Jump Height Is Not Enough: Moving Beyond Peak Height in Jump Testing
Summary
Jump height is the most widely used output from jump testing—but relying on it alone misses most of what a force plate or contact mat can tell you. Here's what else to look at and why it matters.
Jump height has dominated the athlete monitoring landscape for good reason: it is easy to understand, easy to communicate, and responsive to training and fatigue. But as a single metric, it hides as much as it reveals. Two athletes who jump the same height may do so in completely different ways — and understanding those differences is where the real training information lives.
What Jump Height Actually Tells You
Jump height is a direct function of vertical velocity at takeoff. Higher velocity means more height, all else equal. But the velocity at takeoff is the product of everything that happened during the push-off phase: the impulse applied, the time over which it was applied, and the mechanical efficiency of the movement. Jump height collapses all of this into a single number.
Linthorne (2001) showed that jump height can be accurately derived from flight time using h = g·t²f/8, making it accessible from even basic contact timing equipment. The issue is not measuring it — it is assuming that's enough.
What Else to Look At
Reactive Strength Index (in drop jumps): As discussed extensively in this blog, RSI adds ground contact time to the equation and gives you a rate metric. Same jump height, shorter contact time = better RSI = more reactive athlete.
Force-time curve shape (with force plate access): The shape of the force-time curve during a CMJ tells you whether the athlete is loading effectively, whether they are producing force early or late in the push-off phase, and whether there are mechanical asymmetries. McMahon et al. (2018) identified a battery of phase-specific CMJ variables — including eccentric deceleration impulse, propulsive peak force, and braking phase duration — that capture nuances completely invisible in the jump height number.
Asymmetry: Single-leg jump testing alongside bilateral testing identifies limb asymmetries that bilateral jump height masks. An athlete who jumps 38 cm bilaterally but shows a 15% asymmetry on single-leg tests has a meaningful functional deficit that bilateral jump height will never flag.
CMJ vs Squat Jump difference: This pre-load benefit (the extra height achieved from the countermovement relative to a matched starting position) quantifies the slow SSC contribution. An athlete with a large CMJ-SJ difference is effectively utilising the stretch-shortening cycle; one with a small difference is not, regardless of absolute jump height.
Peak velocity: The velocity at take-off is more directly interpretable than height for some purposes — particularly when tracking changes in explosive capacity relative to body mass.
Building a Jump Testing Battery
The pragmatic approach is to use the equipment you have and extract as many meaningful variables as your equipment supports:
- Contact mat only: Jump height (from flight time), RSI (from contact + flight time), CMJ-SJ comparison (if both tests performed)
- Force plate: Full force-time curve analysis, asymmetry, phase variables, impulse-momentum relationships
- Dual-beam timing system: Jump height, contact time, flight time — similar to contact mat with gate-based measurement
The key is consistency. Use the same equipment, the same protocol, and the same time of day. Trends within an athlete are more informative than comparisons to population norms.
A Note on Sensitivity
Jump height is actually quite sensitive to fatigue — a 2–3% decline in a well-trained athlete is meaningful if the testing conditions are controlled. The value of adding other variables is not primarily sensitivity; it is specificity. When jump height declines, does the athlete know *why*? Is it a force production problem, a velocity problem, or a timing/technique problem? Additional variables answer that question.
More information, correctly interpreted, always beats less.
References
Mark Fisher
Founder, Swift Performance
Mark Fisher is the founder of Swift Performance and has spent 30 years designing and building athlete testing equipment used by elite sport programmes and universities worldwide. He has worked alongside researchers and PhD candidates across biomechanics, sprint mechanics, and strength science — developing the hardware and software they use to collect and analyse performance data. His writing comes from three decades at the intersection of applied sport science and precision measurement technology.
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