Comparison of modeled lactate threshold 2 with MLSS in running and cycling

The study investigated 1.The agreement of modeled lactate threshold 2 (modLT2) using maximal oxygen uptake (V̇O2peak),cost of locomotion (C), and fractional utilization of (V̇O2peak) at LT2 (LT2%) with maximal lactate steady state (MLSS) in running and cycling. 2.The impact of different C determination methods on the accuracy of the model. 3.The contributions of V̇O2peak,C, and LT2% to work rate at MLSS. Thirty-four endurance-trained athletes (27.7±6.9 yrs, 56.2±5.5 ml∙kg-1∙min-1) completed an incremental step test on a treadmill or cycling ergometer.V̇O2peak,C at lactate threshold 1, 80% of V̇O2peak and LT2 (CLT2), and LT2% were assessed.Two to five 30 min constant work rate tests were performed for MLSS determination. Moderate to good agreement was found between modLT2 and MLSS for running and cycling (ICC ≥ 0.698) with the smallest mean difference (± limits of agreement) for CLT2 with -2.0±5.2% and -0.9±6.0%, respectively.83% and 79% of the total variance of MLSS was explained by V̇O2peak,CLT2 and LT2%, respectively.V̇O2peak and CLT2 contributed the most to the regression R2 in running (54% and 40%) and cycling (74% and 51%), while LT2% had the smallest contribution (4% and 5%). Based on the high accuracy of the model with the major contribution of V̇O2peak and CLT2, MLSS could be improved focusing on these two variables during training.