Plyometrics
Counter Movement JumpThe counter movement jump is a plyometric based movement. As the movement transitions from an eccentric contraction to a concentric contraction rapidly. The aim of the countermovement jump is to reach maximum vertical distance away from the ground, using a countermovement (the squat at the start of the movement) and arm swing to propel yourself as far off the ground as possible.
The counter movement jump is typically used to assess concentric strength and the ability to utilise the stretch shortening cycle (SSC) which is discussed in more detail on the Plyometric training page. The video to the left provides an example of an effective counter movement jump. |
Skill Breakdown
Eccentric PhaseFrom the standing position the subject, breaks at the hip and knee, creating flexion. Quadriceps and Gluteus muscles eccentrically contract lowering the body down into a squat position. Weight is transferred to the heels, whilst looking forward. Centre of gravity transitions downward. Maintaining balance in the bottom position. Arms are positioned towards the back of the body.
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Concentric PhaseFrom the bottom of the squat position the SSC is utilised to switch from an eccentric contraction to a concentric contraction rapidly. As the finish position of the eccentric phase is reached, Quadriceps and Gluteus muscles concentrically contract creating knee extension. Force is exerted through the floor as weight is distributed towards the front of the feet. Arm swing is used to generate extra momentum as feet start to take off from the ground, transitioning from behind to in front of and above head height. Arms should reach full extension simultaneously with full leg extension at the top of the counter movement jump.
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