Jump performance and thigh muscle cross-sectional area in young female rhythmic gymnasts

BACKGROUND: It has been shown that stress, diet control and intensive trainings have impact on growth in young rhythmic gymnasts (RG). Body fat content has been widely investigated in this category of athletes, while muscles development, less and on small samples. The aim of the present study was to investigate associations between jump characteristics, anthropometry and anatomical cross-sectional area (ACSA) of thigh in competitive RG. METHODS: Forty girls aged 9-16 years (mean age 12.4 +/- 1.8 years, body mass 40.9 +/- 8.8 kg, height 152.2 +/- 9.1 cm) participated in the study. ACSA of thigh and jump height in squat (SQJ), counter movement (CMJ), and counter movement jumps with arms swinging (CMJA) were measured. RESULTS: ACSA of thigh was 88.9 +/- 15.4 cm(2) (range 61-122 cm(2)) and correlated with jumps height and with age (r=0.619, P<0.001) showing a decline (if normalized for BMI) with aging with a major gap between 10 and 12 years old. All jumps/BMI declined with age showing significant differences between the age of 10, 13, 13, and 15. It can be hypothesized the increase in body size with no parallel gains in strength affect the jumps performance. Elasticity (difference between CMJ and SQJ) increased from the age of 12 and was significantly higher in older RG. CONCLUSIONS: Results of the study demonstrated a decline in thigh muscle mass development and the relationship mass/jumps in the growing gymnasts. As a countermeasure, training to keep and develop muscle mass should be recommended to this category of athletes.