Repeatability and Meaningful Change of CPET Parameters in Normal Subjects

DeCato TW, Bradley SM, Wilson EL, Hegewald MJ.

Med Sci Sports Exerc. 2017 Nov 7. doi: 10.1249. [Epub ahead
of print]

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
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.