Objective: 

We investigated to the effect of hypoventilation on physiological response to bicycle exercise.

Methods: 

Ten healthy male subjects [mean (SD) age 22.9 (2.8) years, height 172.8 (2.5) cm, body weight 67.5 (6.1) kg] performed two occasions for 5-min bicycle exercise at 65% of peak oxygen uptake with normal breathing (NB) and with hypoventilation (HV). Cardiorespiratory parameters were measured continuously and blood lactate was obtained at end of exercise by finger capillary blood sample. Furthermore we monitored continuously muscle oxygenation as concentration changes of oxyhemoglobin (Oxy-Hb), deoxyhemoglobin (Deoxy-Hb) and total hemoglobin (Total-Hb), and surface electromyogram (EMG) from the right vastus lateralis.

Results: 

Ventilation, oxygen uptake and arterial oxygen saturation were significantly lower (p < 0.05), and blood lactate was significantly higher (p < 0.05) in HV trial than NB trial. In HV trial, DOxy-Hb was lower and DDeoxy-Hb was higher compared to those in NB trial, respectively significant (p < 0.05), while DTotal-Hb was not significantly difference compared to that of NB trial. Integrated EMG was no significantly difference between trials. Moreover, there was a significantly correlation (r = -0.76; p < 0.05) between ratio of NB trial/ HV trial of oxygen uptake and that of blood lactate.

Conclusion: 

These results demonstrate that HV during bicycle exercise causes hypoxic stimulation, which reaches to the working muscle. In addition, we found an attractive association between decreased oxygen uptake and increased blood lactate induced by HV during cycle exercise.