Table 2.
Regression analysis predicting bone mineral content and bone mineral density at the femoral neck and lumbar spine in younger and older females.
| Adolescents (n = 337) |
Young adults (n = 721) |
Middle-aged Adults (n = 847) |
Older adults (n = 327) |
|
|---|---|---|---|---|
| Femoral BMC (g) | ||||
| MVRPAa | ||||
| I-MVRPA | 28.37 (0.77) | 30.43 (0.32) | 28.94 (0.35) | 26.32 (0.39) |
| S-MVRPA | 30.97 (0.78) | 30.66 (0.39) | 29.55 (0.44) | 26.71 (0.66) |
| P | .013 | .612 | .269 | .590 |
| Sedentary minutesb | ||||
| b (SE) | − 0.02 (0.08) | − 0.002 (0.03) | − 0.019 (0.02) | − 0.104 (0.04) |
| P | .777 | .959 | .451 | .021 |
| Femoral BMD (g·cm− 2) | ||||
| MVRPAa | ||||
| I-MVRPA | 0.95 (0.02) | 0.98 (0.01) | 0.91 (0.01) | 0.80 (0.01) |
| S-MVRPA | 1.01 (0.01) | 0.99 (0.01) | 0.92 (0.01) | 0.81 (0.01) |
| P | .010 | .475 | .293 | .592 |
| Sedentary minutesb | ||||
| b (SE) | − 0.0004 (.0002) | − 0.0002 (.0005) | 0.0005 (.0007) | − 0.0028 (0.0001) |
| P | .815 | .761 | .408 | .027 |
| Spinal BMC (g) | ||||
| MVRPAa | ||||
| I-MVRPA | 52.16 (1.23) | 60.45 (0.52) | 56.78 (0.74) | 49.99 (0.80) |
| S-MVRPA | 56.45 (1.30) | 60.63 (0.61) | 56.50 (1.01) | 50.46 (2.37) |
| P | .003 | .781 | .737 | 0.847 |
| Sedentary minutesb | ||||
| b (SE) | 0.19 (0.13) | 0.07 (0.07) | − 0.02 (0.08) | − 0.02 (0.09) |
| P | .166 | .348 | .781 | .816 |
| Spinal BMD (g·cm− 2) | ||||
| MVRPAa | ||||
| I-MVRPA | 0.98 (0.01) | 1.07 (0.01) | 0.99 (0.01) | 0.91 (0.01) |
| S-MVRPA | 1.03 (0.02) | 1.08 (0.01) | 0.99 (0.01) | 0.91 (0.03) |
| P | .012 | .438 | .660 | .851 |
| Sedentary minutesb | ||||
| b (SE) | 0.0013 (0.0017) | 0.0010 (0.0008) | 0.0005 (0.0011) | − 0.0004 (0.0012) |
| P | .465 | .198 | .613 | .720 |
Abbreviations: BMC = bone mineral content; BMD = bone mineral density; MVRPA = self-reported moderate- to vigorous-intensity recreational physical activity (activities of at least 10 min continuously that cause a small to a large increases in breathing or heart rates); I-MVRPA = insufficient MVRPA (0 to < 150 min·week− 1 for adults and < 60 min·day− 1 for adolescents); S-MVRPA = sufficient MVRPA (≥ 150 min·week− 1 for adults and > 60 min·day− 1 for adolescents); SE = standard error.
Unstandardized estimates (b) are adjusted for race/ethnicity, milk consumption/supplement use, and body mass index (BMI) for adolescents; additional covariates including smoking, osteoporosis history, prednisone or cortisone use, and menopausal status were adjusted for other age groups.
Least square adjusted mean values of BMC and BMD.
Unstandardized beta values for sedentary minutes reflect changes in BMC and BMD per 30 min of sedentary time.