The 90 Degree Myth: Acceleration Mechanics - Part One.

Recently I trained a group of 7 athletes for speed development - specifically a 40-yard dash, I improved their times by implying the 90-degree myth. Find out what it is and how it can help you become faster.
Part 1  |  Part 2
Ask most coaches about arm position, specifically elbow angle, in the sprint, and they will tell you that the elbow should be held at a 90-degree angle. While in theory this may be mechanically accurate (I am not sure), it does not hold water in the real world of sprint training and speed development.

I recently trained a group of 7 athletes for speed development - specifically a 40-yard dash. While all of them got a personal best in their post test, 3 of them broke the magical 4.50-second barrier. One of these athletes pre tested at 5.00 and post tested at 4.47!

Don't get me wrong, I am not trying to pat myself on the back for a job well done. All I do is show the athletes the right way to do things, correct their errors, teach them to relax, and run faster than ever. The athletes themselves actually do the work.

Relaxation Is The Key

One of the key words in the previous paragraph is relax! If you ever watch a world class sprinter from a front view, the jaw is so relaxed that it moves all over the place. The reason is that the jaw has no function in a sprint.

The only thing a jaw could possibly do is slow the runner down by having a secondary tightening effect on the shoulders, which causes stiffer, slower arm motion, which causes slower, stiffer hip motion - you get the point.

A chain reaction of tightness occurs. One sure way to not relax is to hold the elbows at a 90-degree angle.

While I have never seen research on the topic, there is no doubt in my mind that locking the elbows at 90 degrees causes the same avalanche-like effect on speed as a clinched jaw. Tight elbow causes tight shoulders, which causes tight hips and so on.

   Examples

    The pictures below show the first and second stride of the three athletes that ran 4.49 seconds or better on their 40-yard dash post test. You will notice that none of the angles are anywhere near 90 degrees.

    Two of them are much closer to 180 degrees. Also notice the recovery arm (forward arm). The angle is generally smaller than 90 degrees.

    The main point to note here is that the athlete should drive from the shoulder and relax the elbow -especially at the start. The goal is not to achieve a particular elbow angle in the drive or recovery phase of a sprint.


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Click To Enlarge.
Note the large elbow angles on the driving arm of these athletes.


Click To Enlarge.
Note the second stride also results in a large elbow angle.


Conclusion

In this article we took a look at three athletes who ran sub 4.5 second 40-yard dashes and showed how "open" their elbow angles were when they were in the first steps of their acceleration position. This was due to their learning to relax muscles in the body that accomplish nothing in sprinting beyond slowing the sprinter down. In the next article we will take a look at improving speeds ...

Part 1  |  Part 2