Countermovement Jump (CMJ): Technique, Measurement & Norms

The countermovement jump (CMJ) is the most widely used test in sports science for assessing lower body power and neuromuscular function. It's used by professional teams, Olympic programs, and researchers worldwide as a reliable marker of athletic readiness and performance.

The CMJ is a vertical jump test performed from a standing position where the athlete rapidly dips downward (the countermovement) before immediately jumping as high as possible. Unlike a squat jump, which starts from a static squatting position, the CMJ utilizes the stretch-shortening cycle (SSC) — the body's ability to store elastic energy during the downward phase and release it during takeoff.

The CMJ is considered more sport-specific than the squat jump because most athletic movements involve a countermovement phase.

Follow these steps for a standardized CMJ test:

1. Stand upright with feet shoulder-width apart, hands on hips (for standardized testing) or free to swing (for sport-specific testing)
2. Quickly dip downward by flexing at the hips, knees, and ankles — aim for approximately 90° knee flexion
3. Immediately reverse direction and jump as high as possible
4. Extend fully through ankles, knees, and hips at takeoff
5. Land softly with knees slightly bent

Common errors to avoid:

• Pausing at the bottom of the dip (this turns it into a squat jump)
• Not achieving full extension at takeoff
• Tucking knees during flight phase (artificially inflates some measurement methods)
• Inconsistent dip depth between attempts

Several methods exist for measuring CMJ performance:

• Force plates: Gold standard. Measures ground reaction forces at 1000Hz+. Provides jump height, peak force, rate of force development, and many other variables. Expensive ($5,000-$30,000) and lab-based.
• IMU sensors: Portable devices like PoinT GO that use accelerometers and gyroscopes to calculate jump height, flight time, and RSI from body acceleration data. Accuracy within 1-2cm of force plates at a fraction of the cost.
• Jump mats/contact mats: Measure flight time and calculate jump height. Simple and affordable but only provide height data.
• Video analysis: Use slow-motion video to measure takeoff and landing frames. Accuracy depends on frame rate.
• Vertec/reach devices: Measure the difference between standing reach and jump reach. Subject to technique variation.

Here are general CMJ norms based on published research:

These norms vary significantly by sport. Basketball and volleyball players tend to have the highest CMJ scores, while endurance athletes typically score lower.