Author(s): LINDSTROM, B., FLEITAS-PANIAGUA, P.R.1, MARINARI, G.1, RASICA, L.1, ZAGATTO, A.M.1,2, MURIAS, J.M.1,3, Institution: UNIVERSITY OF CALGARY , Country: CANADA, Abstract-ID: 758

INTRODUCTION:
Critical power (CP) estimation is a well-established method to identify the power output (PO) associated with the maximal metabolic steady state (MMSS) of exercise. CP estimation requires multiple time to task failure (TTF) trials and the precision of this evaluation in untrained individuals could be questionable due to their inexperience with performing maximal efforts up to volitional exhaustion. Thus, the goal of this study was to compare whether the accuracy of CP to approximate the MMSS was affected by the training status of the individuals.
METHODS:
Twelve trained (5 females) and 12 untrained (6 females) participants underwent: i) a ramp incremental test (males 30 females 20 W/min) to task failure to determine maximal oxygen consumption (VO2max) and peak PO (POpeak); ii) a series of 4-5 TTF trials at POs ranging from 70 to 90% of POpeak performed on separate days, to obtain TTF durations of ~2-20 min for CP estimations. CP was calculated from three different models (CP2hyp, CPlinear, and CP1/time) and the one demonstrating the lowest combined error of its parameters was selected as the final value; iii) at least 2 (or as many as needed) 30-min constant PO rides to establish MMSS. Measurements of VO2 and blood lactate concentrations ([La-]b) were performed. MMSS was defined as the highest PO associated with steady-state VO2 (<120 ml/min) and stable [La-]b values (<1 mM) between the 15th and 30th min of the ride.
RESULTS:
VO2 and [La-]b at MMSS were stable in both trained (3.22±0.58 L/min-3.25±0.57 L/min, 6.18±1.6 mM-6.65±1.8 mM; p>0.05) and untrained (2.23±0.43 L/min-2.28±0.45 L/min, 6.72±1.57 mM-7.16±1.62 mM; p>0.05). The PO at CP was greater than that at MMSS in both trained (233±37 W vs. 225±39 W, respectively; p<0.05; effect size d=0.19; mean bias= +7.5 W, 95% LOA= -11-26 W) and untrained (155±39 W vs. 147±34 W, respectively; p<0.05; effect size d=0.20; mean bias= +7.5 W, 95% LOA= -13-28 W). A mixed-model ANOVA revealed no significant differences in the variances of CP and MMSS values between the trained and untrained groups (p=0.99, statistical power =99%).
CONCLUSION:
These findings indicate that, despite a significant (albeit small) difference between CP and MMSS, the CP model provided a close approximation of the PO associated with the MMSS. Most importantly, the quality of the CP model was not affected by training status, which suggests that previous experience with maximal efforts is not a key component of the quality of the prediction. (Dr. Juan M. Murias’ work was supported by the Natural Sciences and Engineering Research Council of Canada (RGPIN-2016-03698) and the Heart & Stroke Foundation of Canada (1047725).