End-tidal CO2 and ventilation: Novel markers for assessing performance levels in elite long-distance runners.

Well-trained individuals, compared to less well-trained individuals, exhibit a lower minute ventilation (V̇E) and higher end-tidal partial pressure of CO2 (PETCO2) at a given work rate. This study investigated whether such breathing adaptations seen in well-trained individuals also applied to elite long-distance runners. Forty-one long-distance runners were categorized into high (Long-High, consisting of Tokyo-Hakone College Ekiden [relay marathon] runners and Olympic athletes, n = 23), or low performance-level group (Long-Low, n = 18) according to their race times. Ten middle-distance runners (Middle) also participated in a comparison group. All subjects performed an incremental exercise test on a motorized treadmill until exhaustion. Maximum V̇O2 and velocity were greater for the Long groups than the Middle group, however these measures were not distinguishable between the Long-High and the Long-Low groups. By contrast, V̇E and PETCO2 were able to identify the Long-High group. Submaximal V̇E were lowest, whilst PETCO2 especially at high running velocities were highest for the Long-High group. This study confirms that breathing patterns with lower V̇E and higher PETCO2 are relevant adaptation markers for assessing endurance race performance in elite long-distance runners.