Monday, November 30, 2009

Evaluating and Comparing your Broad Jump

The broadjump is a drill used to measure how far an athlete can jump from a standing position. The NFL has potential players perform this exercise during its annual combine, and uses the results as one of the many ways to evaluate the athletes' power. Below we have synchronized two athletes' broadjump trials. We've also slowed down the side-by-side video to help with the comparisons. And beneath the video window, we've included stillshot images of each athlete during key positions of their trials.

1. Loading Phase
During the loading phase, the athletes swing their arms back, in preparation to swing them forward. They will use this forward momentum to help them jump as far as possible. Also, notice their hips, knees, and ankles are all flexed (sometimes referred to as "triple flexion"). By flexing at these joints, the athletes are building up potential energy that will be released during the liftoff phase. From these two images, we see that the second subject has a slightly deeper knee bend than the first subject.

2. Liftoff Phase
During the liftoff phase, the subjects swing their arms forward and upward, and use this momentum to help propel their bodies forward. We see that the first subject extends his arms all the way, while the second subject has his arms flexed at the elbows. The second subject can definitely improve his form by extending his arms fully. Driving your arms forward as far as possible will allow you to use all the energy your arm swing can provide.

Also worth noting, their lower bodies also go through "triple extension" now (hips, knees, ankles), converting the potential energy into kinetic energy. We see that both subjects take off at about the same angle relative to the ground.

3. Maximum Height
In the pictures below, we see the key positions showing the subjects' centers of mass (COM) at their maximum heights, and at what distance from the start their maximum heights occurred. An athlete's COM during a jump follows a path similar to that of a ball flying through the air - in other words, it follows a parabolic arc. It will reach its highest point midway between the distance it is thrown. By driving your arms upward and forward you can get your COM higher and further forward. By then driving the arms down and bending your hips and knees forward at the top of the jump, you keep your COM elevated allowing you to gain added distance before touching down. Lifting your arms arms/knees and bending hips raises your COM. We see that the first subject reaches his maximum height at a further distance than the second subject.For the second subject, it's difficult to anticipate whether he will land closer or farther than the first subject though, as his maximum height is a few inches higher.

Both subject 1 and subject 2 have not remained fully extended through the peak of their jumps and have started to rotate for the landing. Subject 1 has begun to lift his chest, while subject 2 has already dropped his arms and brought his knees forward. Keeping yourself extended, as long as possible, through the peak height of your jump will allow you to jump further. A body position midway between that of subject 1 and 2 would probably be ideal.

At the peak of the jump it is now time to start rotating your body to get your legs out in front of you. The distance of the broadjump is measured where your toes land, so upon reaching the top of the jump, you should get your legs out in front of you. To make this happen, drive your arms downward and bend your hips and knees up toward your chest. Do not lean back as subject one has began to do; it is better to bring your hips and knees up to your chest.

4. Landing
In order to land safely and get the most distance out of the jump, our subjects flex their hips and extend their legs, landing on their heels with their toes pointed upwards. The second subject lands with his torso bent forward a bit more; but besides this and the placement of their arms, the subjects' landing techniques look quite similar.

5. Finish
The broadjump distances were measured from the subjects’ starting toe positions to their final toe positions. In order to absorb the shock of their landings, it’s important that the subjects bend their knees through impact. We see that the first subject doesn’t flex his knees as much as the second subject, and as a result ends up falling forward a bit at the end of the trial. This shouldn’t matter much though, as the jump distance has already been measured and the purpose of the drill isn’t to work on the landing. However, if someone was performing additional movements at the end of the broadjump (some training camps have the athletes do three consecutive broadjumps and measure the overall distance), it’s recommended to have more of a controlled landing at the end of each jump.

We hope you’ve enjoyed this article, and that you’re getting out there and filming great videos of yourselves and your athletes for detailed analysis!

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