It is the fashion,it is the world: Speedendurance.com

Friday, 25 March 2011

Speedendurance.com

Velocity = Contact Length / Ground Contact Time

Posted: 25 Mar 2011 01:00 AM PDT

I was watching an interesting video from UKA Coaching. Due to excessive bandwidth costs, the coaching videos are only available to UK residents. I am fortunate to have clients in the UK so I can watch them!

The video was a 2 part series by Jon Goodwin.

It continues the whole debate on Stride Rate and Stride Frequency. We can go back to 2007 and talk about Ralph Mann's research on how he wanted to reduce ground contact by 0.01 seconds. Take 43 strides, and that cuts your time by 0.43 seconds. (Hmm, can a 10.00 sprinter really improve to 9.57 if this was true?)

This video is another take on the Velocity theory but looking at another angle.

Some Definitions

Contact Length (CL) is the distance covered during Ground Contact Time (CT).

As you can see from the formula:

Velocity = Contact Length / Contact Time

… even the minutest reduction in CT will increase the velocity.

In the slide below, taken from the video, a 5 cm difference in CL due to anthropometric leg length will yield more CT at the same velocity.

But the big difference is the same CT and longer CL will yield a higher velocity (13.1 compared to 12.5 m/s)

Since you can't do anything during air time (flight time), a greater force during ground contact is your only chance to run faster. Greater force means greater length. Let stride rate and stride frequency take care of itself. Speed is all about how fast you can cover ground.

Higher top end speeds, and the ability to sustain it (i.e speed endurance), will win Gold medals any day!

So why does Usain Bolt run so fast? What's his trick?

I'll save that for another article. UK residents can watch the video to find out.