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OBJECTIVE To evaluate the effect of calcium supplementation on bone acquisition in adolescent white girls. DESIGN A randomized, double-blind, placebo-controlled trial of the effect of 18 months of calcium supplementation on bone density and bone mass. SUBJECTS Ninety-four girls with a mean age of 11.9 + 0.5 years at study entry. SETTING University(More)
The precise timing for the onset of trabecular bone loss in women is a matter of controversy. To address this issue, we studied the relationship between age and vertebral trabecular bone density (measured by computed tomography) in 74 healthy premenopausal women from 18 to 48 years old. We also measured radial cortical bone density (by single photon(More)
BACKGROUND Although clinical investigators are regarded as an endangered species, no systematic investigation of the factors that influence doctor participation in clinical research has previously been performed. AIM The objective of this study was to evaluate the influences of selected aspects of medical education, specialty selection and practice type(More)
We used 10 years of longitudinal data from Penn State Young Women's Health Study to explore predictors of adult bone structural geometry and strength. One hundred twelve participants were enrolled in the study at age 12. We report findings on the 76 participants who remained in the study for 10 years. Measurements were recorded biannually for the first 4(More)
OBJECTIVE To evaluate the contributions of adolescent calcium intake, oral contraceptive use, and exercise on bone mass and bone strength.Study design Eighty white women participated in 10 years of the Penn State Young Women's Health Study, a longitudinal study of community participants. We measured bone mineral mass (g), density (BMD, g/cm(2)), and body(More)
The need to quantify agreement between two raters or two methods of measuring a response often arises in research. Kappa statistics (unweighted and weighted) are appropriate when the data are nominal or ordinal, whereas the concordance correlation coefficient is more appropriate when the data are measured on a continuous scale. We develop weighted(More)
To determine the relationship of gonadotropin excretion to spermarche, 26 boys ranging in age from 10.3 to 17.5 years each provided ten overnight urine samples. Microscopic observation of sperm was found in 33 (13%) of the 260 samples, with 50% of the boys exhibiting sperm in at least one specimen. No further cumulative gain in detecting spermaturia(More)
We have performed a retrospective three-phase study to evaluate the effect of menstrual status upon musculoskeletal injuries in women athletes. Initially, we collected the menstrual and running histories of women participants in a regional 10-km footrace. In this study, 61% of the respondents to our questionnaire reported a continuous running program, and(More)
To elucidate determinants of peak trabecular bone density, we studied the role of androgens, estrogen, and aerobic exercise in 30 women from 18 to 22 years old. The women were divided into three groups: Sedentary, 11 normal women who did not exercise regularly; eumenorrheic, 10 athletes with normal menstrual function; and oligomenorrheic, 9 athletes with(More)
OBJECTIVE This study was conducted to determine whether dietary caffeine consumed by American white females between ages 12 to 18 affects total body bone mineral gain during ages 12 to 18 or affects hip bone density measured at age 18. METHODS The Penn State Young Women's Health Study is a longitudinal investigation of bone, endocrine and cardiovascular(More)