Effect of ramp bicycle exercise on exhaled carbon monoxide in humans

Abstract

The effect of exercise on the increase of exhaled CO in smokers compared to non-smokers has not been clarified yet. In this study we compared the dynamics of exhaled CO before, during and after exercise between smokers and non-smokers. A group of 8 smokers and a group of 8 non-smokers underwent a bicycle exercise in a ramp fashion to near maximum intensity. Ventilation and gas exchange, and CO exhalation were continuously measured every 30-s before, during and after the exercise. The fraction of CO (F (CO)) in the exhaled air decreased gradually, but the total amount of exhaled CO (V(CO)) increased in a linear manner during the ramp exercise, and F (CO) and returned to the pre-exercise level within several minutes after exercise in all subjects. A linear relationship was observed between V (O(2)) and V (CO) and between V (E) and V (CO) in both the whole period of measurement and during the ramp exercise period in all subjects. However, the at V (CO) 0 W, the peak V (CO) and the slope coefficients in the regression equation between V (CO) and V (O(2)) and between V (CO) and V (E) in the ramp exercise as well as the entire periods of measurement were significantly higher in smokers compared with those in non-smokers, and these were correlated with the number of cigarettes smoked per day. It was concluded that CO exhalation increases linearly with the increase of V (O(2)) and V (E) during exercise, and habitual smoking shifts these relationships upward depending on the number of cigarettes smoked daily.

Pathophysiological significance of measuring exhaled gasotransmitters during exercise

“…・ E against time in one non-smoker. Note that ∆FCO, gradually decreased, but V ・ CO increased during ramp exercise, similar to the changes of V ・ O 2 and V ・ E. This was reported by Yasuda et al 15) .…”

“…With respect to exhaled CO during exercise, Horbáth et al 13) reported a significant increase in exhaled CO output (V ・ CO) from rest to 60 W, and to maximal exercise in healthy children. Yasuda et al 15) also confirmed a linear increase of V ・ CO against workloads during a ramp exercise protocol in young male subjects as shown in Fig. 4.…”

“…This is because carboxyhemoglobin concentration in the blood tended to decrease in relation to the exercise intensity 41,42) . Furthermore, V ・ CO during exercise was much higher in smokers compared with that of nonsmokers 15) . Therefore, it is assumed that at least in part V ・ CO, in the exhaled air during exercise, can be derived from carboxyhemoglobin in the blood.…”

“…Furthermore, these gases themselves and their donors have also been used for therapeutic and ergogenic purposes 10,11) . It was also found that exhalation of NO and CO increased with an increase in exercise intensity [12][13][14][15] . However, the real origin and the pathophysiological roles of GTs in exhaled air, especially during exercise, are not completely understood.…”