What the formula assumes
When a system measures the time between leaving the ground and touching down, it can estimate the rise using projectile motion: jump height equals gravitational acceleration multiplied by flight time squared, divided by eight. That shortcut assumes the athlete's center of mass is at the same height at take-off and landing. A different arm action, leg tuck or landing position can change the measured interval without representing the same change in jump performance.
A running gate generally reports an interruption at its sensor plane. It may not know whether that interruption represents take-off, a hand, a swinging leg or a landing. A jump system is designed around the intended event and a defined calculation. Do not infer that a timer's small display increment means the displayed jump height is accurate to that same precision.
Repeatability is not the same as agreement
Research on dedicated jump photocells shows why both terms matter. In a 2017 study, 20 participants performed squat jumps, countermovement jumps and countermovement jumps with arm swing while an OptoJump and a force platform measured them. The photocell system repeated its own results consistently, but the flight-time values showed a systematic difference from the force-platform method. The size of that difference varied by jump type.
A 2023 study tested a different device, ADR Jumping, with 13 highly trained female volleyball players. The photocell's countermovement-jump estimates were also repeatable within that session, yet the average values differed by about 10.6 cm from motion capture in the study. The researchers proposed a device-specific correction equation. That equation is not a universal adjustment for other equipment or athletes.
A systematic review of photocells in sport likewise concluded that jump estimates and force-plate values should not be treated as interchangeable without attention to method. The review also discusses horizontal running gates separately; those findings do not validate a sprint gate for vertical jump testing.
Check these four details before testing
| Question | What the documentation should say |
|---|---|
| What event starts the clock? | How take-off is detected, and whether the first body part or a defined foot contact is used. |
| What event stops it? | How landing is detected, including the body position or contact rule required. |
| What does the output mean? | Raw flight time, estimated jump height, a corrected value, or another metric. |
| What validates the result? | A comparison with a criterion method for the same device, population and jump type. |
What 01TIMER publishes for its systems
The public 01TIMER pages describe running, shuttle, lap and split timing modes for the listed systems. They do not currently specify a validated vertical-jump-height mode or a jump-specific formula. That does not establish that no configuration could ever be adapted; it means the published information is not enough to recommend one for this purpose. Check the exact model manual and ask for written confirmation before purchasing or using a system for jump-height reporting.
For example, the S-003 product page describes dual-track running use, and the S-007 page describes multi-point timing. Those published use cases should not be stretched into a jump-validation claim. The photocell-versus-laser guide explains why sensor type and trigger behavior are separate from the question of what a system has been validated to measure.
Choose the instrument around the decision
Use a validated jump tool
When you need a jump-height value, comparison with published norms or agreement with force-platform data, choose a method validated for the jump and population.
Use a running gate for a running question
For approach speed or a timed run-up, define the start and finish beam planes. The high-jump approach guide and long-jump run-up guide cover those separate tasks.
Whichever tool you use, standardize warm-up, footwear, surface, jump instructions, arm use and the number of attempts. Keep raw trials as well as the selected best or average. Document the device and calculation so a later coach does not mistake a method change for an athlete change. The athlete data workflow can help preserve that context.
For running-gate layouts, see the alignment and beam-height guide and the S-001 setup guide. If a test requires an unlisted measurement mode, check the S-002 shuttle product information only for its published shuttle use, and use the support inquiry form to confirm the intended application rather than assuming compatibility.
Research used
- Attia AF et al. (2017), measurement errors when estimating vertical jump height with flight time.
- Villalon-Gasch L et al. (2023), criterion validity and reliability of an infrared-based jump photocell.
- Concurrent validity and reliability of photocells in sport: a systematic review (2023).
Common questions
Does a 0.001-second display increment prove jump-height accuracy?
No. Display resolution is not the same as measurement validity. The event definition and the conversion method also need validation.
Can I use the flight-time equation for every jump style?
It relies on an assumption about center-of-mass height at take-off and landing. The jump style and landing position should match the validation method.
Should I compare photocell results with a force plate?
Only when the device has been validated for that comparison. Otherwise, keep the measurement method consistent and label the results clearly.