Weight-Bearing Physical Activity and Bone Mineral Density Among Women Using Depo-Provera.

Abstract

Depo-Provera (DEPO) is a widely-used contraceptive method. While effective in preventing pregnancy, DEPO also decreases bone density. In contrast, weight-bearing activity has been shown to increase bone density. Currently, it is unknown if a relationship exists between physical activity and bone density in the presence of hormones that may inhibit bone development, such as DEPO. PURPOSE: To determine if weight-bearing activity is related to bone mineral density among women taking DEPO. METHODS: A total of 13 women, (age 19–37 years) who had been taking DEPO for at least one year participated in this study. Bone mineral density at each hip and the lumbar spine were measured using a Hologic 4500W DEXA. Physical activity was measured using a pedometer (New Lifestyles NL-2000) for a period of one week. Participants were also asked to complete a 3-day dietary record to assess calcium intake. RESULTS: When controlling for calcium intake, average step count and bone density were not significantly correlated (P >.05) at the right hip (r = −.28), left hip (r = −.28), or lumbar spine (r = −.17). However, calcium intake was significantly associated with bone mineral density (g/cm2) at the right hip (r = .66), left hip (r = .74), and lumbar spine (r = .62). Overall, activity step counts were below recommended amounts and only three participants consumed the recommended amount of dietary calcium. CONCLUSION: Weight-bearing activity was not linked to bone mineral density in this investigation. This observation may reflect the low physical activity levels exhibited by a majority of study participants. Conversely, it appears that calcium intake may play an important role in combating the negative consequences of DEPO in young adult women.