Spinal sagittal mobility and joint laxity in young ballet dancers. A comparative study between first-year students at the Swedish Ballet School and a control group.

The present study compares spinal configuration, spinal range of motion and joint mobility in first-year students of the Swedish Ballet School and in nondancing students of corresponding age and sex in a state school. The study comprises all the first-year (fourth grade) students (n = 23) at the Swedish Ballet School: 11 boys and 12 girls. Their dance practice time was 10 h per week. Thirty-six children in the fourth grade at a state school comprised the control group. None of the controls took ballet classes or participated in organised gymnastics out of school. The neutral spine configuration in standing and the sagittal spine mobility were measured using Debrunner's kyphometer and Myrin's inclinometer. Joint laxity was measured by employing a modified form of the Contompasis method. Compared with the controls, the dancers showed a higher incidence of joint hypermobility, greater mobility of the thoracic spine, a less prominent lordosis of the lumbar spine and a less prominent kyphosis in the thoracic spine in the neutral standing position. The dancers had done little or no ballet training before entering the ballet school at the age of ten. The results agree with those of earlier studies and suggest that increased flexibility is an asset for those being selected as future ballet dancers.