The CO2 responsiveness and ventilatory response to leg and arm exercise in female swimmers

The primary purpose of this study was to compare the ventilatory response to CO2 during rebreathing (delta VI/delta PCO2) among 8 competitive synchronized swimmers (SS), 8 competitive speed swimmers (CS) and 8 recreation swimmers (RS) who acted as controls. A secondary purpose was to study the relationship between delta VI/delta PCO2 and the ventilatory equivalent to the metabolic CO2 output (delta VE/delta VCO2) during graded exercise consisting of treadmill walking and arm cranking. No significant difference was observed amongst the groups in either the intercept or slope of the ventilatory response to increasing alveolar PCO2 was 1.48 +/- 0.33, 2.04 +/- 0.13 and 1.87 +/- 0.18 (mean +/- SEM) in the SS, CS and RS, respectively. The delta VI/delta PCO2 during rebreathing; delta VI/delta PCO2 during rebreathing was not significantly related to the delta VE/delta VCO2 obtained during either treadmill walking or arm cranking. The delta VE/delta VCO2 achieved during treadmill walking was similar for the 3 groups. However, during arm cranking, the delta VE/delta VCO2 was similar for the SS and CS, but both values were significantly lower than the delta VE/delta VCO2 achieved by the RS. It appears that the training regime experienced by the SS and CS did not alter their responsiveness to CO2 during rebreathing. The reduced delta VE/delta VCO2 observed during exercise with the trained limbs (arms) in the SS and CS compared to RS cannot be explained by altered responsiveness to CO2 secondary to training.