The Effects of a Single Session of a Rhythmic Movement Program on Selected Biopsychological Parameters in PD Patients: A Methodological Approach.

The aim of the present study is to examine the acute effects of a specially designed musicokinetic (MSK) program for patients with Parkinson's disease (PD) on (a) anxiety levels, (b) select kinematic and kinetic parameters, and (c) frontal cortex hemodynamic responses, during gait initiation and steady-state walking. Methods: This is a blind cross-over randomized control trial (RCT) in which 13 volunteers with PD will attend a 45 min MSK program under the following conditions: (a) a synchronous learning format and (b) an asynchronous remote video-based format. Changes in gait biomechanics and frontal cortex hemodynamic responses will be examined using a 10-camera 3D motion analysis (Vicon T-series, Oxford, UK), and a functional near-infrared spectroscopy (f-NIRS-Portalite, Artinis NL) system, respectively, while anxiety levels will be evaluated using the Hamilton Anxiety Rating Scale. Expected results: Guided by the rules of music, where periodicity is distinct, our specially designed MSK program may eventually be beneficial in improving motor difficulties and, hence, reducing anxiety. The combined implementation of f-NIRS in parallel with 3D gait analysis has yet to be evaluated in Parkinsonian patients following a MSK intervention. It is expected that the aforementioned intervention, through better rhythmicity, may improve the automatization of motor control, gait kinematics, and kinetics-supported by decreased frontal cortex hemodynamic activity-which may be linked to reduced anxiety levels.

Relationship Between Performance Competence and Cardiorespiratory Fitness in Contemporary Dance.

AIMS: While a foundation of basic cardiorespiratory fitness is beneficial for coping with the physiological demands of dance training and performance, the extent to which cardiorespiratory fitness levels are related to performance ability is not all-together clear. This study aimed to directly compare aerobic capacity (VO2peak) and anaerobic threshold (AT) to an aesthetic competence measure (ACM) in student contemporary dancers. METHODS: Participants were 18 contemporary dance students and all undertook a one-off treadmill test to volitional exhaustion in the week leading up to a performance to determine VO2peak and AT. In the same week, a final rehearsal for the performance was filmed to allow retrospective analysis of specific performance competence. RESULTS: Mean VO2peak values of 47.67 ± 5.84 ml/kg/min and AT values of 43.18 ± 7.72 ml/kg/min (90.68 ± 11.87 %VO2peak) were recorded, and the mean total ACM score was 52.67 ± 8.74. No significant correlations were found between cardiorespiratory fitness variables and ACM scores. Regression analyses revealed experience level to be the only significant predictor of total ACM score (p<0.05, R2=0.12, SEE=11.91). CONCLUSIONS: The range of choreography used for assessment may limit the present study; nevertheless, as level of experience did significantly predict ACM total score, it is suggested that vocational dance training may be developing the performance and technical skills of students but not sufficiently developing their physical conditioning.

Changes in Energy Demand of Dance Activity and Cardiorespiratory Fitness During 1 Year of Vocational Contemporary Dance Training.

Beck, S, Wyon, MA, and Redding, E. Changes in energy demand of dance activity and cardiorespiratory fitness during 1 year of vocational contemporary dance training. J Strength Cond Res 32(3): 841-848, 2018-Previous literature has demonstrated that the intensity of dance class as well as its discontinuous nature is not sufficient to elicit an aerobic training response and that the aerobic capacity of dancers is relatively low. These findings have raised questions on the suitability of training, through class and rehearsal, as adequate preparation for the physical demands of performance and a sustained, successful career in dance. The aim of this study was to describe changes in aerobic fitness and energy cost of dance movement occurring throughout 1 year of training. Subjects were 13 female dance students; 7 first-year undergraduate (UG) students, and 6 postgraduate (PG) students. At 3 time points (TP1, TP2, and TP3) during 1 academic year, each subject completed a treadmill test to determine V[Combining Dot Above]O2peak (ml·kg·min) and lactate threshold (LT) (ml·kg·min and %V[Combining Dot Above]O2peak) and a standardized 4-minute dance sequence, where the mean demand was expressed as V[Combining Dot Above]O2 (ml·kg·min), heart rate (b·min), %V[Combining Dot Above]O2peak, and %LT. Both groups displayed an overall decrease in mean V[Combining Dot Above]O2peak throughout the year, despite a peak in fitness at TP2 in the PG students. No significant changes in LT were noted over time for either group. A significant reduction in the relative intensity of the dance sequence, particularly in relation to mean VO2 (ml·kg·min) and %LT data, was observed over time in both groups, although the degree of change was less in the UG group than the PG group. Apparent adaptations during a rehearsal period in the PG group are presented in contrast to previous research findings. Recommendations for future research include further investigation into the energy demand of rehearsal and cardiorespiratory adaptation during rehearsal periods as well as further reporting of measures related to LT and movement economy.

Lower Extremity Horizontal Work But Not Vertical Power Predicts Lower Extremity Injury in Female Collegiate Dancers.

Ambegaonkar, JP, Schock, CS, Caswell, SV, Cortes, N, Hansen-Honeycutt, J, and Wyon, MA. Lower extremity horizontal work but not vertical power predicts lower extremity injury in female collegiate dancers. J Strength Cond Res 32(7): 2018-2024, 2018-Dancers often perform powerful and explosive movements that require adequate lower extremity (LE) activity in horizontal and vertical directions. We examined whether these measures were interrelated and whether they predicted LE injury status in dancers using binary logistic regressions and receiver operator characteristic (ROC) curve analyses. Forty-three collegiate female dancers (18 ± 0.7 years; 162.6 ± 5.9 cm; 59.4 ± 7.1 kg) performed single leg hop (SLH, m) and vertical jump (VJ, cm) tests. Single leg hop and VJ distances were used to calculate SLH norm (as a % of body height) and vertical power (vPower, watts). Lower extremity injuries and dance exposure hours (DEhrs) were recorded for 16 weeks. Dancers had 51 injuries resulting in a 3.7/1,000 DEhr injury incidence rate (95% confidence interval [CI]: 2.7-4.7). Twenty dancers were injured, whereas 23 remained injury free. Injured dancers had significantly lower SLH norm than noninjured dancers (t = 2.7, p = 0.009, 85.2 ± 11.2% vs. 76.8 ± 8.4%, respectively), but vPower was similar (t = 0.6, p = 0.53, injured = 2,632.0 ± 442.9 watts, noninjured = 2,722.7 ± 480.0 watts). SLH norm, but not vPower significantly predicted injury status χ(1,43) = 5.9, p = 0.02. Specifically, an SLH norm cut-off value of 78.2% identified dancers at injury risk (area under the curve = 0.73, SE = 0.08, p = 0.01, 95% CI = 0.57-0.89, sensitivity = 0.75, specificity = 0.70). However, vPower was not able to identify dancers at risk (p = 0.36). vPower had moderate relationships with SLH norm (r = 0.31, p = 0.04). Compared with injured dancers, noninjured dancers had greater SLH norm but similar vPower. Only SLH norm predicted injury status in female collegiate dancers. Thus, the SLH test may possibly predict LE injury risk in dancers. Strength and conditioning coaches can prospectively use baseline SLH test screenings to identify dancers whose SLH is less than 78.2% of their height because these dancers may have increased probability of LE injury risk. Coaches can then include horizontal direction exercises when designing training programs and examine whether these programs reduce LE injury risk in female collegiate dancers.

Cardiorespiratory Profile and Performance Demands of Elite Hip-Hop Dancers: Breaking and New Style.

AIMS: Dancers need to constantly maintain and develop their physiological capabilities to support their performances. Previously these physiological demands have been investigated only in traditional dance styles such as ballet and modern. The aim of this study was to examine the physiological demands of two types of hip-hop: new style and break dance. METHODS: Nine female new style dancers (age 20±6 yrs, height 163.5±1.4 cm, mass 55.8±22 kg) and 9 male break dancers (age 23±4.2 yrs, height 178.2±5.7 cm, mass 62.1±7.7 kg) volunteered for the study. Each subject completed a maximal graded treadmill test and a dance performance routine, either new style (approx 1:45-2:30 min) or breaking (2 min). Breathe-by-breathe gas analysis and heart rate (HR) were collected by a portable gas analyser, and blood lactate (BLa) was measured at the end of the treadmill test and each routine. RESULTS: The male breaker dancers had significantly higher VO2 peak than other equivalent dancers in other genres, whilst the female new style dancers were similar to that previously reported for female dancers. Performance data showed significant differences between the two styles for VO2, HR, and BLa (p<0.001) and for VO2 and HR relative to individual maximal treadmill data (p<0.05). CONCLUSION: New style is more comparable to other theatrical dance genres, with a lower relative mean VO2 demand, whilst break dance is shorter in duration, allowing a higher cardiorespiratory demand and generating significant levels of blood lactate. This difference is also reflected in the dancers' cardiorespiratory profiles.

Influence of Movement Quality on Heart Rate While Performing the Dance-Specific Aerobic Fitness Test (DAFT) in Preprofessional Contemporary Dancers.

OBJECTIVES: To explore whether movement quality has influence on heart rate (HR) frequency during the dance-specific aerobic fitness test (DAFT). METHODS: Thirteen contemporary university dance students (age 19 ± 1.46 yrs) underwent two trials performing the DAFT while wearing a Polar HR monitor (Kempele, Finland). During the first trial, dancers were asked to perform the movements as if they were performing on stage, whereas during the second trial, standardized verbal instructions were given to reduce the quality of movement (e.g., no need to perform technically correct pliés). The variables measured at each trial were HR for all five stages of the DAFT and HR recovery (1 and 2 min after finishing the DAFT), movement quality (MQ) score, and rate of perceived exertion score (RPE). RESULTS: There were significant differences in HR between Trial 1 and Trial 2. For all stages and the resting period, HR was lower during Trial 2 (p<0.001). Also, the RPE score was significantly lower and the MQ score was significantly higher, indicating a poorer performance, during Trial 2 (both p<0.001). CONCLUSION: The results suggest that DAFT performance with lower movement quality elicits lower HR frequency and RPE during the DAFT. We recommend that specific instructions be given to participants about executing the movement sequence during the DAFT before testing commences. Also, movement quality must be taken into account when interpreting HR results from the DAFT in order to distinguish if a dancer's low HR results from good aerobic fitness or from poor performance of the movement sequence.

Acute Effects of Vitamin D3 Supplementation on Muscle Strength in Judoka Athletes: A Randomized Placebo-Controlled, Double-Blind Trial.

OBJECTIVE: Indoor athletes have been shown to be prone to vitamin D3 deficiency. The aim of the study was to examine the acute effects of vitamin D supplementation on muscle function using isokinetic dynamometry. DESIGN: Randomized placebo-controlled, double-blind study. SETTING: Institutional. PARTICIPANTS: Adult male white national level judoka athletes (n = 22) who were involved in full-time training. Exclusion criteria were vitamin supplementation, overseas travel to sunny climes, and/or an injury incurred during the last 3 months before testing. INTERVENTIONS: Subjects were randomly allocated to the treatment (150 000IU vitamin D3) or placebo and given blinded supplements by an independent researcher. Participants were tested twice, 8 days apart, on a Monday morning before the start of judo training and after 2 days of rest. A 5 to 7 mL of blood sample was collected followed by isokinetic concentric quadriceps and hamstring muscle function assessments on the right leg at 30 and 200°·s. MAIN OUTCOME MEASURES: Repeated-measures analysis of variance was used to analyze isokinetic muscle force and serum 25(OH)D3. Regression to the mean was used to examine changes in 25(OH)D3 levels over the study period. RESULTS: The treatment group demonstrated a significant increase in serum 25(OH)D levels (34%, P ≤ 0.001) and muscle strength (13%, P = 0.01) between days 1 and 8. No significant differences were found for the placebo group for the same period. CONCLUSIONS: A single bolus of 150 000IU vitamin D3 had a significant positive effect on serum 25(OH)D levels and muscle function in vitamin D insufficient elite indoor athletes. CLINICAL RELEVANCE: Serum 25(OH)D3 levels of indoor athletes should be monitored throughout the year and especially during winter months. Beneficial responses, in muscle strength and serum 25(OH)D3, to 1 dose of vitamin D3 supplementation can be observed within 1 week of ingestion. Muscle strength is linked to serum 25(OH)D levels.

Assessment of Maximum Aerobic Capacity and Anaerobic Threshold of Elite Ballet Dancers.

An athlete's cardiorespiratory profile, maximal aerobic capacity, and anaerobic threshold is affected by training regimen and competition demands. The present study aimed to ascertain whether there are company rank differences in maximal aerobic capacity and anaerobic threshold in elite classical ballet dancers. Seventy-four volunteers (M 34, F 40) were recruited from two full-time professional classical ballet companies. All participants completed a continuous incremental treadmill protocol with a 1-km/hr speed increase at the end of each 1-min stage until termination criteria had been achieved (e.g., voluntary cessation, respiratory exchange ratio <1.15, HR ±5 bpm of estimated HRmax). Peak VO2 (5-breathe smooth) was recorded and anaerobic threshold calculated using ventilatory curve and ventilatory equivalents methods. Statistical analysis reported between-subject effects for gender (F1,67=35.18, p<0.001) and rank (F1,67=8.67, p<0.001); post hoc tests reported soloists (39.5±5.15 mL/kg/min) as having significantly lower VO2 peak than artists (45.9±5.75 mL/kg/min, p<0.001) and principal dancers (48.07±3.24 mL/kg/min, p<0.001). Significant differences in anaerobic threshold were reported for age (F1,67=7.68, p=0.008) and rank (F1,67=3.56, p=0.034); post hoc tests reported artists (75.8±5.45%) having significantly lower anaerobic threshold than soloists (80.9±5.71, p<0.01) and principals (84.1±4.84%, p<0.001). The observed differences in VO2 peak and anaerobic threshold between the ranks in ballet companies are probably due to the different rehearsal and performance demands.

Body mass index, nutritional knowledge, and eating behaviors in elite student and professional ballet dancers.

OBJECTIVE: It is recognized that there is a high esthetic demand in ballet, and this has implications on dancers' body mass index (BMI) and eating behaviors. The objective of this study was to examine the association between BMI, eating attitudes, and nutritional knowledge of elite student and professional ballet dancers. DESIGN: Observational design. SETTING: Institutional. PARTICIPANTS: One hundred eighty-nine participants from an elite full-time dance school (M = 53, F = 86) and from an elite ballet company (M = 16, F = 25) volunteered for the study. There were no exclusion criteria. INTERVENTIONS: Anthropometric data (height and mass), General Nutrition Knowledge Questionnaire (GNKQ), and the Eating Attitude Test-26 (EAT-26) were collected from each participant. MAIN OUTCOME MEASURES: Univariate analysis of variance was used to examine differences in gender and group for BMI, GNKQ, and EAT-26. Regression analyses were applied to examine interactions between BMI, GNKQ, and EAT-26. RESULTS: Professional dancers had significantly greater BMI than student dancers (P < 0.001), and males had significantly higher BMI scores than females (P < 0.05). Food knowledge increased with age (P < 0.001) with no gender difference. Student dancers had a significant interaction between year group and gender because of significantly higher EAT-26 scores for females in years 10 and 12. Regression analysis of the subcategories (gender and group) reported a number of significant relationships between BMI, GNKQ, and EAT-26. CONCLUSIONS: The findings suggest that dancers with disordered eating also display lower levels of nutritional knowledge, and this may have an impact on BMI. Female students' eating attitudes and BMI should especially be monitored during periods of adolescent development.

Reliability, Variability and Minimal Detectable Change of the Isometric Mid-Thigh Pull in Adolescent Dancers.

INTRODUCTION: The importance and potential benefits of muscular strength in the adolescent's development for health and fitness has been demonstrated in the literature. Maximal muscular strength and its assessment, however, is not a primary assessment criterium in the selection of young talented dancers. METHODS: The present study evaluated the within- and between session reliability, variability, and minimal detectable change (MDC) of the isometric mid-thigh pull (IMTP). Thirty-five participants (female n = 17) participated in 2 identical assessments on the same day with 4-hour break in between. Three 3-second IMTP were performed, and the mean peak force value was used for the analyses. RESULTS: Within-session the ICC indicated excellent reliability (ICC = .99, 95% CI: 0.98-0.99). Between-session reliability was excellent (ICC = .98, 95% CI: 0.95-0.99). The standard error of measurement was 4% (48 N), the minimum detectable change was 12% (134 N) and the CV was 3%. There were no within-session statistically significant differences, but statistically significant differences between-session were observed (P < .001). Limits of agreement ranged from -121 N (95% CI -186 to -56 N) to 307 N (95% CI 243-372 N). CONCLUSION: The observed results demonstrated excellent within- and between sessions reliability, low variability, and an MDC of 12%. The consistency of the within-session scores suggest that peak force data may be obtained with single try efforts. The statistically significant difference in the means of the retest session, however, suggests that the time of the day or the time since entrained awakening may be affecting performance in adolescent dancers. The results of the current study indicate that the IMTP is a reliable assessment tool for maximal muscular strength in adolescent dancers.

Strength and conditioning in dance: A systematic review and meta-analysis.

To assess the evidence for the effect of strength and conditioning on physical qualities and aesthetic competence in dance populations, three electronic databases (PubMed, Scopus, SPORTDiscus) were searched (until September 2022) for studies that met the following criteria: (i) dancers aged >16 years; (ii) structured strength and conditioning intervention; and (iii) with physical qualities and aesthetic competence as outcome measures. Methodological quality and risk of bias of the included studies were assessed through the systematic review tool "QualSyst". Meta-analyses of effect sizes (Hedges' g) with forest plots explored the effects of the strength and conditioning interventions. Thirty-six studies met the inclusion criteria and were included in this review. Meta-analysis indicated strength and conditioning significantly (p < 0.05) improved lower body power (g = 0.90, 95% CI: 0.53-1.27), upper body strength (g = 0.98, 95% CI: 0.39-1.57), lower body strength (g = 1.59, 95% CI: 0.97-2.22), and flexibility (g = 0.86, 95% CI: 0.05-1.66). Strength and conditioning interventions were found to be effective at improving physical qualities in dancers, recommending their participation in additional sessions to enhance overall fitness and ultimately dance performance. It is recommended that future strength and conditioning intervention research should include sample size calculations, with participants recruited from a specific dance genre and skill level in order to evaluate how strength and conditioning influences dance performance.

The effect of a comprehensive injury audit program on injury incidence in ballet: a 3-year prospective study.

OBJECTIVE: The aim of this study was to determine whether an intervention with individualized conditioning program based on injury history and functional movement screening would be effective in reducing ballet injury incidence. DESIGN: Prospective 3-year epidemiological study. SETTING: Professional ballet company and its in-house medical facility. PARTICIPANTS: Dancers from a professional ballet company over the 3-year study period. Participant numbers ranged from 52 to 58 (year 1: 52; year 2: 58; year 3: 53). INTERVENTIONS: The intervention consisted of individual conditioning programs developed using injury history and functional movement screening. Analysis was undertaken of the all dancers who were present in the company during the study period. The significance of change in injuries over a 3-year period was determined using a Poisson distribution model. MAIN OUTCOMES MEASURES: To determine whether individual conditioning programs resulted in a decrease in injury incidence over the study period. RESULTS: The injury count reduced significantly in years 2 and 3 (P < 0.001). Injury incidence for male dancers declined from year 1 (in year/1000 h) (4.76/1000 h) to year 2 (2.40/1000 h) and year 3 (2.22/1000 h). For women, a reduction in the injury incidence was observed from year 1 (4.14/1000 h) to year 2 (1.71/1000 h) and year 3 (1.81/1000 h). CONCLUSIONS: Through prospective injury surveillance, we were able to demonstrate the benefit of individualized conditioning programs based on injury history and functional movement screening in reducing injuries in ballet. CLINICAL RELEVANCE: The implementation of well-structured injury surveillance programs can impact on injury incidence through its influence on intervention programs.

A comparison of strength and stretch interventions on active and passive ranges of movement in dancers: a randomized controlled trial.

The majority of stretching interventional research has focused on the development of a muscle's passive range of movement (PROM). Active range of movement (AROM) refers to the functional range of movement (ROM) available to the participant and provides a better insight into the relationship between muscular antagonistic pairings. The purpose of this study was to assess the effect of 3 strengthening or stretching interventions on hip and lower limb active (AROM) and passive (PROM) ranges of movement. Thirty-nine female dance students (17 ± 0.52 years; 61.7 ± 8.48 kg; 164.4 ± 5.49 cm) volunteered. They were randomly divided into 3 groups, strength training (n = 11); low-intensity stretching (n = 13); moderate-intensity or high-intensity stretching (n = 11). Four dancers withdrew during the study. All groups carried out a 6-week intervention. The strength training group focused on end of range hip flexor strength; the low-intensity and moderate-intensity stretch group carried out a series of stretches at 3/10 and 8/10 perceived exertion, respectively. Active range of movement and PROM were measured preintervention and postintervention using 2-d video analysis. Repeated measures analysis indicated that although all 3 groups improved their PROM during the experimental period (range increase: 9-200 p < 0.01), no significant differences were found between the groups. For AROM, both the strength training and the low-intensity stretch groups revealed significant improvements in ROM (range increase: 20-300) compared with the moderate-intensity or high-intensity stretch group (p < 0.01). The present data show that interventions based on strengthening agonist muscles or decreasing the resistance of antagonist muscles through low-intensity stretching are beneficial in the development of both active and passive ranges of movement and provide functional training techniques that are often over looked in favor of the more conservative moderate-intensity stretching programs.

Effect of midsole thickness of dance shoes on dynamic postural stability.

Landing from jumps is one of the main causes of injury within dance. A number of studies have reported a negative effect of shoe midsole thickness on lower limb kinematics during running due to the reduction in afferent sensory outputs from the foot's epithelium. The purpose of this study was to examine the influence of varying midsole thicknesses in dance shoes on dynamic postural stability during a single-leg landing. Twenty-eight female undergraduate dance participants volunteered for the study. They carried out three trials under four conditions: barefoot and in ballet flats (2 mm midsole thickness), jazz shoes (7 mm), and dance sneakers (30 mm). The task consisted of a single-leg forward jump over a hurdle at 50% of their maximal vertical jump height, landing on a force platform, and balancing for 3 seconds. The stability indices for vertical stability (VSI), anterior-posterior stability (APSI), medial-lateral stability (MLSI), and dynamic postural stability (DPSI) were calculated using Wikstrom's revised method. Significant differences were reported between the midsole thicknesses for both DPSI and VSI (p<0.01). No statistical differences were noted for the indices SPSI or MLSI. The present data agree with the running studies in that increased midsole thickness has a negative influence on landing stability.

Anthropometry, somatotypes, and aerobic power in ballet, contemporary dance, and dancesport.

This study compared anthropometric variables, somatotypes, and aerobic capacity between three groups of dancers: classical ballet dancers (M 33, F 56), contemporary dancers (M 28, F 109), and dancesport dancers (M 30, F 30). The assumption was that different functional requirements should produce differences in the anthropometric and aerobic capacity variables among the three groups. Anthropometric data for body mass index (BMI) and somatotypes were measured. Body fat percentage was measured by dual-energy x-ray absorptiometry. Maximal oxygen consumption and aerobic power were measured during an incremental treadmill test until exhaustion. Dancesport athletes were taller compared with same gender contemporary dancers (p<0.05). Female ballet dancers had a lower body mass and BMI compared with their contemporary dance and dancesport equivalents (p<0.001). There was significant difference between dance styles in endomorphy (F2,221 = 8.773, p<0.001) and mesomorphy (F2,221 = 21.458, p<0.001) scores. Dancesport dancers had significantly greater VO2max values (p<0.01). It was concluded that female contemporary dancers are generally more muscular than their ballet counterparts, while dancesport dancers are taller and heavier, less muscular, with slightly greater adioposity compared to the classical ballet dancers. Ballet dancers had the lowest body fat percentage, weight, and BMI values. Dancesport dancers had greater aerobic capacity than the ballet dancers. Based on this study, we conclude that dancers in these three styles differ in some aspects of anthropometric variables, somatotypes, and aerobic capacity, but we cannot say is it because of the training or selection or both.

The Effects of the 11+ Dance Neuromuscular Program on Jump Height and Lower Extremity Biomechanics in Female Adolescent Dancers: A Non-Randomized Controlled Pilot Trial.

INTRODUCTION: Neuromuscular warm-up programs, such as FIFA 11+ were developed as early as 2006. These programs have been effective in reducing the risk of injury in female athletes by decreasing the moments surrounding the knee and improving neuromuscular control during static and dynamic movements such as jumping and landing. In addition, they have been effective for improving jump height in soccer, volleyball, and basketball. METHODS: The effects of the 11+ Dance, a dance-specific neuromuscular warm-up program, was examined on jump height and lower extremity biomechanics during bilateral and single leg countermovement jumps in recreational dancers. Twenty female adolescents from 2 dance schools participated in this 2-centered 8-week controlled non-randomized trial. The intervention group (IG) performed the 11+ Dance program 3×/week for 8-weeks during the first 30-minute of their regularly scheduled dance classes. The control group (CG) continued with their regular dance classes routine. Ground reaction force and motion capture data were used to assess jump height and lower extremity biomechanics pre and post intervention. RESULTS: Both groups statistically increased their jump height (CG: Z = 1.89-2.45, P ≤ .0167; IG: Z = 2.18-2.76, P ≤ .0167). However, no statistical between group differences were observed (Z = 0.38-1.22, P > .05). During takeoff, the IG statistically reduced peak knee extension moments (t(18) = -3.04 to -3.77, P ≤ .0167) while increasing peak hip extension moments (t(18) = 2.16-2.79, P ≤ .05) and peak hip flexion angles (t(18) = 2.68-3.72, P ≤ .0167) compared to the CG. The IG also increased the hip flexion angles compared to the CG during landing (t(18) = 2.78-5.13, P ≤ .0167) while no systematic differences were observed in all other variables of lower extremity biomechanics. CONCLUSION: The reduced joint load at the knee observed during takeoff needs further investigation. Neuromuscular training, such as the 11+ Dance, is supported by numerous quality research. Due to its simplicity, the 11+ Dance may be feasible and beneficial to complement regular warm-ups in recreational dance practice.

The effect of whole-body vibration on jump height and active range of movement in female dancers.

Whole-body vibration (WBV) has been shown to have beneficial effects on strength and power indices in sedentary and moderately trained individuals. The aim of this study was to investigate the effect of 4 weeks of WBV on jump height, active range of motion (AROM), and leg anthropometry in conservatoire dance students. Seventeen female dancers were randomly assigned to a control or intervention group. The intervention group trained for 30 seconds per position at a 35-Hz frequency, 8-mm displacement in the first 2 weeks, and 40 seconds at 40 Hz for the final 2 weeks, whereas the control group carried out the same exercises but without vibration stimulation. A significant (p < 0.01) difference in the intervention group was noted over time for vertical jump and active ROM. No significant changes over time were noted in the anthropometric data. In conclusion, WBV can be used as a beneficial supplemental training intervention to increase jump and active flexibility in highly trained dancers without corresponding increases in relative anthropometric data.

Dance as an eccentric form of exercise: practical implications.

The eccentric action is an integral part of the stretch-shortening (or eccentric-concentric) cycle of muscle movement, especially when repositioning of the centre of gravity is required. Jumps and landing tasks are examples of this cycle and are incorporated in most dance activities. However, unaccustomed eccentric muscle action can cause muscle damage, which is characterised by the development of delayed-onset muscle soreness and swelling, decline of pain-free range of motion, as well as sustained loss of muscle force and range of motion. Furthermore, unaccustomed eccentric muscle action can induce disturbances in movement economy and energy expenditure, so dancers spend more energy during a routine than usual. Such negative effects are gradually reduced and eventually disappear due to physiological adaptations to this form of muscular activity. Given that eccentric exercises also appear to induce greater muscle performance improvements than other forms of muscle conditioning, it is advised that they should be integrated into dancers' weekly schedules. The purpose of the present review is to examine the possible effects of the eccentric component of dance on the performance and health status of dancers.

Perceived Severity and Management of Low Back Pain in Adult Dancers in the United States.

INTRODUCTION: Low back pain (LBP) lifetime prevalence in dancers reportedly ranges from 17% to 88%. Low back pain can have negative secondary consequences on dancers' lives and careers. Still, how LBP impacts dancer function and medical care-seeking behaviors and whether these issues differ across dance genres, is understudied.
Materials and Methods: Two hundred and eight-nine ballet, modern, and hip-hop dancers and teachers (median age: 20.3 years; range: 18 to 69 years) in the United States completed an online 24-question survey assessing LBP related self-reported injury history, impact on their lives, and management strategies. We defined LBP as occurrence of acute or chronic pain in the lumbar or sacral regions of the back.
Results: Two hundred and fifty-seven participants (88.9% of 289 total) reported at least one instance of LBP during their lifetime and 220 participants reported LBP in the prior 4 weeks. Of these 220, 72 (32.7%) had LBP severe enough to limit their activities of daily living. Of the 213 who had LBP and danced during that time, 89 (41.8%) reported that LBP limited their dancing. Pain intensity (median: 4 on a 0 to 10 scale, IQR: 3.0) and LBP prevalence were similar across dance genres. Dancers sought multiple medical professionals, most often chiropractors (n = 94, 33.8%), medical doctors (n = 77, 27.7%), and physiotherapists (n = 60, 21.6%). Ninety dancers (35.0% of those with LBP) never sought medical care. Dancers who did seek care reported higher pain intensities (median: 4, IQR: 3.8) than those who did not (median: 3, IQR: 3.0).
Conclusion: Overall, most participants did suffer from LBP. Low back pain negatively impacts dancers' everyday activities and dancing. Pain intensity and loss of function may impact care-seeking. Our findings highlight the need for all dance stakeholders to educate dancers about their health, provide resources for dancer health care, and proactively create an environment that supports injury reporting behaviors in dancers.

The Relationship of Year Group and Sex on Injury Incidence and Countermovement Jump in Adolescent Ballet Dancers: A Cross-Sectional Analysis.

INTRODUCTION: Pre-professional ballet training involves long training hours from an early age that could influence young dancers' physical performance and injury incidence. This cross-sectional analysis investigated the relationship of year group and sex with countermovement jump and injury incidence (primary outcome) in adolescent ballet dancers at a pre-professional dance school.
Method: Countermovement jump (CMJ) height was recorded at the start of the academic year for 179 participants (M = 68, F = 111) spread across eight year-groups. Injury etiology and incidence was prospectively recorded over a 6-month period (September through February) by the medical team using a time-loss definition.
Results: Between-subject statistically significant differences were reported for sex [F(1, 153) = 101.46; p < 0.001], year group [F(7, 153) = 12.57; p < 0.001], and sex*year group [F(7, 153) = 9.22; p < 0.001]. Mean CMJ across the year groups ranged between 24.7 to 41.3 cm for males and 23.5 to 25.1 cm for females. Injury incidence per dancer was 0.84 (CI: 0.13, 1.56) and injury incidence per 1,000 hours of dance was 1.94 (CI: 1.63, 2.25). No statistically significant differences between sexes or year groups were reported for injury incidence per 1,000 dance hours and time-loss. Hours dancing was statistically significantly positively associated with CMJ (r = .481, p < 0.05) and negatively associated with injury incidence (r = -.253, p < 0.05) for males; for females it was positively associated with time-loss (r = .254, p < 0.05).
Conclusion: Even though CMJ was cross-sectionally monitored, the expected increased physical abilities in males as they grew older and progressed through their training was observed. Females did not indicate a similar increase in their physical ability, but they seemed to become more susceptible to injuries as they grow older. The lack of this speculative physiological development for the females may be associated with the ballet-only approach in their training. The use of CMJ as an injury screening tool may be limited, however, it could still be used as a tool to monitor physiological and fundamental motor skill development of adolescent dancers, as jumping is an integral part of ballet.