Physical activity volume and intensity for healthy body mass index and cardiorespiratory fitness: Enhancing the translation of children and adolescent’s accelerometer physical activity reference values

Abstract

Introduction: This secondary data analysis aimed to demonstrate the utility of physical activity (PA) wrist accelerometer outcome reference values by identifying the PA volume (average acceleration) and intensity distribution (intensity gradient) centiles and values associated with body mass index (BMI) status (normal weight, overweight, obese) and cardiorespiratory fitness (CRF, multi-stage shuttle runs test) status (low, moderate high) in children and adolescents. Methods: We assessed the dose-response associations between average acceleration and intensity gradient with BMI and CRF outcomes using restricted cubic spline linear mixed models. To aid translation of the findings we calculated the increases in average acceleration needed to shift exemplar participants to ‘healthy’ weight and CRF status. Results: For boys and girls there was a non-linear inverse association between average acceleration and BMI. In both sexes a positive dose-response was observed between average acceleration and intensity gradient with CRF. The values and centiles of average acceleration and intensity gradient that aligned with BMI and CRF statuses were identified. To move from an average acceleration associated with overweight to healthy weight 10-year-old boys and girls would need to increase daily average acceleration by 23 mg (~30 minutes running) and 16 mg (~18 minutes running) respectively. Conclusions: These findings further demonstrate the importance of PA in relation to BMI and CRF and the utility of PA reference values for the translation of accelerometer outcomes into meaningful information. Additional studies demonstrating how PA reference values can be used to track behaviours and provide insights into health associations could inform practice further.