Correlation between physical activity, aerobic fitness and body fat against autonomic function profile in children

Aim To evaluate correlations between physical activity, VO2PEAK and body fat versus autonomic function in children. Methods Children (n = 98) between 10 and 12 years underwent a maximal exercise test (VO2PEAK) and dual-energy X-ray absorptiometry measured body fat. General physical activity, moderate to vigorous physical activity and vigorous physical activity were assessed by accelerometers. Deep breath test with E/I-ratio calculation and a head-up tilt test were performed. The sum of z-scores represented an index score for autonomic function profile and included E/I-ratio plus difference in blood pressure and heart rate between supine and tilted position. Correlation analyses were performed between physical activity parameters, body fat and VO2PEAK versus autonomic function profile. Results No significant correlations were found between autonomic function profile and physical activity or body fat (p > 0.05). VO2PEAK was correlated with autonomic function profile in boys (r = 0.30, p < 0.05), but not in girls (r = 0.04, NS). One girl and eight boys terminated head-up tilt test prematurely due to intolerance. Minutes of vigorous physical activity per day was lower in these boys compared with those (n = 48) who completed the head-up tilt test (5.1 +/- 3.3 vs. 10.4 +/- 6.6, p < 0.05). Conclusion Physical activity or body fat was not associated with autonomic function profile. VO2PEAK correlated to autonomic function profile in boys.