Pediatric exercise testing. In health and disease

Measuring peak oxygen uptake (VO2peak) during progressive cardiopulmonary exercise testing (CPET) up to maximal exertion is widely recognized as the best single measure of aerobic exercise capacity. It is an important determinant of health, even in childhood and adolescence. Measuring VO2peak facilitates an accurate and objective assessment of the integrative physiological response to exercise of the pulmonary, cardiovascular, hematopoietic, and metabolic systems, and can be used for diagnostic, prognostic, and evaluative purposes. However, VO2peak is strongly influenced by the child’s motivation, the selected exercise protocol, verbal encouragement, and the skills and experience of the tester to determine peak exercise. Lastly, performing CPET up to maximal exertion is not feasible in children or adolescents where maximal exercise testing is contraindicated, or when performance may be impaired by pain, shortness of breath, or fatigue rather than exertion. Due to these limitations, experts developed alternative indices that do not rely on a maximal effort, such as the oxygen uptake efficiency slope (OUES). The OUES includes a submaximal parameter of aerobic exercise capacity that can be calculated by using exercise data collected during progressive CPET in addition to the measured VO2peak, or might even act as an alternative for VO2peak. It describes the relationship between the VO2 and the common logarithm of the minute ventilation (VE) throughout CPET. The linearity of this relationship during the last part of CPET implies that the use of submaximal exercise data does not significantly alter the value of the OUES. This is an either unwilling or unable to essential characteristic when a participant is complete CPET up to maximal exertion. Before the OUES can be implemented in daily pediatric (clinical) practice, more profound investigation concerning its validity is necessary in healthy children, as well as in pediatric patient populations, Performing respiratory gas analysis measurements throughout CPET, required for VO2peak and OUES measurements, is sometimes not feasible, due to the expense, the need for special equipment, and the required trained staff. Moreover, the use of a facemask or mouthpiece might frighten children. Due to these limitations, standardized CPET remains underused in daily (clinical) practice, which underlines the need for non-sophisticated pediatric exercise testing procedures that do not require respiratory gas analysis measurements. Such a test might help to increase the utilization of pediatric exercise testing. The steep ramp test (SRT) is an incremental exercise test up to maximal exertion performed on a cycle ergometer that does not require respiratory gas analysis measurements. The attained peak WR (WRpeak) is the SRT’s primary outcome measure that largely exceeds the WRpeak achieved during regular CPET. Since the attained WRpeak at the SRT correlates strongly with the VO2peakattained during traditional CPET, the SRT might be useful as a simple screening tool that provides the clinician with an indication about a child’s aerobic exercise capacity. However, prior to implementing the SRT in daily pediatric (clinical) practice, knowledge is required concerning its reliability and validity in healthy children, as well as in pediatric patient populations.