Protocol comparison
Flight-time vertical vs jump-and-reach vertical
Both methods can be useful, but they measure different things. A flight-time result estimates centre-of-mass rise from time in the air. A jump-and-reach result subtracts standing reach from the highest touch.
Flight-time method
- Uses takeoff-to-landing time.
- Calculates h = g·t²/8.
- Needs comparable takeoff and landing body position.
- Is sensitive to tucked legs, foot reach, and event selection.
Jump-and-reach method
- Uses standing reach and maximum touch height.
- Includes the gain from rising from flat feet onto the toes.
- Is sensitive to shoulder mobility, reach technique, and baseline measurement.
- Often produces a different number from flight time even on the same jump.
Why VertChecker shows a reach-comparable estimate
The raw result remains the flight-time measurement. Where the video supplies a usable body scale, VertChecker also estimates the extra standing-reach distance created by plantarflexion, bounded between 2.5 and 6 inches. When scale is unavailable it uses a labeled 4-inch default. That adjusted number is a comparison aid, not a direct Vertec measurement.
How to track progress
Pick one method, keep the protocol fixed, and compare like with like. Use the same camera rate and angle, the same jump style, similar footwear and surface, and the same landing instruction. A consistent series is more useful than forcing one device's number to match another.