INTRODUCTION AND OBJECTIVES: Investigate whether the inclusion of the blood lactate (BL) energy equivalent at submaximal intensities would change the energy cost of running (CR) predicted to supramaximal high-intensity running as well as its precision. METHODS: The CR was determined from the slope of the VO2-speed regression. For each subject an alternative regression was established where an energy equivalent of 3 ml O2 kg-1∙mM-1 BL was added to the VO2. Paired t-tests, pairwise correlations and Bland-Altman plots were used to investigate whether the two methods represent the same phenomena. RESULTS: The main findings were that CR predicted to supramaximal intensities comprised between 110% and 160% of that corresponding to the individuals' peak VO2, increased significantly when the BL measurements were included in the regressions. The inclusion of BL measurements also increased the imprecision of the CR at 110%, 120%, 130%, 150% and 160%. CONCLUSIONS: Our results indicate that inclusion of lactate O2 equivalent in the VO2-exercise intensity regression increases the energy cost of running and lowers its precision.
oxygen consumption; energy metabolism; lactates
