Countermovement Jump Test - CMJ

Evaluate explosive power and stretch-shortening cycle efficiency through countermovement jump.

Countermovement Jump (CMJ) Test

Test Objective

To evaluate the explosive power of the lower limbs with the active contribution of the stretch-shortening cycle (SSC).

Required Equipment

  • Force platform or jump sensor (e.g., Optojump, MyJump, Chronojump, etc.).
  • OR a graduated tape and a wall (manual version, less precise).
  • A flat and non-slip surface.
  • An assistant or specialized measurement software.

Test Protocol

  • The subject stands with feet shoulder-width apart and hands placed firmly on the hips.
  • At their own pace or upon a signal, they perform a rapid leg flexion (half-squat) immediately followed by a maximal vertical jump.
  • They must not use their arms (which must remain on the hips at all times) to properly isolate lower-body strength.
  • Jump height is measured based on flight time (via the platform/sensor) or the maximum height reached (via the graduated wall).

Evaluation

  • Perform 2 to 3 trials and record the best jump (in cm).
  • The greater the height, the higher the mechanical power and neuromuscular efficiency.
  • Mechanical power output can be calculated in watts using validated equations (such as Bosco, Sayers, etc.).

Interpretation of Results

  • Comparing the CMJ with the Squat Jump (SJ) allows coaches to evaluate:
    • Utilization of the SSC: A CMJ score greater than the SJ score indicates effective and proper use of elastic energy and momentum.
    • Neuromuscular deficits: If the difference between the two tests is minor, non-existent, or inverted.
  • The CMJ is highly sensitive to neuromuscular fatigue, making it an excellent tool for tracking training load and monitoring recovery status.

Variations

  • CMJ with free arm swing: Closer to actual sport-specific movements, but less standardized.
  • Unilateral CMJ: Performing the jump on a single leg.
  • Repetitive CMJ: A continuous series of consecutive jumps to test endurance power.

Recommendations

  • Complete a comprehensive warm-up prior to testing (both general and lower-body specific).
  • Always test under identical conditions (same time of day, similar fatigue levels, and same equipment).
  • Maintain the exact same measurement technology across all testing sessions to ensure data reliability.

 

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