High-intensity activity is more strongly associated with metabolic health in children compared to sedentary time: a cross-sectional study of the I.Family cohort

Abstract

Background: Physical activity (PA) during childhood is important for preventing future metabolic syndrome (MetS). To examine the relationship between PA and MetS in more detail, accurate measures of PA are needed. Previous studies have only utilized a small part of the information available from accelerometer measured PA. This study investigated the association between measured PA and MetS in children with a new method for data processing and analyses that enable more detailed interpretation of PA intensity level.

Methods: The association between PA pattern and risk factors related to MetS was investigated in a cross- sectional sample of children (n = 2592, mean age 10.9 years, 49.4% male) participating in the European multicenter I. Family study. The risk factors examined include body mass index, blood pressure, high-density lipoprotein cholesterol, insulin resistance and a combined risk factor score (MetS score). PA was measured by triaxial accelerometers and raw data was processed using the 10 Hz frequency extended method (FEM). The PA output was divided into an intensity spectrum and the association with MetS risk factors was analyzed by partial least squares regression.

Results: PA patterns differed between the European countries investigated, with Swedish children being most active and Italian children least active. Moderate intensity physical activity was associated with lower insulin resistance (R² = 2.8%), while vigorous intensity physical activity was associated with lower body mass index (R² = 3.6%), MetS score (R² = 3.1%) and higher high-density lipoprotein cholesterol (R² = 2.3%). PA of all intensities was associated with lower systolic- and diastolic blood pressure, although the associations were weaker than for the other risk factors (R² = 1.5% and R² = 1.4%). However, the multivariate analysis implies that the entire PA pattern must be considered. The main difference in PA was observed between normal weight and overweight children.

Conclusions: The present study suggests a greater importance of more PA corresponding to an intensity of at least brisk walking with inclusion of high-intense exercise, rather than a limited time spent sedentary, in the association to metabolic health in children. The methods of data processing and statistical analysis enabled accurate analysis and interpretation of the health benefits of high intensity PA that have not been shown previously.

Keywords: Cardiovascular disease; Frequency filtering; Metabolic syndrome; Multicollinearity; Multivariate pattern analysis; Obesity.

Fig. 1

Standardized means (95% CI) of physical activity (PA) across the spectrum of PA intensity for different A countries and B BMI categories. Different scales for PA intensity are included as well as the cut-points for traditional PA intensity categories (dotted vertical lines) in order to facilitate understanding. SED sedentary time, LPA light PA, MPA moderate PA, VPA vigorous PA, VVPA very vigorous PA

Fig. 2

Selectivity ratio plots showing the explained variance (95% CI) and direction (positive values mean positive associations) of the predictor variables in the PLS models with A) BMI and B) MetS as response variables. The left panel displays the explained variances of the physical activity intensity spectrum (main predictor). The right panel shows the explained variances by age, country, income and education (confounders). Different scales for PA intensity (x-axes) are included as well as the cut-points for traditional PA intensity categories (dotted vertical lines) in order to facilitate understanding. SED sedentary time, LPA light PA, MPA moderate PA, VPA vigorous PA, VVPA very vigorous PA

Fig. 3

Selectivity ratio plots showing the explained variance (95% CI) and direction (positive values mean positive associations) of the predictor variables in the PLS models with A) SBP, B) DBP, C) HDL and D) IR as response variables. The left panel displays the explained variances of the physical activity intensity spectrum (main predictor). The right panel shows the explained variances by age, country, income and education (confounders). Different scales for PA intensity (x-axes) are included as well as the cut-points for traditional PA intensity categories (dotted vertical lines) in order to facilitate understanding. SED sedentary time, LPA light PA, MPA moderate PA, VPA vigorous PA, VVPA very vigorous PA