Supplementary Content 1. Associations of physical activity volume (average-acceleration) and intensity distribution (intensity-gradient) with bone outcomes in females (n = 121).
1-s epoch 5-s epoch 15-s epoch 30-s epoch 60-s epoch
Model 1 Model 2 Model 1 Model 2 Model 1 Model 2 Model 1 Model 2 Model 1 Model 2
β(95% CI) p β(95% CI) p β(95% CI) p β(95% CI) p β(95% CI) p β(95% CI) p β(95% CI) p β(95% CI) p β(95% CI) p β(95% CI) p
TBLH BMC (g)
Average-acceleration 25.61 (-10.02 to 61.25) 0.16 2.54 (-36.46 to 41.53) 0.90 25.61 (-10.02 to 61.25) 0.16 8.39 (-29.33 to 46.11) 0.66 25.61 (-10.02 to 61.25) 0.16 5.71 (-35.88 to 47.29) 0.79 25.61 (-10.02 to 61.25) 0.16 4.44 (-41.06 to 49.95) 0.85 25.61 (-10.02 to 61.25) 0.16 3.54 (-48.14 to 55.23) 0.89
Intensity-gradient 47.64 (24.11 to 71.17) < 0.001 46.47 (18.40 to 74.55) 0.001 36.32 (6.67 to 65.96) 0.02 32.43 (0.20 to 64.66) 0.05 36.47 (7.14 to 65.81) 0.02 33.60 (-2.33 to 69.53) 0.07 34.14 (3.95 to 64.32) 0.03 31.50 (-8.54 to 71.54) 0.12 30.77 (1.27 to 60.27) 0.04 28.45 (-16.01 to 72.91) 0.21
Spine aBMD (g/cm2)
Average-acceleration 0.01 (-0.01 to 0.03) 0.40 0.00 (-0.02 to 0.03) 0.74 0.01 (-0.01 to 0.03) 0.40 0.00 (-0.02 to 0.03) 0.78 0.01 (-0.01 to 0.03) 0.40 0.00 (-0.02 to 0.03) 0.77 0.01 (-0.01 to 0.03) 0.40 0.00 (-0.02 to 0.03) 0.75 0.01 (-0.01 to 0.03) 0.40 0.01 (-0.03 to 0.04) 0.75
Intensity-gradient 0.01 (-0.01 to 0.03) 0.17 0.01 (-0.01 to 0.03) 0.24 0.01 (-0.01 to 0.04) 0.19 0.01 (-0.01 to 0.03) 0.24 0.01 (-0.01 to 0.03) 0.27 0.01 (-0.01 to 0.04) 0.39 0.01 (-0.01 to 0.03) 0.36 0.01 (-0.02 to 0.04) 0.58 0.01 (-0.01 to 0.03) 0.40 0.01 (-0.03 to 0.04) 0.70
Spine BMC (g)
Average-acceleration 1.09 (-0.58 to 2.75) 0.20 0.57 (-1.22 to 2.35) 0.53 1.09 (-0.58 to 2.75) 0.20 0.30 (-1.39 to 1.99) 0.72 1.09 (-0.58 to 2.75) 0.20 0.21 (-1.62 to 2.03) 0.82 1.09 (-0.58 to 2.75) 0.20 0.20 (-1.88 to 2.28) 0.85 1.09 (-0.58 to 2.75) 0.20 0.43 (-1.93 to 2.8) 0.72
Intensity-gradient 1.31 (-0.12 to 2.73) 0.07 1.05 (-0.05 to 2.59) 0.18 1.62 (0.09 to 3.14) 0.04 1.48 (-0.14 to 3.09) 0.07 1.59 (-0.02 to 3.19) 0.05 1.48 (-0.37 to 3.34) 0.12 1.44 (-0.20 to 3.08) 0.09 1.32 (-0.08 to 3.44) 0.22 1.13 (-0.48 to 2.74) 0.17 0.84 (-1.47 to 3.16) 0.47
Total hip aBMD (g/cm2)
Average-acceleration 0.02 (-0.00 to 0.04) 0.09 0.01 (-0.01 to 0.03) 0.44 0.02 (-0.00 to 0.04) 0.09 0.01 (-0.01 to 0.03) 0.45 0.02 (-0.00 to 0.04) 0.09 0.01 (-0.02 to 0.03) 0.63 0.02 (-0.00 to 0.04) 0.09 0.01 (-0.02 to 0.04) 0.70 0.02 (-0.00 to 0.04) 0.09 0.01 (-0.03 to 0.04) 0.74
Intensity-gradient 0.02 (0.01 to 0.04) 0.006 0.02 (0.00 to 0.04) 0.05 0.02 (0.00 to 0.04) 0.02 0.02 (-0.00 to 0.04) 0.08 0.03 (0.01 to 0.04) 0.009 0.02 (-0.00 to 0.04) 0.06 0.02 (0.00 to 0.04) 0.02 0.02 (-0.01 to 0.05) 0.15 0.02 (0.00 to 0.04) 0.04 0.02 (-0.01 to 0.05) 0.25
Total hip BMC (g)
Average-acceleration 0.73 (-0.21 to 1.67) 0.12 0.27 (-0.77 to 1.30) 0.61 0.73 (-0.21 to 1.67) 0.12 0.37 (-0.63 to 1.38) 0.47 0.73 (-0.21 to 1.67) 0.12 0.22 (-0.91 to 1.34) 0.71 0.73 (-0.21 to 1.67) 0.12 0.28 (-1.01 to 1.57) 0.67 0.73 (-0.21 to 1.67) 0.12 0.52 (-0.94 to 1.97) 0.48
Intensity-gradient 1.06 (0.39 to 1.72) 0.002 0.94 (0.17 to 1.71) 0.02 0.85 (0.11 to 1.59) 0.03 0.68 (-0.12 to 1.47) 0.09 0.98 (0.24 to 1.72) 0.01 0.87 (-0.06 to 1.80) 0.07 0.84 (0.05 to 1.63) 0.04 0.67 (-0.44 to 1.79) 0.24 0.62 (-0.18 to 1.41) 0.13 0.28 (-0.96 to 1.52) 0.66
Femoral neck cross-sectional area (cm2)
Average-acceleration 0.05 (-0.02 to 0.12) 0.17 0.02 (-0.06 to 0.09) 0.65 0.05 (-0.02 to 0.12) 0.17 0.02 (-0.06 to 0.10) 0.63 0.05 (-0.02 to 0.12) 0.17 0.01 (-0.07 to 0.09) 0.77 0.05 (-0.02 to 0.12) 0.17 0.02 (-0.07 to 0.11) 0.73 0.05 (-0.02 to 0.12) 0.17 0.02 (-0.08 to 0.13) 0.66
Intensity-gradient 0.07 (0.02 to 0.13) 0.01 0.06 (0.01 to 0.12) 0.03 0.07 (0.01 to 0.13) 0.03 0.06 (-0.00 to 0.12) 0.07 0.07 (0.01 to 0.13) 0.03 0.06 (-0.01 to 0.13) 0.07 0.06 (-0.01 to 0.13) 0.07 0.05 (-0.03 to 0.13) 0.23 0.05 (-0.02 to 0.12) 0.13 0.03 (-0.06 to 0.13) 0.47
Femoral neck section modulus (cm3)
Average-acceleration 0.03 (-0.01 to 0.08) 0.14 0.03 (-0.02 to 0.07) 0.30 0.03 (-0.01 to 0.08) 0.14 0.03 (-0.02 to 0.08) 0.22 0.03 (-0.01 to 0.08) 0.14 0.02 (-0.03 to 0.08) 0.37 0.03 (-0.01 to 0.08) 0.14 0.03 (-0.03 to 0.09) 0.31 0.03 (-0.01 to 0.08) 0.14 0.02 (-0.04 to 0.09) 0.52
Intensity-gradient 0.03 (-0.02 to 0.07) 0.20 0.02 (-0.03 to 0.06) 0.47 0.02 (-0.02 to 0.06) 0.34 0.00 (-0.04 to 0.05) 0.82 0.03 (-0.01 to 0.07) 0.16 0.02 (-0.03 to 0.06) 0.51 0.02 (-0.02 to 0.06) 0.26 0.00 (-0.05 to 0.06) 0.86 0.03 (-0.01 to 0.07) 0.13 0.02 (-0.04 to 0.07) 0.59

Values are regression coefficients (ß), their 95% confidence intervals (CI), and p values from linear regression models. Activity metrics were standardised before entry into analysis, so values represent the change in the outcome associated with a 1 standard deviation change in the activity metric.

aAverage-acceleration (average of waves 6 to 9) is the mean acceleration across wear-time.

bIntensity-gradient (average of waves 6 to 9) calculated, with imputing zeros for non-wear during the night, as the regression line from log-log plot of intensity (x) and time accumulated (y).

Model 1 includes the activity variable (average-acceleration or intensity-gradient) adjusted for age at wave 9, stature at wave 9, mass at wave 9, years from peak height velocity at wave 9, the proportion of the 24-hour cycle the accelerometer was worn, and the mean age for physical activity measures. Model 2 includes both activity variables in the same model (average-acceleration and intensity-gradient).

Bold emphasis indicates statistical significance at p < 0.05.

TBLH, total body less head; BMC, bone mineral content; aBMD, areal bone mineral density.