For the past 15 years, the BFS coaching staff has done a lot of research and experiments on endless products in an effort to find the best ways to accomplish these measurement tasks. The Just Jump or<
By Matt Shepard
Published: Fall 1999
It is relatively easy to come up with point after point on why it is important keep accurate measurements of your athletes speed, jumping ability, etc.; however, it isn’t always as easy to find the best, quickest, and most accurate ways to do all of this measuring. For the past 15 years, the BFS coaching staff has done a lot of research and experiments on endless products in an effort to find the best ways to accomplish these measurement tasks. In our next few issues, we will discuss the products that we feel are the absolute best for accurate and quick measurements. The first product that I will discuss is the Just Jump or Run. The BFS staff has found this product to be the easiest and most reliable way of measuring the vertical jump. Added bonuses to the Just Jump or Run are it’s ability to accurately time sprints. It also works well with speed/quickness drills such as shuttle runs. The Just Jump or Run consist of one pressure sensitive mat and one hand held computer that calculates and displays times and distances. The Just Jump or Run has 3 different modes: the 1-Jump Mode, the 4-Jump Mode, and the Sprint Timer Mode.
The 1-Jump Mode is ideal for quickly and accurately measuring the vertical jump. It has a very small margin of error of + or - 1/2 inch. One of the most popular alternatives to the Just Jump or Run is the Vertec. We preferred the Just Jump or Run over the Vertec because of the difficulty involved with trying to hit the Vertec at the apex of your jump; it is quite common to either hit it on the way up or on the way down between 1/2 to 1 inch away from the maximum height of your jump. With the Just Jump or Run, all you need to do is “just jump”. Another advantage of the Just Jump or Run is the the speed in which you can test groups of athletes on their vertical jumps. Let me explain step by step how quick and easy it is (see illustration 1):
1. Place the mat on a hard, level surface. 2. Select the 1-Jump mode. 3. Have the athlete stand on the mat and jump. 4. The computer will display the athletes hang time and jump height in inches. 5. As soon as that athlete steps off the mat, it is ready for the next athlete.
Because there is no need to reset anything after each jump, you can record your athletes’ vertical jumps one after the other at a rate of about 7 athletes per minute (give or take 2 athletes depending on how fast your athletes are able to get on, jump, and get off the mat). Quickness drills can be done from this mode as well. As soon as the athlete is off the mat for 1.1 seconds, the computer automatically goes into timing mode. Shuttle runs can be performed by standing on the mat and running some distance and then returning to the mat. The computer will compute the time the athlete was off the mat (see illustration 2).
This mode is unique only to the Just Jump or Run. It is an extremely important function because of its ability to put a measurable number to an athletes’ ability to explosively jump out of a down position such as a sprinter exploding out of the blocks or jumping after a rebound several times. Of course, the faster your athletes can explode out of these positions, the greater advantage they will have over their opponents. It’s reactive jumping power. In this mode, the athlete will need to jump consecutively 4 times as quick and as high as possible. The computer will compute the athletes average ground time, average jump height, and explosive leg power factor (ELPF). The ELPF is the air time divided by the ground time. Therefore, the less time on the ground and the higher the jump, the greater the ELPF. A good performance number for ground time is .20 to .23 seconds. A good number for ELPF would be anything greater than 2.50 (Athletes with an ELPF less than 2.50 need to work extra hard on the quick lifts such as the Clean and Snatch). For the athletes jump height, a good performance number would be anything greater than 20 inches.
SPRINT TIMER MODE
This mode is designed to accurately measure an athletes running speed. The computer is sound activated so when the coach yells “GO” or blows his whistle, the time starts; and when the runner finally steps on the mat at the finish line, the time stops. A feature we found impressive in this mode was it’s ability to compensate for the time it takes the sound of the coach’s voice (or his whistle, etc.) at the finish line, to reach the runner at the starting line. The Just Jump or Run allows for a more accurate time in two ways. First, of course, is the elimination of the sound-wave, travel-time discrepancy and second, the elimination of human error due to the reaction time it takes for the coach to stop a conventional timer. It is quite simple to use the Just Jump or Run for timing sprints (see illustration 3). First you need to measure the desired distance of the run (40 yards for example). Second, place the computer and mat at the finish line. Third, enter the distance of the run into the computer (this must be done in feet, so if you have 40 yards you would enter 120 feet). Now, once the runner is set, yell “GO” or blow your whistle and wait for the runner to finish by stepping on the mat.
The Just Jump or Run is not just limited to the ideas presented in this article. You can make up endless drills and tests to use with it. Because of it’s versatility along with it’s accuracy and efficiency, the Just Jump or Run is a great buy.