Abstract
The maximal lactate steady state (MLSS) is one of the factors that differentiates performance in aerobic events. The purpose of this study was to investigate the sex differences in oxygen consumption (VO2), heart rate (HR), and the respiratory exchange ratio (RER) at the MLSS in well-trained distance runners. Twenty-two (12 female, 10 male) well-trained distance runners (23 ± 5.0 years) performed multiple 30-min steady-state runs to determine their MLSS, during which blood lactate and respiratory gas exchange measures were taken. To interpret the MLSS intensity as a training tool, runners completed a time-to-exhaustion (TTE) run at their MLSS. The relative intensity at which the MLSS occurred was identical between males and females according to both oxygen consumption (83 ± 5 %O2max) and heart rate (89 ± 7 %HRmax). However, female runners displayed a significantly lower RER at MLSS compared to male runners (p < 0.0001; 0.84 ± 0.02 vs. 0.88 ± 0.04, respectively). There was not a significant difference in TTE at MLSS between males (79 ± 17 min) and females (80 ± 25 min). Due to the observed difference in the RER at the MLSS, it is suggested that RER derived estimates of MLSS be sex-specific. While the RER data suggest that the MLSS represents different metabolic intensities for males and females, the relative training load of MLSS appears to be similar in males and female runners.
Highlights
Performance in aerobic events is largely dependent on maximal sustainable power or velocity.The oxygen consumption (VO2 ) at this velocity is referred to as the performance VO2 [1], and is primarily determined by the maximal lactate steady state (MLSS) or lactate threshold [2]
The relative intensity at which the MLSS occurred was identical between males and females according to both oxygen consumption (83 ± 5 %O2 max) and heart rate (89 ± 7 %HRmax)
While the respiratory exchange ratio (RER) data suggest that the MLSS represents different metabolic intensities for males and females, the relative training load of MLSS appears to be similar in males and female runners
Summary
Performance in aerobic events is largely dependent on maximal sustainable power or velocity. The oxygen consumption (VO2 ) at this velocity is referred to as the performance VO2 [1], and is primarily determined by the maximal lactate steady state (MLSS) or lactate threshold [2]. The determination of the MLSS is laborious, as the associated blood lactate analysis requires the collection of multiple blood samples multiple 30-min exercise tests. The respiratory exchange ratio (RER) is typically used to estimate caloric expenditure and oxidative substrate utilization [3]. Previous reports [7,8] indicate that during submaximal-intensity aerobic exercise, females demonstrate lower RER values and higher fat utilization rates than their male counterparts
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
