Resistance Training Threshold for Elevating Bone Mineral Density in Growing Female Rats.

The purpose of this study was to determine the minimum amount of resistance exercise that would stimulate bone formation yielding an elevation in bone mineral density (BMD) during the growth period in female rats. Female rats were randomly divided into: Control (Con, n=8), 3 ladder climb resistance-trained group (3LC, n=8), 4 ladder climb resistance-trained group (4LC, n=8), 5 ladder climb resistance-trained group (5LC, n=8), and 6 ladder climb resistance-trained group (6LC, n=8). All exercised groups were conditioned to climb a vertical ladder with weights appended to their tail 3 days/wk for a total of 6 wks. After 6 wks, left tibia BMD (g/cm2) was significantly greater for 4LC (0.197±0.003), 5LC (0.200±0.004) and 6LC (0.202±0.003) when compared to Con (0.185±0.006). Left femur BMD (g/cm2) was significantly greater for 4LC (0.260±0.005), 5LC (0.269±0.004) and 6LC (0.272±0.006) when compared to Con (0.244±0.006). There were no significant differences in tibia and femur BMD between 4LC, 5LC, and 6LC groups. The results suggest that during growth, a high volume of resistance exercise was required to elicit an elevation in BMD in females.

Prevalence of vitamin D3 deficiency in orange county residents.

With the prevalence of sunlight exposure in Orange County, California, one would expect it to be rare and unusual to find high incidence of Vitamin D deficiencies among its residents. This study evaluated the concentration of Vitamin D3 as part of a larger study to evaluate bone health in Orange County residents. Our preliminary data shows that 19.2% of the 151 subjects evaluated had low Vitamin D3 (<30 pg/ml) and illuminates a growing problem in the United States. We speculate that the widespread sensitivity to skin cancer and sun exposure, the increased use of sun-screens and the filtering of UV waves in automobile glass has put the public at risk for low Vitamin D.