Validating Commercial Wearable Sensors for Running Gait Parameters Estimation

A growing number of people all over the world are running. Gathering in-field data with wearable sensors is attractive for runners, clinicians and coaches to improve running performance, avoid injury or return to running after an injury. However, it is yet to be proven that commercially available wearable sensors provide valid data. The objective of this study was to assess the validity of five wearable sensors (Moov Now (TM), MilestonePod, RunScribe (TM), TgForce and Zoi) to measure ground reaction force related metrics, step rate, foot strike pattern, and vertical displacement of the center of mass during running. Concurrent/criterion validity was assessed against a laboratory-based system using Pearson's correlation coefficients and ANOVAs. Step rate measurement provided by all wearable sensors was valid (all r > 0.96 and p < 0.001). Only Zoi provided valid vertical displacement of the center of mass (r = 0.81, p < 0.001); only TgForce provided meaningful estimates of instantaneous vertical loading rate (r = 0.76, p < 0.001); only MilestonePod could discriminate between a rear-, mid- and fore-foot strike pattern during running (p < 0.001). None of the wearable sensors was valid for estimating peak braking force. In conclusion, only a few metrics provided by these commercially available wearable sensors are valid. Potential buyers should therefore be aware of such limitations when monitoring running gait variables.