A study was conducted to clarify the validity and availability of inclination of exponential curve-fitting model for oxygen uptake (VO₂) and heart rate (HR) during incremental exercise (IECOH) as an index of cardio-pulmonary functional reserve in healthy subjects. A treadmill exercise test was used to measure the VO₂ (L/kg/min) and HR (beat /min) during incremental exercise of all subjects. The IECOH was derived from the following equation : HR=A⋅exp^B·VO₂. The constant “B” represents the IECOH. The following three identifications were made : 1) the relationship between maximal oxygen uptake (VO₂max) and IECOH in 82 healthy males ; 2) the relationship between IECOH and age in 428 healthy males and females ; 3) the effect of physical training in 8 healthy males.
There was inverse correlation between IECOH and VO₂max (r= -0.824) . And also, there were inverse correlations between IECOH detected from submaximal tests and VO₂max (above r=-0.6) . There were no differences in the IECOH detected from maximal and submaximal tests. In Bland-Altman plot method, accuracy of measurment in the IECOH detected from submaximal exercise test was precise. There was a significant relationship between IECOH and age in male and female subjects (r=0.499 and r=0.310, respectively) . Physical training increased VO₂max and decreased IECOH significantly. The VO₂max before and after physical training correlated inversely with the IECOH before and after physical training (r=-0.514) .
In conclusion, these results suggest that IECOH is adequate and useful as an index of cardio-pulmonary functional reserve which can be measured by the submaximal exercise test in healthy subjects.

This study examined the effects of physical training on exercise hyperpnea (EH) in patients on hemodialysis (HD) . In baseline, 17 (trained group) and 12 (control group) patients on HD performed symptom limited exercise test using a treadmill. Trained group, but not control group, exercised 2 to 3 times weekly on non-dialysis days under medical supervision. Exercise testing was repeated 20 weeks after the baseline. Ventilatory response to exercise was evaluated using the regression slope relating minute ventilation (VE) to carbon dioxide output (VCO₂ ) during incremental exercise (VE/VCO₂ slope) below the point of respiratory compensation. In trained group, VE, oxygen uptake ( VO₂) and VCO₂ at peak exercise increased and VE/VO₂ and VE/VCO₂ decreased after physical training, respectively. No change was observed in control group. VO₂ at the anaerobic threshold increased in trained group, but not in control group. The post training VE/VCO₂ slope (33.9±5.0) was significantly (p<0.05) lower than the pre-training slope (38.0± 4.8) and remained constant in control group. In trained group, changes in the VE/VCO₂ slope correlated with those in peak VO₂ (p<0.05) . These results suggest that physical training decreases EH in patients on HD and that it correlates with changes in exercise tolerance.

This study was conducted to clarify the validity and availability of inclination of exponential curve-fitting model for oxygen uptake (VO₂) and heart rate (HR) during incremental exercise (I-ECOH) as an index of cardio-pulmonary functional reserve in patients with ischemic heart disease (IHD). A treadmill exercise test was used to measure the VO₂(L/kg/min) and HR (beat/min) during incremental exercise of all subjects. I-ECOH was derived from the following equation : HR=A·exp^B·VO2. The constant "B" represents I-ECOH. The following two identifications were made : 1) the relation between peak oxygen uptake (VO₂peak) and I-ECOH in IHD patients with normal left ventricular function and with chronic heart failure (CHF); 2) the relation between I-ECOH and the New York Heart Association (NYHA) functional classification of IHD patients with CHF.There were significant differences among IHD patients with normal left ventricular function, CHF patients, normal controls and long distance runners in I-ECOH and VO2peak, respectively (p<0.001). There were inverse correlations between I-ECOH and VO2peak in IHD patients with normal left ventricular function (r=-0.64, p<0.001) and CHF (r=-0.63, p<0.001). I-ECOH could be used to discriminate effectively between NYHA functional classes (p<0.001).In conclusion, these results suggest that I-ECOH is adequate and useful as an index of cardio-pulmonary functional reserve in patients with ischemic heart disease.