Vitamin D, calcium and physical activity are important factors for bone health. A
cross sectional study was conducted in Chapter 2 to assess vitamin D intake,
calcium intake and physical activity among children with wrist or ankle injuries and
their association with fracture risk. The majority of children had low vitamin D and
calcium intake. The logistic regression indicated that there was a small but
significant relationship between calcium intake and fracture risk (OR per SD
increase = 0.998; 95% CI, 0.997 – 0.999) but no significant relationship was found
between vitamin D intake and fracture risk.
In the following section (Chapters 3, 4, 5 and 6), a randomised controlled trial was
conducted to determine the effect of whole body vibration and a large single dose
of vitamin D (150,000 IU) on bone density of the distal tibia as measured by HRpQCT. The study consisted of four parallel groups of equal numbers (40 in total);
WBV and placebo group, placebo group, vitamin D group and vitamin D+ WBV
group. Measurements (HR-pQCT, serum 25 (OH)D, PTH, bone profile) were
collected at baseline and after 12 weeks (during week 13).
The median baseline serum 25(OH)D for all participants was 23 nmol/L. The high
dose of vitamin D was well tolerated. There was a significant increase in serum 25
(OH)D in vitamin D and vitamin D+WBV groups relative to the placebo group (all
p<0.01). There was a significant decrease in PTH in vitamin D group relative to the
placebo group (p=0.013). After 12 weeks, vitamin D group showed the greatest
increase in total bone density (increased by 2.7 mg/cm3 relative to the placebo
group, p= 0.05). The main findings of this study indicated that the large single dose
of vitamin D and 12 weeks of WBV did not improve bone density, bone
microarchitecture or bone strength
