Key Points
- To clarify the kinetics of excess carbon dioxide output and its relationship to lactic acid production during and after bouts of intensive exercise.
- Six male subjects performed 40-, 60-, and 80-second bouts of cycle ergometer exercise at 282 ± 9 W and 90 rpm.
- Ventilation and gas exchange parameters were measured breath-by-breath alongside repeated fingertip blood lactate concentration sampling.
- Lactate concentration increase correlated linearly with exercise duration (r = 0.91, p < 0.01), while total excess carbon dioxide output correlated with lactate elevation at 10 minutes post-exercise (r = 0.88, p < 0.01).
- Excess carbon dioxide output showed a transient negative value at exercise onset, peaked at 60 seconds post-exercise, and returned to zero approximately 9 minutes after 80 seconds of exercise.
Structured PICO
PPopulation6 male subjects
IIntervention40-, 60- and 80-s cycle ergometer exercises (282 +/- 9 W, 90 rpm)
OOutcomeKinetics of excess CO2 output and lactate concentration during and after intensive exercisesurrogate
Excess CO2 output in response to intensive exercise correlates with lactic acid increase, but its time course is delayed relative to lactic acid production and is affected by hyperventilation.