A Study Of The Correlation Between Physical Activity And Bone Mineral Density In Adolescent Students

Objective:This study adopts a tracking study of the correlation between physical activity and bone mineral density(BMD) during the period of adolescence that the deadline of tracking is one year. The statistical method is to analyze longitudinal data whose important period is analyzing and dealing with data. More clearly and accurately embodying the stage of adolescence is the characteristic of this study. The features of BMD and growth and development finally establish a theoretical basis for accumulating bone mass in adolescence.Methods:This article is to evaluate the parameters of calcaneal quantitative ultrasound measurement of96junior middle-school students in age13～15of Jin Hua area through the methodology of questionnaire survey, test and mathematical statistics and using Achilles Insight ultrasound apparatus. According to the investigation of physical activity in subjects,58students without exercise habits were compared with those of students who has better exercise habits. This article analyzes the correlation between physical activity and bone mineral density in adolescent students further and find a reasonable physical activity that suits bone health of adolescent students to analyze according to the status of physical activity and bone mineral density in adolescent students.Results:(1)Overall, the physical activity of boys in exercise group reaches the highest level that the monthly average has been884.7±544.7minutes. The time of physical activity in other groups including girls in exercise group, boys in ordinary group and girls in ordinary group from high to low is679.3±504.2minutes,379.5±179.8minutes, and360.5±186.7minutes, respectively. The energy expenditure of monthly physical activity for boys in ordinary group of adolescenct junior middle-school students is1886.8MET-min/week and that of girls in ordinary group is1608.7±839.8MET-min/week. The energy expenditure of monthly physical activity for boys in exercise group is5412.1±3431.7MET-min/week and that of girls in exercise group is4029.3±3049.7MET-min/week.(2)Although the bone mineral density for girls in ordinary group of adolescence in the second test decreased compared with that in the first test, there was significant difference(P<0.01). The bone mineral density of boys in ordinary group in the second test was on the rise compared with that in the first test, and there was significant difference(P<0.01). The bone mineral density of boys in exercise group in the three tests showed a rising trend in general. Except for girls in exercise group, there was significant difference among other groups in the third test compared with those in the second test.(3)The correlation between high level physical activity and the third BMD test for girls in ordinary group of adolescence(r=0.89, p<0.05); the correlation between high level physical activity and the third BMD test for boys in ordinary group (r=0.94, p<0.05); the correlation between high level physical activity and the first and the third BMD test for boys in exercise group(r=0.65, p<0.05),(r=0.75, p<0.01); the correlation between high level physical activity and the first and the second BMD test for girls in exercise group(r=0.89,p<0.01),(r=0.76, p<0.01). High level physical activity correlates signigicantly with BMD.Conclusion:(1)In physical activity of adolescent junior middle-school students, the overall level is not high. There is significant difference between boys and girls. The physical activity time and energy expenditure of boys is significantly larger than that of girls.(2)The BMD of junior middle-school students in age13～15is similar to those of adults and BMD in exercise group is higher than that in ordinary group. Over the past one year, the BMD of boys has been on the rise and that of girls has trended down, which was relatively significant. As well, the BMD of adolescence has been influcenced by growth and development.(3)The physical activity of high level energy expenditure, especially the high level physical activity over a long period of time, may have a significant impact on improving BMD of adolescence. In the future, we can evaluate the intensity of training through the energy expenditure in the motor process of junior middle-school students to realize self monitoring for the best results of scientific guidance.