Vertical Jump Test/Power test: Indicator of Muscle Fiber Type

The vertical jump is a common practical application to determine explo­sive athletic abilities. We use vertical jump test frequently with professional athletes, especially to track improvements during training.

Your performance in this test will indicate if you are more fast-twitch or slow-twitch muscle. The higher you jump, the more you are a fast-twitch person; the lower you jump, the more your muscles are slow-twitch.

Because vertical jumping is a common testing mechanism in a vari­ety of research projects, several studies have been done on how to best calculate the production of power while jumping. After reading these studies, we came to the conclusion that a Vertical Jump/Power Test would be more effective at determining muscle fiber type than a simple vertical jump test, which measures the distance jumped, but not the power produced.

The most recent and accurate calculation of power while jumping comes from Stephen P. Sayers, a professor of Health and Fitness Studies at Central Connecticut State University. His equation is based on a study that used men and women athletes and non-athletes, and produces a number that considers a person’s body mass.

Steps for Performing the Test Without Any Equipment

Here are step-by-step instructions on how to perform and measure the vertical jump test without using any equipment.

1. Warm up properly before starting the test. Include a light jog and some low-intensity jumps.
2. Find a wall you can jump against. Stand beside a wall with your strong side next to the wall.
3. Stand next to the wall with one arm reaching as high as possible, while your heels stay on the ground. The height where the stretched fingers reach is measured. Mark the wall using chalk or have a friend mark the wall.
4. Next is the jump. According to Dr. Sayers, you need to be specific with your technique in how you jump. His study found that jumping without using an approach or dipping down immediately before exploding up gives the most accurate, predictable results. You can use your arms as you wish, swinging them behind you and then upward when you jump. Take the pencil in your hand and hold it so that the tip does not go higher than your finger, or, even better, simply wet your finger and mark the wall with a watermark. Or put some chalk on your fingers before jumping. The chalk should leave a mark on the wall. Then squat down, pause momentarily, and jump up as high as you can. The pause is very important to get an accurate result. Dr. Sayers tested what is called a counter movement jump as well, in which you dip down and then jump up immediately. Subjects jumped higher, but because of the amount of technique involved, it caused varying, less accurate results. So, remember to pause.
5. Try again. Bend your knees and jump as high as you can. At the height of your jump, reach as high as you can and touch the wall. The chalk should leave a mark. You get a total of three jumps.
6. Calculate your vertical jump by measuring the distance between your first mark (when you were standing) and your best mark when you were jumping. If you can, measure in centimeters, the measurement needed for this equation.

Using Vertical Jump Test Equipment

In this case we use special testing equipment, called the Vertec vertical jump device. This way the tester does not need a tape measure for measuring or chalk to mark the wall.

The Vertec device is like a flag pole with thin flags on top. Each flag is ½ inch thick making it easy to measure. What the athlete does is jump and tap away as many flags as they can. The more flags the higher the jump. By looking at the flags the testers can tell the height they reached and compare that to the player’s standing reach.

Calculating Your Results

Here’s how to calculate the power you produce when jumping:

• Step 1. Convert the height of your vertical jump into centimeters, if necessary. Use the equation: [number of inches]x 2.54 – number of centimeters.
• Step 2. Convert your weight into kilograms. Your weight in pounds divided by 2.2 – your weight in kilograms.
• Step 3. To compute your power, use a calculator and plug your vertical jump and weight into this equation: Power – (60.7 x [vertical jump in centimeters]) + (45.3 x [weight in kilograms]); then subtract 2,055 from the resulting number.
• Step 4. Now, see where your power number falls on the Sayers Power Curve, a theoretical curve based on Sayers’ study. Locate your power number on the bell curve. Keep in mind that this equation works for both men and women; no separate equation is needed. If your power number puts you in the gray area to the right, your increased power output indicates you have a high degree of fast-twitch muscle fiber. On the other hand, if the number you calculate puts you in the white area to the left, your power output indicates you are predominately slow-twitch muscle fiber. If you happen to fall somewhere in the black area, your power production indicates you have an even split between fast-twitch and slow-twitch muscle fibers (combination).

Further breakdown of the calculation

Just in case it has been a while since you used an equation, here is a further breakdown of the calculation:

Multiply your jump height in centimeters by 60.7
Multiply your body weight in kilograms by 45.3
Add those two numbers together
Subtract 2,055 from the total Sample calculation:

Numerical example:
Vertical jump is 15 inches x 2.54 centimeters = 38.1 centimeters
38.1 centimeters x 60.7 = 2,312 centimeters
Body weight is 140 pounds divided by 2.2 – 63.6 kilograms
63.6 kilograms x 45.3 – 2,882.7 kilograms
2,882.7 plus 2,312 – 5,194.7
5,194.7 minus 2,055 = 3,139.7. This is your power number.

Pros and Cons of the Vertical Jump Test / Power Test

We recommend the Vertical Jump/Power Test because it is very easy— anyone can do it at home. Also, it is relatively inexpensive. If you do not happen to have a measuring tape, it costs only a couple of dollars. It is quick and should only take ten minutes to complete.

However, in examining how to best distinguish the results, we came across two potential problems.

First, the vertical jump test works best as an indicator of fiber type after a period of training, and it does not work well for untrained people. For example, if you have not exercised for some time, you may jump only 6 inches. If you take a vertical jump test, it might show you as a slow-twitch person. Once you start to train and your fast-twitch muscles are utilized, however, you may improve and jump much higher, eventually finding that you are a combination person or even a fast-twitch person. Therefore you should train for some time before taking the vertical jump test (power test). If you skipped at least six week training program and are going right to the test, you risk not determining what fiber type you really are.

The second problem with the vertical jump test is determining an accurate result with a person who is overweight. An individual more than a few pounds overweight may not be able to jump as high as he or she would otherwise. That person might be more fast-twitch fibers than the results show. So, body weight must be taken into consideration with the results. The way to do that is to look at not just the overall distance or height that you jump, but at the actual power you produce.

Closing thoughts: Vertical jump test

Muscle fiber type can be an important factor for individualization of an athlete’s training program. The vertical jump test /power test is a simple and quick method you can use to estimate what predominant muscle fiber type are you – slow twitch or fast twitch.

The only downside to the test is that you will not get an exact percentage of muscle fiber. This curve is a projection based on the Sayers study. Therefore, it only gives you a range compared to your peers—a good indication of your fiber type but not an exact percentage. Nevertheless, it is accurate and gives you a good idea of how you should be exercising.

For example, long-distance runners (marathoners) have a higher percentage of slow-twitch fibers, while sprinters and power lifters typically have more fast-twitch fibers. In fact, some athletes may have as much as 80 percent of one muscle fiber type.

This is not because the athlete chose a sport and then developed a greater percentage of appropriate fibers to suit the demands of the sport. As earlier mentioned in our previous article, the percentage of fast-twitch and slow-twitch fibers is fixed at birth. Thus, these people dis­covered the sport in which they excelled and they excelled at these sports because their bodies were designed for these specific endeavors, largely based on their individual composition of muscle fibers.

This was a twofold process: the person realized that they were good at a sport, and then found enjoyment or fun in being able to succeed. This sense of sat­isfaction was due in large part to muscle composition.

Related articles:

1. Types of muscle fibers: Slow-twitch Vs. Fast-twitch
2. What Predominant Muscle Fiber Type You Are? Methods & Tests!
3. Thorstensson Fatigue Test: Determining Muscle Fiber Composition