Journal of Dance Medicine & Science最新文献

Introduction: The purpose of the study was to examine if dance-specific aerobic fitness test (DAFT) heart rate variables were associated to lower-extremity injuries in contemporary dance students.

Methods: A total of 235 first-year contemporary dance students (18.6 ± 1.2 years) were prospectively followed over the first 4 months of their academic year. Peak heart rate (HR_peak) in the final stage of the DAFT and heart rate recovery (HRR) 1 minute after DAFT completion were measured. Lower-extremity injuries were registered using a self-reported monthly questionnaire including the Oslo Sports Trauma Research Centre Questionnaire on Health Problems (OSTRC-H). Three injury definitions were used (all-complaint injury, substantial injury, and time-loss injury). Associations between DAFT HR_peak, HRR and lower-extremity injury prevalence and severity were examined with regression analyses.

Results: Lower-extremity injury prevalence was 36.2% (n = 85), 13.6% (n = 32), and 22.6% (n = 53) for all-complaint, substantial and time-loss injuries, respectively. There were no significant associations between HR_peak or HRR and injury prevalence using either of the 3 injury definitions. There were no significant associations between DAFT HR_peak or HRR and injury severity (days off due to injury or OSTRC-H severity score). Multivariate analyses showed significant associations between age and substantial injuries (OR 1.807; 95% CI 1.242-2.630; P < .01) and between age and time-loss injuries (OR 1.441; 95% CI 1.074-1.933; P < .05).

Conclusion: Aerobic fitness measured with the DAFT was not associated with lower-extremity injury risk or injury severity. Higher age was associated with substantial and time-loss lower-extremity injuries.

Introduction: Elite ballet is one of the most demanding physical activities for the skeleton, making dancers susceptible to bone stress injuries. This pilot study compared bone remodeling in professional female ballet dancers from the Royal Ballet Company with controls from Imperial College London. Methods: The study included dancers (n = 5, median age 29 ± 16 years) and controls (n = 6, median age 24 ± 8.5 years). The main outcome measure was bone turnover, assessed by measuring the ratio of resorption (NTX) and formation (P1NP) markers in urine and serum. Estrogen metabolism was evaluated through 2OH/16OH metabolite ratios. Both markers were measured using ELISA kits. Diet was tracked using 72-hour diaries, and weekly exercise hours were recorded through 2-week diaries and cross referenced with training logs. Results: Results showed significantly higher bone resorption to formation ratio (NTX/P1NP) in dancers versus controls (P < .050), and elevated estrogen metabolite ratios (2OH/16OH) (P < .010). These findings occurred despite similar dietary profiles between groups including fat (P = .874) carbohydrate (P = .501) and protein (P = .099). Dancers showed significantly higher weekly exercise hours (46.50 ± 38.75 vs 14.75 ± 11.75 hours/week, P < .001) and lower BMI (18.36 ± 1.35 vs 20.77 ± 3.66, P = .020). Conclusions: The pilot data suggest elite ballet dancers may exhibit an imbalance in bone remodeling with high resorption and low formation relative to controls. This imbalance in bone turnover markers could serve as a screening tool for identifying dancers at increased risk of bone stress injuries. The NTX/P1NP ratio could potentially offer a low-cost, non-invasive approach to identify at-risk dancers early and implement preventative measures. Further research and longitudinal trials are needed to test whether these markers can predict bone stress injury risk.

Introduction: Knee-drop landings following a dance leap are often used in contemporary dance choreography, but there is limited research into the biomechanical demands of these types of landing. This study aimed to investigate the effects of a verbal cueing intervention on the performance and kinetics of a common knee-drop landing in contemporary trained dance students. Method: Pre-vocational dance students participated in this study (n = 8). A quasi-experimental research design was followed to collect kinematic and kinetic data using 3D motion capture and force plates following the take-off and during a knee-drop landing of a contemporary dance style leap pre and post a verbal cueing intervention. Performance variables analysed were jump height and flight time, while kinetic variables included vertical ground reaction forces (vGRFs) and loading rates. Results: A statistically significant increase in jump height and flight time was found post intervention; There was no significant difference between pre and post intervention for peak vGRFs at foot or knee impact or loading rate of the whole landing phase. Conclusion: The verbal cueing intervention was successful in increasing flight time and jump height, indicating optimised performance. The lack of significant difference in peak vGRFs and loading rate in the landing phase implies that the intervention did not have a detrimental effect on musculoskeletal loading. These findings demonstrate the positive influence of a verbal cue which focusses on increasing flight time and opposing the landing for enhancing the execution of a dance leap without negatively affecting the forces being experienced in the knee-drop landing that followed. However, it should be noted that the small sample size and lack of a control group in this study may limit the reliability of findings and mean that the generalizability of these findings should interpreted with caution.

Introduction: There is a dearth of dance-related injury epidemiology within the breaking competition setting. Breaking injury surveillance data has predominantly been collected retrospectively at healthcare facilities or through survey research. Methods: Medical staff were available at 6 breaking competitions between 2021 and 2023 to provide musculoskeletal care and triage. In addition to consent of treatment, participants provided their age, gender, and injured body area(s), symptom onset, and description. A total of 157 patient reports were obtained, de-identified, and utilized for comparative frequency and logistic regression analysis. Results: The most common body areas that breakers sought care for were: 39% (n = 61) shoulder, 32% (n = 51) neck, 32% (n = 50) lower back, and 25% (n = 40) upper back. The majority of injuries 61% (n = 95) occurred >3 months prior to competition. The most common descriptions of injury were: 57% (n = 89) tightness, 46% (n = 73) pain, and 33% (n = 52) soreness. Logistic regression analysis revealed that: older patients have higher odds of experiencing the issue during or before the competition (P-value = .003); and that age was the only variable that was borderline statistically significant for hip injury (P-value = .055). Conclusion: The highest frequency of dance-related injury within a breaking competition setting cohort was found to be in the shoulder, neck, and back. The highest frequency of injury description were tightness, pain, and soreness. There was a large frequency of chronic injuries that were seen, and older patients were found to have a higher odds of experiencing and seeking medical treatment for a chronic injury. Access to injury management services and education for the shoulder, neck, and back should be provided at breaking competitions to improve health outcomes. Level of Evidence: Level 4.

Background: Dance is a popular activity worldwide that comes with inherently high injury rates. Despite the call for implementation and evaluation of injury prevention strategies, the utility and efficacy of injury prevention practices in dance are unknown. Objective: The primary objective of this systematic review was to describe dance-specific injury prevention strategies in any dance population. The secondary objective was to evaluate the effectiveness of these strategies in the reduction of injury prevalence or incidence rates. Methods: Six electronic databases were searched to March 2024 (Medline, EMBASE, SportDiscus, CINAHL, SCOPUS, Cochrane). Selected studies met a priori inclusion criteria that required original data describing an injury prevention strategy for any genre of dance. Studies were excluded if; no injury outcomes were reported, no injury prevention strategy was utilized, or if dance was used as a therapeutic intervention/fitness. Two reviewers independently assessed abstracts and full texts for inclusion. Study quality was evaluated using the Joanna Briggs Institute Level of Evidence tool. Results: From 2209 potentially relevant records, 8 studies met criteria for inclusion. Injury prevention strategies were diverse across conditioning and exercise programs, neuromuscular training warm-up, psychological coping skills training, and educational programs, with a range of duration and adherence measures. Due to inconsistent injury surveillance methodology, efficacy of these programs could not be determined. Quality of included studies was moderate to high, with moderate to low risk of bias. Conclusions: Efficacy and adherence to dance-specific injury prevention strategies are understudied in the dance science literature. Conditioning and exercise programs are currently the most common injury prevention strategies, with initial evidence suggesting they may be efficacious in reducing injury rates. Further research using valid injury surveillance methodologies and standardized injury definitions to examine the efficacy of these strategies in reducing dance-related injury is needed. Level of evidence: I.

Introduction: Ballet-based dance training emphasizes the equal development of both legs. However, dancers often perceive differences between their legs during balance or landing. There still needs to be more consensus on the functional difference between dominant (D) and non-dominant legs (ND). Therefore, this study investigated both legs' neuromuscular strategy in single-leg balance and landing based on leg dominance. Methods: Thirteen female dancers (age: 22.2 ± 2.8 years) with no history of ankle injuries in the past year participated in the study. Based on the questionnaire, the dominant leg was set, which legs were preferred to balance, generate strength, and land. Joint kinematics and ground reaction force (GRF) were analyzed using a three-dimensional motion analysis system and force plates during single-leg balance (SLB), passé balance (PB), sissone simple (SS), and sissone ouverte (SO). The tibialis anterior (TA), medial gastrocnemius (MG), peroneus longus (PL), and gluteus medius (GM) activation were measured by wireless surface electromyography (EMG). Displacement (cm) of the center of pressure and the dynamic postural stability index (DPSI), a balanced score post dynamic tasks, were calculated. Results: Bilateral leg balance ability was observed based on joint kinematics and DPSI during SLB, PB, SS, and SO. Higher TA activity was noted during PB in ND legs than in D legs (P = .038). PL activation was significantly increased in ND legs (69.3 ± 34.4%) than in D legs (45.6 ± 19.2%) before contact during SS and SO (P < .05). After landing with ND legs, dancers regulated postural stability with increasing TA activation (P < .05). Conclusions: Pre-activation of PL before landing with ND legs increases ankle stiffness, enhancing stability. Conversely, D legs achieve balance with lower activation levels. The findings highlight significant differences between legs in dancers, suggesting that leg dominance should be considered in future training and performance strategies.

Introduction: There is currently little research relating specifically to the muscular strength and endurance requirements of the upper body such as lifts at varying heights, ground floor contact with the hands and inversions such as handstands. Enhanced understanding of muscular demands can inform training program design to build physical tolerance to meet the demand of the activity. The aim of this study was to ascertain the frequency of upper body muscular skills in contemporary and ballet dance performance. Methods: Analysis of 46 individual ballet performers (F = 23, M = 23) from 12 performances (duration 63.5 ± 44.5 minutes) and 44 individual contemporary performers (F = 21, M = 23) from 12 performances (duration 35.7 ± 4.3 minutes) was carried out. Frequency of upper body skills was recorded using Dartfish Easytag-Note and converted to mean frequency per minute of total performance and per performance by genre and by sex. Differences in frequency between genre were analyzed via Mann-Whitney U. Phase two analyzed differences between sex via Mann-Whitney U. Finally, analysis of differences between sex within dance genre was carried out via Wilcoxon signed rank test. Significance was accepted at P < .05. Results: A significant difference was apparent between ballet and contemporary dance for holding own weight (P < .05) with a greater total mean frequency within contemporary performances of 8.50 ± 9.03 compared to a total mean frequency of 1.51 ± 3.13 within ballet performances. Additionally, there was a significant difference for above shoulder assisted lift (P < .05) when comparing male dancers, with male contemporary dancers carrying out significantly more (9.82 ± 8.56) per performance than male ballet dancers (2.33 ± 4.66). A higher mean frequency of below shoulder lifts than above shoulder lifts was also noted, with the majority of above shoulder lifts remaining at eye level. Conclusion: Training programs must prepare dancers for upper body movements that consider differing biomechanical demands of a variety of lifts and inversions.

Introduction: As demanding as dancing en pointe is, no universal standard exists to determine when a ballet dancer is ready to advance to this next level. The goal of this study was to provide preliminarily tested and reliable guidelines for a screening tool that can be used to determine (1) if a dancer is ready for pointe, (2) reasons why a dancer may not be ready, and (3) areas for improvement to guide training and preparation. Methods: Participants: Seventeen dancers aged 9 to 17 years with a minimum 4 years of ballet and who were either possibly ready for pointe or had been in pointe class less than 3 months participated in this study. Study Design: Dancers were prospectively assessed by two physicians using the Pointe Assessment Screening Shah Edison (PASSÉ) tool for assessing pointe readiness. Interrater reliability and the relationship of individual tests to overall pointe readiness were evaluated using descriptive statistics, kappa, diagnostic metrics, and logistic regression. Setting: Private practice office; ballet studios. Results: There was 94% agreement among raters in determining overall pointe readiness, and individual tests all had significant interrater agreement ranging from 62% to 97% (P ≤ .04). Ankle plantarflexion >90° (100%), stability in grand plié (100%), and holding relevé (96%) had the highest sensitivity for overall readiness, indicating their necessity to advance to pointe. The tests with greatest specificity for identifying lack of readiness were relevé passé (72%), sauté (72%), and airplane (69%). Conclusions: This study provides preliminary testing of a reliable screening tool, the PASSÉ screen, which can be utilized to determine pointe readiness with excellent interrater agreement for the overall pass/fail and significant agreement for tests that contribute to readiness. At minimum, dancers must be able to pass the grand plié, ankle plantar flexion, and relevé tests. Also passing the sauté, relevé passé, and airplane tests indicates high likelihood of readiness.

Introduction: Dance is physically demanding and often involves unilateral movements performed within a small base of support. Prior authors have reported that dancers use one leg preferentially over the other (ie, lower extremity asymmetry). Increased leg asymmetry-quantified using the Limb Symmetry Index (LSI), is associated with increased injury risk. Clinicians often use LSI to make return-to-performance decisions (eg, >85% performance on injured vs non-injured limb). However, limited research has examined leg symmetry in collegiate dancers. Purpose: To examine LSI in collegiate dancers using the modified star excursion balance test (mSEBT) and single-leg hop test (SLH). Methods: 120 healthy collegiate dancers (105 females, 15 males; 18.31 ± 0.80 years; 164.18 ± 7.12 cm; 61.18 ± 8.46 kg) performed the mSEBT (normalized to % leg-length: LL) in the anterior, posteromedial, and posterolateral directions and the SLH test (normalized to % body height: BH) across both legs using previously published guidelines. mSEBT scores were averaged for all three directions per leg. SLH scores were averaged per leg. LSI was calculated as (lower value/higher value) × 100 to obtain a percentage. Results: Mean mSEBT scores were 95.7 ± 14.2%LL (lower score) and 96.6 ± 14.3%LL (higher score). Dancers LSI for mSEBT was 99.1 ± 0.9%. Mean SLH scores were 82.8 ± 13.3%BH (lower score) and 86.4 ± 13.5%BH (higher score). Dancers LSI for SLH was 95.9 ± 3.5%. Conclusions: Dancers' LSI% was greater than 90% for mSEBT and SLH, concurrent with the normal values of LSI > 90% in healthy, physically active adults. Dancers displayed lower leg symmetry. Practitioners can thus use the contralateral leg as a reference for return-to-performance decisions following injury in dancers. LSI should be integrated into a comprehensive screening process to identify large (>85%) asymmetries and guide training programs post-injury to assist educators and practitioners' evidence-based return-to-performance decisions. Future researchers should examine LSI in other dance genres and across levels.Level of Evidence: 2C.

Introduction: Sedentary lifestyles remain a persistent health issue in Japan. Ballroom dancing has recently gained attention as a potential means of maintaining physical activity, but there are very few reports on Japanese subjects. Exploratory research is therefore needed to investigate the effects of ballroom dancing on the physical and mental health of sedentary middle-aged Japanese adults. The aim of this study was to assess the impact of ballroom dancing on various health-related physical and psychological outcomes in middle-aged adults compared to a control group. Methods: A parallel-group study was carried out. Thirty healthy but inactive middle-aged adults with no previous dance experience were divided into 2 groups: an intervention group which participated in a recreational level ballroom dance program for 10 weeks (60 minutes, once per week) and a control group which had no dance lessons. Subjects completed questionnaires regarding subjective mood changes and daily physical activity. Objective measures of physical fitness, oxidative stress, antioxidant capacity, and autonomic nervous system function were also assessed before (T0) and after 10 weeks (T11) of dance practice. Results: In the subjective questionnaire, the Profile of Mood States 2 (POMS^®2) survey, one of the health-related indicators, T-scores of the Total Mood Disturbance (TMD) after the intervention showed a difference (P = .014) between the dance group and the control group. In post hoc tests, increases of autonomic activity and number of days of high-intensity physical activity correlated positively with a reduction in TMD in the dance group. Conclusion: Among inactive middle-aged adults, participation in weekly ballroom dance lessons for 10 weeks improved their psychological mood compared to a control group. The improvement was found to have the positive effects of activating autonomic nervous system activity and increasing high-intensity physical activity. The results suggest that ballroom dancing may be effective in improving exercise habits and physical and mental health.