The Steep Ramp Test in Dutch White Children and Adolescents: Age- and Sex-Related Normative Values

Abstract

The Steep Ramp Test (SRT), a feasible, reliable, and valid exercise test on a cycle ergometer, may be more appealing for use in children in daily clinical practice than the traditional cardiopulmonary exercise test because of its short duration, its resemblance to children's daily activity patterns, and the fact that it does not require respiratory gas analysis. The aim of the present study was to provide sex- and age-related normative values for SRT performance in Dutch white children and adolescents who were healthy and 8 to 19 years old. This was a cross-sectional, observational study. A total of 252 Dutch white children and adolescents, 118 boys (mean age=13.4 years, SD=3.0) and 134 girls (mean age=13.4 years, SD=2.9), performed the SRT (work rate increment of 10, 15, or 20 W·10 s(-1), depending on body height) to voluntary exhaustion to assess peak work rate (WRpeak). Normative values are presented as reference centiles developed by use of generalized additive models for location, scale, and shape. Peak work rate correlated highly with age (r=.915 and r=.811), body mass (r=.870 and r=.850), body height (r=.922 and r=.896), body surface area (r=.906 and r=.885), and fat free mass (r=.930 and r=.902) in boys and girls, respectively. The reference curves demonstrated an almost linear increase in WRpeak with age in boys, even when WRpeak was normalized for body mass. In contrast, absolute WRpeak in girls increased constantly until the age of approximately 13 years, when it started to level off. Peak work rate normalized for body mass in girls showed only a slight increase with age until 14 years of age, when a slight decrease in relative WRpeak was observed. The sample may not have been entirely representative of the Dutch population. The present study provides sex- and age-related normative values for SRT performance in terms of both absolute WRpeak and relative WRpeak, thereby facilitating the interpretation of SRT results by clinicians and researchers.