Spinal Counts, Impact, and Partnering Movements in Ballet, Modern, and Hip Hop dance: A YouTube Video Analysis Study

INTRODUCTION

Dancers have self-reported a link between spinal extension movements and low back pain (LBP). Researchers have not reported the total number or frequency that spinal movements occur in ballet, modern, or hip-hop dance classes or performances. The purpose of this study was to report the number of spinal movements dancers are exposed to in different dance environments.

MATERIALS AND METHODS

We analyzed 65 dance videos on YouTube.com for dance movements within 7 dance environments: ballet class and performance, modern class and performance, and hip-hop breaking, ciphers (large groups), and battles ("1v1s"). Two reviewers recorded counts of spinal (spinal flexion, extension, lateral flexion, and rotation), impact (jumps, leaps, and falls), and partnering movements (lifts, catches, and leans). Data analyses were processed in Jamovi (the jamovi project, Sydney, Australia). We reported movement totals, percentages, frequency, ranges, means with standard deviations (SD), and medians with interquartile range (IQR). We calculated significant differences using Mann-Whitney U tests.

RESULTS

Video length ranged from 3 to 141 minutes (mean ± SD: 38.4 ± 38.3, range: 138). the average spinal extension movements ranged from 2 ± 0.8 to 7 ± 9.6 movements per minute across genres. Modern dance class had the most spinal flexion (89 ± 53.6), rotation (60 ± 40.8), and lateral flexion (74 ± 20.7) movements. Ballet performance had the most spinal extension movements (77 ± 69.8), jumps (74 ± 48), and leaps (19 ± 18.2). Hip-hop breaking had the highest number of falling movements (2 ± 2.3). Partnering movements were only present in ballet performance, modern dance performance, and hip-hop breaking environments.

CONCLUSIONS

Movements that increase LBP occur often in all 3 dance genres. Dancers can expect frequent exposure to spinal extension movements; therefore, we recommend strengthening back and core musculature for all dancers. We recommend that ballet dancers also strengthen their lower extremity muscles. For modern dancers, we recommend strengthening their obliques. For hip-hop dancers, we recommend increasing muscular power and muscular endurance.

Perceptions and Attitudes Toward the Use of Wearable Technology in the Dance Studio Environment

Introduction: Wearable technology (WT) has become common place in sport. Increased affordability has allowed WT to reach the wrists and bodies of grassroots and community athletes. While WT is commonly used by sport populations to monitor training load, the use of WT among dancers and dance teachers is unknown. Therefore, the purpose of this study is to explore the perspectives of dancers, dance teachers, and dance parents on using WT in the dance studio environment. Methods: Dancers (aged 14+), dance teachers (aged 18+), and dance parents (with a child <18 years registered in a dance program) were recruited from local dance studios (including those offering vocational programs and/or professional training opportunities), and dance retail stores. Participants provided informed consent/assent and completed a one-time online survey about their attitudes, self-efficacy, motivations, barriers, and current practices of using WT in the studio. Results: Sixty-seven participants (19 dancers, 32 dance teachers, and 16 dance parents) completed the survey. Attitudes toward using WT were similar across all groups (mean score range = 34-38/45). Thirteen dancers (68%), 29 teachers (91%), and 7 dance parents reporting on behalf of their children (47%) were permitted to use WT in the studio. Smartwatches were the most common WT used in the studio by dancers (7/9) and teachers (13/17), while dance parents reported that their children primarily used wristband activity trackers (3/4). Among all groups, the primary reason for using WT was to track personalized training data, with calories, total duration, and heart rate being the most important perceived metrics for improving dancing. Conclusion: Across all groups, attitudes toward WT were modest. Prevalence of WT use in the dance studio varied, with wrist-based gadgets being the most common. As WT research continues in dance populations, it will be important for future studies to consider studio permissions as well as participants' existing WT use practices.

Comparison of Braces for Treatment of Sever's Disease (Calcaneal Apophysitis) in Barefoot Athletes: A Randomized Clinical Trial

CONTEXT

Sever's disease (calcaneal apophysitis) is a common condition in youth athletes, including those who participate in barefoot sports. Health care professionals often recommend that young athletes with Sever's disease wear heel cups in their shoes while active, but barefoot athletes are unable to use heel cups.

OBJECTIVE

To compare the efficacy of 2 braces used by barefoot athletes with Sever's disease.

DESIGN

Randomized controlled clinical trial.

SETTING

Pediatric sports medicine clinic.

PATIENTS OR OTHER PARTICIPANTS

A total of 43 barefoot athletes aged 7 to 14 years were enrolled, and 32 completed the study (age = 10.3 ± 1.6 years; 29 girls, 3 boys).

INTERVENTION(S)

Participants were randomized to the Tuli's Cheetah heel cup (n = 16) or Tuli's The X Brace (n = 16) group for use during barefoot sports over the 3-month study period.

MAIN OUTCOME MEASURE(S)

Participants completed self-reported assessments after diagnosis (baseline) and 1, 2, and 3 months later. The primary outcome was the Oxford Ankle Foot Questionnaire for Children (OxAFQ-C) physical score (3 months postenrollment). The secondary outcomes were OxAFQ-C school or play and emotional scores and the visual analog scale pain score.

RESULTS

The percentage of time wearing the brace during barefoot sports was not different between the Cheetah heel cup and The X Brace groups (82% versus 64% of the time in sports; P = .08). At 3 months, we observed no differences for the OxAFQ-C physical (0.79 versus 0.71; P = .80; Hedges g = 0.06), school or play (0.94 versus 1.00; P = .58; Hedges g = 0.26), or emotional (1.00 versus 1.00; P = .85; Hedges g = 0.21) score. Visual analog scale pain scores during activities of daily living and sports were lower (better) at the 2- and 3-month time points than at baseline (P < .001).

CONCLUSIONS

Both groups demonstrated improvements in ankle and foot function across time, but no between-groups differences were seen at 3 months. Given these results, barefoot athletes with Sever's disease may consider using either brace with barefoot activity to help improve pain and functional status.

Estimates of Agreement Between Three Low-cost and One High-cost Bioelectrical Impedance Analyzers using Classical and Contemporary Dancers

The aim of this study was to determine the concordance between the estimates of three low-cost and one high-cost electrical bioimpedance equipment (BIA) in classical and contemporary dancers. Participation in the study included 28 subjects (15 men and 13 women) 18 to 35 years old, who perform classical and/or modern dance, thrice weekly, from 60 to 120 min per session, for 10 years or more. Those who presented any disease, consumed drugs, supplements or multivitamins; had prostheses, surgical metal parts or pacemakers, had problems maintaining the correct anatomical positions for taking measurements, and pregnant women were excluded. Their body composition was determined with 3 low-cost BIA equipment (OMRON HBF-306C, SKULPT CHISEL and BEURER BF 1000) and one high-cost equipment (SECA mBCA 515). The results indicated that in men, SKULTP in its "complete" modality had the highest agreement with SECA (CCC=0.73, 95% CI=0.46-0.88) for body fat percentage (%BF); in women, OMRON in its "normal" modality had the highest agreement with SECA (CCC=0.85, 95% CI=0.62-0.94) for %BF; while BEURER had poor concordances (CCC=0.86-0.03) for the rest of the estimates in its different modalities, in both sexes. It is concluded that the lower cost equipment (SKULPT and OMRON) were the most consistent with SECA for %BF in normal weight dancers. BEURER had the lowest agreements with SECA, in all its modalities, as well as inconsistent estimates for all parameters. Therefore, there was no relationship between the cost of the low-cost impedance equipment and its agreement with those of a high-cost one.

Eating behaviours, the frequency of consumption of selected food products, and selected elements of lifestyle among young dancers

Background

Proper nutrition and balanced physical activity have a beneficial effect on the growth and development of young athletes, supporting their endurance and health, which is particularly important in the period of adolescence.

Objective

Aim of this study was to assess eating behaviours, frequency of consumption of some food products and selected elements of lifestyle among young dancers, as well as to compare the age of the dancers and the assessed behavior.

Material and methods

The study included 198 dancers aged 10-15 years. An originally developed questionnaire was used as a research tool.

Results

The largest group of dancers (43%) spent on training up to 2 hours per week. The recommended 4-5 meals/day were consumed by 61.1% of dancers, with 87.4% of respondents having breakfast on a daily basis. The recommendations on the daily intake of several portions of fruit and vegetables were followed by 49% and 36.9% of dancers, respectively. It is observed, that the consumption rates of sweets increased, while the consumption rates of fruit decreased with dancers'age. The consumption rates of packed lunch and afternoon snack increased, whereas the consumption rates of dinner decreased with an increasing number of hours spent training.

Conclusions

Eating behaviours and the frequency of consumption of food products by young dancers can be described as varied. Their diet is characterised by regular consumption of meals and a correct frequency of consumption of most food products, including high intake of fruit and vegetables, yoghurt and kefir, as well as low consumption of fast food products. The selected elements of dancers' lifestyle, such as sleep time and physical activity, are mostly correct.

Disordered eating attitudes and body shape concerns among North Indian Kathak dancers

OBJECTIVE

To determine the prevalence and association between disordered eating attitudes and body shape concerns in a sample of North Indian Kathak dancers.

METHOD

Participants were 206 Kathak female dancers and 235 healthy controls, ages 18-45 years. Participants completed questionnaires assessing demographics, disordered eating attitudes, and body dissatisfaction. Pearson correlations assessed the association between the disordered eating attitudes and body dissatisfaction, and binary logistic regression identified the risk of having a possible eating disorder.

RESULTS

Kathak dancers reported significantly greater disordered eating attitudes compared to controls (12.1% vs. 5.9%, p = .023). Dancers endorsed greater dieting behaviors (M = 5.6 vs. 4.5, p = .031), and binge eating episodes (p < .001) relative to their counterparts. Body dissatisfaction was significantly positively correlated with disordered eating attitudes among the dancers (p < .001). Dancers with elevated body shape concerns were five times more likely to report disordered eating attitudes, relative to their peers (p < .001).

DISCUSSION

Disordered eating attitudes and body shape concerns are prevalent among North Indian Kathak dancers. Future research should aim to develop targeted prevention and intervention programs that focus on reducing these behaviors and promoting a positive body image to mitigate the risk of disordered eating among this group.

Multimodal Sensory-Spatial Integration and Retrieval of Trained Motor Patterns for Body Coordination in Musicians and Dancers

Dancers and musicians are experts in spatial and temporal processing, which allows them to coordinate movement with music. This high-level processing has been associated with structural and functional adaptation of the brain for high performance sensorimotor integration. For these integration processes, adaptation does not only take place in primary and secondary sensory and motor areas but also in tertiary brain areas, such as the lateral prefrontal cortex (lPFC) and the intraparietal sulcus (IPS), providing vital resources for highly specialized performance. Here, we review evidence for the role of these brain areas in multimodal training protocols and integrate these findings into a new model of sensorimotor processing in complex motor learning.

Surgical Outcomes of Os Trigonum Syndrome in Dancers: A Case Series

Background

Management of ankle pain in dancers can be challenging because of the repetitive stress and complex demands placed on this region. Despite the prevalence of ankle injuries in this population, literature on surgical outcomes and return to dance is limited.

Purpose

To retrospectively evaluate the efficacy and functional outcomes after surgical excision of a symptomatic os trigonum in dancers.

Study Design

Case series; Level of evidence, 4.

Methods

Between June 2006 and June 2016, a total of 44 dancers underwent surgical excision of a symptomatic os trigonum at a single institution and by a single surgeon. All patients presented with symptoms of posterior ankle impingement syndrome and subsequently failed nonsurgical treatment. Clinical analysis was conducted using various pre- and postoperative patient-reported outcome questionnaires, including the Veterans RAND 12-Item Health Survey (VR-12), Foot Function Index-Revised (FFI-R), and visual analog scale (VAS) for pain, as well as subjective patient satisfaction.

Results

A total of 44 patients (54 ankles; mean age, 18.2 years) were retrospectively evaluated at a mean follow-up of 33.4 months. The VR-12 Physical Health score improved from a mean score of 37.8 ± 11.9 to 51.2 ± 10.5 (P < .001). The cumulative FFI-R score improved from 46.45 ± 13.8 to 31.2 ± 9.7 (P = .044), with the subcategory of "activity limitation" representing the highest-scoring FFI-R subcategory at 65.28 ± 13.4 preoperatively and improving to 34.47 ± 12.4 at follow-up (P < .001). The mean VAS score for subjective pain improved significantly from 5.39 ± 2.84 to 1.73 ± 2.10 (P < .00044).

Conclusion

Overall, the findings of the present study demonstrate that dancers of varying style and level improved significantly according to various clinical measures. Patients included in this study reported that they returned to their previous level of dance upon completion of physical therapy and maintained thriving postoperative careers, which for several meant dancing at the professional level.

Examining the Mediating Role of Motivation in the Relationship between Multidimensional Perfectionism and Well- and Ill-Being in Vocational Dancers

Perfectionism is considered to be an important personality factor within the dance context given the high number of dancers whose psychological health is influenced by its consequences. The relationship between perfectionism and dancers' well- and ill-being can be mediated by a range of variables. The present study explores the role of forms of motivation (i.e., autonomous motivation, controlled motivation and amotivation) as mediators in the relationship between perfectionism (i.e., self-oriented and socially prescribed) and an indicator of well-being (i.e., subjective vitality) and ill-being (i.e., burnout). Participants of the study were 146 male and female Spanish vocational dancers aged between 12 and 26 years old (Mean age = 15.40 ± 2.96) who completed questionnaires measuring the variables of interest. Results of multiple mediator regression analyses showed that amotivation mediated the relationships between self-oriented and socially prescribed perfectionism with burnout and subjective vitality. Self-oriented perfectionism was negatively correlated, and socially prescribed perfectionism positively associated with amotivation. Amotivation of dancers was a positive predictor of burnout and a negative predictor of subjective vitality. Overall, the findings corroborate the importance of amotivation in the relationship between perfectionism dimensions and well-being and ill-being in dancers.

When Task Constraints Delimit Movement Strategy: Implications for Isolated Joint Training in Dancers

Athletic performance is determined by numerous variables that cannot always be controlled or modified. Due to aesthetic requirements during sports such as dance, body alignment constrains possible movement solutions. Increased power transference around the ankle-joint, coupled with lower hip-joint power, has become a preferential strategy in dancers during leaps and may be considered a dance-specific stretch-shortening cycle (SSC) demand. Newell's theoretical model of interacting constraints includes organismic (or individual), environmental, and task constraints describing the different endogenous and exogenous constraints individuals must overcome for movement and athletic performance. The unique task constraints imposed during dance will be used as a model to justify an isolated joint, single-targeted block progression training to improve physical capacity within the context of motor behavior to enhance dance-specific SSC performance. The suggested ankle-specific block progression consists of isometrics, dynamic constant external resistance, accentuated eccentrics, and plyometrics. Such programming tactics intend to collectively induce tendon remodeling, muscle hypertrophy, greater maximal strength, improved rate of force development, increased motor unit firing rates, and enhanced dynamic movement performance. The current perspective provides a dualistic approach and justification (physiological and motor behavioral) for specific strength and conditioning programming strategies. We propose implementation of a single-targeted block progression program, inspired by Newell's theoretical model of interacting constraints, may elicit positive training adaptations in a directed manner in this population. The application of Newell's theoretical model in the context of a strength and conditioning supports development of musculoskeletal properties and control and is conceptually applicable to a range of athletes.

Female Collegiate Dancers Body Composition, Macronutrient and Micronutrient Intake Over Two Academic Years: A Longitudinal Analysis

Collegiate dancers face unique challenges to maintain a lean aesthetic, optimal diet, and a high-performance level due to the various stressors in college. The purpose of this study was to examine changes in body composition (BC) and diet over two years. Participants (N = 17, 19.6 ± 1.6 years) completed two laboratory sessions per semester. Sessions included height and weight, BC, dietary intake, and a health history questionnaire. Regardless of rigorous dance training and variations in the academic calendar, no significant changes in BC or diet were observed within semesters of over two years. BMI was normal (24.9 ± 4.1 kg/m²) with fat mass exceeding 30% at all timepoints. Fat mass was negatively correlated with carbohydrate, fat, and protein intake (g/kg/day; r = -0.291, p = 0.004; r = -0.372, p < 0.0001; r = -0.398, p < 0.0001; respectively). Energy intake was within the recommended daily allowance (2040 ± 710 kcal/day), however may be insufficient for an active dance population. Protein (1.1 ± 0.5 g/kg), carbohydrate (3.7 ± 1.6 g/kg), calcium (835 ± 405 mg/day), iron (17 ± 15 mg/day), and potassium (1628 ± 1736 mg/day) intake fell below recommendations for an active population. Alterations in dance training and the demands of the academic calendar may be contributing to suboptimal dietary intake and BC in female collegiate dancers.

Association between coping skills, past injury and hip pain and function in adolescent elite female ballet dancers

OBJECTIVES

The purpose of this study was to investigate the relationship between coping skills and current hip pain and function scores in ballet dancers. Secondly, we examined the relationship between coping skills and past injuries. Thirdly, we investigated the association between past injuries and current pain and function scores.

METHODS

This was a cross-sectional observational study. Twenty-six young elite female dancers (mean age 15.9 years, range 14-17 years) participated. Participants completed surveys indicating past injury history, rating pain and function on the short International Hip Outcome Tool (iHOT-12), and assessing coping skills on the Athletic Coping Skills Inventory Score (ACSI-28). Independent t-tests, Cohen's d, effect size, chi-square and correlation coefficient and determination analyses were conducted.

RESULTS

There was no significant relationship between iHOT-12 scores and ACSI-28 scores (r = -0.250, p = 0.087). There was no significant difference (p = 0.289) in past injuries comparing those with ACSI-28 scores above and below the mean ACSI-28. A significant moderate negative correlation was detected between both iHOT-12 scores and total past injuries (r = -0.609, p < 0.001), and iHOT-12 scores and past non-hip injuries (r = -0.628, p < 0.001).

CONCLUSION

Past injuries may influence current hip pain and function in young female dancers. Correlation determination (r²) indicated that 37% of current pain and function scores were explained by total past injuries in a small group of young high-level ballet dancers. Further research should engage a prospective design to investigate the predictive ability of findings.

Should Ballet Dancers Vary Postures and Underfoot Surfaces When Practicing Postural Balance?

BACKGROUND

Postural balance (PB) is an important component skill for professional dancers. However, the effects of different types of postures and different underfoot surfaces on PB have not adequately been addressed.

PURPOSE

The main aim of this study was to investigate the effect of different conditions of footwear, surfaces, and standing positions on static and dynamic PB ability of young ballet dancers.

METHODS

A total of 36 male and female young professional ballet dancers (aged 14-19 years) completed static and dynamic balance testing, measured by head and lumbar accelerometers, while standing on one leg in the turnout position, under six different conditions: (1) "relaxed" posture; (2) "ballet" posture; (3) barefoot; (4) ballet shoes with textured insoles; (5) barefoot on a textured mat; and (6) barefoot on a spiky mat.

RESULTS

A condition effect was found for static and dynamic PB. Static PB was reduced when dancers stood in the ballet posture compared with standing in the relaxed posture and when standing on a textured mat and on a spiky mat (p < .05), and static PB in the relaxed posture was significantly better than PB in all the other five conditions tested. Dynamic PB was significantly better while standing in ballet shoes with textured insoles and when standing on a spiky mat compared with all other conditions (p < .05).

CONCLUSIONS

The practical implications derived from this study are that both male and female dancers should try to be relaxed in their postural muscles when practicing a ballet aligned position, including dance practice on different types of floors and on different types of textured/spiky materials may result in skill transfer to practice on normal floor surfaces, and both static and dynamic PB exercises should be assessed and generalized into practical dance routines.

DANCE, BALANCE AND CORE MUSCLE PERFORMANCE MEASURES ARE IMPROVED FOLLOWING A 9-WEEK CORE STABILIZATION TRAINING PROGRAM AMONG COMPETITIVE COLLEGIATE Dancers

BACKGROUND

Dance performance requires not only lower extremity muscle strength and endurance, but also sufficient core stabilization during dynamic dance movements. While previous studies have identified a link between core muscle performance and lower extremity injury risk, what has not been determined is if an extended core stabilization training program will improve specific measures of dance performance.

HYPOTHESIS/PURPOSE

This study examined the impact of a nine-week core stabilization program on indices of dance performance, balance measures, and core muscle performance in competitive collegiate dancers.

STUDY DESIGN

Within-subject repeated measures design.

METHODS

A convenience sample of 24 female collegiate dance team members (age = 19.7 ± 1.1 years, height = 164.3 ± 5.3 cm, weight 60.3 ± 6.2 kg, BMI = 22.5 ± 3.0) participated. The intervention consisted of a supervised and non-supervised core (trunk musculature) exercise training program designed specifically for dance team participants performed three days/week for nine weeks in addition to routine dance practice. Prior to the program implementation and following initial testing, transversus abdominis (TrA) activation training was completed using the abdominal draw-in maneuver (ADIM) including ultrasound imaging (USI) verification and instructor feedback. Paired t tests were conducted regarding the nine-week core stabilization program on dance performance and balance measures (pirouettes, single leg balance in passe' releve position, and star excursion balance test [SEBT]) and on tests of muscle performance. A repeated measures (RM) ANOVA examined four TrA instruction conditions of activation: resting baseline, self-selected activation, immediately following ADIM training and four days after completion of the core stabilization training program. Alpha was set at 0.05 for all analysis.

RESULTS

Statistically significant improvements were seen on single leg balance in passe' releve and bilateral anterior reach for the SEBT (both p ≤ 0.01), number of pirouettes (p = 0.011), and all measures of strength (p ≤ 0.05) except single leg heel raise. The RM ANOVA on mean percentage of change in TrA was significant; post hoc paired t tests demonstrated significant improvements in dancers' TrA activations across the four instruction conditions.

CONCLUSION

This core stabilization training program improves pirouette ability, balance (static and dynamic), and measures of muscle performance. Additionally, ADIM training resulted in immediate and short-term (nine-week) improvements in TrA activation in a functional dance position.

LEVEL OF EVIDENCE

2b.

Is There a Correlation Between Static and Dynamic Postural Balance Among Young Male and Female Dancers?

Aimed to investigate whether young male and female dancers have different patterns of association between static and dynamic postural balance (PB), 60 dancers from the Australian Ballet School (14-19 years old) were tested for static and dynamic PB with head and lumbar accelerometers. Monotonic relationships between static and dynamic PB were found in head movements among young female dancers in all three directions, but were found for young male dancers in the mediolateral (ML) and anteroposterior (AP) directions only. In lumbar movements, monotonic relationships were found for young female dancers in the AP direction only. Comparing head with lumbar movements in static PB, young male dancers demonstrated monotonic relationships between head and lumbar movements in all 3 directions; however, young female dancers demonstrated monotonic relationships in the AP direction only. In the dynamic measurements, both male and female dancers demonstrated monotonic relationships between head and lumbar movements for all parameters measured in the ML and vertical directions (p < .05). In conclusions, among female dancers static PB ability is correlated with their dynamic ability, whereas among male dancers, no relationship between the static and dynamic PB in the AP direction exists. Male dancers showed head and lumbar coordination in the static PB movement, but both genders manifested no head and lumbar coordination in the AP direction measured for dynamic PB.

The role of psychological factors in the career of the independent dancer

Previous research indicates that psychological factors such as motivation and mental skills play an important role in relation to performance and to negotiating talent development stages. However, little is known about these factors in dance, particularly with regard to the independent dancer whose career may involve multiple roles, varied work patterns, and periods of instability. The aim of this study was to explore dancers’ motivation to work in an independent capacity, and the extent to which dancers’ psychological characteristics and skills enabled them to navigate a career in this demanding sector. In-depth semi-structured interviews were conducted with 14 dancers at different stages of their careers. Interviews were transcribed verbatim and content analyzed. Analysis revealed that the dancers were intrinsically motivated and highly committed to the profession. Working in the independent sector offered dancers opportunities for growth and fulfillment; they appreciated the autonomy, flexibility and freedom that the independent career afforded, as well as working with new people across roles and disciplines. In order to overcome the various challenges associated with the independent role, optimism, self-belief, social support, and career management skills were crucial. The mental skills reported by the participants had developed gradually in response to the demands that they faced. Therefore, mental skills training could be invaluable for dancers to help them successfully negotiate the independent sector.

Body dissatisfaction and self-esteem in female students aged 9-15: the effects of age, family income, body mass index levels and dance practice

This study aimed to analyze the effects of age, family income, body mass index and dance practice on levels of body dissatisfaction and self-esteem in female students. The sample consisted of 283 female subjects attending a public school with a mean age of 11.51±1.60 years and a mean body mass index of 18.72 kg/m2 (SD=3.32). The instruments used were the Body Dissatisfaction Scale for Adolescents and the Rosenberg Self-Esteem Scale, both of which showed good internal consistency (0.77 and 0.81, respectively). The tests were applied (two-factor ANOVA) to compare the students practicing and those not practicing dance; the differences in the levels of body dissatisfaction (p=0.104) and self-esteem (p=0.09) were considered significant. The results demonstrated that age negatively correlated with body dissatisfaction (r=-0.19; p<0.01) and that higher body mass index levels were associated with greater body dissatisfaction (r=0.15, p=0.016) and lower levels of self-esteem (r=-0.17, p<0.01) only in non-practitioners. The practice of dance had a significant effect on levels of body dissatisfaction (F=4.79; p=0.030; η(2)=0.02), but there was no significant difference in self-esteem (F=1.88; p=0.172; η(2)=0.02). It can be concluded that female children and adolescents practicing dance have higher self-esteem, and are more satisfied with their body weight and their appearance. Moreover, results showed that self-esteem and body dissatisfaction were influenced by the body mass index levels only in the non-practitioners group.

Comparison of landing biomechanics between male and female dancers and athletes, part 1: Influence of sex on risk of anterior cruciate ligament injury

BACKGROUND

The incidence of anterior cruciate ligament (ACL) injuries among dancers is much lower than among team sport athletes, and no clear disparity between sexes has been reported in the dance population. Although numerous studies have observed differences in landing biomechanics of the lower extremity between male and female team sport athletes, there is currently little research examining the landing biomechanics of male and female dancers and none comparing athletes to dancers. Comparing the landing biomechanics within these populations may help explain the lower overall ACL injury rates and lack of sex disparity.

HYPOTHESIS

The purpose was to compare the effects of sex and group (dancer vs team sport athlete) on single-legged drop-landing biomechanics. The primary hypothesis was that female dancers would perform a drop-landing task without demonstrating typical sex-related risk factors associated with ACL injuries. A secondary hypothesis was that female team sport athletes would display typical ACL risk factors during the same task.

STUDY DESIGN

Controlled laboratory study.

METHODS

Kinematics and kinetics were recorded as 40 elite modern and ballet dancers (20 men and 20 women) and 40 team sport athletes (20 men and 20 women) performed single-legged drop landings from a 30-cm platform. Joint kinematics and kinetics were compared between groups and sexes with a group-by-sex multivariate analysis of variance (MANOVA) followed by pairwise t tests.

RESULTS

Dancers of both sexes and male team sport athletes landed similarly in terms of frontal-plane knee alignment, whereas female team sport athletes landed with a significantly greater peak knee valgus (P = .007). Female dancers were found to have a lower hip adduction torque than those of the other 3 groups (P = .003). Dancers (male and female) exhibited a lower trunk side flexion (P = .002) and lower trunk forward flexion (P = .032) compared with team sport athletes.

CONCLUSION

In executing a 30-cm drop landing, female team sport athletes displayed a greater knee valgus than did the other 3 groups. Dancers exhibited better trunk stability than did athletes.

CLINICAL RELEVANCE

These biomechanical findings may provide insight into the cause of the epidemiological differences in ACL injuries between dancers and athletes and the lack of a sex disparity within dancers.

Comparison of landing biomechanics between male and female dancers and athletes, part 2: Influence of fatigue and implications for anterior cruciate ligament injury

BACKGROUND

Fatigue is strongly linked to an increased risk of injuries, including anterior cruciate ligament (ACL) ruptures. Part 1 of this study identified differences in the biomechanics of landing from a jump between dancers and team athletes, particularly female athletes, which may explain the epidemiological differences in ACL injuries between dancers and team athletes and the lack of a sex disparity within dancers. However, it is not known if these biomechanical variables change differently between team athletes and dancers in the face of fatigue. PURPOSE/ HYPOTHESIS: The purpose of this study was to compare dancers' and team athletes' resistance to fatigue and its effect on the biomechanics of single-legged drop landings. The primary hypotheses were that dancers may be more resistant than team athletes to the onset of fatigue and/or may have different biomechanical responses than athletes in landing tasks once fatigue has been achieved.

STUDY DESIGN

Controlled laboratory study.

METHODS

Kinematics and kinetics were recorded as 40 elite modern and ballet dancers (20 men and 20 women) and 40 team sport athletes (20 men and 20 women; National Collegiate Athletic Association Division I-III) performed single-legged drop landings from a 30-cm platform before and after a fatigue protocol consisting of step-ups and vertical jumps. Unfatigued and fatigued joint kinematics and kinetics were compared between groups and sexes with multivariate analyses of variance, followed by pairwise t tests as appropriate.

RESULTS

Dancers took longer (P = .023) than team athletes to reach a similar state of fatigue. Multiple kinetic (eg, increased peak knee valgus moment; P < .001) and kinematic (eg, increased lateral and forward trunk flexion; P < .001 and P = .002, respectively) parameters of landing changed with fatigue, such that both fatigued dancers and athletes landed with mechanics that were more at risk for ACL injuries as compared with before fatigue.

CONCLUSION

Dancers took significantly longer to reach fatigue than team athletes. Female athletes consistently exhibited landing patterns associated with a risk for ACL injuries when compared with the other 3 groups. Fatigue changed landing mechanics similarly in both dancers and athletes, such that all groups landed with worse alignment after being fatigued.

CLINICAL RELEVANCE

Dancers are more resistant to lower extremity fatigue than athletes, and this may partially explain the lower incidence of ACL injuries in both male and female dancers compared to team athletes. The extensive training in landing technique and daily practice that dancers undergo from a young age may be responsible for the higher levels of endurance.

The neuroanatomical correlates of training-related perceptuo-reflex uncoupling in dancers

Sensory input evokes low-order reflexes and higher-order perceptual responses. Vestibular stimulation elicits vestibular-ocular reflex (VOR) and self-motion perception (e.g., vertigo) whose response durations are normally equal. Adaptation to repeated whole-body rotations, for example, ballet training, is known to reduce vestibular responses. We investigated the neuroanatomical correlates of vestibular perceptuo-reflex adaptation in ballet dancers and controls. Dancers' vestibular-reflex and perceptual responses to whole-body yaw-plane step rotations were: (1) Briefer and (2) uncorrelated (controls' reflex and perception were correlated). Voxel-based morphometry showed a selective gray matter (GM) reduction in dancers' vestibular cerebellum correlating with ballet experience. Dancers' vestibular cerebellar GM density reduction was related to shorter perceptual responses (i.e. positively correlated) but longer VOR duration (negatively correlated). Contrastingly, controls' vestibular cerebellar GM density negatively correlated with perception and VOR. Diffusion-tensor imaging showed that cerebral cortex white matter (WM) microstructure correlated with vestibular perception but only in controls. In summary, dancers display vestibular perceptuo-reflex dissociation with the neuronatomical correlate localized to the vestibular cerebellum. Controls' robust vestibular perception correlated with a cortical WM network conspicuously absent in dancers. Since primary vestibular afferents synapse in the vestibular cerebellum, we speculate that a cerebellar gating of perceptual signals to cortical regions mediates the training-related attenuation of vestibular perception and perceptuo-reflex uncoupling.

Micro-finite element analysis applied to high-resolution MRI reveals improved bone mechanical competence in the distal femur of female pre-professional dancers

Micro-finite element analysis applied to high-resolution (0.234-mm length scale) MRI reveals greater whole and cancellous bone stiffness, but not greater cortical bone stiffness, in the distal femur of female dancers compared to controls. Greater whole bone stiffness appears to be mediated by cancellous, rather than cortical bone adaptation.

INTRODUCTION

The purpose of this study was to compare bone mechanical competence (stiffness) in the distal femur of female dancers compared to healthy, relatively inactive female controls.

METHODS

This study had institutional review board approval. We recruited nine female modern dancers (25.7±5.8 years, 1.63±0.06 m, 57.1±4.6 kg) and ten relatively inactive, healthy female controls matched for age, height, and weight (32.1±4.8 years, 1.6±0.04 m, 55.8±5.9 kg). We scanned the distal femur using a 7-T MRI scanner and a three-dimensional fast low-angle shot sequence (TR/TE=31 ms/5.1 ms, 0.234 mm×0.234 mm×1 mm, 80 slices). We applied micro-finite element analysis to 10-mm-thick volumes of interest at the distal femoral diaphysis, metaphysis, and epiphysis to compute stiffness and cross-sectional area of whole, cortical, and cancellous bone, as well as cortical thickness. We applied two-tailed t-tests and ANCOVA to compare groups.

RESULTS

Dancers demonstrated greater whole and cancellous bone stiffness and cross-sectional area at all locations (p<0.05). Cortical bone stiffness, cross-sectional area, and thickness did not differ between groups (>0.08). At all locations, the percent of intact whole bone stiffness for cortical bone alone was lower in dancers (p<0.05). Adjustment for cancellous bone cross-sectional area eliminated significant differences in whole bone stiffness between groups (p>0.07), but adjustment for cortical bone cross-sectional area did not (p<0.03).

CONCLUSIONS

Modern dancers have greater whole and cancellous bone stiffness in the distal femur compared to controls. Elevated whole bone stiffness in dancers may be mediated via cancellous, rather than cortical bone adaptation.

Early knee changes in dancers identified by ultra-high-field 7 T MRI

We aimed to determine whether a unique, ultra-high-field 7 T magnetic resonance imaging (MRI) scanner could detect occult cartilage and meniscal injuries in asymptomatic female dancers. This study had Institutional Review Board approval. We recruited eight pre-professional female dancers and nine non-athletic, female controls. We scanned the dominant knee on a 7 T MRI scanner using a three-dimensional fast low-angle shot sequence and a proton density, fast spin-echo sequence to evaluate cartilage and menisci, respectively. Two radiologists scored cartilage (International Cartilage Repair Society classification) and meniscal (Stoller classification) lesions. We applied two-tailed z- and t-tests to determine statistical significance. There were no cartilage lesions in dancers or controls. For the medial meniscus, the dancers demonstrated higher mean MRI score (2.38 ± 0.61 vs 1.0 ± 0.97, P < 0.0001) and higher frequency of mean grade 2 lesions (88% vs 11%, P < 0.01) compared with the controls. For the lateral meniscus, there was no difference in score (0.5 ± 0.81 vs 0.5 ± 0.78, P = 0.78) in dancers compared with the control groups. Asymptomatic dancers demonstrate occult medial meniscal lesions. Because this has been described in early osteoarthritis, close surveillance of dancers' knee symptoms and function with appropriate activity modification may help maintain their long-term knee health.

Comparison of Cervical and Ocular Vestibular Evoked Myogenic Potentials in Dancers and Non-Dancers

The objective of the study was to assess the sacculocollic and otolith ocular pathway function using cervical vestibular evoked myogenic potentials (cVEMP) and ocular vestibular myogenic potentials (oVEMP) in dancers and non dancers. Total 16 subjects participated in the study. Out of 16 participants, 8 were trained in Indian classical form of dance (dancers) and other 8 participants who were not trained in any dance form (non dancers). cVEMP and oVEMP responses were recorded for all the subjects. Non Parametric Mann-Whitney U test revealed no significant difference between dancers and non dancers for the latency and amplitude parameter for cVEMP and oVEMP, i.e. P13, N23 latency and P13-N23 complex amplitude and N10, P14 latency, N10-P14 complex amplitude respectively. The vestibular system comprises of several structures. It is possible that the dance style practiced by the dancer’s group assessed in this study does not contribute towards improving the plasticity of the sacculocollic and otolith-ocular pathways. It can be concluded that not all forms of dance training brings about a change in the plasticity of the sacculocollic and otolithocular pathways.

Hip dysplasia and the performing arts: is there a correlation?

Dancers frequently present with hip pain. The etiology of this pathology has not been clearly identified from an anatomical perspective. Structural variations including hip dysplasia and dynamic variables from the foot to the pelvis will be discussed. Understanding the etiology as a structural entity, neuromuscular entity or a combination of the two, allows for a successful rehabilitative process and a successful return to dance. This article describes the possible correlation between hip dysplasia and hip pain in the dancer, the relationship of dance postures to the kinematic chain and outlines possible treatment strategies for management.

Body image, anthropometric measures, and eating-disorder prevalence in auxiliary unit members

CONTEXT

Medical professionals have recognized eating disorders and related problems in competitive athletes. Auxiliary members (color guard, dance, majorettes) experience the same appearance-related pressures observed in sports commonly associated with eating disorders.

OBJECTIVE

To estimate eating-disorder prevalence based on associated eating-disorder characteristics and behaviors in female auxiliary members and to compare perceived and ideal body images and anthropometric measurements between at-risk and not-at-risk participants for eating-disorder characteristics and behaviors.

DESIGN

Cross-sectional design.

SETTING

Three universities in the southeastern United States.

PATIENTS OR OTHER PARTICIPANTS

Participants (n = 101, mean age = 19.2 +/- 1.2 years) represented 3 auxiliary units, including color guard (n = 35), dance line (n = 47), and majorettes (n = 19).

MAIN OUTCOME MEASURE(S)

Participants self-reported menstrual history, height, and weight. Anthropometric measurements included height, weight, body fat percentage, and waist and hip circumferences. We screened for eating-disorder risk behavior with the Eating Attitudes Test (EAT)-26 and for body dissatisfaction with the Figural Stimuli Survey.

RESULTS

Based on the EAT-26, we estimated eating-disorder prevalence among members to measure 29.7% (95% confidence interval = 20.8%, 38.6%). The EAT-26 results revealed that 21% of participants used purgatives and 14% vomited to control weight or shape. The at-risk group had higher scores on the EAT-26 total (P

CONCLUSIONS

Collegiate auxiliary unit members may have an unacceptable prevalence of eating disorders. Our results validate concerns that auxiliary members may exhibit an unacceptable eating-disorder risk, highlighting the need to examine and address unhealthy weight-management behaviors independent of eating-disorder status.

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Key Words

• EAT-26
• athletes
• body image
• dancers

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MESH Headings

• Adult
• Analysis of Variance
• Anthropometry
• Body Image
• Body Mass Index
• Competitive Behavior
• Confidence Intervals
• Cross-Sectional Studies
• Dancing
• Feeding and Eating Disorders/epidemiology
• Female
• Humans
• Menstruation
• Nutritional Status
• Prevalence
• Psychometrics
• Risk Factors
• Sex Factors
• Surveys and Questionnaires
• United States/epidemiology
• Weight Loss

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Affiliation(s)

Toni M Torres-McGehee University of South Carolina, Columbia, SC 29208, USA.
James M Green
James D Leeper
Deidre Leaver-Dunn
Mark Richardson
Phillip A Bishop

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