Prediction of power output at different running velocities through the two-point method with the Stryd™ power meter

Background: The force- and power-velocity (F-V and P-V, respectively) relationships have been extensively studied in recent years. However, its use and application in endurance running events is limited. Research question: This study aimed to determine if the P-V relationship in endurance runners fits a linear model when running at submaximal velocities, as well as to examine the feasibility of the "two-point method" for estimating power values at different running velocities. Methods: Eighteen endurance runners performed, on a motorized treadmill, an incremental running protocol to exhaustion. Power output was obtained at each stage with the Stryd (TM) power meter. The P-V relationship was determined from a multiple-point method (10, 12, 14, and 17 km.h(-1)) as well as from three two-point methods based on proximal (10 and 12 km.h(-1)), intermediate (10 and 14 km.h(-1)) and distal (10 and 17 km.h(-1)) velocities. Results: The P-V relationship was highly linear ( r = 0.999). The ANOVAs revealed significant, although generally trivial (effect size < 0.20), differences between measured and estimated power values at all the velocities tested. Very high correlations ( r = 0.92) were observed between measured and estimated power values from the 4 methods, while only the multiple-point method ( r(2) = 0.091) and two-point method distal ( r(2) = 0.092) did not show heteroscedasticity of the error. Significance: The two-point method based on distant velocities (i.e., 10 and 17 km.h(-1)) is able to provide power output with the same accuracy than the multiple-point method. Therefore, since the two-point method is quicker and less prone to fatigue, we recommend the assessment of power output under only two distant velocities to obtain an accurate estimation of power under a wide range of submaximal running velocities.