Cerezuela-Espejo et al. 2021, Repeatability and validity of running-power devices

Comparison of five commercial running-power technologies. The Stryd foot-pod was the most repeatable (CV ≤4.3%, ICC ≥0.980) and correlated strongly with oxygen uptake, while Polar, Garmin and RunScribe showed poor repeatability. Crucially, running power has no agreed criterion measure, so absolute accuracy cannot be judged and the brands disagree with each other. Moderate.