Running Critical Power and W´: Influence of the Environment, Timing and Time Trial Order.

This study aimed to determine the influence of the testing environment (track vs. treadmill), time trial order (long-short vs. short-long) and timing (within-session vs. between-sessions) on the critical power (CP) and work over CP (W´) using the power metric in runners. Fifteen highly trained athletes performed three testing sessions composed of two time trials of 9- and 3-min, interspaced by 30-min. One session was performed on track, and two on treadmill altering the order of the time trials. The CP and W´ determined on the track were significantly greater than on treadmill (p < 0.001; CP ≥ 89 W; W´ ≥ 3.7 kJ). Their degree of agreement was low, (SEE CP > 5%; W´ > 10%) and therefore not interchangeably. There were no performance differences in the timing of the time trials (p = 0.320). Lastly, performing the 9-min first resulted in a greater power output compared to when it was last executed (p < 0.001; 4.9 W), although resulted in similar CP and W´ values (Bias < 5 and 10%, respectively). In conclusion, it is feasible to test CP and W´ in a single testing session, irrespectively of the time trial order, although not interchangeably between track and treadmill.