The oxygen uptake efficiency slope does not accurately predict O of children - the Arkansas Active Kids study.

BACKGROUND

Cardiorespiratory fitness (CRF) is a vital indicator of health. However, accurately measuring peak oxygen consumption ( O) to determine CRF in children can be challenging. The oxygen uptake efficiency slope (OUES) has been proposed as an alternative metric for predicting O in children, but its accuracy and agreement with measured O remain unclear.

METHODS

A post hoc analysis was conducted in 94 children (ages 7-10 years) who completed an incremental cycle ergometer test to measure O. Body composition (Dual-energy X-ray absorptiometry) was measured, and fat mass index (FMI, kg/m) and fat-free mass index (FFMI, kg/m) were calculated. OUES was determined using all respiratory data (OUES) collected during the cycle ergometer test and using data only up to 60% of heart rate reserve (OUES). Regression equations to predict O (Pred- O) were derived from simple and multiple linear regression analysis. Bland-Altman analysis assessed the level of agreement between Pred- O and measured O.

RESULTS

OUES (β = 0.46, < 0.0001), age (β = 56.0, = 0.0004), White race (β = 173.3, < 0.0003), FFMI (β = 0.98.6, < 0.000), and FMI (β = -0.40.8, < 0.000) were retained in the final model. The difference between measured O and Pred- O was not different from zero ( = 0.999). There was a positive association between the difference of measured O and Pred- O and the average of the two methods (β = 0.79, = 0.0028).

CONCLUSION

There was no mean bias between measured O and Pred- O. However, magnitude bias was present even after considering other significant predictors of O (FMI, FFMI, race, and age) in the regression equation. Caution is advised when using OUES to predict O in children.