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

To analyze the relationship between critical power (CP) and different lactate threshold (LT2) markers in cyclists. 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) and individualized (Dmax, Dmax, and LT) LT2 markers was determined during a maximal incremental cycling test, and CP was calculated from three trials of 1-, 5-, and 20-min duration. The relationship and agreement between each LT2 marker and CP were then analyzed. Strong correlations ( = 0.81-0.98 for all markers) and trivial-to-small non-significant differences (Hedges' = 0.01-0.17, bias = 1-9 W, and > 0.05) were found between all LT2 markers and CP with the exception of Dmax, which showed the strongest correlation but was slightly higher than the CP (Hedges' = 0.43, bias = 20 W, and < 0.001). Wide limits of agreement (LoA) were, however, found for all LT2 markers compared with CP (from ±22 W for Dmax to ±52 W for Dmax), and unclear to most likely practically meaningful differences (PO differences between markers >1%, albeit <5%) were found between markers attending to magnitude-based inferences. LT2 markers show a strong association and overall trivial-to-small differences with CP. Nevertheless, given the wide LoA and the likelihood of potentially meaningful differences between these endurance-related markers, caution should be employed when using them interchangeably.