Are we ready to measure running power? Repeatability and concurrent validity of five commercial technologies

Training prescription in running activities have benefited from power output (P_W) data obtained by new technologies. Nevertheless, to date, the suitability of P_W data provided by these tools is still uncertain. The present study aimed to: (i) analyze the repeatability of five commercially available technologies for running P_W estimation, and (ii) examine the concurrent validity through the relationship between each technology P_W and oxygen uptake (VO₂). On two occasions (test-retest), twelve endurance-trained male athletes performed on a treadmill (indoor) and an athletic track (outdoor) three submaximal running protocols with manipulations in speed, body weight and slope. P_W was simultaneously registered by the commercial technologies Stryd_App, Stryd_Watch, RunScribe, Garmin_RP and Polar_V, while VO₂ was monitored by a metabolic cart. Test-retest data from the environments (indoor and outdoor) and conditions (speed, body weight and slope) were used for repeatability analysis, which included the standard error of measurement (SEM), coefficient of variation (CV) and intraclass correlation coefficient (ICC). A linear regression analysis and the standard error of estimate (SEE) were used to examine the relationship between P_W and VO₂. Stryd device was found as the most repeatable technology for all environments and conditions (SEM ≤ 12.5 W, CV ≤ 4.3%, ICC ≥ 0.980), besides the best concurrent validity to the VO₂ (r ≥ 0.911, SEE ≤ 7.3%). On the contrary, although the Polar_V, Garmin_RP and RunScribe technologies maintain a certain relationship with VO₂, their low repeatability questions their suitability. The Stryd can be considered as the most recommended tool, among the analyzed, for P_W measurement.