[Association between physical development and spermatorrhea during puberty among boys aged 11 to 15 years in China].

Objective: To explore the association between spermatorrhea and physical development during puberty for boys aged 11 to 15 years old in China.

Methods: The height, weight, chest circumference, waist circumference, hip circumference and the station of spermatorrhea of boys aged 11-15 years old were selected from the data of 2010 National Survey on Students Constitution and Health. Body mass index (BMI) and waist to height ratio were calculated. After 1: 1 random matching in every 0.1 year of age, 6880 boys (3440 with spermatorrhea and 3440 without spermatorrhea) were included in our study. t-test was used to analyze differences in anthropometry measurements between boys with spermatorrhea and boys without spermatorrhea in each age group. Multilevel model was used to analyze the relationship between anthropometry measurements and spermatorrhea.

Results: A total of 6880 boys were put in this research. Heights of boys with spermatorrhea aged 11 to 15 years old were (150.96 ± 8.01), (159.46 ± 8.03), (163.76 ± 7.43), (167.03 ± 7.12) and (169.50 ± 6.64) cm, respectively, while heights of boys without spermatorrhea aged 11 to 15 were (147.38 ± 6.54), (153.55 ± 8.68), (160.35 ± 8.66), (164.44 ± 7.98) and (167.98 ± 7.80) cm, respectively. The differences were significant (t values were 3.70, 9.96, 10.76, 8.26, and 3.21 respectively with all P values < 0.01).

Results: of multilevel analysis showed that the differences of weight were the largest from 11 to 13 years old, boys with spermatorrhea having a 4.20, 7.23 and 3.93 kg (Waldχ(2) values were 13.11, 70.73 and 72.93 respectively, all P values < 0.01) larger weight than boys without spermatorrhea, respectively. Differences of height were the largest from 14 to 15 years old, boys with spermatorrhea having a 2.81 and 1.99 cm (Waldχ(2) values were 87.80 and 19.54, P < 0.01) larger height than boys without spermatorrhea. The trends of the differences between boys with spermatorrhea and boys without spermatorrhea (β value) with age were parabolic on weight, BMI, height, chest circumference, waist circumference, hip circumference and waist to height ratio. The β values reached maximum at 12 years old, which were 7.23 kg, 1.64 kg/m(2), 5.55 cm, 4.40 cm, 4.63 cm, 4.94 cm, and 0.015, respectively. The β values reached minimum at 15 years old, which were -0.39 kg, -0.56 kg/m(2), 1.99 cm, -0.57 cm, -1.59 cm, -0.42 cm and -0.015, respectively.

Conclusion: There is an association between spermatorrhea and physical development among boys aged 11 to 15 years in China , which has a parabolic trend with age.