Contributions of physical activity, body composition, age, and nutritional factors to total and regional bone mass in premenopausal aerobic dancers and walkers
Alekel, Deborah Lee
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https://hdl.handle.net/2142/21626
Description
Title
Contributions of physical activity, body composition, age, and nutritional factors to total and regional bone mass in premenopausal aerobic dancers and walkers
Author(s)
Alekel, Deborah Lee
Issue Date
1993
Department of Study
Nutritional Sciences
Discipline
Nutritional Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Animal Physiology
Health Sciences, Nutrition
Language
eng
Abstract
The purposes of this cross-sectional study were to determine whether exercisers had greater bone mass than non-exercisers, and among exercisers, whether aerobic dancers had greater bone mass than walkers. Another purpose was to identify body composition and nutrition factors related to total and regional bone mass in physically active and sedentary premenopausal women. It was hypothesized that aerobic dancers would have the highest and non-exercisers the lowest total body and regional bone mineral density (BMD) and that a history of participation in aerobic dance or walking would contribute to the total body, vertebral, femoral, and radial bone mineral content (BMC) and BMD of subjects. Subjects included 93 eumenorrheic walkers (n = 28), dancers (n = 34), and non-exercisers (n = 31) aged 25 to 41 years. Total body, lumbar spine, and proximal femur (via dual energy X-ray absorptiometry) measurements for all subjects were obtained. Mean height, weight, body mass index, and age were similar for the three groups, but the exercisers were significantly leaner. The non-exercisers had significantly (p $<$ 0.05) lower total body BMC (2197 gm) and BMD (1.15 gm/cm$\sp2$) than either the walkers (2403 gm; 1.21 gm/cm$\sp2$) or dancers (2422 gm; 1.21 gm/cm$\sp2$). Although no consistent pattern of differences among the three groups was apparent for the spine, a more consistent pattern emerged for the proximal femur, with significantly greater neck, trochanter, and total femoral BMC and BMD values for the exercisers than the non-exercisers. Calcium intake from milk and yogurt was similar among the groups for any period during the life cycle. Stepwise multiple regression analyses indicated that exercise significantly and consistently contributed to increases in total body, lumbar, and femoral BMC and BMD, particularly for the femur. Femoral BMD was more readily influenced by lifestyle factors (exercise and kilocalorie expenditure), while the lumbar and total body BMD were more readily influenced by the biological characteristics of age and weight. Total body and lumbar BMD did not decline before 40 years of age, but rather increased across the 25 to 41 year age span. These findings suggest that habitual weight-bearing exercise may provide physically active premenopausal females with greater peak BMD than their sedentary counterparts.
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