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Table 4 Associations between independent variables (TV, computer/game time, age, sex, physical activity, and BMI) and strength measures

From: Screen-based sedentary behavior and associations with functional strength in 6–15 year-old children in the United States

  TV change in strength per 1 hr increase Computer change in strength per 1 hr increase Age change in strength per 1 year increase Sex Males - Females Physical Activity change in strength per 1 day increase BMI-Z-Score change in strength per 1 z-score increase
  Beta (95 % CI) Beta (95 % CI) Beta (95 % CI) Beta (95 % CI) Beta (95 % CI) Beta (95 % CI)
    Absolute strength
Gripa (kg) −0.31* (−0.56, −0.06) 0.05 (−0.12, 0.22) 2.79*** (2.69, 2.89) 3.16*** (2.53, 3.79) 0.02 (−0.11, 0.15) 1.58*** (1.30, 1.86)
Leg Extensionsa (kg) −0.99** (−1.70, −0.28) 0.35 (−0.42, 1.13) 3.31*** (2.75, 3.86) 1.35* (0.091, 2.62) −0.14 (−0.57, 0.29) 3.22*** (2.46, 3.98)
    Relative strength
Gripa (kg per kg of body weight) −0.006* (−0.011, −0.001) −0.002 (−0.006, 0.002) 0.009*** (0.007, 0.011) 0.049*** (0.039, 0.060) 0.003** (0.001, 0.005) −0.058*** (−0.064, −0.053)
Leg Extensionsa (kg per kg of body weight) −0.018* (−0.033, −0.004) 0.001 (−0.013, 0.015) 0.009** (0.004, 0.014) 0.001 (−0.021, 0.024) 0.001 (−0.007, 0.010) −0.048*** (−0.064, −0.033)
Planka (seconds) −3.49*** (−5.18, −1.18) −2.04 (−4.22, 0.13) 6.19*** (5.00, 7.39) 7.45 (−0.10, 15.01) 1.76** (0.67, 2.86) −12.39*** (−14.53, −10.26)
Pull-upsbc (odds ratio for completing ≥1 pull-ups) 0.83*** (0.76, 0.92) 0.86** (0.78, 0.94) 0.99 (0.94, 1.05) 3.41*** (2.36, 4.93) 1.05 (0.99, 1.12) 0.40*** (0.31, 0.51)
Pull-upsb (# of pull-ups for children with ≥1 pull-ups) −0.34 (−0.84, 0.15) −0.23 (−0.61, 0.14) 0.72*** (0.53, 0.90) 2.63*** (1.77, 3.49) 0.31** (0.12, 0.49) −1.18*** (−1.48, −0.88)
  1. a Coefficients were estimated from linear regression models including all covariates in the table
  2. b Due to the large number of children unable to complete one modified pull-up, two types of models were used to analyze the data. The first model estimated the association of the covariates with the ability of a child to complete at least one modified pull-up using a logistic regression model. The second model estimated the association of the covariates with the number of modified pull-ups completed only among children that completed at least one modified pull-up using a linear regression model. Both types of models included all covariates listed
  3. c Females were coded as the reference group (denominator) for the logistic regression model
  4. *p < 0.05, **p < 0.01, ***p < 0.001