Daily physical activity, cardiorespiratory fitness, nutritional status, endothelial function, and autonomic modulation in school-age adolescents: A principal component analysis.

Purpose: This study evaluated the association between cardiorespiratory fitness, abdominal obesity, blood pressure, endothelial function, and autonomic modulation in school-age adolescents exhibiting different levels of habitual physical activity and nutritional status, through a multivariate statistical approach.

Methods: 101 adolescents aged 15-18 years (54 females) underwent assessments of daily physical activity, body mass index, cardiorespiratory fitness, reactive hyperemia, and heart rate variability. Based on BMI adjusted for age and sex (z-BMI), 21 adolescents were classified as 'overweight' (9 girls), and 9 as 'obese' (4 girls). The common variation between those variables was assessed through Principal Component Analysis (PCA).

Results: Main axis of common variation of outcomes analyzed defined four principal components (PCs) accounting for 69.7% of overall variance, related to 'abdominal obesity and blood pressure' (PC1; eigenvalue=2.76), 'cardiorespiratory fitness, endothelial function, and autonomic modulation' (PC2, eigenvalue=1.98), 'cardiorespiratory fitness' (PC3, eigenvalue=1.21), and 'sedentary behavior' (PC4, eigenvalue=1.02). Girls reported longer screen time and sedentary behavior than boys. Notwithstanding, in both sexes poorer cardiorespiratory fitness corresponded to lower reactive hyperemia and vagal modulation, irrespective of the nutritional status. Overall, adolescents classified as 'obese' and 'sedentary' exhibited poorer CRF concomitantly to autonomic and endothelial dysfunctions.

Conclusion: In school-age adolescents, endothelial and autonomic dysfunctions related to poor cardiorespiratory fitness, irrespective of the nutritional status and physical activity level. However, endothelial and autonomic dysfunctions were more prevalent among adolescents combining poor cardiorespiratory fitness, reduced levels of daily physical activity, and overweight/obesity.