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Rigorously determined peak oxygen uptake is internationally recognized as the criterion measure of youth cardiorespiratory fitness. The assessment and interpretation of children's and adolescents'peak oxygen uptake and the relationship of the measure with other health-related variables are well documented. There has been a recent resurgence of interest in the prediction of peak oxygen uptake from field performance tests in young people. However, coupled with ratio-scaling of data and the raising of clinical red flags, these practices risk clouding our understanding of youth cardiorespiratory fitness and its relationship with current and future health. We believe these methods have the potential to mislead clinical practice and misguide recommendations for the promotion of youth cardiovascular health. We discuss relevant scientific evidence and interpretations that have emerged from predicting youth cardiorespiratory fitness from performance test scores. We argue that children deserve to have health care founded on evidence- based science and not on myths and misconceptions. La consommation maximale d'oxygene rigoureusement determinee est reconnue a I'echelle internationale comme la mesure du critere de la capacite cardiorespiratoire des jeunes. On dispose de nombreuses informations sur devaluation et l'interpretation de la consommation maximale d'oxygene des enfants et des adolescents, ainsi que sur le lien de la mesure avec d'autres variables relatives a la sante. On a recemment constate un regain d'interet a l'egard de la prediction de la consommation maximale d'oxygene a partir de tests de performance sur le terrain chez les jeunes. Neanmoins, associees a une mise a l'echelle proportionnelle des donnees et a la diffusion d'alertes cliniques, ces pratiques risquent de brouiller notre comprehension de la capacite cardiorespiratoire des jeunes et de son lien avec leur sante actuelle et future. Nous pensons que ces methodes sont susceptibles d'alterer les pratiques cliniques et les recommandations liees a la promotion de la sante cardiovasculaire des jeunes. Nous examinons les donnees et les interpretations scientifiques pertinentes qui ont emerge de la prediction de la capacite cardiorespiratoire des jeunes a partir des resultats des tests de performance. Nous soutenons que les enfants meritent de beneficier de soins de sante fondes sur des donnees scientifiques, et non sur des mythes et des idees fausses. La rigurosa determinacion del consumo maximo de oxigeno es reconocida internacionalmente como la medida de criterio de la condicion cardiorrespiratoria de los jovenes. La evaluacion e interpretacion del consumo maximo de oxigeno de ninos y adolescentes y la relacion de la medida con otras variables relacionadas con la salud estan bien documentadas. Recientemente ha resurgido el interes por la prediccion del consumo maximo de oxigeno a partir de pruebas de rendimiento en campo en personas jovenes. Sin embargo, junto con los datos de la escala de razon y el incremento de las senales de alerta clinicas, estas practicas corren el riesgo de nublar nuestra comprension de la condicion cardiorrespiratoria en los jovenes y su relacion con la salud actual y futura. Se considera que estos metodos pueden inducir a error a la practica clinica y a las recomendaciones mal orientadas para la promocion de la salud cardiovascular en los jovenes. Se analizan las evidencias cientificas relevantes y las interpretaciones que han surgido de la prediccion de la condicion cardiorrespiratoria en los jovenes a partir de los puntajes de las pruebas de rendimiento. Se argumenta que los ninos merecen que el cuidado de la salud se base en la ciencia basada en la evidencia y no en mitos y conceptos erroneos., Introduction Cardiorespiratory fitness defines the ability of the body to deliver oxygen from the atmosphere to the skeletal muscles and to use it to generate energy to support muscle activity [...]

The authors convey their response to a feedback about their report on evidence-based discussion of the development of youth aerobic fitness. Topics mentioned include the principal reason that ratio scaling is still used to control for body mass in most publications, the credibility and simplicity of allometric scaling of cross-sectional data with multiple covariates based in log-linear regression, and the pitfalls of ratio scaling for a single anthropometric variable in cross-sectional data.

Purpose: To investigate peak oxygen uptake ( V ˙ O 2 ) in relation to sex, age, body mass, fat-free mass (FFM), maturity, and overweight status. Methods: Multiplicative, allometric models of 10- to 18-year-olds were founded on 1057 determinations of peak V ˙ O 2 supported by anthropometry and estimates of maturity status. Results: Baseline models with body mass controlled for showed age to exert a positive effect on peak V ˙ O 2 , with negative estimates for age2, sex, and a sex-by-age interaction. Sex-specific models showed maturity status to have a positive effect on peak V ˙ O 2 in addition to the effects of age and body mass. Introducing skinfold thicknesses to provide, with body mass, a surrogate for FFM explained maturity effects and yielded a significantly (P <.05) better statistical fit in all models compared with those based on FFM estimated from youth-specific skinfold equations. With girls only, the introduction of overweight, defined by body mass index, resulted in a small but significant (P <.05) negative effect, with an age-by-overweight status interaction. Conclusions: FFM has a powerful influence on peak V ˙ O 2 in both sexes. Interpretation of the development of youth aerobic fitness and its application to health should reflect the sex- and maturity-associated variation in FFM. [ABSTRACT FROM AUTHOR]

In this paper, we draw on cross-sectional, treadmill-determined, peak oxygen uptake data, collected in our laboratory over a 20-year period, to examine whether traditional per body mass (ratio) scaling appropriately controls for body size differences in youth. From an examination of the work of pioneering scientists and the earliest studies of peak oxygen uptake, we show how ratio scaling appears to have no sound scientific or statistical rationale. Using simple methods based on correlation and regression, we demonstrate that the statistical relationships, which are assumed in ratio scaling, are not met in groups of similar aged young people. We also demonstrate how sample size and composition can influence relationships between body mass and peak oxygen uptake and show that mass exponents derived from log-linear regression effectively remove the effect of body mass. Indiscriminate use of ratio scaling to interpret young people's fitness, to raise "Clinical Red Flags", and to assess clinical populations concerns us greatly, as recommendations and conclusions based upon this method are likely to be spurious. We urge those involved with investigating youth fitness to reconsider how data are routinely scaled for body size. [ABSTRACT FROM AUTHOR]

The author conveys his thoughts about the use of the 20-metre shuttle run test (20mSRT) as a valid alternative for a direct determination of peak pulmonary oxygen uptake. Topics mentioned include conversion of 20mSRT data from children as young as two years into reference standards for preschool children, criterion validity of the 20mSRT in children according to meta-analysis, and reliability of the 20mSRT based on intraclass correlations and mean differences.

The article discusses a study by F. Zhang and colleagues which reported 20-metre shuttle run test (20mSRT) scores from Chinese school students. Topics include caution against the use of fallacious methods of estimating and interpreting the peak VO2 of children and adolescents, an appreciation for the researchers for raising the profile of pediatric health and well-being in China, and suggestions for researchers in China and elsewhere.

Competing Interests: Competing interests: None declared.