Seasonal variations of ventilatory response to hypercapnia at rest

In order to examine the seasonal variation of CO2 sensitivity, the slope (S) of the ventilatory response to CO2 was determined in 10 healthy males throughout a year. It was found that the average value of logarithm S was significantly (p less than 0.05) higher in the September than in the annual average, though average magnitude of S was not significantly different. In addition, the average value of ventilation (VE(60] corresponding of PACO2 60 mmHg was significantly (p less than 0.05) lower in January than in September. These results indicate that the timing of the start and/or finish of training is an important factor in the effect of physical training on the S and VE(60).