Table 1.
Adjusted means (95% CI) for continuous cardio-metabolic biomarkers across quartiles of total sedentary time and breaks in sedentary time in US adults ≥20 years (NHANES 2003–06)
| Cardio-metabolic biomarker | Mean (SD) or Median (IQR) | Sedentary variable | Quartile 1 | Quartile 2 | Quartile 3 | Quartile 4 | P for trend |
|---|---|---|---|---|---|---|---|
| Full sample (n= 4757) | |||||||
| Waist circumference, cm | 96.8 (12.7) | Total | 96.3 (95.3, 97.4) | 96.6 (95.4, 97.8) | 96.5 (95.4, 97.6) | 97.9 (97.0, 98.8)* | 0.0495 |
| Breaks | 99.2 (97.9, 100.6) | 96.8 (95.5, 98.1)* | 96.3 (95.4, 97.2)*** | 95.1 (94.0, 96.1)*** | <0.001 | ||
| Systolic blood pressure, mmHGa | 119 (110, 132) | Total | 121 (121, 122) | 121 (120, 123) | 121 (119, 122) | 120 (119, 122) | 0.056 |
| Breaks | 121 (119, 122) | 121 (120, 122) | 121 (120, 122) | 121 (120, 123) | 0.664 | ||
| Diastolic blood pressure, mmHG | 91.2 (15.4) | Total | 91.4 (89.6, 93.2) | 91.5 (89.5, 93.5) | 91.4 (89.9, 92.8) | 90.7 (89.1, 92.4) | 0.503 |
| Breaks | 91.8 (90.5, 93.2) | 91.5 (89.6, 93.5) | 91.3 (90.1, 92.4) | 90.3 (88.7, 92.0) | 0.095 | ||
| HDL-cholesterol, mmol/La | 1.34 (1.09, 1.63) | Total | 1.38 (1.34, 1.41) | 1.36 (1.34, 1.38) | 1.35 (1.32, 1.37) | 1.32 (1.30, 1.35)* | 0.014 |
| Breaks | 1.34 (1.32, 1.37) | 1.35 (1.32, 1.38) | 1.34 (1.32, 1.36) | 1.37 (1.35, 1.40) | 0.150 | ||
| C-reactive protein, mg/dLa | 0.18 (0.07, 0.42) | Total | 0.17 (0.15, 0.19) | 0.17 (0.16, 0.19) | 0.18 (0.17, 0.20) | 0.19 (0.17, 0.21) | 0.032 |
| Breaks | 0.20 (0.18, 0.21) | 0.17 (0.16, 0.19)* | 0.18 (0.16, 0.19)* | 0.16 (0.15, 0.18)*** | 0.001 | ||
| Fasting sub-sample (n = 2118) | |||||||
| Fasting triglycerides, mmol/La | 1.30 (0.90, 1.96) | Total | 1.22 (1.16, 1.28) | 1.34 (1.27, 1.42)* | 1.41 (1.35, 1.48)*** | 1.48 (1.38, 1.58)*** | <0.001 |
| Breaks | 1.35 (1.28, 1.43) | 1.41 (1.35, 1.48) | 1.33 (1.25, 1.42) | 1.35 (1.28, 1.43) | 0.700 | ||
| Fasting plasma glucose, mmol/La | 5.35 (5.01, 5.79) | Total | 5.49 (5.39, 5.60) | 5.51 (5.43, 5.59) | 5.47 (5.40, 5.54) | 5.52 (5.41, 5.63) | 0.872 |
| Breaks | 5.55 (5.46, 5.64) | 5.51 (5.43, 5.60) | 5.41 (5.33, 5.49)* | 5.51 (5.40, 5.62) | 0.267 | ||
| Insulin, pmol/La | 42.1 (24.6, 73.3) | Total | 36.2 (33.6, 39.1) | 40.1 (36.7, 43.8)* | 42.3 (39.5, 45.3)** | 47.8 (44.5, 51.4)*** | <0.001 |
| Breaks | 43.6 (40.7, 46.6) | 42.2 (38.7, 46.0) | 39.8 (37.2, 42.7) | 41.0 (37.0, 45.4) | 0.233 | ||
| HOMA-%Ba | 67.9 (96.1, 49.4) | Total | 61.2 (58.2, 64.4) | 65.1 (61.9, 68.5) | 68.7 (65.7, 71.8)** | 72.8 (68.2, 77.7)*** | <0.001 |
| Breaks | 67.5 (63.9, 71.3) | 67.3 (63.6, 71.1) | 67.4 (63.9, 71.0) | 66.1 (61.3, 71.3) | 0.707 | ||
| HOMA-%Sa | 124 (70.1, 211) | Total | 145 (134, 158) | 130 (120, 142)* | 123 (115, 132)** | 109 (101, 118)*** | <0.001 |
| Breaks | 120 (113, 129) | 124 (113, 135) | 131 (122, 140) | 127 (115, 141) | 0.259 | ||
| OGTT sub-sample (n = 910) | |||||||
| 2 h plasma glucose, mmol/La | 5.94 (4.83, 7.55) | Total | 5.89 (5.55, 6.24) | 6.09 (5.76, 6.44) | 6.28 (6.02, 6.55) | 6.32 (5.92, 6.75) | 0.119 |
| Breaks | 6.29 (6.03, 6.57) | 6.19 (5.83, 6.56) | 6.35 (5.95, 6.79) | 6.32 (5.78, 6.91) | 0.831 | ||
Data are adjusted means (95% CI), weighted to the USA population. Adjusted for age, sex, race/ethnicity, and quartiles of exercise (≥1952 cpm) h/day, sedentary time (breaks only) plus significant socio-demographic, behavioural, and medical history covariates identified through outcome-specific backward elimination (retained at P < 0.2: see Supplementary material online, Table S2). Quartile cutpoints, corrected for wear time, are 7.24, 8.51, 9.57 h/day for total sedentary time; 470, 559, 645 for breaks in sedentary time. *P < 0.05; **P < 0.01; ***P < 0.001 from Quartile 1 (reference).
aBack-transformed from the log scale.
Bold indicates P < 0.05.