Lifetime physical activity is associated with bone mineral density in premenopausal women.

Osteoporosis causes premature disability among millions of elderly people in the United States, particularly women. Exercise helps to maintain bone mass, yet it remains unclear what type of physical activity during what age periods is most beneficial for bone mass and density. This cross-sectional study investigated the relationship between different measures of lifetime physical activity and bone mineral density (BMD) in 25 premenopausal women (mean age 41 years, range 28-50 years). BMD of the total, entire axial, and entire peripheral skeleton were measured by dual energy x-ray absorptiometry (DXA). Lifetime history of physical activity was obtained by a structured interview, and estimates of lifetime weight-bearing exercise, total exercise, total weight-bearing physical activity (including occupational and household activities), and perceived physical activity were computed. Adjustments were made for current body weight and height and lifetime milk consumption. Lifetime weight-bearing exercise was significantly correlated with total and peripheral BMD (total BMD: r = 0.54; peripheral BMD: r = 0.54, all p < 0.05). Total weight-bearing physical activity, including occupational and household activity, was associated with total BMD (r = 0.51, p < 0.05). Physical activity during early age periods was more strongly associated with BMD at all sites than was physical activity in the past 2 years. Our findings suggest that lifetime weight-bearing exercise is more strongly related to BMD of the total and peripheral skeleton than is nonweight-bearing exercise. The inclusion of nonweight-bearing activity resulted in a weakening of the association. Weight-bearing household and occupational activity appeared to be related to BMD. Our results support recommendations to increase physical activity throughout life, particularly during early ages, as a means of osteoporosis prevention.

Among young adults, college students and graduates practiced more healthful habits and made more healthful food choices than did nonstudents.

OBJECTIVES: Health-related characteristics and habits and food choices of young adults were compared for three groups: college students, college graduates, and nonstudents. DESIGN: Subjects completed a mailed survey that included questions about demographics, attitudes, and behaviors and a food frequency questionnaire. Main outcome measures were health-related characteristics and habits and food choices. SUBJECTS: Female (n = 758) and male (n = 580) 18- to 24-year-olds in nine states who were selected randomly by zip code in each state. The response rate averaged 43% for all states. STATISTICAL ANALYSES PERFORMED: Analysis of variance of chi 2 tests were applied to health-related personal characteristic variables and the Kruskal-Wallis analysis of variance was applied to food consumption variables for women and men separately. RESULTS: According to self-reported heights and weights, female nonstudents were more often overweight than female students or graduates. Nonstudents of both genders reported smoking more often than students or graduates. College students and graduates ate more grain foods high in dietary fiber, more fruits and dark-green vegetables, and more lower-fat milk and meats than nonstudents. CONCLUSIONS/APPLICATIONS: Nonstudents were at greater health risk for some chronic illnesses, because of poorer health habits and food choices, than were college students and graduates. The behavior of nonstudents implies weaker response to messages promoting weight control, smoking cessation, and observance of the Dietary Guidelines for Americans than behavior exhibited by students or college graduates. Health promotion efforts could be enhanced by identifying demographic, educational, situational, and formative influences on positive health and dietary behaviors of young adults.

Bone mineral density in mother-daughter pairs: relations to lifetime exercise, lifetime milk consumption, and calcium supplements.

This study investigated associations between lifetime milk consumption, calcium intake from supplements, lifetime weight-bearing exercise, and bone mineral density (BMD) among 25 elderly women (mean age 72 y) and their premenopausal daughters (mean age 41 y). The BMD of the total, axial, and peripheral skeleton was measured by dual-energy X-ray absorptiometry. Lifetime milk consumption, supplemental calcium intake, and weight-bearing exercise were estimated retrospectively by questionnaire and interview. In multiple-linear-regression analyses, mothers' total and peripheral BMD were positively associated with supplemental calcium intake after age 60 y, body weight, current estrogen replacement therapy (ERT), and past oral contraceptive (OC) use, and negatively associated with age and height (all P < 0.05). Mothers' axial BMD was positively correlated with body weight and past OC use. Among daughters, lifetime weight-bearing exercise was a predictor of total and peripheral BMD, whereas total lean mass was a predictor of axial BMD. Mothers' lifetime milk consumption was positively associated with that of their daughters. Mothers' and daughters' peripheral BMD values were positively correlated after adjustment for daughters' exercise, and mothers' age, body weight, and ERT. These results suggest that calcium supplementation and exogenous estrogen positively influence bone mass in postmenopausal years. Our findings lend support to recommendations for physical activity as a means of osteoporosis prevention. In the age groups studied, the effects of behavioral and hormonal factors on BMD appeared to dominate over familial similarity, which suggests that women may successfully enhance their genetically determined bone mass through weight-bearing exercise, post-menopausal ERT, and adequate calcium intake.