Cyclic Jump

An objective way to measure double leg stretch-shortening cycle capacity.

Table of Contents

• What is the cyclic jump test?
• Test Instructions and Demo
• What do the metrics mean?

What is a Cyclic Jump test?

Cyclic jump is a plyometric movement involving consecutive jumps to measure double leg reactive strength index. RSI represents an athlete's ability to effectively use the stretch-shortening cycle and explosive capacity during dynamic jumping activities.

The stretch-shortening cycle is the ability to use reactive strength, stiffness and braking ability to store elastic energy and use it to propel during repeated movements. This property is important for injury prevention, athletic performance and functional movement across the age adult age span.

Cyclic Jump test instructions:

Start the Test

1. In plantiga.io, go to Record (left sidebar)
   1. From the Activity Type drop-down, select Cyclic Jump
   2. From the Select People drop-down, select the athlete profile(s) being tested

Check for Warnings

2. It's important to resolve all warnings before starting, or data may not be recorded.
3. Click Start

Calibrate

4. Instruct the athlete to stand still for 3 seconds at the start of the assessment

Perform the Test

5. Instruct the athlete to start with both feet on the ground and hands on their hips

6. Once ready, have the athlete perform 10 consecutive hops with minimal knee bend.

   Cue: Instruct the test subject to jump as high as they can and spend as little time on the ground as possible.

End the Test

5. Click Stop when finished
   1. (Optional) Add contextual notes
6. Choose one of the following:
   1. Done – finish and save
   2. Next – start another assessment
   3. Reset – discard the assessment

Cyclic Jump demo

What do the metrics mean?

Average jump height: the average height from all cyclic jumps during a single test.

• Low cyclic jump heights indicate poor leg strength capacity.

Average reactive strength index (RSI): the ratio between air time during the jump and ground contact time between jumps. It is a reliable indicator of strength and explosive power capabilities.

• An individual with a high RSI during the cyclic jump (>1.0) can either jump higher, or have shorter ground contact time or both, in comparison to low RSI (<0.5) cyclic jumpers.

Push-off asymmetry: a comparison of how quickly the left vs. right foot swings immediately after toe-off between jumps

• Push-off asymmetry may occur when the one limb's hip musculature and surrounding tissues are fatigued, weak, or unable to produce enough energy to get off the ground.

Impact asymmetry: a comparison of the ability of the left vs. right to absorb impact when the foot lands on the ground between successive jumps.

• Impact asymmetry may occur when the athlete lands stiffer or more abruptly on one limb than the other, or if they are using a protective strategy.