Table 3.
Percentage Differences in DXA‐ and pQCT‐Derived Outcomes by Changes in Leisure‐Time Physical Activity (LTPA) Between Ages 36 and 60 to 64 (Inactive at Both Ages as the Reference Category) a
| Men | Women | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Inactive at 36, active at 60 to 64 | Active at 36, inactive at 60 to 64 | Active at both ages | p value* | Inactive at 36, active at 60 to 64 | Active at 36, inactive at 60 to 64 | Active at both ages | p Value* | p Sex int | |
| % diff (95% CI) | % diff (95% CI) | % diff (95% CI) | % diff (95% CI) | % diff (95% CI) | % diff (95% CI) | ||||
| Trabecular radius vBMD | |||||||||
| N, men = 584; women = 616 | |||||||||
| Model 1 | −0.83 (−9.30 to 7.63) | 3.87 (−0.71 to 8.45) | 8.74 (4.07 to 13.42) | 0.0001 | −3.68 (−11.02 to 3.67) | −2.11 (−7.78 to 3.55) | −3.99 (−9.66 to 1.68) | 0.550 | 0.007 |
| Model 2 b | −0.61 (−9.03 to 7.82) | 3.37 (−1.19 to 7.93) | 8.64 (4.00 to 13.29) | 0.0001 | −1.43 (−8.84 to 5.98) d 0.52 (0.02 to 1.01) e | −0.52 (−6.31 to 5.28) d 0.30 (‐0.06 to 0.66) e | −0.86 (−6.72 to 4.99) d 0.70 (0.29 to 1.11) e | 0.980 0.006** | 0.028*** |
| Model 3 b , c | −1.49 (−10.01 to 7.03) | 3.08 (−1.50 to 7.67) | 8.06 (3.30 to 12.82) | 0.003 | −2.31 (−9.77 to 5.16) d , f | −0.89 (−6.70 to 4.93) d , f | −1.70 (−7.67 to 4.27) d , f | 0.92 | 0.007*** |
| 0.48 (−0.02 to 0.97) e | 0.29 (−0.08 to 0.65) e | 0.72 (0.31 to 1.14) e | 0.005** | ||||||
| Total density vBMD | |||||||||
| N, men = 586; women = 617 | |||||||||
| Model 1 | −5.90 (−12.79 to 0.99) | −1.26 (−4.98 to 2.46) | −1.46 (−5.26 to 2.34) | 0.41 | 1.55 (−4.43 to 7.53) | −2.42 (−7.03 to 2.19) | −2.62 (−7.24 to 1.99) | 0.380 | 0.29 |
| Model 2 | −5.77 (−12.67 to 1.13) | −1.43 (−5.17 to 2.30) | −1.49 (−5.29 to 2.31) | 0.43 | 4.54 (−1.49 to 10.57) | 0.17 (−4.50 to 4.84) | 0.47 (−4.28 to 5.21) | 0.43 | 0.28 |
| Model 3 c | −6.66 (−13.64 to 0.32) | −1.71 (−5.45 to 2.04) | −2.15 (−6.04 to 1.75) | 0.29 | 4.22 (−1.88 to 10.32) | 0.24 (−4.45 to 4.93) | 0.34 (−4.53 to 5.21) | 0.51 | 0.28 |
| Hip aBMD | |||||||||
| N, men = 691; women = 769 | |||||||||
| Model 1 | 0.81 (−4.53 to 6.15) | 4.51 (1.63 to 7.39) | 3.41 (0.48 to 6.35) | 0.016 | −1.18 (−5.01 to 2.64) | 0.27 (−2.57 to 3.11) | −1.08 (−3.93 to 1.77) | 0.710 | 0.13 |
| Model 2 b | −0.49 (−5.22 to 4.25) | 3.20 (0.64 to 5.75) | 2.87 (0.27 to 5.47) | 0.04 | −1.18 (−2.18 to 4.54) d | 1.76 (−0.76 to 4.28) d | 2.79 (0.24 to 5.34) d | 0.19 | 0.008*** |
| 0.21 (−0.02 to 0.43) e | 0.16 (0.003 to 0.32) e | 0.37 (0.20 to 0.55) e | 0.001** | ||||||
| Model 3 b , c | −0.45 (−5.23 to 4.33) | 3.33 (0.77 to 5.90) | 3.04 (0.39 to 5.69) | 0.03 | 0.42 (−2.94 to 3.77) d , f | 1.46 (−1.05 to 3.96) d , f | 2.00 (−0.59 to 4.59) d , f | 0.43 | 0.009*** |
| 0.19 (−0.03 to 0.42) e | 0.14 (−0.02 to 0.29) e | 0.37 (0.19 to 0.54) e | 0.001** | ||||||
| Spine L1 to L4 aBMD | |||||||||
| N, men = 698; women = 774 | |||||||||
| Model 1 | −3.35 (−9.59 to 2.88) | 2.33 (−1.03 to 5.68) | 3.41 (−0.004 to 6.83) | 0.06 | −2.25 (−6.66 to 2.16) | −1.10 (−4.39 to 2.18) | −0.94 (−4.24 to 2.37) | 0.780 | 0.2 |
| Model 2 | −4.48 (−10.42 to 1.46) | 1.37 (−1.83 to 4.57) | 3.00 (−0.25 to 6.25) | 0.04 | −0.54 (−4.78 to 3.69) | 0.07 (−3.11 to 3.25) | 1.57 (−1.65 to 4.79) | 0.64 | 0.46 |
| Model 3 c | −3.96 (−9.97 to 2.05) | 1.67 (−1.55 to 4.89) | 3.33 (0.02 to 6.65) | 0.04 | −1.37 (−5.60 to 2.87) | −0.29 (−3.46 to 2.88) | 1.14 (−2.15 to 4.42) | 0.61 | 0.5 |
vBMD = volumetric bone mineral density; areal bone mineral density = areal bone mineral density.
Model 1: unadjusted; Model 2: current height and weight; Model 3: model 2 + current smoking status, occupational class and long‐term illness.
In women, interaction between change in LTPA x weight p ≤ 0.01.
In women, same adjustments as for men plus type and timing of menopause.
Effect estimate for women of mean weight (72.3 kg).
Change in LTPA x weight interaction term.
Estimates at the 25th (62.8 kg) and 75th (80.2 kg) percentiles are illustrated in Supplemental Fig. 1.
*p value for overall test of association.
**p value for interaction between change in LTPA and weight.
***p value for change in LTPA x weight x sex.