The Relationship Between Bone Mineral Density And Step Count In Adult Women

Abstract

Low bone mineral density (BMD) is a definitive marker of osteoporosis and a leading risk factor for fracture. Physical activity (PA), which is increasingly measured with pedometers, is an important influencing variable of BMD. PURPOSE The purpose of the present study was to determine the relationship between BMD and average daily step count (ADSC). METHODS Forty-nine females, aged 29–61 years, volunteered to participate. Subjects were required to. fill out 5 questionnaires (PAR-Q, general health history, osteoporosis risk assessment, Leisure Time PA Questionnaire, and Food Frequency Questionnaire). Physiological measurements included body composition as measured with 7-site skinfold technique and duel-energy x-ray absorptiometry (DXA), BMD of whole body, lumbar spine, left femoral neck (LFN) and right femoral neck (RFN), and step counts. Upon evaluation of data, subjects were divided into 5 categories based on ADSC- Sedentary, Low Active, Somewhat Active, Active, and Highly Active. RESULTS Among the entire group of subjects, no relationship was found between ADSC and BMD of whole body or regional sites. A significant relationship was found however between BMD and ADSC among the “Somewhat Active” group (7500–9999 steps per day), (n = 14, r = 0.635, p = 0.017). Relationships were also found between age and BMD of LFN and RFN (LFN: r= −0.355, p = 0.012; RFN: r = −0.396, p = 0.005), total PA from the Leisure Time PA Questionnaire and BMD of lumbar spine (r = −0.257, p = 0.075), and body composition (DXA) and ADSC (r = −0.399, p = 0.004). CONCLUSION ADSC does not appear to be related to BMD among middle-aged adult females. The wide range of ages within a relatively small sample size, as well as a narrow range of body compositions and socioeconomic classes may be masking a possible relationship. Additional research assessing effectiveness of pedometers in measuring PA in reference to BMD is warranted.