Hamstring extensibility differences among elite adolescent and young dancers of different dance styles and non-dancers

BACKGROUND: Hamstrings have been analyzed extensively due to their tendency to shorten and their effect in the lumbo-pelvic dynamics and the sagittal position of the spine in trunk flexion with extended knees positions. It has been demonstrated that practicing a certain sport results in long-term changes in hamstring extensibility. Despite this, adequate extensibility of the hamstring musculature is essential for the dancer’s performance. Several studies have found differences in the extensibility of the hamstrings depending on the dance style, but none have compared ballet, Spanish dance and modern dance. The purpose of the present research was to analyze the differences in hamstring extensibility among professional dance students based on dance style practiced and non-dancers. METHODS: The sample was comprised of 210 students from the Professional Dance Conservatory (70 for ballet, 70 for Spanish dance and 70 for modern dance) and 70 non-dancers. For the assessment of hamstring extensibility, the angle in the passive and active straight leg raise (PSLR and ASLR, respectively) test, and the scores of the pelvic tilt in sit-and-reach (SR) test and the toe-touch (TT) test were randomly conducted. RESULTS: The results showed significant differences for all the tests according to group (p < 0.001). In the PSLR and ASLR test, for both legs, and in the pelvic tilt in the SR test, the ballet dancers showed greater ranges of hamstring extensibility than the modern dancers and Spanish dancers (p ≤ 0.001). In the distance in the SR test and in the pelvic tilt in the TT test, the ballet dancers obtained higher values than the Spanish dancers (p = 0.004 and p = 0.003, respectively). The modern dancers showed higher ranges of hip flexion than the Spanish dancers in the ASLR test for both legs and in the pelvic tilt in the SR test (p from 0.007 to <0.001). Dancers showed significantly higher hamstring extensibility than non-dancers in all the tests (p < 0.001). CONCLUSIONS: The systematic practice of dance, regardless of the style, seems to lead to high ranges of hamstring extensibility. Ballet dancers have the greatest hamstring extensibility.