Sunday, March 7, 2010

40 Yard Dash



The 40 Yard Dash

The 40 yard dash is the gold standard test for football speed. By simply cutting down your time by tenths of a second, a player can increase his draft stock drastically. Taylor Mays of USC, for example, ran an unofficial 4.24 at the combine in Indianapolis on the 28th of last month. Had his time stood, he would have tied the fastest electronic time and would immediately be considered one of the Top 10 picks in the upcoming NFL draft, earning him several million dollars more on his contract.



In this video, Mays did not look fast at all. His running mechanics looked sloppy but yet, he recorded the fastest time for all DBs. My goal with the next several blog entries is to discuss all the intricacies that make up a 40 yard dash.

Before beginning to break it down, a few basic performance terms should be addressed. The 40 Yard Dash can be broken down into 4 zones. While everybody has different ideas on this, I have found that these zones are the most common and are used by the most successful people in the industry.

The 4 Zones
1) The Start (or Initial Stance)
2) Acceleration
3) Maximum Velocity (or Top Speed)
4) Finish

Common Terminology for the Mechanical Dynamics of a 40 Yard Dash

Stride Length - Initially, short strides increase to moderate and transition into longer strides throughout acceleration. In the acceleration phase, the goal is to have a high stride frequency that gradually get less frequent and lengthen out. Maximum Velocity stride length is longer and is maintained throughout the final portion of the sprint.

Ground Contact Time - This is what I find the most important and is usually where the athlete improves most. Simply, ground contact time is the amount of time the foot is in contact with the ground. Like stride length, it varies throughout the run. The foot is in contact with the ground initially for about .22 seconds. The span of time is longer at the start and early acceleration because it is the mechanism by which force is generated through striking the ground. As the body transitions into maximum velocity, the ground contact changes to about .11 seconds and then finishes at about .09 seconds.

Flight Time - Flight time is the time spent in the air. It makes sense that the flight time is short during the first few strides of the race and becomes longer throughout the race.
.03 sec -> .08 sec -> .119 sec.

Shin Angle - The shin angle is the angle of the Tibia in relation to the ground. There is a positive shin angle at the beginning of the race. It helps the body overcome inertia and drive forward. As the stride lengthens and body inclination changes, the shin angle increases between 70 and 85 degrees.

Trunk Angle - In the start position, trunk angle from the horizontal is large, and the angle increases rapidly at the beginning of the race and then continues to increase gradually until maximum velocity is reached.

Velocity - This is a pretty obvious term. The speed of the body, or velocity, starts slow and increases rapidly through the first 14 - 18 yards. Velocity increases more gradually after the initial acceleration. Once maximum velocity is achieved, the body can only maintain this speed for about 10 meters. Velocity then gradually decreases throughout the remainder of the race.

Stride Frequency - This is one of the easiest things to teach. Mechanically, the frequency of your strides can increase with increased arm action. If an athlete vigorously drives his elbow backwards, when it returns forward, the contralateral leg naturally drives forward. Stride frequency obviously starts at zero, so it is technically slow at the beginning. It increases very rapidly and then as the stride begins to lengthen, it is less frequent and maintained throughout the remainder of the race.

Heel Recovery - This is directly related to the height that the knee achieves while lifting. If the thigh drives higher, recovery time is longer. It simply is directly proportional to the knee drive. At the beginning of the 40 yard dash, heel recovery is low because the body is oriented forward and the knee height is rather low. As the race develops, the hip angle begins to straighten and allows the knee to naturally drive higher. Heel recovery increases through the acceleration period and is again maintained throughout the remainder of the race.
* To demonstrate this concept, bend over and lift your knee as high as you can. Keep your knee locked in this position and then stand up (without moving the knee at all). Notice that the knee is oriented higher now and all you did was change your hip angle.

Stride Count - This is the most effective way to teach and quantify what is happening during the sprint. The stride is the distance between the feet while running. Generally during maximum velocity, a typical stride is about 40 inches. If you can reduce an athlete's 40 yard dash from say 22 strides to 21 strides, the athlete just covered 3 1/3 more feet in the same amount of time. This could relate to as much as .2 seconds, several million dollars more to your athlete. The stride count is higher initially and as the stride lengthens, reduces and stays fairly constant during the final portion of the race.
* This concept is part of why I believe Coach Tom Shaw is the industry leader for speed. After talking with him for several hours, the guy is simply a genius (especially in this area). He has trained 4 of the 6 fastest athletes in the history of the NFL combine, including Chris Johnson, who ran an electronically timed 4.24 40 yard dash. He has stride count down to a science.


If you have not figured out by now, speed is simply the dynamic relationship between stride length and frequency. Simply put:
Speed = Stride Length x Stride Frequency

The next several blog entries will cover what is happening in each one of the 4 zones mentioned earlier. I hope you, the reader, is beginning to understand how complex sports performance can be. Explaining what is happening, or should be happening, in each phase of a 40 yard dash does not even begin to touch on how you train each of these aspects. It also is just covering one simple thing. The vertical jump, 5-10-5 agility drill, 3 cone drill, and standing long jump are also different events at the NFL combine and each come with their own mechanical breakdowns. This is why I hate being called a "personal trainer". Exercise Physiology is incredibly complex, hence the reason my college text book was over 500 pages. I chose this over my originally intended pre-medicine route because this stuff is so incredibly fascinating.

Finally, while I would love to be the person creating all of this knowledge, the blog excerpts are a combination of stuff that I have learned and created along with knowledge that I have gathered from other sources. Just to name a few, these blog excerpts will be knowledge gained from Coach Tom Shaw, Velocity Sports Performance methodology, Athletes' Performance methodology, resources created by Vern Gambetta, the sprinting expertise of Chuck DeBus, and information provided by the National Strength and Conditioning Association.



1 comment:

  1. seriously?? dude! this stuff is freakin awesome! i can't wait to read more!!!!

    ReplyDelete