined by the average mass-specific force applied vertically against gravity on footfall. Obviously limb length does have a influence on the mass-specific force that is applied.
KK- has the right idea. But you can’t coach athletes to consciously generate higher mass-specific force against gravity. It’s one to know what happening, its another to actually get athletes doing that.
Train for stride frequency and when the athletes get stronger, stride length via greater mass-specific force will naturally happen. Thoughts?