Excess CO2 output response during and after short-term intensive exercise in sprinters and long-distance runners

The purpose of the present study was to examine the response of excess CO2 output to short-term intensive exercise in sprinters (SPR) and long-distanc e runners (LDR), End-tidal CO2 pressure (PETco(2)) increased up to about 20 s postexercise and then returned to the resting level at about 2-3min post exercise. Thereafter, PETco(2) remained below the resting level. (V)over do t O-2 excess, defined as the difference between (V)over dot CO2 and (V)over dot O-2 was integrated from the start of exercise until PETco(2) returned to the resting level, This integrated (V)over dot CO2 excess was defined as the first phase of CO2 excess (Ist CO2 excess), The subsequent integrated (V)over dot CO2, excess until 10 min postexercise was defined as the second phase of CO2 excess (2nd CO2 excess). The ratio of Ist CO2 excess to the l actate rise from rest to the peak value was significantly lower in SPR than in LDR, whereas 2nd CO2 excess was significantly greater in SPR than in LD R. The decrease in PETco(2) at 10 min postexercise was significantly larger in SPR than in LDR. The 2nd CO2 excess was closely related to the decrease in PETco(2). The results in the second phase suggest that the difference i n the response of excess CO2 output is derived from the difference in the r espiratory chemosensitivity to lactic acid rise.