The Effects of Calcium Intake and Physical Activity on the Bone Mineral Content and Bone Mineral Density of the United States Naval Academy Midshipmen.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
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Prevention of osteoporosis depends upon the identification of lifestyle factors that increase peak bone mass. We investigated the effects of calcium intake, weight bearing exercise WBE, and strength training ST on total bone mineral content TBMC and bone mineral density BMD in 22 female and 13 male United States Naval Academy Midshipmen MIDN. Each received 4 dual energy x-ray absorptiometry scans to measure TBMC and spine and hip BMD during the 2.8 year study period. Calcium intake was estimated at baseline and follow-up using a food frequency questionnaire. Frequency of WBE was determined at each visit using a questionnaire. The females TBMC was predicted by calcium intake at baseline p.01 and increased during the study p.001 as did spine BMD. At follow-up calcium was a significant variable in a model predicting TBMC p.001, but was weaker than at baseline and not independent of body weight. In the male subjects, TBMC and spine BMD increased significantly p.005, p.05. Hip BMD did not increase in males or females. WBE was predictive of TBMC p.01, in female subjects weighing greater than 60 kg. This suggests that a threshold level of weight bearing from body weight and exercise is necessary to stimulate osteogenesis. We conclude that bone accretion occurs early in the third decade in MIDN and is highly influenced by body weight. Calcium intake and WBE in female MIDN may positively modify peak bone mass, although these effects were not independent of body weight.
- Anatomy and Physiology
- Medicine and Medical Research