Reference Values for Cardiorespiratory Fitness in Patients Aged 6 to 18 Years

Abstract

Objective: To develop reference values for cardiorespiratory fitness, as quantified by peak oxygen uptake (VO_2peak) and treadmill time, in patients aged 6 through 18 years referred for cardiopulmonary exercise testing (CPET).

Study design: We reviewed a clinical pediatric CPET database for fitness data in children aged 6-18 years with no underlying heart disease. CPET was obtained via the Bruce protocol utilizing objectively confirmed maximal effort via respiratory exchange ratio. Fitness data (VO_2peak and treadmill test duration) were analyzed to determine age- and sex-specific reference values for this pediatric cohort.

Results: Data from 2025 pediatric CPETs (53.2% female) were included in the analyses. VO_2peak increased with age in males, but not females. Treadmill test duration increased with age in both males and females. Fitness was generally higher in males when compared with females in the same age groups.

Conclusions: Our study provides extensive reference values for both VO_2peak and total treadmill test time via the Bruce protocol for a pediatric population without known cardiac disease. Furthermore, the inclusion of objectively confirmed maximal exercise effort increases confidence in these findings compared with prior studies in this area. Clinicians performing CPET in pediatric populations can utilize these reference values to characterize test results according to representative peer data.

Keywords: cardiopulmonary exercise testing; cardiorespiratory fitness; pediatrics; reference values.