Cardiopulmonary exercise testing in children and adolescents at moderate altitude: New normative values

Cardiopulmonary exercise tests (CPETs) measure cardiovascular exercise response. Altitude alters exercise parameters, so standard normative datasets (Cooper, Bruce, Burstein) may not accurately predict exercise parameters for data collected at moderate altitude. This study aimed to: 1) establish modern normative exercise values for children/adolescents at moderate altitude and 2) compare these values against the Cooper, Burstein and Bruce models.

Maximal CPETs in children/adolescents aged 6 to 18 years were evaluated retrospectively (n = 1154, mean age 13.92 ± 2.70 years, 49.7 % female). Separate analysis and modeling were completed for the cycle ergometer (n = 907) and treadmill (n = 247). Polynomial regression models were developed for each exercise variable. A validation cohort of tests on the treadmill and cycle ergometer (n = 100, 50 cycle ergometer, 50 treadmill, mean age 14.44 ± 2.57 years, 47.0 % female) were evaluated with our polynomial models.

On the cycle ergometer, the Burstein dataset had improved root mean square error (RMSE, 7.4) compared to the Cooper dataset (RMSE 9.6) for peak oxygen consumption (VO₂ peak), while our model demonstrated even better RMSE (5.5). Our model had improved RMSE compared to the Burstein equations for all parameters (except resting systolic blood pressure) indicating an improved model.

We present new normative data and predictive equations based on a relatively large population of healthy children/adolescents tested at moderate altitude that outperforms sea-level-based models. Among other variables (age, gender, BMI, ethnicity), altitude must be considered when reporting exercise data so that normal CPET values at moderate altitude are not misinterpreted as pathological CPET findings.