2003 Volume 56 Issue 1 Pages 3-15
To define the effect of physical exercise on bone mineral density (BMD) under nutrient supplementation, an intervention study was performed using 27 healthy female Japanese college students over a 9-month period. All the subjects ingested milk (200mL), calcium (600mg), and magnesium (300mg) every weekday during two intervention periods of 72 days each. The study participants were divided into 3 groups: weight training, walking, and non-exercise. The stiffness index in the calcaneal region as measured by ultrasound was used to determine BMD. Significant BMD increases (1.8%) were observed as early as the first intervention period in the weight-training group, whereas BMD in the walking group increased significantly (2.8%) by the second intervention. BMD did not increase in either the non-exercise group or a non-intervention control sample randomly selected from the same college population. Diet was evaluated and classified into three levels according to the number of nutrients that produced sufficient rates of BMD increase during the study period. Two-factor analysis of covariance controlling for BMD and BMI at the beginning of the study revealed that a balanced diet contributed slightly more to BMD increases than exercise. However, the combination of exercise and a balanced diet was more effective than either exercise or a balanced diet alone for increasing BMD in a short period. The combination of exercise and a balanced diet was estimated to increase BMD by over 4.3%.
