Despite a High Prevalence of Menstrual Disorders, Bone Health Is Improved at a Weight-Bearing Bone Site in World-Class Female Rhythmic Gymnasts

Abstract

Regular physical activity during puberty improves bone mass acquisition. However, it is unknown whether extreme intense training has the same favorable effect on the skeleton. We evaluated the bone mass acquisition in a unique cohort of world-class rhythmic gymnasts. A total of 133 adolescent girls and young women with a mean age of 18.7 ± 2.7 (14.4-26.7) years participated in this study: 82 elite rhythmic gymnasts (RGs) and 51 controls (CONs). Anthropometric variables and body composition were assessed, and all participants completed questionnaires on their general medical, menstrual, and training histories. Broadband ultrasound attenuation (BUA in decibels per megahertz) was determined by quantitative ultrasound at the heel. RGs presented lower weight (-8.5%, P < .001), body mass index (-11.7%, P < .001), and body fat mass (-43%, P < .001) and higher muscle mass (6.3%, P < .01) and height (+2.8 cm, P < .01). RGs presented an age of menarche significantly delayed compared with CONs (15.6 ± 1.6 vs 12.7 ± 1.7 years; P < .001) and a high prevalence of menstrual disorders (64%). BUA values were higher in RGs vs CONs (68.6 ± 4.6 and 65.4 ± 3.3 dB/Mhz, respectively; P < .001). This difference was exacerbated when BUA was adjusted for age and body weight. BUA values in RGs were not affected by menstrual or training status. Among RGs with menarche, BUA was higher (71.5 ± 4.1 and 67.9 ± 3.5 dB/Mhz) for delayed (14.4 ± 0.8 years) vs severely delayed (17.3 ± 1.4 years) menarcheal age. BUA was positively correlated with body weight and body mass index and tended to be correlated with age. Conversely to expectations for adolescents and young women with a high prevalence of menstrual disorders and/or delayed menarche, intense training in rhythmic gymnastics appeared to have a beneficial effect on the bone health of a weight-bearing site. This effect was nevertheless modulated by the age of menarche. The high mechanical loading generated by this activity may counterbalance the negative effect of menstrual disorders.