Characteristics of Eight Irish Dance LandingsConsiderations for Training and Overuse Injury Prevention

Irish dance has evolved in aesthetics that lead to greater physical demands on dancers' bodies. Irish dancers must land from difficult moves without letting their knees bend or heels touch the ground, causing large forces to be absorbed by the body. The majority of injuries incurred by Irish dancers are due to overuse (79.6%). The purpose of this study was to determine loads on the body of female Irish dancers, including peak force, rise rate of force, and impulse, in eight common Irish hard shoe and soft shoe dance movements. It was hypothesized that these movements would produce different ground reac- tion force (GRF) characteristics. Sixteen female Irish dancers were recruited from the three highest competitive levels. Each performed a warm-up, reviewed the eight movements, and then performed each movement three times on a force plate, four in soft shoes and four in hard shoes. Ground reaction forces were measured using a three-dimensional force plate recording at 1,000 Hz. Peak force, rise rate, and vertical impulse were calculated. Peak forces normalized by each dancer's body weight for each of these variables were significantly different between move- ments and shoe types [F(15, 15)= 65.4, p < 0.01; F(15, 15) = 65.0, p < 0.01; and F(15, 15) = 67.4, p < 0.01, respectively]. The variable years of experience was not correlated with peak force, rise rate, or impulse (p > 0.40). It is concluded that there was a large range in GRF characteristics among the eight movements studied. Understanding the force of each dance step will allow instructors to develop training routines that help dancers adapt gradually to the high forces experienced in Irish dance training and competitions, thereby limiting the potential for overuse injuries.

Body Image Dissatisfaction, Eating Disorders, and Associated Factors in Brazilian Professional Ballroom Dancers

The search for movement plasticity causes dancers to seek to achieve and maintain low body weight, which can lead to dissatisfaction with their body image and to eating disorders. The purpose of this study was to analyze body image satisfaction and the presence of eating disorders and associated factors in professional ballroom dancers in Brazil. Three hundred and twenty dancers took part via a self-reported questionnaire. The majority of the dancers proved to be dissatisfied with their body image; the increase with age of body mass index (BMI) influenced the dissatisfaction due to excess weight. It is concluded that body image is associated with eating disorders, age, and BMI in ballroom dancers.

Injury Occurrence in Break DanceAn Online Cross-Sectional Cohort Study of Breakers

Breaking is the most physical of the hip- hop dance styles, but little research has examined the health and well-being of its participants. Using a cross-sectional recall design, a self-reported online health and well-being survey was open for a 5-month period (April 2017 to August 2017). Three hundred and twenty adult break dancers (16% professional, 65% student-recreational) with a minimum of 6-months experience completed the survey. The main outcome measures were injury incidence and etiology and training hours. Fifty-two percent of respondents trained between 4 and 9 hours per week over 3 days, which is significantly less than theatrical dancers. More than 71% reported a dance-related injury in the previous 12 months, and 44.5% were injured at time of the survey. Self-reported types of injury were significantly different from other dance genres. The most frequently injured body parts were arm-hand (40.6%), shoulder (35.9%), knee (32.2%), neck (22.8%), and ankle (15.6%). When injured, 29% of respondents either took their own preventative steps or continued to dance carefully, while 20% sought medical help. "Yourself" was the most cited influence on returning to dance after injury (47%). The current survey highlights breaking's differences from other dance genres, particularly with regard to injury incidence and etiology.

Corticosteroid Injections in Posterior Ankle Impingement Syndrome: A Survey of Professional and Elite Student Ballet Dancers

Posterior ankle impingement syndrome (PAIS) involves pain at the posterior as- pect of the ankle, due in dancers largely to repetitive hyperplantarflexion. In daily practice, corticosteroid injection is often used to relieve the pain of PAIS, but little has been recorded with regard to its effectiveness. The primary objective of this study was to determine the ef- fect on pain of corticosteroid injections in professional and elite student ballet dancers with PAIS. The secondary ob- jectives were to evaluate the prevalence of PAIS, the duration of the effect of injection, patient satisfaction with the effect of injection, time to return to class and performance, and ability to dance after injection. All members of the Dutch National Ballet and the National Ballet Academy Amsterdam received a self-administered questionnaire focused on the use and effect of corticosteroid injections in the treatment of PAIS. The response rate was 61% (77 of 126). Of the included dancers, 38% (29 of 77) had suffered from PAIS, and 38% (11 of 29) had received at least one injection. The numeric rating scale (NRS) was used to assess the severity of pain before and 2 and 6 weeks after injections. The median NRS pain before injection was 9.0 (IQR 8.0-9.5), 3.0 (IQR 0.5-6.5) 2 weeks after injection, and 3.0 (IQR 0.5-6.0) 6 weeks after injection. Overall median NRS satisfaction with the effect of injection was 7.0 (IQR 0-10), and satisfaction with the duration of the effect was 5.0 (IQR 2.0-10). It is concluded that there is a high prevalence of PAIS in ballet dancers and corticosteroid injections are regularly used for pain reduction with good results.

An Updated Systematic Review of Turnout Position Assessment Protocols Used in Dance Medicine and Science Research

Turnout, or external rotation of the lower limbs, is an integral part of classical ballet technique. Contributions of lower limb structures to turnout can be separated into HER (hip external rotation) and NHCTO (non-hip contributions to turnout). This study aimed to review systematically methods used to measure turnout in dance medicine and science research, thereby updating the literature since the Champion and Chatfield review of 2008. CINAHL, EMBASE, PubMed, and Web of Science were searched in January 2018 by two independent reviewers. Peer-reviewed studies measuring turnout in dance were included, except those published prior to March 23, 2006, as that was the last date of publication included in the previous review. Abstracts, theses, and editorials were excluded. From each study, study design, population (sample size, sex, age, genre of dance, and level of training), details of the protocol used, and result of turnout measurement were extracted, as well as reliability data. All included studies were assessed for risk of bias, using either Newcastle-Ottawa scale, AXIS tool, or PEDro scale as appropriate for each study design. A total of 41 studies met the inclusion criteria. Twenty-eight studies measured HER, nine measured NCHTO, and 22 measured total turnout (TTO). An increased number of studies investigated TTO (N = 22; N = 4 passive TTO) and NHCTO (N = 9) since 2006. All studies scored above half the points attainable from their respective tools. Results suggest HER remains the most common protocol for measuring turnout (N = 28), despite the fact it disregards input from structures below the hip. It is concluded that researchers should focus on quality of reporting of protocols to ensure repeatability and facilitate comparison of results. Future studies should include absolute reliability and validity testing of all currently used protocols so that standardization can be fully achieved.

Body Composition Adaptations Throughout an Elite Circus Student-Artist Training Season

The purpose of this study was to perform a longitudinal assessment of body composition of circus student-artists in an elite 3-year college training program. Ninety-two student-artists participated (age = 20.39 ± 2.42 years; height = 170.01 ± 8.01 cm; mass = 66.48 ± 11.07 kg; 36% female and 64% male), representing 92% of the student population. Body composi- tion was assessed using multi-frequency bioelectrical impedance at four strategic time points throughout the training year to evaluate changes over the two semesters (September to December and January to April) and winter vacation (December to January). Workloads were subjectively assessed using ratings of perceived exer- tion (RPE). Averaged over the academic terms, fat mass was 11.5 ± 4.8%, muscle mass was 50.2 ± 3.4%, and body mass index was 22.9 ± 2.2. Males and females differed significantly across all absolute and relative body composition variables. Muscle mass increased (semester one, +1.0%, p < 0.001; semester two, +0.4%, p < 0.05) while fat mass decreased during each semester (semester one, -1.6%, p < 0.001; semester two, -0.6%, p < 0.05) co-varying with changes in RPE (semester one, +2.3, p < 0.05; semester two, +1.7, p < 0.05). During the winter vacation period, percent fat mass increased (males, +1.0%; females, +2.0%) and percent muscle mass decreased (males, -0.6%; females, -0.9%). Discipline-specific differences in body composition were also detected, and significant differences were observed between student-artists grouped by years in school. Over the training year, there was a positive adaptation for muscle and fat mass despite the negative adaptation experienced during the winter vacation period.

Quantitative MRI Analysis of the Talocrural and Talonavicular Joints in Ballet Dancers

The ankles of ballet dancers are routinely under heavy loading that may lead to osteoarthritic changes. It would be clinically useful to identify such pathology as early as possible in a dancer's career. Therefore, the purpose of this study was to compare quantitative measurements in magnetic resonance (MR) images of the talocrural and talonavicular joints in ballet dancers and healthy non-dancers for use in formulating prediction of chronic injury and degenerative joint disease in these locations. Quantitative measurements in MR images of the talocrural and talonavicular joints were compared in 10 female ballet dancers, 10 healthy female non-dancers, and nine male ballet dancers. Fat-suppressed density-weighted proton, T1rho, and T2 mapping images were acquired with a 3.0 T MR scanner. Medial and lateral subchondral bone distance between the tibia and talus (MSBD and LSBD), axial navicular-talus axis angle (ANT angle), sagittal talar neck angle against the posterior talocalcaneal joint (TN angle), and curvature of navicular surface at the talonavicular joint were measured on sagittal images. The medial subchondral bone distance was found to be significantly larger in female dancers than female non-dancers (4.05 mm vs. 2.75 mm, p < 0.05), whereas there were no significant differences in LSBD (2.63 mm vs. 2.63 mm, p = 0.87). Axial navicular talus angles in female dancers were significantly larger than those in female non-dancers (38.9° vs. 24.3°, p < 0.05). There was a tendency for the TN angle to be smaller and navicular curvature (NC) to be larger in female dancers compared to female non-dancers, though the differences were not significant (TN angle: 16.6° vs. 22.3°, p = 0.09, and NC: 0.186 vs. 0.165, p = 0.28). There were no significant differences in T1rho or T2 values of talonavicular joint cartilage. These results show that the bony anatomy of dancers' ankles may adapt to the stresses placed on them by ballet.

The Dance Functional Outcome Survey (DFOS) is Reliable, Valid, and Responsive in Pediatric Dancers

The Dance Functional Outcome Survey (DFOS) is a dance-specific questionnaire developed for use with ballet and modern dancers at all training levels. To date, no study has assessed the psychometric properties of the DFOS in pediatric dancers. The purposes of this study were to determine: 1. the reliability of the DFOS when used with healthy and injured pediatric dancers; 2. the validity of the DFOS com- pared to a well-established generic scale, the Pediatric Quality of Life Inventory Physical Function Scale (PedsQL-PFS); and 3. the sensitivity and responsiveness to change of the DFOS in injured dancers. One hundred and two dancers completed the DFOS twice within 10 days. Intra-class correlation coefficients (ICCs) were used to assess test-retest reliability. In a sample of 148 dancers, construct validity was explored by comparing the DFOS to the PedsQL-PFS using Pearson correlations, and Exploratory Factor Analysis (EFA) and Cronbach's alpha were used for internal consistency analyses. A sub-set of 22 injured dancers was employed to examine responsiveness using repeated measures analysis of variance (p < 0.05). The DFOS demonstrated high test-retest reliability (ICC ≥ 0.90). The DFOS total score, activities of daily living (ADL), and dance technique sub-scores had strong construct validity compared to the PedsQL-PFS (r ≥ 0.79). Cronbach's alpha was high ( α = 0.92), indicating excellent internal consistency. There were significant differences across time in DFOS scores (p < 0.001), demonstrating responsiveness to change. There were no floor or ceiling effects. Thus, the DFOS demonstrates excellent reliability, strong validity, and good responsiveness over time and is a viable tool for assessing function in pediatric dancers.