The 40 yard dash seems to be coming up over and over again as I learn about rehabilitation and performance.
The best athletes have exceptional 40 yard speed. The best the NFL, NBA MLB are all well under 5 seconds? Scouts are looking at these numbers when they select athletes. As part of our training we need to record these numbers and race against ourselves. This should be done at regular intervals. Say once every 3 weeks.
We can also use these numbers as an additional guide to when we can return to play after a lower extremity or spine injury. We are ready to play when we are within 1 second of our pre-injury speed. We need to train sprinting and the 40 yard dash. Here are some nice articles to help with that.
3 Keys To Sprint Faster http://www.stack.com/a/3-keys-to-a-faster-sprint
Don't forget to also train agility.