Dance floor mechanical properties and dancer injuries in a touring professional ballet company

Higher risk of Achilles tendon ruptures at competition than training sites in female collegiate gymnasts

BACKGROUND

Reportedly, 17.2% of collegiate female gymnasts experience Achilles tendon ruptures (ATRs). Cumulative microtraumas resulting in chronic tendinopathy/tendinitis may contribute to this high injury risk. We hypothesized that the risk of ATRs in female collegiate gymnasts increases with years of competitive gymnastics, that non-steroidal anti-inflammatory drug (NSAID) use is associated with less ATRs, and that the risk is larger during competition than training.

METHODS

Female gymnasts from 78 USA collegiate teams completed a survey assessing the prevalence of ATRs, NSAID use, age at which competitive gymnastics started and age at which ATR occurred, and whether ATRs occurred during training or competition.

RESULTS

Twenty-one of 103 gymnasts (20.4%, 95% CI: 13.6% to 29.4%) experienced ATRs. Eighteen of 21 ruptures (85.7%, 95% CI: 61.3% to 95.8%) occurred after more than ten years of competitive gymnastics (mean: 14.0±2.6 years, 95% CI: 12.8 to 15.2 years). ATRs occurred 0.08±0.01 (95% CI: 0.06 to 0.11) times per 1000 hours at training versus 1.85±0.11 (95% CI: 1.60 to 2.10) times per 1000 hours at competition (P<0.05). Prevalence of NSAID use was 27.6% (95% CI: 18.6% to 39.0%) in gymnasts without ATR but only 5.5% (95% CI: 0.6% to 35.5%, P=0.09) in gymnasts with ATR. Multiple regression analysis demonstrated a negative association between NSAID use and incidence of ATRs (P<0.05).

CONCLUSIONS

Female collegiate gymnasts are at high risk for ATRs, especially after more than ten years of competitive gymnastics and during competition.

Force Attenuation Properties of Padded Dance Support Socks

BACKGROUND

Foot injuries occur frequently in dancers, and researchers have investigated different protective measures to reduce their incidence. Research has primarily focused on ballet, but foot injuries also are common in modern and contemporary dance where footwear is not worn. While padded dance socks are a potential solution, the extent to which they provide force reduction for the feet is unknown.<br/> Purpose: This study investigates the extent to which padded dance support socks can reduce force on the foot during a dance sequence and when landing from a sauté jump.<br/> Methods: Twenty-one injury-free dancers (2 M, 19 F; age: 21.5 ± 6.7 years; height: 165.5 ± 6.1 cm; mass: 68.6 ± 15.0 kg) volunteered for this randomized, cross-over design study. Participants per- formed a 40-second modern dance sequence and a sauté jump landing under two conditions: wearing Apolla Performance Shock™ dance socks (DS) and with bare feet (BF). During these activities, 1.0 cm diameter circular force transducers were affixed under the first metatarsophalangeal joint and under the center of the heel. The sensors wirelessly recorded peak toe force, peak heel force, mean toe force, and mean heel force during dancing. A force platform measured vertical ground reaction force (VGRF) and time to peak VGRF, while the foot sensors measured peak toe force and peak heel force, during the jump landings. A Noraxon MR3.12 biomechanics system synchronized and recorded the data. All force data were normalized to body weight (BW). Dependent samples t-tests were used to assess pairwise differences in these measures between the DS and BF conditions. Alpha was set at p < 0.05.<br/> Results: Mean and peak heel forces/BW when dancing with DS were significantly lower than during BF dancing (mean: p = 0.015; peak: p = 0.0004). Peak VGRF/BW when landing from the sauté jump with DS was significantly lower compared with landing in BF (p = 0.035). All other variables were not significantly different between conditions, but all DS force values were lower than BF.<br/> Conclusions: We offer evidence that padded dance socks may reduce foot forces dancers commonly encounter during modern dance. The trends we recorded require further study to assess the extent to which the socks exhibit beneficial effects when considering both the many hours dancers train and the cumulative effects of impacts sustained by their feet.

Management of Stress Fractures in Ballet

Stress fractures are highly prevalent in ballet dancers and lead to notable time loss from dancing. Nutritional status, body composition, bone mineral density, and rate of increase in activity are among the components that influence risk for stress fractures. Proper evaluation and management of stress fractures is essential including a review of the causative factors involved in each stress injury. The purpose of this article was to summarize current evidence for risk factors involved in dancers' stress fractures to optimize prevention and treatment. Identified associated factors include low energy availability, low bone mineral density, low fat body composition, abnormal lower extremity biomechanics, genetic factors, and high training loads.

Impact attenuation and deformation characteristics of dance floors on jump kinematics

Specialist dance floors have been promoted to reduce impact forces and reduce lower limb injury for dancers. 18 trained female dancers carried out 70 continuous ballet jumps on 4 different surfaces wearing an XSENS suit. Three specialist dance floors, Floor A (64% force reduction), Floor B (67% force reduction), Floor C (no data) were compared to Floor D (vinyl-covered concrete - control). Dependent variables for each analysed jump (2,3,4, and 67,68,69) were ankle, knee, hip range of movement (ROM); lower and upper leg angular velocities and pelvis vertical acceleration. No main effects were reported for dance floor, first and last jump series. Comparison of the floors against Floor D reported a main effect for the dance floors (p=0.001), first and last jump series (p=0.001). Between-subject effects noted that ankle ROM was significantly greater for trials on floor A (p=0.007) compared to floor D. ROM data significantly decreased between the first and last jump series whilst vertical pelvis accelerations increased except for floor A. Within the current study, a foam backed vinyl floor (C) provided better shock absorption than floors with higher deformation characteristics (A and B) and none of the specialist dance floors performed better than vinyl covered concrete (D).

Prevalence and Risk Factors of Dance Injury During COVID-19: A Cross-Sectional Study From University Students in China

Objectives: Although coronavirus disease 2019 (COVID-19) has transformed the training environment of dancers worldwide, little is known on how this has affected injury prevalence, causes, and risk factors. Methods: An online investigation involving Chinese full-time dance students was conducted (September-November 2020), which covered two 6-month periods just before and during the first COVID-19 lockdown. Results: 2086 students (19 ± 2.4 years) responded to the investigation. Injury prevalence dropped from 39.6% (before the lockdown) to 16.5% (during the lockdown) (p < 0.01). It was noted that a significant increase in injury severity during the lockdown was caused due to a 4.1% increase in moderate-to-severe injuries (p < 0.05). During the lockdown, the injuries on the lower back, feet, and shoulders decreased significantly (p < 0.01), but the knee, ankle, and groin/hip joint injuries remained the same. Fatigue and the recurrence of an old injury remained as the top two perceived causes of an injury between the two periods with the increase in an unsuitable floor (p < 0.01), a cold environment (p < 0.05), and set/props (p < 0.05). The fatigue degree of students decreased (p < 0.01) and their hours of sleep increased (p < 0.01) during the lockdown. Binary Logistic Regression analysis indicated that dance injury is associated with fatigue, the hours of sleep, and the actions taken if they suspect an injury during the lockdown (p < 0.05), but is only related to the time set aside for a cooldown and age before the lockdown period (p < 0.05). Conclusion: Although injury prevalence dropped significantly during the first COVID-19 lockdown in Chinese dance students, the main dance injury characteristics remained the same. Decreased fatigue and longer hours of sleep could explain the aforementioned drop in injury prevalence during the lockdown.

Safety Comes First: Novel Styrene Butadiene Rubber (SBR) and Ethylene Propylene Diene Monomer (EPDM) Surfaces as a Response to Sport Injuries

An athlete’s performance depends not only on the shoes they wear but also on the surface used in sports facilities. In addition, it can significantly contribute to reducing injuries, which are easy to get during sports competitions. In the present study, we wanted to investigate whether recycled styrene butadiene rubber (SBR) and ethylene propylene diene monomer (EPDM) could be used in the production of sports surfaces. For this purpose, we designed three different sports surfaces: (1) SBR covered with a thin EPDM spray layer on the top, (2) clean EPDM, and (3) bottom SBR layer with the top layer of EPDM. The test program of these surfaces included in its scope: shock absorption, vertical deformation, tensile strength, abrasion resistance, and slip resistance tests. Our research also involved the influence of the substrate under surface, temperature, and surface conditions. Presented results show that both materials, in the right proportions, can be used in the production of sports surfaces.

Injury Incidence and Severity in Musical Theatre Dance Students: 5-year Prospective Study

Dance injury research has mainly focused on ballet and modern dance with little data on musical theatre dancers. The purpose was to assess the incidence and severity of injuries in a musical theatre dance college over a 5-year period; 198 pre-professional musical theatre dancers (3 cohorts on a 3-year training course) volunteered for the study; 21 students left the course over the study period. Injury aetiology data were collected by an in-house physiotherapy team. Differences between academic year and sex were analysed using a Poisson distribution model; significant difference was set at p≤0.05. In total, 913 injuries were recorded, and more injuries occurred in academic year 1 than year 2 and 3. Overall injury incidence was 1.46 injuries per 1000 hours (95% CI 1.34, 1.56); incidence significantly decreased between year 1, 2 and 3 (p<0.05). There was no significant sex difference for incidence or severity. Most injuries were classified as overuse (71% female, 67% male). Pre-professional musical theatre dancers report a high proportion of lower limb and overuse injuries comparable to other dance genres. Unlike other studies on pre-professional dancers, injury incidence and severity decreased with academic year, even though workload increased across the course.

An Injury Prevention Program for Professional Ballet: A Randomized Controlled Investigation

BACKGROUND

Few investigations have examined dance-specific injury prevention programs (IPPs), and no published randomized controlled trials are available that evaluate IPPs for dance.

HYPOTHESIS

The implementation of an IPP will significantly reduce the risk of injury in professional ballet dancers.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

A randomized controlled trial was designed that entailed a superiority model for the intervention group. All professional dancers from a single ballet company were eligible to participate. Randomization and allocation were performed before the start of the season. The control group practiced and performed without change to preexisting standard operating practice. The IPP group was instructed to perform a 30-minute exercise program 3 times per week over the 52-week study period. Injuries were recorded. Standard continuous and categorical data comparisons and correlations were used. Cox proportional hazards regression models for recurrent failures were used wherein the hazard ratio indicates the relative likelihood of injury in the control versus intervention groups.

RESULTS

Of the 52 eligible dancers, 75% (n = 39) participated. Of these 39 dancers, 19 (9 males, 10 females; mean age, 26.6 ± 4.0 years) were randomized to the control group and 20 (11 males, 9 females; mean age, 25.1 ± 5.1 years) to the IPP group. No significant (P > .05) difference was found in baseline demographics between groups. A total of 116 injuries were recorded for the entire study population (49 IPP; 67 control). Traumatic and chronic injuries accounted for 54% and 46% of injuries, respectively. The injury rate was 82% less (IPP hazard ratio, 0.18; z = -2.29; P = .022) in the IPP group after adjustment for confounding variables, and time between injuries was 45% longer (IPP hazard ratio, 0.55; z = -2.20; P = .028) than for controls.

CONCLUSION

The present study is the first prospective randomized controlled investigation of an IPP for professional ballet. The results showed an 82% decrease in injury rate for the intervention group and an extended period from previous injury to subsequent injury.

REGISTRATION

NCT04110002 (ClinicalTrials.gov identifier).

INJURIES IN PROFESSIONAL DANCERS: A SYSTEMATIC REVIEW

ABSTRACT Movement is a fundamental element of dance, and the dancer’s body is the raw material through which the art of dance is expressed; for this, it demands the utmost discipline in the pursuit of technical and artistic excellence. To meet the professional demands, dancers are subjected to strenuous training routines, which can lead to the development of injuries in this environment. The objective was to examine the etiology, main affected segments, prevalence, and instruments used to evaluate the lesions in studies with professional dancers and/or in comparison with similar populations. We selected articles published in the last decade in the databases BIREME, LILACS, MEDLINE EBSCO, WEB OF SCIENCE, SCOPUS (Elsevier), and PubMed, with cross-sectional, observational cohort and case control design published in Portuguese, English, or Spanish. Systematic reviews, case studies, dissertations, theses, book chapters, cross-referenced articles, and studies published outside of the last decade were not included. The search used combinations of the terms “dancing* and athletic injuries* and musculoskeletal* and pain*”. A principal investigator and two reviewers conducted the survey and analyzed all the potentially relevant articles, initially by the abstract and title. Twelve articles were included, with 1,149 participants (965 professional dancers of classical ballet, modern dance, contemporary dance, and breakdance, 104 amateur dancers, and 80 elite athletes). Nine studies found simultaneous lesions with emphasis on the foot and ankle (n=4), upper and lower limbs lesions (n=4) and lower and upper limb joints (n=1). Other studies have found lesions in the anterior cruciate ligament (n=3). There was no agreement regarding the instruments for detecting lesions in professional, pre-professional, and amateur dancers. There was a prevalence of studies aimed at classical ballet modality, evidencing a higher frequency of lower limb involvement in professional dancers.

Occupational Health and the Performing Arts: An Introduction

OBJECTIVE

Workplace hazards in the performing arts cause injuries, disabilities, and deaths every year. Occupational health professionals are familiar with most of these hazards and are particularly qualified to contribute to efforts to reduce them. This article reviews current health issues in the performing arts and highlights opportunities for occupational health contributions.

METHODS

Recognized experts in performing arts medicine were consulted and articles illustrating performing arts health issues were reviewed. Literature sources included medical databases, unindexed art-health publications, and popular press articles.

RESULTS

Resources discussing hazards and health issues in theater, dance, voice, and instrumental musicians were located and reviewed.

CONCLUSIONS

Treatment providers have a history of involvement with segments of the performing arts. The occupational health approach to workplace health issues can effectively complement these efforts. Sources of further information on performing arts health concerns are available.

Dance floor force reduction influences ankle loads in dancers during drop landings

OBJECTIVES

Dance floor mechanical properties have the potential to influence the high frequency of ankle injuries in dancers. However, biomechanical risk factors for injury during human movement on hard, low force reduction floors have not been established. The aim of this study was to examine the ankle joint mechanics of dancers performing drop landings on dance floors with varied levels of force reduction.

DESIGN

Repeated measures cross sectional study.

METHODS

Fourteen dancers performed drop landings on five custom built dance floors. Ankle joint mechanics were calculated using a three dimensional kinematic model and inverse dynamics approach.

RESULTS

Ankle joint kinematic (dorsiflexion; range of motion, peak angular velocity and acceleration) and kinetic (plantar flexion; peak joint moments and power) variables significantly increased with a decrease in floor force reduction. Many of the observed changes occurred within a latency of <0.1s post-contact with the floor and were associated with increased vertical ground reaction forces and decreased floor vertical deformation.

CONCLUSIONS

The observed mechanical changes are interpreted as an increase in the load experienced by the energy absorbing structures that cross the ankle. The short latency of the changes represents a high intensity movement at the ankle during a period of limited cognitive neuromuscular control. It is suggested that these observations may have injury risk implications for dancers that are related to joint stabilization. These findings may be of benefit for further investigation of dance injury prevention and support the notion that bespoke force reduction standards for dance floors are necessary.

Preventing dance injuries: current perspectives

Dancers are clearly athletes in the degree to which sophisticated physical capacities are required to perform at a high level. The standard complement of athletic attributes - muscular strength and endurance, anaerobic and aerobic energy utilization, speed, agility, coordination, motor control, and psychological readiness - all are essential to dance performance. In dance, as in any athletic activity, injuries are prevalent. This paper presents the research background of dance injuries, characteristics that distinguish dance and dancers from traditional sports and athletes, and research-based perspectives into how dance injuries can be reduced or prevented, including the factors of physical training, nutrition and rest, flooring, dancing en pointe, and specialized health care access for dancers. The review concludes by offering five essential components for those involved with caring for dancers that, when properly applied, will assist them in decreasing the likelihood of dance-related injury and ensuring that dancers receive optimum attention from the health care profession: (1) screening; (2) physical training; (3) nutrition and rest; (4) specialized dance health care; and (5) becoming acquainted with the nature of dance and dancers.