Table 3.
Isotemporal substitution of inactive time (30 min/day) with time in bed and physical activity measured with an accelerometer in body composition changes: longitudinal analyses in completers-only
| Percentage of body fat | VAT (g) | Percentage of muscle mass | Muscle-to-fat mass ratio | |||||
|---|---|---|---|---|---|---|---|---|
| β (95% CI) | p value | β (95% CI) | p value | β (95% CI) | p value | β (95% CI) | p value | |
| Inactive time with time in bed | ||||||||
| Minimally-adjusted | − 0.10 (− 0.20; 0.00) | 0.051 | − 26.9 (− 46.5; − 7.27) | 0.007 | 0.09 (− 0.01; 0.19) | 0.067 | 0.93 (0.03; 1.83) | 0.042 |
| Multivariable-adjusted | − 0.09 (− 0.19; 0.01) | 0.079 | − 23.8 (− 43.3; − 4.27) | 0.017 | 0.08 (− 0.02; 0.18) | 0.097 | 0.89 (− 0.01; 1.79) | 0.052 |
| Inactive time with LPA | ||||||||
| Minimally-adjusted | − 0.13 (− 0.25; − 0.00) | 0.044 | − 11.8 (− 36.1; 12.6) | 0.343 | 0.12 (0.00; 0.24) | 0.046 | 0.87 (− 0.24; 1.97) | 0.124 |
| Multivariable-adjusted | − 0.13 (− 0.25; − 0.00) | 0.042 | − 11.2 (− 35.4; 13.0) | 0.363 | 0.12 (0.00; 0.25) | 0.042 | 0.90 (− 0.20; 2.01) | 0.110 |
| Inactive time with MVPA | ||||||||
| Minimally-adjusted | − 0.53 (− 0.76; − 0.29) | < 0.001 | − 98.7 (− 146; − 52.0) | < 0.001 | 0.50 (0.27; 0.73) | < 0.001 | 3.51 (1.43; 5.60) | 0.001 |
| Multivariable-adjusted | − 0.54 (− 0.78; − 0.31) | < 0.001 | − 92.4 (− 139; − 45.6) | < 0.001 | 0.51 (0.28; 0.74) | < 0.001 | 3.74 (1.64; 5.85) | < 0.001 |
The values show the β coefficients (95% CIs). These represent the change in outcome variables when substituting 30 min/day of inactive time with time in bed and physical activity. Isotemporal mixed-effects linear models with random intercepts at recruiting centre, family and patient level were used. Analyses included only completers. Minimally-adjusted model: age, sex, intervention arm, time and total wear time. The multivariable-adjusted model was further adjusted for baseline variables, such as educational level, smoking, diabetes, height, and repeatedly measured total energy intake. The n of each outcome at baseline was for the percentage of body fat n = 388, for VAT n = 380, for the percentage of muscle mass n = 388 and for muscle-to-fat mass ratio n = 388; at 6 months was for the percentage of body fat n = 262, for VAT n = 255, for the percentage of muscle mass n = 262 and for muscle-to-fat mass ratio n = 262; at 12 months was for the percentage of body fat n = 303, for VAT n = 299, for the percentage of muscle mass n = 303 and for muscle-to-fat mass ratio n = 303
VAT visceral adipose tissue, LPA light physical activity, MVPA moderate-vigorous physical activity