Repeatability and Meaningful Change of CPET Parameters in Normal Subjects.

DeCato TW, Bradley SM, Wilson EL, Hegewold MJ

Medicine And Science In Sports And Exercise [Med Sci Sports Exerc] 2017 Nov 07. Date of Electronic Publication: 2017 Nov 07.

Introduction/purpose: Cardiopulmonary exercise testing (CPET) plays an important role in clinical medicine and research. Repeatability of CPET parameters has not been well characterized, but is important to assess variability and determine if there have been meaningful changes in a given CPET parameter.
Methods: We recruited 45 healthy subjects and performed two symptom-limited CPETs within 30 days using a cycle ergometer. Differences in relevant CPET parameters between CPET-1 and CPET-2 were assessed using a paired t-test. Coefficient of variation (CoV) and Bland-Altman plots are reported. Factors that may be associated with variability were analyzed (sex, age, time of day, fitness level). The coefficient of repeatability was calculated for peak V˙O2 and V˙O2 at lactate threshold (LT) to establish a 95% threshold for meaningful change.
Results: There were no significant differences between tests in the parameters reported. Specifically, we found overall low CoV in peak V˙O2 (4.9%), V˙O2@LT (10.4%), peak O2 pulse (4.6%), peak V˙E (7.4%), V˙E/V˙CO2@LT (4.0%) andV˙E/V˙O2@LT (4.8%). The CoV for RER@LT was significantly affected by diurnal factors; age, sex and fitness level did not impact variability. The 95% threshold for meaningful change in peak V˙O2 was 0.540 L/min and for V˙O2@LT was 0.520 L/min.
Conclusions: Repeatability of CPET parameters is generally higher then previously reported. There were no significant differences in variability related to sex, age, fitness level; diurnal factors had a limited impact. The threshold for meaningful change in peak V˙O2 and for V˙O2@LT should be considered when gauging a response to therapies or training.