The differences in CO2 kinetics during incremental exercise among sprinters, middle, and long distance runners

Area of Science:

• Exercise Physiology
• Sports Science
• Human Performance

Background:

• Understanding carbon dioxide output (VCO2) kinetics during exercise is crucial for assessing metabolic responses.
• Previous research has established linear relationships between oxygen uptake (VO2) and VCO2 in steady-state and sub-anaerobic threshold (AT) incremental exercise.
• Differences in exercise intensity and duration among various running disciplines may influence these kinetic responses.

Purpose of the Study:

• To investigate and compare the kinetics of carbon dioxide output (VCO2) during incremental exercise in sprinters, middle-distance runners (MD), and long-distance runners (LD).
• To explore the relationship between CO2 stores and mixed venous CO2 pressure (PVCO2).
• To analyze the concept of CO2 excess and its association with blood lactate accumulation (delta LA) across different running groups.

Main Methods:

• Participants included sprinters (S), middle-distance (MD), and long-distance runners (LD).
• Incremental exercise tests were conducted to measure oxygen uptake (VO2) and carbon dioxide output (VCO2).
• CO2 stores were calculated based on differences in VCO2 estimates between steady-state and incremental exercise; CO2 excess was determined by comparing estimated and measured VCO2 above the anaerobic threshold (AT). Mixed venous CO2 pressure (PVCO2) was measured using the CO2 rebreathing method, and blood lactate levels (delta LA) were assessed.

Main Results:

• Below the anaerobic threshold (AT), VCO2 was linearly related to VO2 in all groups.
• CO2 stores per body weight were significantly related to PVCO2, with no significant differences in the slopes of this relationship among the three running groups.
• CO2 excess per body weight was significantly related to delta LA. The ratio of CO2 excess to delta LA was significantly lower in sprinters compared to long-distance runners.

Conclusions:

• The study highlights distinct patterns in CO2 kinetics during incremental exercise, particularly concerning CO2 excess, which is influenced by anaerobic metabolism and training specificity.
• The findings suggest that the relationship between CO2 production and buffering of metabolic acids differs across running disciplines.
• These insights contribute to a better understanding of the physiological adaptations to endurance training and their impact on gas exchange dynamics during exercise.