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 (VO 2 ). 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 VO 2 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 VO 2 . 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 VO 2 (r ≥ 0.911, SEE ≤ 7.3%). On the contrary, although the Polar V , Garmin RP and RunScribe technologies maintain a certain relationship with VO 2 , their low repeatability questions their suitability. The Stryd can be considered as the most recommended tool, among the analyzed, for P W measurement.