Critical Speed

A datafield that very accurately measures your running critical speed (CS) and curvature constant (D') using a 3 minute all out test as described by Pettitt, Jamnick, Clark (2012). Critical speed can be used to prescribe interval training, selecting race pace for various distances, as well as for monitoring progress. How to install: This is a datafield. Add it to any running activity, better on its own screen since all the data will easily fit, plus the test works better if you don't get any feedback on timing or pace. A datafield is more useful in this case because it allows you to record other third party data at the same time, i.e. running power. How to use: Find a running track or other flat course. Warm up properly. Start the timer and go for it. Pacing is not allowed. Run your absolute max for three minutes. You're supposed to get progressively slower. If you pace and increase your speed near the end the result is not valid. Look at the graph in GC to make sure there's no hammock shape. The watch, depending on the watch, will vibrate and/or make a sound when you're done and immediately show you the result. The numbers are also written to the activity in GC so you can review them later. Have "fun". (ref: https://www.researchgate.net/publication/221709152_3-min_All-out_Exercise_Test_for_Running)

Fixed a bug where the app might crash if you ever tried it without a source of speed/distance, i.e. no GPS and no footpod. Not that you ever would for obvious reasons but it's more robust now. Compatible with all new devices as per October 2025.