Dual force plates can show how each limb contributes to a bilateral countermovement jump. That is useful bilateral information. But if you need to know how one leg absorbs, stabilizes, and rebounds by itself, the test has to ask that leg to do the job by itself.
In a dual-force-plate CMJ, each leg is measured while both legs share the same task. The athlete can redistribute load, change coordination, and use the stronger side to help solve the movement. That makes the result a view of bilateral strategy, not a direct test of one-leg performance.
Force, impulse, and other measures can be separated by limb while the athlete jumps with both feet. This can flag bilateral force distribution and asymmetry in that specific bilateral task.
It does not directly show how either leg performs when it alone must accept the landing, organize the body, and create the next takeoff. That is a different motor problem and requires a unilateral test.
Use it when the performance question is bilateral: how does the athlete produce force and distribute it when both legs jump together?
Use it when the performance question is unilateral: what can this leg do when the other leg cannot assist?
That is not a theoretical concern. In professional basketball and volleyball players, bilateral CMJ and single-leg jump testing produced significantly different asymmetry magnitudes. The authors concluded that the tests should not be used interchangeably, but together when both perspectives are needed. A separate reliability study found that unilateral CMJ produced more reliable single-leg performance measures, while bilateral CMJ produced more consistent inter-limb asymmetry scores. Those findings point to a simple conclusion: the two tests are complementary, not substitutes.
This is also consistent with what we see in high-level athletes. In work with NFL Combine athletes, a bilateral jump can look clean while a single-leg task reveals a meaningful difference in one limb's ability to control and rebound. That field observation is not a universal diagnostic rule or a claim about injury risk. It is the reason to test the question directly before you make a one-leg decision from a two-leg task.
Reactive strength combines the ability to absorb force and produce the next effort quickly. In a bilateral drop jump or repeated-hop test, both legs contribute to the contact and rebound. You can learn about the athlete's bilateral reactivity, but you have not isolated either leg's reactive capacity.
A single-leg drop jump or a progressed single-leg hopping protocol changes the question. Each leg now owns the landing, the brief ground contact, and the rebound. This is the appropriate testing direction when you want leg-specific contact time, jump outcome, and single-limb RSI. It should only be used with appropriate readiness, a progressive box height, clear technique rules, and familiarization. The research also shows that RSI is sensitive to technique, so consistency in task and instruction is essential.
Begin from a sensible, progressive box height and land on the tested leg.
One limb manages the landing, position, and brief ground contact without help from the other.
Measure the outcome and contact time for that leg's reactive response, then repeat on the other side.
A single-leg rebound requires an athlete to hit, control, and leave the testing surface quickly. On a compact force plate, the small target can change how freely an athlete attacks the task or make the test feel unnecessarily unforgiving. Plyomat's 28 × 28 inch mat gives the athlete a broad, familiar landing target for unilateral jumps and hops.
This is a practical design and testing consideration, not a claim that a larger surface prevents injury. Coaches should still screen readiness, progress exposure, set the right height, and supervise the test.
The evidence supports task specificity and careful interpretation. It does not support treating one test as a complete replacement for another.
Professional basketball and volleyball players showed significant differences in asymmetry magnitudes between bilateral CMJ and single-leg jumps. The authors recommend using both to understand performance capabilities and asymmetry.
Read the PubMed abstract →Unilateral CMJ produced more reliable single-leg performance measures for most variables, while bilateral CMJ produced more consistent inter-limb asymmetry measures. Interpret each for what it measures.
Read the open-access study →Different drop-jump techniques produced different RSI, contact-time, and jump-height values. Standardize the task before you compare an athlete across time or legs.
Read the PubMed abstract →Research assessing reactive strength has explicitly included single-leg drop jumps and hopping alongside bilateral jumps. The unilateral test is not a bilateral proxy. It is its own task, with its own protocol.
Read the full study →Use a full landing surface to test unilateral jump and reactive strength with confidence, then track the metrics that matter.
See the 28 × 28 switch mat →