Pedometer Measured Step Counts and Bone Mineral Density among Premenopausal Women

Abstract

Pedometers have become popular physical activity measurement tools and have proven to be valid and reliable. Opportunity for bone impact comes mostly from weight bearing physical activity and is captured by the use of these devises. However, there is question about the intensity of impact needed to stimulate changes in bone tissue. Research focused on walking activity, which comprises a majority of daily physical activity for most individuals, has resulted in conflicting effects on the commencement of bone tissue remodeling. The purpose of this study was to measure pedometer based daily physical activity and determine whether these data significantly correlate with aBMD (areal bone mineral density) (g/cm 2 ) measures among premenopausal women. A secondary purpose was to look specifically at the relationship between moderate intensity level data and aBMD. Forty-two pre-menopausal women from central Minnesota participated in the summer of 2011. Body mass index, calcium, vitamin D, total, and moderate intensity steps were tallied, and hip and lumbar spine aBMD was measured. Significant bivariate correlations (p < .05) were found between calcium and femoral, lumbar spine, and L2 aBMD measures. No correlations were found between age or vitamin D intake and aBMD measures. Significant bivariate correlations were also found between body mass index and L1, L3, L4, and total hip aBMD. No significant bivariate correlations were found between aBMD measures and total step or moderate intensity counts. Partial correlations, controlling for calcium and body mass index, did not reveal any correlations between total or moderate step counts and aBMD. It is plausible to conclude that the Omron HJ-303 pedometer may not be an appropriate tool for tracking bone building activity. Researchers need to continue to look for a consumer tool that effectively tracks this type of activity for those interested in improving bone health.