The Evaluation of Strength, Flexibility, and Functional Performance in the Adolescent Ballet Dancer During Intensive Dance Training.

BACKGROUND: Adolescent ballet dancers have a higher incidence of injury than adult professional dancers. It is unclear which factors, including biomechanical changes related to intense dance training and/or the growth process itself, contribute to increased injury risk in this population. OBJECTIVE: To assess changes in strength, flexibility, and functional performance in adolescent ballet dancers during a summer intensive dance program. DESIGN: Prospective cohort study. SETTING: Performing arts school in a suburb of Massachusetts. PARTICIPANTS: A convenience sample of 58 male and female ballet dancers, 12 to 17 years old, was enrolled. One dancer did not have functional testing due to injury, but strength and range of motion results were included. METHODS: Paired sample t-test was used to evaluate changes in (1) strength: lower abdominal muscle strength evaluated by the Kendall double leg lowering test; (2) flexibility: passive range of motion in hip extensibility, hip internal rotation, hip external rotation, hip turnout, and ankle dorsiflexion; and (3) functional athletic and dance assessment: the star excursion balance test (SEBT), vertical jump test, and dance technique performing demi-plié and passé dance positions. MAIN OUTCOME MEASUREMENTS: Change in strength, flexibility, and functional dance measurements pre- and postsummer intensive dance training. RESULTS: Lower abdominal strength testing improved 11° on the Kendall test (P < .001); lower extremity passive flexibility was reduced in all tested ranges bilaterally. Dance technique, in performing demi-plié and passé dance positions, improved. More dancers demonstrated correct knee alignment during demi-plié (P < .001-.002) and hip alignment during plié (P = .01-.04). Dancers also had greater active hip turnout in first position passé of 2 to 3° (P = .02-.05). No significant change was found in functional athletic performance as measured by the SEBT and vertical jump test. CONCLUSION: Adolescent dancers in this study cohort who participated in a summer intensive dance program improved lower abdominal muscle strength as well as functional dance technique in demonstrating correct alignment performing demi-plié and passé dance positions despite a decrease in passive lower extremity range of motion. Further research is needed to clarify the role of these findings in training for young dancers in order to move forward injury prevention efforts. LEVEL OF EVIDENCE: II.

The Effect of Physical Therapist Involvement in the Diagnosis and Treatment of Youth and Adolescent Dancers' Injuries.

In studies of major dance companies that employ mostly adult dancers, measuring the effect of comprehensive medical management that includes daily on-site physical therapy has shown a decrease in the incidence of dance injuries, days missed from dance, injury-related costs, and Workers Compensation claims. As no comparable data have been collected with regard to youth and adolescent dancers, we sought to assess the effect of physical therapist involvement in the care of injuries sustained by young dancers on the incidence and amount of time missed from dancing. A cross sectional study was conducted by questionnaire of 55 students attending a US school for the arts summer dance program. Dancers ranged in age from 13 to 17 years, with a mean age of 15.0 ± 1.0. Most (87.3%) were female. Participants reported dancing a mean of 4.4 ± 2.6 hours per day prior to arrival at the program. They recorded 37 prior injuries, most of which (51.4%) were diagnosed by a physician, although a substantial proportion were diagnosed by a physical therapist (43.2%). Dancers whose injuries were diagnosed by a physician were more likely to miss dance class than those diagnosed by a physical therapist (100% vs. 50%; p = 0.014). When an injury did result in missed dance time, the median number of days missed was greater when the diagnosis was made by a physician as opposed to a physical therapist, although this finding was not statistically significant (6.0 vs. 2.5 days; p = 0.203). This supports previous literature showing a beneficial effect of health care management that involves physical therapists, especially those with expertise in dance injuries, on outcomes from dance injuries sustained by adult dancers.

Associations Between Sedentary Behaviors, Sleep Patterns, and BMI in Young Dancers Attending a Summer Intensive Dance Training Program.

The purpose of this study was to investigate associations between sedentary behaviors, sleep hours, and body mass index (BMI) in 12- to 17-year-old dancers. This was a cross sectional survey in which bivariate correlation and simple linear regression were used to determine associations between self-reported components. One hundred fifteen dancers were queried, 91.3% of whom were female. The mean BMI was 19.6 ± 2.3 kg/m2. Two-thirds of dancers fell below the 50th percentile for age-adjusted BMI, and 30.4% fell below the 25th percentile. Better than 12% of dancers reported a history of anxiety, and 2.6% reported depression. Mean hours of sleep per night was 7.8 ± 0.9, with 58% of the dancers getting less than 8 hours of sleep per night. The mean total screen time for dancers was 3.4 ± 2.1 hours/day, which consisted of tablet and computer usage: 1.6 ± 1.1 hours/day; texting: 0.5 ± 1.1 hours/day; watching television: 1.2 ± 1.1 hours/day; and playing video games 1.2 ± 1.1 hours/ day. Total screen time was independently associated positively with BMI, explaining nearly 10% of the variability in BMI. Age, hours dancing per day, and hours of sleep per night were not independently associated with BMI. To summarize: screen time was associated with increased BMI in this young dancer cohort; the majority of dancers slept less than 8 hours per night; anticipatory guidance addressing media use and sleep hygiene in the adolescent dancer population is needed.

Body Mass Index and Menstrual Patterns in Dancers.

Questionnaires were distributed to investigate body mass index (BMI) and menstrual patterns in female dancers aged 12 to 17 years. The study cohort consisted of 105 dancers, mean age 14.8 ± 1.1 years, and mean BMI 19.5 ± 2.3 kg/m2. In all, 92% were healthy weight for height. First menses age ranged from 10 to 15 years (mean 12.9 ± 1.1 years). A total of 44% reported irregular menses; of those, 14% described irregularity as "every other month," 37% as "every 3 months," and 49% as "skips a month occasionally." A total of 36% of the dancers stop getting their menses during times of increased activity/dance, and 30% have gone >3 months at any time without getting their menses. A significant negative correlation between BMI and age of first menses was found with lower BMI associated with increased age of first menses (linear regression, ß = -0.49, P = .021). This study supports an association between BMI and age of menarche among young female dancers. Given bone health reliance on hormonal milieu in female dancers, future research is warranted.

Dance-related concussion: a case series.

Sport-related concussion is a topic of increasing public and media attention; the medical literature on this topic is growing rapidly. However, to our knowledge no published papers have described concussion specifically in the dancer. This case series involved a retrospective chart review at a large teaching hospital over a 5.5-year period. Eleven dancers (10 female, 1 male) were identified who experienced concussions while in dance class, rehearsal, or performance: 2 in classical ballet, 2 in modern dance, 2 in acro dance, 1 in hip hop, 1 in musical theater, and 3 were unspecified. Dancers were between 12 and 20 years old at the time of presentation. Three concussions occurred during stunting, diving, or flipping. Three resulted from unintentional drops while partnering. Two followed slips and falls. Two were due to direct blows to the head, and one dancer developed symptoms after repeatedly whipping her head and neck in a choreographed movement. Time to presentation in the sports medicine clinic ranged from the day of injury to 3 months. Duration of symptoms ranged from less than 3 weeks to greater than 2 years at last documented follow-up appointment. It is concluded that dancers do suffer dance-related concussions that can result in severe symptoms, limitations in dance participation, and difficulty with activities of daily living. Future studies are needed to evaluate dancers' recognition of concussion symptoms and care-seeking behaviors. Additional work is also necessary to tailor existing guidelines for gradual, progressive, safe return to dance.