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Table 3 Regression coefficients (B) and 95% CI for anthropometric and body composition measures at 18y, adjusted, Bt20+

From: Adolescent physical activity, sedentary behavior and sleep in relation to body composition at age 18 years in urban South Africa, Birth-to-Twenty+ Cohort

  BMI (kg/m2) Waist circumference (cm) Fat mass index a (kg/m2) Lean mass b index c (kg/m2) Body fat (%)
Males
N B (95% CI) P-value B (95% CI) P-value B (95% CI) P-value B (95% CI) P-value B (95% CI) P-value
Informal activity d
 Decreasing over time ref 0.7 ref 0.9 ref 0.5 ref 0.7 ref 0.4
 Increasing over time −0.2(−1.1–0.68)   0.0 (−2.4–2.4)   − 0.2 (− 0.8–0.4)   0.1 (− 0.5–0.7)   −0.9 (− 3.3–1.4)  
Organized Sports Participation d
 Consistently low ref 0.4 ref 0.2 ref 0.5 ref 0.5 ref 0.4
 Decreasing from adequate to low 0.02 (−0.9–0.8)   0.8 (−1.-3.0) 0.5 0.1 (−0.5–0.8)   − 0.2 (− 0.8–0.3)   0.4 (−2.0–2.8)  
 Increasing from low to adequate −0.2 (− 1.1–0.7)   −1.6 (− 3.7–0.4) 0.1 − 0.3 (− 0.9–0.3)   0.1 (− 0.4–0.7)   −1.4 (− 3.6–0.8)  
Walking to and from school d
 Consistently 150 min/week ref 0.7 ref 0.8 ref 0.4 ref 0.8 ref 0.3
 Consistently 300 min/week − 0.1 (−0.7–0.5)   − 0.2 (−1.9–1.5)   − 0.2 (− 0.7–0.3)   0.0 (− 0.4–0.5)   −0.9 (− 2.7–0.9)  
Overall physical activity e
 Model 1 d
  Decreasing activity over time and do not walk to school ref 0.02 ref 0.01 ref 0.01 ref 0.5 ref 0.004
  Decreasing activity over time but consistently walk to school −0.8 (−1.4--0.2)   −2.1 (− 3.7--0.4)   − 0.7 (− 1.1–0.2)   −0.2 (− 0.6–0.2)   −2.2 (− 3.8--0.6)  
  Consistently more active and consistently walk to school − 0.8 (− 1.5--0.2)   − 2.7 (−4.5−− 0.8)   -0.8 (− 1.3--0.3)   0.0 (− 0.5–0.4)   −3.2 (−5.1--1.3)  
 Model 2 f
  Decreasing activity over time and do not walk to school ref 0.1 ref 0.1 ref 0.02 ref 0.6 ref 0.008
  Decreasing activity over time but consistently walk to school −0.6 (−1.2–0.1)   −1.4 (−3.1–0.3)   − 0.56(− 1.0−− 0.1)   -0.1 (− 0.5–0.3)   −1.9 (− 1.7--0.2)  
  Consistently more active and consistently walk to school − 0.6 (− 1.3–0.0)   −2.0 (− 3.9--0.2)   −0.8 (− 1.2--0.1)   0.1 (− 0.4–0.6)   −2.9 (−4.9--0.9)  
Sedentary behavior d
 Consistently low ref 0.1 ref 0.2 ref 0.2 ref 0.4 ref 0.2
 Consistently high 0.6 (−1.3–1.4)   0.1 (−2.1–2.2)   −0.7 (− 1.5–0.2)   −0.2 (− 0.9–0.6)   −2.7 (−5.8–0.5)  
 Increasing from low to high 0.5 (− 0.2–1.2)   1.8 (− 0.1–3.8)   0.3 (− 0.2–0.8)   0.3 (− 0.2–0.8)   0.6 (− 1.3–2.5)  
Schoolnight sleep d
  ≤ 8 h/night ref   ref   ref   ref   ref  
  ≥ 9 h/night −1.0 (− 1.4--0.5) < 0.0001 − 2.3 (− 3.7--1.1) < 0.0001 − 0.4 (− 0.8--0.1) 0.02 0.1 (− 0.2–0.5) 0.5 −1.5 (− 2.8--0.1) 0.04
Females
N B (95% CI) P-value B (95% CI) P-value B (95% CI) P-value B (95% CI) P-value B (95% CI) P-value
Informal activity d
 Decreasing over time ref 0.2 ref 0.02 ref 0.2 ref 0.2 ref 0.2
 Increasing over time 0.9 (−0.4–2.1)   6.0 (0.9–11.1)   0.8 (− 0.5–2.0)   0.4 (− 0.2–1.1)   2.1 (−1.1–5.3)  
Organized sports participation d
  None ref 0.8 ref 0.6 ref 0.9 ref 0.05 ref 0.6
  Consistently some 0.4 (−0.6–1.4)   −1.4 (−5.0–2.7)   0.1 (− 0.9 1.0)   0.5 (0.0–1.0)   − 0.7 (−3.0–1.67  
Walking to and from school d
 Consistently 150 min/week ref 0.3 ref 0.8 ref 0.7 ref 0.02 ref 0.9
 Consistently 300 min/week 0.4 (−0.3–1.1)   0.4 (−3.4–2.6)   0.1 (−0.5–0.8)   0.4 (0.1–0.7)   0.1 (−1.5–1.7)  
Overall physical activity e
 Model 1 d
  Decreasing activity over time and do not walk to school ref 0.2 ref 0.09 ref 0.5 ref 0.2 ref 0.6
  Decreasing activity over time but consistently walk to school 0.5 (−0.3–1.3)   2.6 (−0.6–5.8)   0.5 (−0.3–1.2)   0.3 (− 0.1–0.7)   0.9 (−1.0–2.7)  
  Consistently more active and consistently walk to school 0.9 (−0.1–1.9)   4.6 (0.5–8.6)   0.4 (−0.6–1.3)   0.4 (− 0.1–0.9)   0.1 (−2.3–2.6)  
 Model 2 f
  Decreasing activity over time and do not walk to school ref 0.2 ref 0.07 ref 0.5 ref 0.2 ref 0.6
  Decreasing activity over time but consistently walk to school 0.5 (−0.3–1.4)   2.9 (− 0.4–6.1)   0.4 (− 0.3–1.2)   0.3 (− 0.1–0.7)   0.8 (−1.1–2.7)  
  Consistently more active and consistently walk to school 0.9 (− 0.1–2.0)   4.8 (0.7–9.0)   0.4 (− 0.6–1.3)   0.5 (0.0–0.1)   0.1 (−2.3–2.6)  
Sedentary behavior d
 Initially low but increasing ref 0.08 ref 0.04 ref 0.1 ref 0.7 ref 0.06
 Consistently high −1.1 (−2.4–0.1) 0.08 5.4 (0.2–10.6)   −1.2 (−2.6–0.2)   −0.2 (−0.9–0.6)   −3.5 (−7.0–0.1)  
Schoolnight sleep d
  ≤ 8 h/night ref 0.8 ref 0.6 ref 0.3 ref 0.7 ref 0.7
  ≥ 9 h/night 0.1 (−0.6–0.8)   0.6 (− 2.2–3.3)   0.3 (− 0.3–0.9)   −0.1 (− 0.4–0.2)   0.3 (− 1.2–1.8)  
  1. a Fat mass index, calculated by dividing fat mass (in kg) by height (in meters) squared
  2. b Lean mass does not include bone mineral content
  3. c Lean mass index, calculated by dividing lean mass (in kg) by height (in meters) squared
  4. d Adjusted for childhood BMIZ at age 7/ 8 or 9 years, birth order, maternal schooling, maternal marital status and SES asset quintile at child age 7/8 years
  5. e Multi-trajectory groups made up of informal activity, organized sports and walking to and from school trajectories representing overall physical activity pattern
  6. f Adjusted for childhood BMIZ at age 7/ 8 or 9 years, birth order, maternal schooling, maternal marital status and SES asset quintile at child age 7/8 years, and sedentary behavior and sleep trajectories