Hyperventilation (HV) occurring out of appropriate context, under some circumstances, can be potentially harmful to health. Nixon (1994) discusses convincingly the negative effects of long-term HV on the alkaloid buffering system and the potential challenge to a person's health status. Using capnography to measure respiration, percent expired CO2, to determine the anaerobic threshold during incremental exercise (the Effort Test), Nixon (1994) documented the onset of metabolic acidosis followed by alkalosis, secondary to the alkaloid buffering system response. Nixon (1994) hypothesized that recurring HV can lead to depletion of the alkaloid buffering system. By combining capnography, during the Effort Test, with analysis of blood gases and specific electrolytes, the effort-syndrome hypothesis was further tested in the present study. Thirteen patients with various kinds of stress-related problems were compared with four control participants. Pretest blood gases, from capillary blood, were collected after 10 minutes rest and 10 minutes of incremental exercise. Exhalation CO2, oxygen saturation, and traditional psychophysiological parameters were measured continuously during the experimental condition. Data from capillary blood and exhalation CO2 are reviewed. Change in patients' alkali buffering system supports the prediction made by Nixon (1994). The complexity of the data as well as methodological procedures of this study warrant a more sophisticated design, with more clearly defined functional analysis.