| Objective To study the characteristic changes of calcaneus bone stiffness index (SI) with sex and age in Han medical students, and to analyze the relationship between SI and body composition and the main factors that affect bone stiffness index. Methods A total of1949 Han medical students (721 males, 1228 females) in Shenyang were recruited in April 2017, aged from 19 to 21. SI of the right calcaneus and body composition were measured using ultrasonic bone densitometer and bioelectrical impedance analyzer. The association between SI and body composition was studied with multiple linear regressing analysis. Results The peak SI of Han medical students in Shenyang was found at 19 years old, and only SI of female students significantly decreased at the age of 20 and 21 respectively (P<0.01). The SI of male students was higher than that of females in each age group (P<0.01). The results of fat mass, body fat percentage, and edema index of Han male medical students of were significantly lower than those of female students in each age group (P<0.01), and the values of body weight, body water, BMI, waist-hip ratio, bone minerals, protein, muscle mass, lean body mass, skeletal muscle mass, and basal metabolic indexes of Han male students were higher than those of female students in each age group (P<0.01 or P<0.05) except of waist-hip ratio at the age of 19. According to the results of multiple linear regression between SI and body composition, BMI and skeletal muscle mass were positively associated with SI, respectively (P<0.01), and fat mass was negatively correlated with SI (P=0.000). Conclusion SI decreases at the age of 20 and 21 in Han medical students of Shenyang, and it is more obvious in female students, indicating they are at risk of osteoporosis. BMI and skeletal muscle mass are protective factors of osteoporosis, and fat mass is a risk factor for osteoporosis in Han medical students. |