Table 2 Longitudinal associations of cumulative sedentary time and physical activity with body composition from ages 11 through 24 years (n = 6059)

From: Effects of accelerometer-based sedentary time and physical activity on DEXA-measured fat mass in 6059 children

N = 6059

Body mass index (z-score)

Waist circumference (z-score)

Trunk fat mass (z-score)

β (95% CI)

p-value

β (95% CI)

p-value

β (95% CI)

p-value

Continuous cumulative predictor variables from ages 11–24 years

Sedentary Time (min/day)

 Model 1

0.142 (0.135–0.150)

<0.0001

0.144 (0.134–0.153)

<0.0001

0.131 (0.123–0.138)

<0.0001

 Model 2

0.027 (0.021–0.032)

<0.0001

−0.011 (−0.017–−0.006)

<0.001

0.026 (0.020–0.032)

<0.0001

 Model 3

0.020 (0.015–0.025)

<0.001

−0.019 (−0.024–−0.014)

<0.001

0.020 (0.014–0.025)

<0.001

 Model 4

0.019 (0.014–0.024)

<0.001

−0.017 (−0.022–−0.012)

<0.001

0.017 (0.012–0.023)

<0.001

Light Physical Activity (min/day)

 Model 1

−0.162 (−0.170–−0.155)

<0.0001

−0.215 (−0.225–−0.204)

<0.0001

−0.149 (−0.156–−0.141)

<0.0001

 Model 2

−0.035 (−0.040–−0.030)

<0.0001

−0.031 (−0.037–−0.026)

<0.0001

−0.033 (−0.039–−0.028)

<0.0001

 Model 3

−0.031 (−0.036–−0.025)

<0.0001

−0.035 (−0.041–−0.030)

<0.0001

−0.029 (−0.035–−0.024)

<0.0001

 Model 4

−0.030 (−0.035–−0.025)

<0.0001

−0.036 (−0.042–−0.031)

<0.0001

−0.028 (−0.034–−0.023)

<0.0001

Moderate-to-Vigorous Physical Activity (min/day)

 Model 1

−0.048 (−0.057–−0.039)

<0.0001

−0.009 (−0.019–0.001)

0.076

−0.061 (−0.070–−0.051)

<0.0001

 Model 2

−0.014 (−0.020–−0.008)

<0.001

0.019 (0.014–0.024)

<0.001

−0.027 (−0.034–−0.020)

<0.001

 Model 3

−0.011 (−0.017–−0.005)

<0.001

0.018 (0.013–0.023)

<0.001

−0.025 (−0.031–−0.018)

<0.001

 Model 4

−0.010 (−0.015–−0.004)

<0.001

0.019 (0.014–0.024)

<0.001

−0.024 (−0.030–−0.017)

<0.001

Categorical cumulative predictor variable from ages 11–24 years

Moderate-to-Vigorous Physical Activity ( < 40 min/day as reference)

 40 – < 60 min/day

−0.011 (−0.026–0.003)

0.117

−0.007 (−0.019–0.006)

0.288

−0.053 (−0.068–−0.038)

<0.001

 ≥60 min/day

−0.020 (−0.036–−0.005)

0.011

0.012 (−0.002–0.026)

0.081

−0.097 (−0.114–−0.080)

<0.0001

N = 6059

Total fat mass (z-score)

Lean mass (z-score)

Lean mass/fat mass ratio (z-score)

β (95% CI)

p-value

β (95% CI)

p-value

β (95% CI)

p-value

Continuous cumulative predictor variables from ages 11–24 years

Sedentary Time (min/day)

 Model 1

0.120 (0.113–0.128)

<0.0001

0.225 (0.217–0.233)

<0.0001

−0.064 (−0.593–0.465)

0.813

 Model 2

0.029 (0.023–0.035)

<0.0001

0.040 (0.035–0.045)

<0.0001

−0.071 (−0.735–0.593)

0.833

 Model 3

0.022 (0.016–0.027)

<0.001

0.032 (0.027–0.037)

<0.0001

−0.189 (−0.814–0.437)

0.554

 Model 4

0.019 (0.013–0.024)

<0.001

0.033 (0.028–0.038)

<0.0001

−0.174 (−0.776–0.429)

0.572

Light Physical Activity (min/day)

 Model 1

−0.140 (−0.148–−0.133)

<0.0001

−0.237 (−0.245–−0.229)

<0.0001

−0.330 (−0.933–0.273)

0.283

 Model 2

−0.038 (−0.044–−0.032)

<0.0001

−0.042 (−0.048–−0.037)

<0.0001

−0.490 (−1.083–0.103)

0.105

 Model 3

−0.033 (−0.039–−0.028)

<0.0001

−0.035 (−0.040–−0.031)

<0.0001

−0.531 (−1.078–0.015)

0.057

 Model 4

−0.032 (−0.038–−0.027)

<0.0001

−0.036 (−0.041–−0.031)

<0.0001

−0.537 (−1.072–−0.001)

0.050

Moderate-to-Vigorous Physical Activity (min/day)

 Model 1

−0.056 (−0.065–−0.046)

<0.0001

−0.055 (−0.067–−0.044)

<0.0001

0.081 (−0.439–0.602)

0.760

 Model 2

−0.031 (−0.038–−0.024)

<0.001

0.000 (−0.006–0.005)

0.902

0.125 (−0.428–0.677)

0.659

 Model 3

−0.028 (−0.035–−0.021)

<0.001

0.004 (−0.001–0.010)

0.110

0.118 (−0.396–0.623)

0.653

 Model 4

−0.027 (−0.034–−0.020)

<0.001

0.006 (0.000–0.011)

0.038

0.138 (−0.365–0.641)

0.591

Categorical cumulative predictor variable from ages 11–24 years

Moderate-to-Vigorous Physical Activity (<40 min/day as reference)

 40 – < 60 min/day

−0.048 (−0.063–−0.033)

<0.001

0.012 (−0.001–0.025)

0.061

0.809 (−1.009–2.627)

0.383

 ≥60 min/day

−0.090 (−0.107–−0.073)

<0.0001

0.017 (0.002–0.032)

0.025

1.366 (−0.218–2.951)

0.091

  1. For continuous variable analyses, model 1 was unadjusted. Model 2 was adjusted for sex, family history of hypertension/diabetes/high cholesterol/vascular disease, socioeconomic status, and other time-varying covariates measured at both baseline and follow-up such as age, low-density lipoprotein cholesterol, triglyceride, high sensitivity C-reactive protein, high-density lipoprotein cholesterol, heart rate, systolic blood pressure, glucose, insulin, smoking status, and fat mass or lean mass, depending on the outcome. Model 3 was an additional adjustment for sedentary time (LPA and MVPA model) or light physical activity (Sedentary time model). Model 4 was an additional adjustment for light physical activity (MVPA model) or moderate-to-vigorous physical activity (Sedentary time and LPA model). For categorical predictor variable analyses, all the above-listed covariates were adjusted for in one model. Skewed covariates were logarithmically transformed. Standardized regression coefficients (β) were computed from the generalized linear mixed-effect model for repeated measures, direct effect estimates are presented; CI, confidence interval. A 2-sided P-value < 0.05 is considered statistically significant. Multiple testing was corrected with Sidak correction. Multiple imputations were used to account for missing variables. For continuous variable predictors (ST, LPA and MVPA), a 1-standard deviation change is associated with a 1-standard deviation change in the outcome. For categorical variable predictor (MVPA), time spent in a category in relation to the reference is associated with 1-standard deviation change in the outcome.
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