Table 1.
Characteristics of children
| Boys (n = 185) | Girls (n = 192) | P value for sex differencec | |||
|---|---|---|---|---|---|
| Mean | SD | Mean | SD | ||
| Age (years) | 7.7 | 0.4 | 7.6 | 0.4 | 0.149 |
| Peak height velocity (years) | − 4.4 | 0.3 | − 3.6 | 0.3 | < 0.001 |
| Body height (cm) | 130 | 5.3 | 128 | 5.6 | < 0.001 |
| Body weight (kg) | 27.5 | 5.0 | 26.2 | 4.8 | 0.003 |
| Body mass index standard deviation scorea (kg/m2) | − 0.2 | 1.1 | − 0.2 | 1.1 | 0.61 |
| Body fat content (%) | 17.4 | 8.0 | 21.9 | 7.5 | < 0.001 |
| Overweight or obeseb (N, %) | 22 (11.9) | 24 (12.5) | 0.857 | ||
| Waist circumference (cm) | 57.5 | 5.9 | 55.6 | 5.7 | < 0.001 |
| Insulin (mU/L) | 4.2 | 2.6 | 4.7 | 2.4 | 0.008 |
| Glucose (mmol/L) | 4.9 | 0.3 | 4.7 | 0.4 | < 0.001 |
| Triglycerides (mmol/L) | 0.58 | 0.25 | 0.62 | 0.25 | 0.034 |
| High-density lipoprotein cholesterol (mmol/L) | 1.63 | 0.31 | 1.58 | 0.29 | 0.084 |
| Systolic blood pressure (mm Hg) | 100.3 | 7.1 | 99.6 | 7.2 | 0.358 |
| Diastolic blood pressure (mm Hg) | 62.1 | 6.8 | 61.1 | 7.5 | 0.233 |
| Cardiometabolic risk score | 0.0 | 3.7 | − 0.3 | 3.3 | 0.475 |
| Heart rate variability variables | |||||
| Mean heart rate (beats/min) | 83 | 10.0 | 85 | 9.7 | 0.043 |
| Mean of RR intervals (ms) | 739 | 89 | 720 | 85 | 0.034 |
| Standard deviation of all RR intervals (ms) | 62.0 | 28.8 | 58.5 | 27.9 | 0.291 |
| Root mean square of successive RR interval differences (ms) | 70.2 | 43.2 | 65.5 | 39.3 | 0.537 |
| Low-frequency power (ms2) | 1309 | 985 | 1134 | 961 | 0.050 |
| High-frequency power (ms2) | 53.1 | 16.9 | 55.3 | 15.7 | 0.313 |
| Ratio of low- and high-frequency power | 1.0 | 1.0 | 0.8 | 0.6 | 0.148 |
| Sedentary time, physical activity, and cardiorespiratory fitness | |||||
| Sleep time (hours/night) | 9.6 | 0.5 | 9.7 | 0.5 | 0.444 |
| Sedentary time (min/day) | 231 | 131 | 242 | 130 | 0.390 |
| Light physical activity (min/day) | 496 | 102 | 520 | 109 | 0.011 |
| Moderate physical activity (min/day) | 103 | 56 | 82 | 47 | < 0.001 |
| Vigorous physical activity (min/day) | 30 | 26 | 16 | 16 | < 0.001 |
| Moderate-to-vigorous physical activity (min/day) | 133 | 67 | 97 | 55 | < 0.001 |
| Physical activity energy expenditure (kJ/kg/day) | 104 | 34 | 90 | 28 | < 0.001 |
| Cardiorespiratory fitness (Watt/kg) | 3.8 | 0.5 | 3.6 | 0.5 | < 0.001 |