The Brookbush Institute Publishes NEW Glossary Updates: 'Counter-movement Jump' and 'Power'
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- Additional Glossary Term: Power2
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DEFINITION
The Counter-movement Jump (CMJ) is a vertical jump performed with a preparatory downward movement prior to take-off (the "counter-movement"). It begins with a quick eccentric/pre-stretch phase (rapid squat-like descent and arm backswing), followed by a brief amortization phase (transition), and ends with a forceful concentric phase (upward jump). This jump pattern utilizes the stretch-shortening cycle (SSC) to enhance power output by optimizing elastic energy storage, stretch reflex activation, and neuromuscular coordination.
The CMJ is widely used in sports performance testing to assess lower-body power and rate of force development (RFD) . It is often contrasted with the squat jump (which begins from a static position) to evaluate an athlete’s ability to use the SSC effectively.
FREQUENTLY ASKED QUESTIONS
What is the purpose of the counter-movement in a CMJ?
- The counter-movement enhances jump height by using the stretch-shortening cycle. The pre-stretch results in stored elastic energy in tendons and muscles, and activates the stretch reflex, both of which contribute to a more powerful concentric contraction.
How is the CMJ different from a squat jump?
- A squat jump begins from a static position without a prior descent, eliminating the stretch-shortening cycle. The CMJ includes a dynamic pre-load (eccentric phase), which typically results in higher jump heights and greater peak power output.
What does the CMJ test measure?
- The CMJ is primarily used to assess explosive lower-body power and, indirectly, neuromuscular readiness, fatigue, or asymmetries. It is a common performance metric in strength and conditioning, rehabilitation, and sports science.
What are the phases of the counter-movement jump?
- Eccentric Phase: Rapid descent and arm backswing
- Amortization Phase: Shortest possible pause at the bottom
- Concentric Phase: Explosive upward jump
Can CMJ performance be improved with training...
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Brent D Brookbush
Brookbush Institute
Brent@BrookbushInstitute.com
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1 https://brookbushinstitute.com/glossary/counter-movement-jump-cmj
2 https://brookbushinstitute.com/glossary/power
3 https://brookbushinstitute.com/info/certified-personal-trainer
