Changes in hip and ankle range of motion and hip muscle strength in 8-11 year old novice female ballet dancers and controls: a 12 month follow up study

Objectives-To evaluate in a 12 month longitudinal study changes in hip and ankle range of motion and hip muscle strength in young female novice ballet dancers. Methods-Fifty three of the original 77 (69%) female dancers aged 8-11 years and 40 of the original 49 (82%) controls returned for follow up measuremen ts one year later. Supine right active hip external (ER) and internal (IR) rotation were measured using an inclinometer. A turnout protractor was used to assess standing active turnout range. Range of right weight bearing ank le dorsiflexion and calf muscle length were measured in a standing lunge po sition using an inclinometer. A manual muscle tester was used to assess rig ht hip flexor, LR, ER, abductor and adductor strength. Results-The mean (SD) 12 month change in hip ER did not differ between danc ers (11.7 (11.3)degrees) and controls (8.1 (17.6)degrees). Dancers gained 1 2.5 (13.5)degrees hip IR which was significantly greater than controls (0.5 (13.9)degrees). Greater IR change was associated with improved IR strength (r = 0.34, p<0.001). Dancers increased total turnout (12.0 (16.7)<degrees> ) significantly more than controls (2.2 (20.0)degrees). There was no signif icant change in ankle dorsiflexion range in either group. Dancers and contr ols increased in all measures of hip muscle strength (p<0.001) and dancers achieved significantly greater gains in three out of five muscle groups (al l, p<0.05). Conclusions-Total hip range of motion increased in both ballet students and controls at this young age. However, ankle dorsiflexion did not, which is probably due to this movement being blocked by bony apposition, rather than soft tissue stretch. This has implications for ballet teachers, as it has long been accepted that this movement could be improved with training. Danc ers had greater increases in hip strength after 12 months compared with con trols in muscles specific for ballet, suggesting that hip strength can be t rained at this young age. Whether these gains are permanent requires furthe r study.