The ability to jump high is a game-changer in many sports like soccer, basketball, handball, or volleyball. Vertical jumping often allows you to outperform your opponent in heading a corner kick, grabbing a rebound before your adversary, clearing a barrier in handball, or reaching higher for a slam dunk in volleyball. In other words, vertical jump ability is a crucial factor in athletic performance across various sports.

There are numerous ways to measure leg power for assessing vertical jump. Likewise, there are multiple methods to quantify that vertical jump. For instance, one of the most common tests has always been the chalk test. You stand next to a chalkboard, jump as high as you can while holding a piece of chalk, and mark the board at the highest point of your jump. The height of the mark is then measured and subtracted from your height, giving you the distance you’ve jumped in centimeters. This method, although widely used for a long time, has evolved to the point that nowadays, with the use of force platforms, pressure platforms, photoelectric cells, linear encoders, or even your own mobile phone, you can calculate your vertical jump height.

But the classification doesn’t end there. Moreover, when it comes to vertical jumps, we have different types of jumps:

• Squat Jump (SJ): It’s a type of jump exercise performed from a deep squat position. From this position, eliminating the elastic force that occurs when descending into the squat, a vertical jump is executed.
• Drop Jump (DJ): The drop jump involves immediately performing a jump after a controlled drop from an elevated platform. The individual positions themselves on a box, drops down from a predetermined height, and as soon as their feet touch the ground, they execute an explosive vertical jump, utilizing the elastic energy stored during the descent phase.
• Countermovement Jump (CMJ): The CMJ, also known as the “Countermovement Jump,” is a jump where the individual starts from a standing position and performs a knee flexion movement before executing the jump. Unlike the SJ, in this case, the accumulated elastic energy is utilized.
• Abalakov Jump: It’s similar to the CMJ, but you can use arm swing to propel yourself to a greater extent.

Despite all of them being used to assess lower body strength and power, it is true that the CMJ has taken a significant advantage over the others. That’s why in today’s Vitruve blog post, we will conduct an analysis of this jump and identify why it is one of the best tests for measuring leg power using a linear encoder like the one from Vitruve.

What’s a Countermovement Jump?

The CMJ is a physical test to assess leg strength. It is used in various entrance exams for Bachelor’s Degree studies in Physical Activity and Sports Sciences, and it indicates leg power. Over the years, jumping capacity tends to decrease, leading to adaptations for older individuals, such as the Sit & Up Test.

Why is it interesting to measure the Countermovement Jump?

The CMJ is a highly interesting test for athletes and fitness professionals to measure lower body power. As mentioned earlier, this variable is crucial in various sports. Additionally, it is a straightforward test that requires minimal equipment or complex apparatus. It provides a quick and simple evaluation of the ability to generate explosive force in the jump. Achieving high values in the CMJ often indicates the capacity to perform dynamic squats with maximum loads and power exercises effectively.

The CMJ has become one of the most effective methods to assess an athlete’s capacity to perform in sports that require high levels of explosive strength. But it’s not just about competitiveness, it’s also about prevention. By improving your performance in the CMJ, you will strengthen the muscles in your legs and enhance your body’s stability and control. This will help prevent injuries since you’ll have a solid foundation of strength and muscular power.

Many times, we focus on the direct performance of an exercise or training program. In other words, we concentrate on quantitatively improving the CMJ over X weeks of training. However, the qualitative improvement in the CMJ is evident. In fact, even though we don’t measure the deceleration that occurs when landing from the CMJ, we are also enhancing our ability to absorb that impact.

At Vitruve, we encourage you to use this test to measure your athletes’ performance and not underestimate the power of the CMJ. It’s a versatile and effective assessment that allows you to evaluate and develop your lower body muscular power. Give it a try and discover how you can take your athletic abilities to the next level!

How to Take The Countermovement Jump Test

As we mentioned before, the CMJ test is an easy-to-use resource with many benefits. First and foremost, it’s crucial to consider the environment in which you’re performing the CMJ. It’s not the same to do this test on a windy street at 38 degrees Celsius as it is in an exercise physiology lab. Similarly, it’s important to ensure consistent conditions for each CMJ measurement, both external factors (like time of day, surface, and footwear) and internal factors specific to the individual.

Speaking of consistency, if the first time you measure the CMJ, the athlete had a cup of coffee and did a series of squats beforehand, and then for the second measurement, they didn’t have the same coffee and haven’t trained for two weeks, the difference will be clear. That’s why it’s crucial to standardize both the internal and external conditions for each individual.

To wrap up this section, at Vitruve, as exercise science professionals, we recommend familiarizing yourself with the exercise you’re about to perform. Neuromuscular adaptations to new stimuli happen rapidly and can significantly impact the results. Therefore, doing a TEST-RETEST would be beneficial, as well as becoming familiar with the technical movement.

Often, we focus solely on the direct performance of an exercise or training program. In other words, we concentrate on the quantitative improvement of the CMJ over X weeks of training.

Equipment needed

Depending on how you’re going to assess the CMJ, the equipment needed may vary. As we mentioned earlier, this exercise can be evaluated using photoelectric cells, pressure platforms, or a linear encoder. However, apart from the measuring device itself, it’s also important to have:

• Sports facilities that are consistent at all times. This can be achieved through a specialized laboratory or a well-maintained gym.
• The technology we’re going to use. In our case, we’re going to focus on the Vitruve system.
• A spreadsheet to keep track of the results.

How to evaluate

Next, we are going to describe some of the procedures that are essential when conducting a CMJ test. If you follow these points during your test, I assure you there will be no mistakes.

• Arm swing: If we strictly adhere to the CMJ technique, arm movement is nonexistent. The hands should be placed on the hips, resembling a jar. However, if the individual requires the use of arms for better balance, or if we believe that arm assistance could be beneficial for our athlete, we can introduce it. It’s important to note that arm swing improves jump performance by 10% compared to a jump without arm swing, so if we do decide to include it, we should make a note of it.
• Depth of countermovement: It has been demonstrated that the depth of the descent in the CMJ is a variable that determines the height. This depth will vary among athletes as it depends on their own structure and range of motion or flexibility. Greater depth is associated with greater power.
• During the flight: Although it may be challenging to achieve, athletes must maintain extension in the ankle, knee, and hip joints during the flight phase of the CMJ. This means that athletes should not flex their knees at any point during the jump, and if they do, it will not be considered valid. The main purpose of this limitation is to prevent any additional flight time.
• Jump displacement: It is not only necessary for an athlete to jump as high as possible during a CMJ test but also to ensure that they land in the same posture and position from which they took off. Usually, floor markings are used to ensure that the participant has not moved. However, if we use any technology that determines the starting and landing positions of the CMJ, it will indicate this to us.

What Does The Countermovement Jump Actually Measure?       

This question is tricky because depending on the technology used, the answer can vary. For example, if we measure using the chalk test we mentioned earlier, we would be measuring the number of centimeters jumped. However, if we use photoelectric cells, we measure the flight time of the person and estimate the height reached. A similar principle applies to force or pressure platforms. And if we evaluate with a linear encoder, we measure the velocity in meters per second and estimate the power of each jump.

In response to this question, what the countermovement jump actually measures is the height achieved, although it’s true that analyzing other factors is necessary to obtain that data.

The two alternative variables used to calculate countermovement jump performance are jump height (in centimeters) and relative maximum power production. Some other variables are also used to calculate this performance, but they generally require specialized equipment. For this reason, not many variables are considered in a CMJ test.

Here’s the list of variables, in addition to jump height and maximum power, that are used to calculate CMJ performance:

• Relative maximum strength
• Maximum strength
• Maximum velocity
• Power output
• Impulse
• Rate of force development

Flight time is the most reliable and valid variable used to measure CMJ performance related to vertical jumps. This variable is based on calculating the time an athlete spends in the air after takeoff and before touching the ground. Components used to measure jump height include a contact mat, high-speed camera, force platform, infrared platform, and linear position transducer (accelerometer).

Is The Countermovement Jump Test Reliable?        

Markovic G. and colleagues have already demonstrated that CMJ is a reliable and valid test for measuring leg power in physically active men (1). Similarly, Slinde F. and colleagues also analyzed different ways of performing the CMJ and concluded that CMJ and Abalakov jumps are vertical jump tests that have high reproducibility and can be used as measures of power development (2). Moreover, we have not only these specialized articles validating the CMJ as a test, but also a large number of studies that use CMJ as a variable to determine neuromuscular performance (3-5). Additionally, CMJ validations have been conducted with different tools and technology. Here are several references regarding its validation with:

• Force platforms (6)
• Photoelectric cells (7)
• Linear encoders (8)
• High-resolution cameras (9, 10)

When it comes to the question of whether the CMJ is a reliable and valid test, the answer is a resounding yes. In fact, a colleague, Carlos Balsalobre, has created and validated a mobile application that determines CMJ height by recording a video (11).

Countermovement Jump vs Squat Jump

In previous sections, we clarified the difference between the CMJ and the SJ. The main difference between the two jump tests is that one takes into account the accumulated elastic force during the descent phase, while the other does not. The SJ measures the concentric power of the quadriceps, while the CMJ measures the reactive power or eccentric/concentric power of the quadriceps.

As we can assume, when we accumulate that elastic energy before the jump, the generated power is greater. However, when we eliminate that elastic force and perform an SJ, the power is lower. Therefore, if we want to achieve higher power values, it is logical to use the CMJ for training and as a measurement test.

Important considerations

It is necessary to pay attention to some important considerations when conducting a CMJ test. These considerations include:

• Individual effort: The athlete should not perform submaximal efforts as they do not yield accurate scores.
• Take-off and landing positions
• Depth of countermovement
• Testing with or without arm swing
• Maintaining extended knees, ankles, and hips during flight

Finishing Up

A CMJ test is undoubtedly the best option to consider if you want to measure lower body power or lower limb strength. However, conducting this test without the supervision of a qualified individual will not help you obtain the most accurate score.

Now, you may be wondering if you need to have a coach or an administrator to note your movements, even when you have all the equipment set up. The point is that the CMJ test is not just about tracking height and flight time using the equipment. Administrators analyze various different metrics to ensure the accuracy of the test.

Conclusion

In conclusion, let’s review the most important points of this entry and recommend a first familiarization with the exercise. Remember to follow key steps to ensure that the CMJ is performed in the best possible way. Don’t skip any steps and always consider the important aspects. Adapt the location for the exercise, explain the most important parts, have a system that accurately measures the CMJ, and instruct the athlete on what to do.

On the other hand, you should analyze your athlete’s capabilities and their specific sport in order to choose between SJ, CMJ, Abalakov jump, or loaded jumps. You should select a valid and reliable tool to measure it, and we recommend the Vitruve linear encoder. With it, you can obtain power and speed measurements, as higher speed correlates with greater force and lower body power.

Unai Adrián Pérez de Arrilucea Le Floc’h

References

1. Markovic G, Dizdar D, Jukic I, Cardinale M. Reliability and factorial validity of squat and countermovement jump tests. The Journal of Strength & Conditioning Research. 2004;18(3):551-5.
2. Slinde F, Suber C, Suber L, Edwén CE, Svantesson U. Test-retest reliability of three different countermovement jumping tests. The Journal of Strength & Conditioning Research. 2008;22(2):640-4.
3. Claudino JG, Cronin J, Mezêncio B, McMaster DT, McGuigan M, Tricoli V, et al. The countermovement jump to monitor neuromuscular status: A meta-analysis. Journal of science and medicine in sport. 2017;20(4):397-402.
4. Pérez-Castilla A, Rojas FJ, Gómez-Martínez F, García-Ramos A. Vertical jump performance is affected by the velocity and depth of the countermovement. Sports Biomechanics. 2021;20(8):1015-30.
5. Yapici H, Soylu Y, Gulu M, Kutlu M, Ayan S, Muluk NB, et al., editors. Agility Skills, Speed, Balance and CMJ Performance in Soccer: A Comparison of Players with and without a Hearing Impairment. Healthcare; 2023: Multidisciplinary Digital Publishing Institute.
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7. Bosquet L, Berryman N, Dupuy O. A comparison of 2 optical timing systems designed to measure flight time and contact time during jumping and hopping. The Journal of Strength & Conditioning Research. 2009;23(9):2660-5.
8. Nuzzo JL, Anning JH, Scharfenberg JM. The reliability of three devices used for measuring vertical jump height. The Journal of Strength & Conditioning Research. 2011;25(9):2580-90.
9. García-López J, Peleteiro J, Rodgriguez-Marroyo J, Morante J, Herrero J, Villa J. The validation of a new method that measures contact and flight times during vertical jump. International journal of sports medicine. 2004:294-302.
10. Requena B, García I, Requena F, de Villarreal ES-S, Pääsuke M. Reliability and validity of a wireless microelectromechanicals based system (Keimove™) for measuring vertical jumping performance. Journal of sports science & medicine. 2012;11(1):115.
11. Balsalobre-Fernández C, Glaister M, Lockey RA. The validity and reliability of an iPhone app for measuring vertical jump performance. Journal of sports sciences. 2015;33(15):1574-9.