Table 1 Descriptive characteristics for the study sample

From: Independent and combined influence of healthy lifestyle factors on academic performance in adolescents: DADOS Study

  All Boys Girls p
n (%) 262 (100) 137 (52.3) 125 (47.7)  
Demographics
  Age (y) 13.9 ± 0.3 13.9 ± 0.3 13.9 ± 0.3 0.956
  Tanner stage (I–V) (%) 0/8/34/49/9 0/10/32/44/14 0/6/35/54/5
  SES score (0–8) 4.2 ± 1.4 4.0 ± 1.3 4.4 ± 1.4 0.031
Weight status
  Height (cm) 163.1 ± 7.9 164.7 ± 8.6 161.4 ± 6.7 < 0.001
  Weight (kg) 54.2 ± 9.3 54.5 ± 9.7 53.9 ± 8.8 0.574
  Body mass index (kg/m2) 20.3 ± 2.7 20.0 ± 2.6 20.6 ± 2.9 0.053
  Overweight (%)a 13.0 11.7 14.4 0.513
 Screen time (h/day) 4.8 ± 2.5 4.7 ± 2.5 5.0 ± 2.6 0.299
 Sleep quality score (0–21) 4.8 ± 2.8 4.2 ± 2.7 5.5 ± 2.7 < 0.001
 Good sleep quality (%) 64.1 73.7 53.6 < 0.001
 Daily meal frequency (meals/day) 4.5 ± 0.8 4.6 ± 0.8 4.4 ± 0.9 0.014
 Optimal daily meal frequency (%) 58.0 67.2 47.9 0.002
 CRF (stages) 7.7 ± 2.5 9.0 ± 2.0 6.2 ± 2.2 < 0.001
Physical activity (min/day)
  Light 174.6 ± 56.4 173.7 ± 59.1 175.6 ± 53.4 0.781
  Moderate 76.7 ± 25.6 81.6 ± 24.8 71.2 ± 25.4 < 0.001
  Vigorous 12.4 ± 8.3 15.6 ± 7.8 8.9 ± 7.6 < 0.001
Academic grades (1–10)
  Math 6.9 ± 1.6 7.0 ± 1.6 6.8 ± 1.6 0.316
  Language 6.8 ± 1.5 6.6 ± 1.5 6.9 ± 1.5 0.123
  GPA 7.1 ± 1.3 7.0 ± 1.3 7.2 ± 1.3 0.306
Academic abilities
  Verbal (0–50) 18.7 ± 5.3 19.1 ± 5.8 18.2 ± 4.6 0.154
  Numeric (0–30) 13.4 ± 4.7 14.8 ± 4.5 12.0 ± 4.5 < 0.001
  Reasoning (0–30) 16.5 ± 5.9 16.1 ± 5.7 17.0 ± 6.1 0.220
  1. Data are presented as mean ± SD or percentages. Differences between sexes were examined by t test or chi-square test. Statistically significant values are in bold
  2. SES socioeconomic status, CRF cardiorespiratory fitness, GPA grade point average
  3. aIncludes obese adolescents. Good sleep quality was defined as PSQI scores ≤ 5. Optimal daily meal frequency was defined as five-meal-a-day