AUTHOR=Valenzuela Pedro L. , Alejo Lidia B. , Montalvo-Pérez Almudena , Gil-Cabrera Jaime , Talavera Eduardo , Lucia Alejandro , Barranco-Gil David 

TITLE=Relationship Between Critical Power and Different Lactate Threshold Markers in Recreational Cyclists

JOURNAL=Frontiers in Physiology

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.676484

DOI=10.3389/fphys.2021.676484

ISSN=1664-042X

ABSTRACT=Purpose: To analyze the relationship between critical power (CP) and different lactate threshold (LT2) markers in cyclists. 
Methods: Seventeen male recreational cyclists (33 ± 5 years, peak power output [PO]=4.5 ± 0.7 W/kg) were included in the study. The PO associated with four different fixed (onset of blood lactate accumulation [OBLA]) and individualized (Dmaxexp, Dmaxpol, and LTΔ1) LT2 markers was determined during a maximal incremental cycling test, and CP was calculated from three trials of 1, 5 and 20 minute-duration. The relationship and agreement between each LT2 marker and CP was then analyzed. 
Results: Strong correlations (r-values=0.81–0.98 for all markers) and trivial-to-small non-significant differences (Hedges’ g=0.01–0.17, bias=1–9 W, p>0.05) were found between all LT2 markers and CP with the exception of Dmaxexp, which showed the strongest correlation but was slightly higher than the CP (Hedges’ g=0.43, bias=20 W, p<0.001). Wide limits of agreement were, however, found for all LT2 markers compared with CP (from ±22 W for Dmaxexp to ±52 W for Dmaxpol), and unclear to most likely practically meaningful differences (>1% of difference in PO, albeit <5%) were found between markers attending to magnitude-based inferences.  
Conclusions: LT2 markers show a strong association and overall trivial-to-small differences with CP. Nevertheless, given the wide limits of agreement and the likelihood of potentially meaningful differences between these endurance-related markers, caution should be employed when using them interchangeably.