Figure 2.

Cardiopulmonary exercise testing (CPET) in an 11‐year‐old boy. CPET remains the predominant testing approach to determine gas exchange during exercise in children and adults. Tests are typically performed in laboratory using a cycle ergometer (shown here) or treadmill. CPET provides invaluable clinical insight both during the exercise protocol (submaximal) and at the limit of the child's tolerance (VO₂max or peak VO₂). CPET requires sophisticated equipment, precise calibration, skilled technicians, and robust data analysis and storage capabilities, and, consequently, is not readily accessible for field or most primary care assessments of exercise responses in children.