Supine cycling in pediatric exercise testing: disparity in performance measures.

Supine cycling may be an important alternative modality for exercise testing. Subtle differences in supine and upright exercise physiology have been suggested but not fully explored in the pediatric population. The aim of this study was to compare peak and submaximal metabolic data in the upright and supine exercise positions. Healthy children (N = 100) performed cardiopulmonary exercise tests using supine and upright cycle ergometry. Recruitment was governed by grant funding and not based on sample size calculations. Subjects exercised to exhaustion. Paired Student's t-tests were used to compare upright and supine data; simple linear regression analyses examined correlations between the two modalities. Peak heart rate was similar in both testing positions. Although peak oxygen uptake (peak VO2), oxygen uptake at anaerobic threshold (VO2@AT), VO2 when the respiratory exchange ratio is consistently at or above 1.0 (VO2@RER1.0), and the oxygen uptake efficiency slope were significantly higher in the upright position, no difference was considered of practical significance when applying Cohen's effect size criteria. Therefore, it may be reasonable for pediatric exercise laboratories to use established normative data and predictions for upright cycling position and apply them to metabolic measures obtained in supine exercise testing. Supine cycling with submaximal parameters may allow objective assessment of exercise capacity in children who undergo exercise echocardiography or cannot perform upright exercise testing.