Using minute ventilation for ambulatory estimation of additional heart rate.

Both physical activity and emotion produce physiological activation. The emotional component of heart rate (HR) can be estimated as the additional HR (aHR) above that predicted by O2 consumption. Our innovation was to substitute minute ventilation (V) for O2 consumption, calculating aHR from individual relations between V and HR during an exercise test. We physiologically monitored 28 flight phobics and 15 non-anxious controls while walking (leaving the hospital, entering a plane), and during a commercial flight. Raw HR did not differ between phobics and controls when leaving the hospital (118/114 bpm) or entering the plane (117/110 bpm). However, although aHR was not different when leaving the hospital (7.0/8.6 bpm), it was significantly greater when entering the plane (17.5/9.9 bpm), accurately reflecting the increased subjective anxiety of the phobics. V was not higher in phobics than controls during any condition, suggesting an absence of hyperventilation in the phobics. The results demonstrate the utility of our method for analyzing HR in people whose stress occurs when they are physically active.