Changes in ventilatory anaerobic threshold over time: How does the years of experience of the observer affect the results?

AimsTo determine the extent to which years of experience in anaerobic threshold (AT) assessment affects the reliability of AT determination at a regional general cardiovascular hospital under a strictly blinded protocol. MethodsA controller was established to blind the data. The observers who determined AT were non-controller physical therapists working at the facility: three observers, with 4-17 years of experience, and one consultant physician with 30 years of experience. The data analyzed included 130 patients (260 data points) with cardiac disease who underwent a cardiopulmonary exercise test during the inpatient and maintenance phases. The observers determined AT twice from blinded and randomized data using the V-slope method. ResultsThe inter-rater reliability (intra-class correlation coefficient [ICC]) of the AT assessment was good (0.87, range 0.87-0.94). The limits of agreement (LOA: two standard deviations of the difference between the two AT determinations, mL/min) ranged between 103.6-185.0. The overall change in AT over time was not significantly different between observers (66.6{+/-}121.4 mL/min; p<0.001); neither was the observers years of experience, ICC, or LOA. However, the magnitude of error in AT assessment in the inpatient and maintenance phases was significantly related to the error in change in AT over time (r=0.685-0.861, p<0.001). ConclusionAT was assessed under a blinded protocol by four observers with 4-30 years of experience at a cardiovascular hospital. The reliability of their AT determinations was high, and the change in AT over time readings did not differ significantly by the years of observer experience, ICC, or LOA.