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What does this tool do?

Load raw force-time data from a force plate, select the time and force columns, and the tool automatically detects the jump phases - quiet standing (bodyweight), movement initiation, take-off, flight, and landing.

Load Data

Excel, CSV, TSV, or text file.

📊 Sample CMJKistler 9281EA · BioWare 5.3 · 500 Hz · dual plate bilateral CMJ

Kistler data: Bournemouth University. Also accepts BioWare .txt exports directly — open the .txt file and Fz from both plates is summed automatically.

Data file iSupports .xlsx, .xls, .csv, .tsv, and .txt (including BioWare exports). Delimiter is auto-detected.

No file loaded.

Select Columns

Map your data to time and force.

Source type

Sheet iFor Excel files with multiple sheets. Ignored for text/CSV files.

Header row?

Jump type iCMJ - countermovement jump (most common).
SJ - squat jump (no countermovement).
DJ - drop jump (contact time from landing to second take-off).

Time column iThe column containing timestamps (in seconds). If your data has no time column, the tool generates one from the sampling rate.

Force column (vGRF) iThe column containing vertical ground reaction force in Newtons. Should include a quiet standing period at the start for bodyweight estimation.

Detection Settings

Tune event detection parameters.

Sampling rate iYour force plate's sampling frequency in Hz. Common values: 1000, 1200, 2000. If a time column is provided, dt is estimated from the data and this is used as fallback.

BW window iNumber of samples used to estimate bodyweight. The subject must be standing still during this window. At 1000 Hz, 300 samples = 0.3 s.

samples

BW window start iSample index where the BW estimation window begins. Default 0 = start of file. For BioWare/Kistler files where the person steps on mid-trial, set this to the first quiet-standing sample (e.g. 1500 at 500 Hz = 3 s in).

sample

Data zeroed at bodyweight (tared on plate) iCheck this if the force plate was zeroed while the subject was already standing on it — e.g. standard BioWare/Kistler export practice. The quiet-standing signal will read ~0 N instead of ~700 N. You must then enter the subject's body mass below so the tool can reconstruct absolute force and compute metrics correctly.

Take-off / landing threshold iForce drops below this percentage of bodyweight = take-off. Force rises above it again = landing. Typically 3–10% BW. Lower values are more sensitive but may false-trigger on noise.

% of bodyweight

Show velocity on secondary axis

Run + Export

Detect events, compute metrics, plot.

Status

Load a file to begin.

Force–time trace

Dashed lines: StartMove / TakeOff / Landing — drag to fine-tune

Metrics

References

Flight time method: Linthorne, N.P. (2001). Analysis of standing vertical jumps using a force platform. American Journal of Physics, 69(11), 1198-1204. https://doi.org/10.1119/1.1397460

Impulse-momentum method: Moir, G.L. (2008). Three different methods of calculating vertical jump height from force platform data in men and women. Measurement in Physical Education and Exercise Science, 12(4), 207-218.

RSI: Young, W., Wilson, G., & Byrne, C. (1999). Relationship between strength qualities and performance in standing and run-up vertical jumps. Journal of Sports Medicine and Physical Fitness, 39(4), 285-293.

General: Winter, D.A. (2009). Biomechanics and Motor Control of Human Movement (4th ed.). Wiley.

What does this tool do?

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