Comparison of physiological response to cardiopulmonary exercise testing among cancer survivors and healthy controls

Selected physiological responses, including lactate kinetics, to cardiopulmonary exercise testing (CPET) were evaluated among a group of cancer survivors (CS, n = 55) and healthy controls (HC, n = 213). It was uncertain if lactate testing in a group of cancer survivors could provide useful information about training intensity. It was hypothesized that chemotherapy, radiation, surgery, physical inactivity or some combination thereof would alter the normal lactate kinetics (curvilinearity) in the relationship of lactate concentration versus power. Physiologic responses of CS (heart rate, blood pressure, O₂ saturation, RPE, lactate, VO_2peak, and peak power) during cycle ergometry were compared to HC. Comparisons (t tests and Chi-square) were made between the groups and shape of lactate plots were analyzed for determination of a breakpoint. Multiple logistical regressions were then utilized to identify factors related to the inability to determine lactate breakpoints. Lactate breakpoints were common to all but one HC whereas among the CS there was a small subset of subjects (n = 5) who did not show a lactate breakpoint. Group differences indicated that female CS were significantly older, had greater BMI’s, and lower work capacity than HC. Males CS had significantly lower work capacity than HC. Multiple logistical regression analyses, in all instances, yielded no statistically significant models predictive of the inability to determine a lactate breakpoint. In this sample of CS and HC, physiological responses and lactate kinetics during CPET were similar while work capacity among the CS was lower. Because lactate breakpoints were found, lactate threshold could be determined for all but a few individuals. For those working with CS, CPET with ECG monitoring and lactate threshold measures should be considered for those wishing for precise and safe training intensities.