Maximal Lactate Steady State Versus the 20-Minute Functional Threshold Power Test in Well-Trained Individuals: “Watts” the Big Deal?

Purpose: This study aimed to i) compare the power output (PO) for both the 20-minute functional threshold power (FTP20) field-test and the calculated 95% (FTP95%) with power at maximal lactate steady state (MLSS); and ii) evaluate the sensitivity of FTP95% and MLSS to training induced changes. Methods: Eighteen participants (12 males- 37± 6 years; 6 females- 28 ± 6 years) performed a ramp-incremental cycling test to exhaustion, 2 to 3 constant load MLSS trials, and a FTP20 test. 10 participants returned to repeat the test series after 7-months of training. Results: PO at FTP20 and FTP95% was greater than that at MLSS (p=0.00), with the PO at MLSS representing 88.5 ± 4.8% and 93.1 ± 5.1% of FTP and FTP95%, respectively. MLSS was greater POST compared to PRE training (12 ± 8 W) (p=0.002). No increase was seen in mean PO at FTP20 and FTP95% (p=0.75). Conclusion: The results indicate that the PO at FTP95% is different to MLSS, and that changes in MLSS PO after training were not reflected by FTP95%. Even using an adjusted percentage (i.e., 88% rather than 95% of FTP20), the large variability in the data is such that it would not be advisable to use this as a representation of MLSS.