Effect of sub-elite competitive running on bone density, body composition and sexual maturity of adolescent females

Abstract

The attainment of optimal peak bone mass during adolescence is important in the primary prevention of osteoporosis. Exercise may contribute to skeletal development and bone density during growth, although competitive exercise is suggested to have an adverse effect. This study assesses the effect of moderate exercise on the bone density of adolescent females. Additionally, other factors which significantly influence attainment of peak bone mass were identified. This was a cross-sectional study of 42 adolescent females, classified as runners (n=15) or non-runners (n=27). Nutrient intake, energy expenditure, menstrual history and pubertal stage were recorded. Bone age, skinfold thickness, body composition and bone mineral density (BMD) of total body, lumbar spine and proximal femur were measured. Statistical analyses used Student's t-test, Pearson correlation and multiple regression analyses. Runners had lower fat mass and higher lean mass, with a trend to higher BMD in all sites measured. There were no significant differences in menstrual cycle regularity, age at menarche or number who had attained menarche. Pubic hair development was similar in both groups. Breast development was delayed in runners, although this may have been a function of lower fat mass in this group. When subjects were categorized according to menarchal status, postmenarchal girls were significantly taller and heavier, with higher fat mass and significantly higher total body and lumbar spine BMD. There was no significant relationship between BMD at any site and dietary nutrient intake. Multiple regression analyses, using BMD as the dependent variable, identified running status, pubertal stage, fat mass and lean mass as significant determinants. When BMD/height was used, significant determinants in total body BMD were fat mass, pubertal stage and running status, while in the lumbar spine, only the latter two variables remained significant. In conclusion, body composition, physical activity and sexual maturity were identified as significant determinants of bone density during adolescence. Runners had significantly lower body fat than non-runners, but this did not interfere with hormonal cyclicity, and caused no detriment to their bone density. The results of this study are reassuring, since they indicate that sub-elite competitive athletics has no detrimental effect on bone mass accrual in adolescent females.

Cross-sectional evidence of suppressed bone mineral accrual among female adolescent runners

“…(39)(40)(41)(42) A previous study by Lucas and colleagues that compared adolescent runners and nonrunners found no differences between runners (n ¼ 15) and nonrunners (n ¼ 27) in body weight or BMD at each bone site, and it therefore was concluded that runners' exercise activity did not negatively affect their bone mass. (43) Although the results of that study might appear contradictory to our findings, the runners in that study sample ranged in age from 12 to 14 years. (43) Since the bone-mass differences between runners and nonrunners in the current sample became recognizable after age 14 years, our findings do not contrast with the results from Lucas and colleagues (43) ; instead, they may provide an expanded understanding of the effect of prolonged exposure to endurance running on adolescent bone mass.…”

“…(43) Although the results of that study might appear contradictory to our findings, the runners in that study sample ranged in age from 12 to 14 years. (43) Since the bone-mass differences between runners and nonrunners in the current sample became recognizable after age 14 years, our findings do not contrast with the results from Lucas and colleagues (43) ; instead, they may provide an expanded understanding of the effect of prolonged exposure to endurance running on adolescent bone mass. The primary limitation of this study is its cross-sectional design.…”

Influence of high-intensity training and of dietetic and anthropometric factors on menstrual cycle disorders in ballet dancers

“…This finding suggests that intensive sports training before menarche delays menarche. The possible reasons for this late onset of menarche may include the small amount of fat tissue, as well as the physical and mental stress to which athletes are exposed [3,[13][14][15][16][17][18].…”

Menstrual function in sports

“…42 On the other hand, in sub-elite, moderately exercising female runners, no effect on pubertal development was demonstrated. 43 Dance training has been shown to be associated with a high incidence of menstrual dysfunction, particularly in disciplines such as ballet. 35 Ballet dancers begin strenuous training at an early age while undergoing intensive exercise and heavy caloric restrictions (this leading to energy deficit) in order to perform at a competitive level and retain a lean physique.…”