The CMJ (Countermovement Jump) test is one of the most widely used physical performance tests in training and rehabilitation. Its popularity isn't a coincidence: it's quick to perform, doesn't require expensive equipment, and provides extremely valuable information about lower-body power.

In this guide, I'll walk you through everything you need to know to apply it correctly with your athletes.

What does the CMJ test measure?

The CMJ assesses explosive lower-body power, specifically the neuromuscular system's ability to produce force quickly using the stretch-shortening cycle (SSC).

Unlike the Squat Jump (SJ), the CMJ includes a countermovement phase (a dip before take-off), which allows elastic energy to be stored in the tendons and activates the stretch reflex. This is why CMJ values are always higher than SJ values for the same athlete.

The difference between CMJ and SJ (called the "elasticity index") is also a relevant data point: it shows how well the athlete makes use of the SSC.

Equipment needed

To measure the CMJ you can use:

Force platform (gold standard, but expensive)
Contact mat (affordable and reliable)
Video analysis apps (like the ones built into Movalytics)
Linear encoder

With Movalytics, you can measure jump height directly from your phone's camera, with no extra hardware needed.

Protocol

Follow these steps to ensure the test is valid:

Warm-up: 5-10 minutes of general activation + 3 practice jumps with 2 minutes of rest between sets
Starting position: athlete standing, hands on hips or free (pick one and keep it consistent)
Execution: a quick, free downward movement to about 90° of knee flexion, followed by an explosive extension and vertical jump
Landing: on the same spot, with knees slightly flexed
Number of attempts: 3-5 jumps with 45-60 seconds of rest
Recording: note the best jump (some protocols record the average)

Common mistakes

Taking off with an arm swing from behind (invalidates comparisons unless done consistently every time)
Bending the knees mid-flight (artificially increases flight time)
Not keeping the trunk upright during the descent

Reference values

Values vary by sex, age, and athletic level. These are approximate ranges for healthy adults:

Level	Men (cm)	Women (cm)
Low	< 25	< 18
Medium	25-40	18-28
Good	40-55	28-38
Very good	55-65	38-48
Elite	> 65	> 48

In elite athletes (basketball, volleyball, track and field), values can exceed 70 cm for men and 50 cm for women.

How to interpret the results

The absolute value (height in cm) is the main data point, but it's not the only relevant one:

1. Comparison with normative values Place the athlete in their percentile based on age, sex, and sport. 2. Individual progression The most valuable data point is comparison with the athlete's own history. A 5-10% drop from their personal average can indicate accumulated fatigue, insufficient recovery, or a latent injury. 3. Elasticity index (CMJ - SJ) If the CMJ doesn't improve but the SJ does, there may be a limitation in the athlete's ability to use the SSC. 4. Asymmetry If you perform the test on a single leg, differences greater than 15% between legs are an injury risk indicator worth paying attention to.

How often should you run the CMJ?

It depends on the goal:

Performance monitoring: every 4-6 weeks as part of a broader test battery
Neuromuscular fatigue monitoring: weekly (or even daily during preseason) to adjust training loads
Post-injury assessment: before progressive return to training

CMJ within a test battery

The CMJ on its own provides limited information. It becomes much more valuable when combined with:

SJ (to calculate the elasticity index)
Speed test (to relate power and speed)
Isometric strength test (to understand the force-power relationship)
Body composition analysis (power relative to body weight is more relevant than absolute power)

Movalytics includes all of these tests and automatically lets you analyze the relationships between them.

Conclusion

The CMJ test is an essential tool for assessing physical performance. It's fast, reliable, non-invasive, and applicable both in performance training and sports rehabilitation contexts.

The key to getting the most out of it lies in standardizing the protocol, systematic recording, and contextualized interpretation of the results.

CMJ Test (Countermovement Jump): The Complete Guide for Trainers