Single Leg Jump for RSI Test
An objective way to measure reactive strength and movement quality on one leg, independently of the other.
What is a single leg jump for RSI test?
Single Leg Jumps (SLJ) are a type of plyometric exercise involving consecutive jumps to measure the reactive strength index (RSI). Plyometrics are exercises that enable a group of muscles to reach maximal strength in as short a time as possible. They help bridge the gap between speed and strength training to provide practitioners with an objective measure of power and movement quality improvements during the final stages of rehabilitation for lower limb injuries. Additionally, SLJ testing help to quantify asymmetries as they assess each leg independently of the other.
A practitioner can perform the SLJ RSI test to evaluate the following areas of functional movement performance:
Muscle strength reserves and power
Propulsive and absorptive strategies with foot-ground interactions
Degree of inter-limb asymmetry for all of the above components of movement performance
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Tip: Instruct the person you're collecting data on that this test aims to evaluate their ability to use the stretch-shortening cycle in their leg muscles. The person being tested should try to jump as high as they can and spend as little time on the ground as they can like they're "hopping on a hot stove."
1. Tester navigates to the measure page of the Plantiga web applicaiton and selects either the Single Leg Jump RSI Test.
2. Tester selects the subject that will be performing the activity. Address any warnings that may come up once they have been selected.
3. Tester instructs the subject to stand still with hands on hips and feet planted firmly on the ground.
4. Tester begins the Single Leg Jump Test, and the subject remains still as the stopwatch counts down from 5.
5. Once ready, the subject performs five consecutive jumps with each leg. It does not matter which leg the subject chooses to start with.
6. Once all jumps have been performed, the tester instructs the subject to stop and plant their feet firmly on the ground.
7. Once still, the tester stops the stopwatch, and the subject remains still for 5 seconds.
8. Tester saves the Single Leg Jump Test.
What does Plantiga measure?
Jump height asymmetry: comparing left vs. right max jump heights to indicate thigh muscle strength and power performance capabilities.
High jump height asymmetry (> 10%) indicates a compensatory shifting of demands due to an affected and/or weaker limb. It is a vital rehabilitation functional milestone indicator for return to activity after orthopeadic and musculoskeletal injury.
Poor symmetry scores (<4/10) occur when one limb is significantly underperforming and requires strengthening interventions.
When combined with single leg jump for height and distance testing, muscle symmetry scores can identify trainable muscle deficits between the hip (glutes & hamstrings) vs. knee (quadriceps) to help improve overall movement symmetry and efficiency.
Reactive Strength Index (RSI) asymmetry: a comparison of left vs. right foot strength and power performance capabilities throughout a single SLJ RSI jump test.
High RSI asymmetry (> 10%) indicates a compensatory shifting of demands due to an affected and/or weaker limb. It is a critical rehabilitation functional milestone indicator for return to activity after orthopaedic and musculoskeletal injury.
Vertical take-off acceleration (VTA) asymmetry: a comparison of how quickly the left vs. right foot leaves the ground immediately after toe-off.
High VTA asymmetry (> 10%) occurs when the opposite limb's quadriceps musculature and surrounding tissues are fatigued, weak, or experiencing pain.
Vertical landing acceleration (VLA) asymmetry: a comparison of the ability of the left vs. right to absorb impact when the foot lands on the ground between successive jumps.
High VLA asymmetry (> 10%) occurs when landing more abruptly on one limb than the other.
How can my athletes benefit from SLJ RSI testing with Plantiga?
To simplify data interpretation and provide actionable movement insights to our users for better rehabilitation and performance outcomes, we’ve created instant and customizable reporting features that can be accessed and shared within minutes.
