Effects of weight-bearing dance aerobics on lower limb muscle morphology, strength and functional fitness in older women.

Objective: To investigate the effects of 12-week weight-bearing dance aerobics (WBDA) on muscle morphology, strength and functional fitness in older women. Methods: This controlled study recruited 37 female participants (66.31y ± 3.83) and divided them into intervention and control groups according to willingness. The intervention group received 90-min WBDA thrice a week for 12 weeks, while the control group maintained normal activities. The groups were then compared by measuring muscle thickness, fiber length and pennation angle by ultrasound, muscle strength using an isokinetic multi-joint module and functional fitness, such as 2-min step test, 30-s chair stand, chair sit-and-reach, TUG and single-legged closed-eyed standing test. The morphology, strength, and functional fitness were compared using ANCOVA or Mann-Whitney U test to study the effects of 12 weeks WBDA. Results: Among all recruited participants, 33 completed all tests. After 12 weeks, the thickness of the vastus intermedius (F = 17.85, P < 0.01) and quadriceps (F = 15.62, P < 0.01) was significantly increased in the intervention group compared to the control group, along with a significant increase in the torque/weight of the knee flexor muscles (F = 4.47, P = 0.04). Similarly, the intervention group revealed a significant improvement in the single-legged closed-eyed standing test (z = -2.16, P = 0.03) compared to the control group. Conclusion: The study concluded that compared to the non-exercising control group, 12-week WBDA was shown to thicken vastus intermedius, increase muscle strength, and improve physical function in older women. In addition, this study provides a reference exercise program for older women.

Women with disabilities, body image, and wellbeing: Assessing the effectiveness of dance sessions.

INTRODUCTION: There is growing research evidence on bodily discourses and body image issues of women with disabilities. Within the art-based intervention repertoire for persons with disabilities, dance and movement-based therapies and interventions are gaining prominence. The aim of this study was to examine the impact of dance sessions (delivered online) on body image, body satisfaction/dissatisfaction, and wellbeing of women with disabilities. METHOD: A quasi-experimental waitlist control design study was conducted with data collected at two time points: baseline or pre-test and five-months later or post-test. Outcomes were measured using the Body Image Scale and the WHO-5-Wellbeing Index. RESULTS: The dance sessions were effective (Hedges' g = -0.56 -0.88; p < 0.01) and post-test body dissatisfaction scores were lower and wellbeing scores were higher for participants with a college degree or postgraduate degree, self-employed or students, and whose intervention compliance was above threshold (>50% dance sessions attended and corresponding homework sessions completed). Tobit regression models indicated that it was possible to estimate post-test outcomes due to dance sessions alone, controlling for significant socio-demographics. DISCUSSION: The domain knowledge of non-pharmacological art-based interventions for persons with disabilities, particularly women, is supported. CONCLUSIONS: Findings commend dance sessions as effective psychotherapeutic mechanisms to mitigate body dissatisfaction, improve body image and wellbeing of women with disabilities. Future research may focus on large-scale cross-sectional trials, variations in the repertoire for women with different disability types and histories, and qualitative narratives.

Translation, cross-cultural adaptation, reliability and validity of the Brazilian Portuguese version of the 'Fit to Dance?' survey.

BACKGROUND: The 'Fit to Dance?' survey has been used in a number of studies to understand the health and wellbeing of dancers. These data have not been collected in Brazil as there is no validated questionnaire available in Brazilian Portuguese, culturally validated in Brazil with a scope as broad and comprehensive as that of 'Fit to Dance?'. OBJECTIVE: Translate into Brazilian Portuguese and culturally validate the questionnaire 'Fit to Dance?' in Brazil. METHODS: This was a validity and reliability study of the Brazilian Portuguese version of the 'Fit to Dance?' SURVEY: The stages of the research were: translation into the target language (Brazilian Portuguese), translation synthesis, translation validation and cross-cultural adaptation by a committee of experts in Dance Medicine and Science (DMS), reverse translation into English, pilot study (test/retest), and final version of the questionnaire. RESULTS: The questionnaire was applied to 21 dancers of different dance genres, with an age average of 25 ± 7.0 years. Cronbach's alpha (0.705), ICC (0.984) and Kappa (0.794) results reached adequate values. CONCLUSION: The Brazilian Portuguese version of the questionnaire 'Fit to Dance?' is effective, has adequate levels of validity and reliability, and can be used to report injuries and aspects of health and well-being of Brazilian dancers.

Multi-person dance tiered posture recognition with cross progressive multi-resolution representation integration.

Recognizing postures in multi-person dance scenarios presents challenges due to mutual body part obstruction and varying distortions across different dance actions. These challenges include differences in proximity and size, demanding precision in capturing fine details to convey action expressiveness. Robustness in recognition becomes crucial in complex real-world environments. To tackle these issues, our study introduces a novel approach, i.e., Multi-Person Dance Tiered Posture Recognition with Cross Progressive Multi-Resolution Representation Integration (CPMRI) and Tiered Posture Recognition (TPR) modules. The CPMRI module seamlessly merges high-level features, rich in semantic information, with low-level features that provide precise spatial details. Leveraging a cross progressive approach, it retains semantic understanding while enhancing spatial precision, bolstering the network's feature representation capabilities. Through innovative feature concatenation techniques, it efficiently blends high-resolution and low-resolution features, forming a comprehensive multi-resolution representation. This approach significantly improves posture recognition robustness, especially in intricate dance postures involving scale variations. The TPR module classifies body key points into core torso joints and extremity joints based on distinct distortion characteristics. Employing a three-tier tiered network, it progressively refines posture recognition. By addressing the optimal matching problem between torso and extremity joints, the module ensures accurate connections, refining the precision of body key point locations. Experimental evaluations against state-of-the-art methods using MSCOCO2017 and a custom Chinese dance dataset validate our approach's effectiveness. Evaluation metrics including Object Keypoint Similarity (OKS)-based Average Precision (AP), mean Average Precision (mAP), and Average Recall (AR) underscore the efficacy of the proposed method.

The geometry of interpersonal synchrony in human dance.

Collective synchronized behavior has powerful social-communicative functions observed across several animal taxa.1,2,3,4,5,6,7 Operationally, synchronized behavior can be explained by individuals responding to shared external cues (e.g., light, sound, or food) as well as by inter-individual adaptation.3,8,9,10,11 We contrasted these accounts in the context of a universal human practice-collective dance-by recording full-body kinematics from dyads of laypersons freely dancing to music in a "silent disco" setting. We orthogonally manipulated musical input (whether participants were dancing to the same, synchronous music) and visual contact (whether participants could see their dancing partner). Using a data-driven method, we decomposed full-body kinematics of 70 participants into 15 principal movement patterns, reminiscent of common dance moves, explaining over 95% of kinematic variance. We find that both music and partners drive synchrony, but through distinct dance moves. This leads to distinct kinds of synchrony that occur in parallel by virtue of a geometric organization: anteroposterior movements such as head bobs synchronize through music, while hand gestures and full-body lateral movements synchronize through visual contact. One specific dance move-vertical bounce-emerged as a supramodal pacesetter of coordination, synchronizing through both music and visual contact, and at the pace of the musical beat. These findings reveal that synchrony in human dance is independently supported by shared musical input and inter-individual adaptation. The independence between these drivers of synchrony hinges on a geometric organization, enabling dancers to synchronize to music and partners simultaneously by allocating distinct synchronies to distinct spatial axes and body parts.

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.

6-week time-restricted eating improves body composition, maintains exercise performance, without exacerbating eating disorder in female DanceSport dancers.

BACKGROUND: Despite the high risk of eating disorder (ED)-related attitudes and behaviors among female dancers, targeted scientific dietary regimens are currently inadequate. Time-restricted eating (TRE), a popular intermittent fasting protocol, has been shown to be effective in enhancing body composition and exercise performance in athletes. In this study, TRE was employed as a dietary regimen to improve body composition and exercise performance and address ED attitudes and behaviors in DanceSport dancers. METHODS: Twenty female DanceSport dancers were recruited and divided into two groups: TRE (n = 10) and normal diet (ND) (n = 10). The TRE group consumed their self-selected necessary energy intake exclusively between 11 a.m. and 7 p.m. (utilizing a 16-hour fasting and 8-hour eating window) for 6 weeks, while the ND group maintained their regular dieting patterns. The consumption of water, black tea, or coffee without added sugar or milk was not restricted. Physical activity and calorie intake were systematically recorded during the TRE intervention. Body composition, aerobic and anaerobic performance, and ED attitudes and behaviors were assessed before and after the TRE intervention. The trial was registered in the Chinese Clinical Trial Registry under the identifier ChiCTR2200063780. RESULTS: The fixed effects tests (p < 0.0001) and estimates for the intercept (p < 0.0001) of hunger level indicated a noticeable effect on the initial state of hunger during TRE. No significant differences were observed in ED attitudes or behaviors (p > 0.05). TRE resulted in a reduction in hip circumference (p = 0.039), fat mass (kg) (p = 0.0004), and body fat percentage (p = 0.0005), with no significant decrease in fat-free mass (p > 0.05). No significant improvement was observed in aerobic performance (p > 0.05). The average power (AP) (p = 0.01) and AP/Body weight ratio (p = 0.003) significantly increased. Additionally, the power drop decreased significantly (p = 0.019). Group-by-time interactions were observed for fat mass (kg) (p = 0.01), body fat percentage (p = 0.035), and AP/Body weight (p = 0.020). CONCLUSION: TRE can be considered a feasible nutritional strategy for DanceSport dancers, facilitating improvements in body composition without compromising aerobic and anaerobic exercise performance or exacerbating ED attitudes and behaviors. Moreover, TRE may facilitate more favorable physiological adaptations, potentially contributing to improved exercise performance.

Step type is associated with loading and ankle motion in tap dance.

Tap dance generates forces and joint motions that can lead to injury; however, little is known about the magnitude of load across different tap steps. The purpose of this study was to calculate peak vertical forces, average vertical foot velocities, and maximum/minimum ankle angles produced by tap dancers with different levels of experience performing the toe cannon, heel cannon, flap, and cramp roll. This prospective cross-sectional study included 14 female tap dancers aged ≥18 years with varying tap experience. Participants were recorded by three cameras while performing a choreographed tap combination containing four steps of interest on a force platform. Adjusting for experience and dancer-level clustering, we identified the steps-cramp roll and toe cannon-that had the highest peak vertical ground reaction force, angles, and velocities compared to flap and heel cannon. There was no effect of experience. The results supported our hypothesis and provide new insights into step production. Over time, the larger forces associated with these steps could pose an increased risk of injury to bones and joints when compared to smaller forces, which may suggest the importance of adjusting routines to reduce or avoid injury.

Muscle Strength Asymmetries of the Lower Limbs and Trunk in Ballet Dancers.

BACKGROUND: Ballet dancers are expected to use their bodies symmetrically during training, because dance movements are performed on both sides. However, there is a general belief that ballet training encourages the use of one side of the body more than the other. Frequent repetition of a particular exercise can lead to body asymmetries and musculoskeletal injuries. The aim of this cross-sectional study was to investigate the presence of lower limbs and trunk muscle strength asymmetries in ballet dancers and secondly to assess whether there is a difference between professional dancers and ballet students. METHODS: Ballet students (n=19) and professional ballet dancers (n=23) performed maximal voluntary isometric contractions of the trunk (flexion, extension, lateral flexion), hip (flexion, extension, adduction, abduction, external and internal rotation), knee (flexion, extension) and ankle (flexion, extension) on isometric dynamometer. RESULTS: The results showed that the percentage of ballet dancers with contralateral muscle strength asymmetries >10% ranged from 22.5% (ballet students) to 31.6% (professional dancers). The percentage of ballet dancers deviating by >10% from the normative maximum torque agonist/antagonist ratio ranged from 56.5% to 100%. A statistically significant difference between ballet students and professional ballet dancers was found in the trunk flexion/extension ratio (t(40) = -3 .55; p = 0.001; d = 0.55). CONCLUSION: This study revealed strength asymmetries in the lower limbs and trunk in ballet dancers, both professionals and students. Further research is needed to develop appropriate complementary exercise to address and eliminate asymmetries in muscle strength in ballet dancers.

Moving together - benefits of an online dance program on physical and mental health for older women: an exploratory mixed-method study.

BACKGROUND: Previous studies show that in-person dance training is a beneficial form of physical activity that involves mental, social, and physical dimensions. This exploratory study investigated the benefits of a 12-week online dance training intervention on mental and physical health outcomes for older women. METHODS: A convergent parallel mixed-method design was used. Forty-five older adults (74.0 ± 5.3 yrs old, 44 women) were recruited through advertisements at activity and rehabilitation centers in the North Denmark region. The intervention consisted of two weekly 60-min classes of improvisation and salsa delivered online through video call applications. Changes in physical health outcomes (body mass and composition, resting blood pressure, Senior Fitness Test battery) and self-rated health and wellbeing (health-related quality of life (HRQOL), feelings of loneliness) were assessed prior to and after 12 weeks of dancing. Focus group interviews were conducted post-intervention to further explore the benefits as well as the participant's experience of the intervention. Thematic analysis of the qualitative data was conducted. RESULTS: Thirty-two participants (all women) completed the study. Significant improvements in fitness were found for the number of arm curls performed (baseline: 12.3 ± 3.0; post-intervention: 13.7 ± 3.0, P = 0.005), 2-min step test performance (baseline: 66.5 ± 20.0 reps.; post-intervention: 73.8 ± 22.6 reps., P = 0.016), and chair sit-and-reach (baseline: 0.4 ± 11.3 cm; post-intervention: 5.5 ± 10.1 cm, P < 0.001). There was a significant increase in body mass from baseline to post-intervention (P < 0.015). The themes from the focus groups included (1) Participation, (2) Challenges, (3) Progression, (4) Motivation, (5) Perceived health and wellbeing, and (6) Online dance instruction. No significant changes were reported in HRQOL and loneliness from the quantitative data, although the qualitative data did reveal improved feelings of physical health and wellbeing. CONCLUSIONS: The intervention improved several aspects of fitness in older women and improved the participants' perceptions of their own physical abilities and wellbeing. While most participants found the online intervention enjoyable, several participants missed the feedback from the instructors that naturally occurs with in-person instruction.

The association of range of motion, lower limb strength, and load during jump landings in professional ballet dancers.

This study aimed to investigate the associations between peak plantarflexion ankle joint moments and vertical ground reaction forces (vGRF) during jump landings, and static ankle dorsiflexion range of motion (ROM), three-dimensional ankle excursions, and lower extremity strength in professional ballet dancers. Twenty-seven professional ballet dancers volunteered to participate (men = 14, women = 13). Participants attended one data collection session to measure dorsiflexion ROM and isometric lower extremity strength. Two further sessions were used to establish ankle mechanics and vGRFs during countermovement jump landings in seven foot positions, via a seven-camera motion capture system and piezoelectric force platform. Two linear mixed-effects models were used to investigate associations between the target variables and strength, dorsiflexion ROM, and ankle excursions. Dancer identification, sex, and foot position were entered as random effects. Model fit, when considered independent of random effects, was generally poor with the predictor variables explaining little of the variance of peak plantarflexion ankle joint moments (R2 = 0.02) or vGRF (R2 = 0.01). Model fit improved when random effects were considered (R2 = 0.65 & 0.34). Frontal plane ankle excursion was the only predictor variable with a significant negative association with peak plantarflexion ankle joint moments (p = .016), although coefficient estimates were small. Strength, static ankle dorsiflexion ROM, and three-dimensional ankle excursions are poor predictors of load experienced at a joint and system level in professional ballet dancers. Differences between individuals, sex, and foot position may be better indicators of the load experienced during jump landings.

[Dance-specific eligibility of vocational ballet students - examinations at a governmental training institution for classical ballet]. / Tanzspezifische Eignung professioneller Ballettschüler*innen ­ Untersuchungen an einer Ausbildungseinrichtung für klassischen Bühnentanz.

BACKGROUND: During their training, pre-professional ballet students are confronted with physical stresses comparable to those of competitive sports. In competitive sports, there are mandatory and binding aptitude tests to ensure that the growing athlete meets the requirements. In ballet, there are no such mandatory examinations preceding the start of training. For adult professional dancers, musculoskeletal ideals could be isolated from the dance medicine literature. However, only a few studies describe musculoskeletal characteristics of pre-professional ballet students. It is neither known at what age a student should meet the ideal measurements for an adult nor what deviations from the ideal can be considered normal. This study aims to describe sociodemographic and musculoskeletal characteristics of pre-professional ballet students and discusses to what extent they already meet or deviate from dance-specific eligibility criteria for adult professional ballet dancers. MATERIAL AND METHODS: In this study, n = 414 female and n = 192 male students of John Cranko School (JCS) were seen by an experienced orthopaedist and dance physician. Mean age was 13.9 years (SD 3.5, range 5-22 years). Their medical history was taken (age; nationality; start of ballet/training) and a physical examination was performed (height/weight; symmetry of shoulder girdle, spine, waist triangles; pelvic tilt; tibial torsion; range of motion of base of index finger joint, spine, hips, ankle and base of great toe joint). Subsequently, the results of this study were compared with suitability criteria for adult professional ballet dancers that had been isolated from the dance medicine literature for a previous article. RESULTS: Examinees were from 49 different nations. 34.6% of the female subjects (≥16 years) were between 165 and 170 cm and 33.3% of the male subjects (≥18 years) were between 178 and 185 cm tall. 45.0% of those examined showed low body weight (<10th percentile, BMI <18.5 kg/m²). The trunk of 61.0-84.8% of those examined was erect and symmetrical. 25.2% had scoliosis. Half (53.5%) were found to have a bilateral external rotation of the hips of at least 60°, and 68.7% had a bilateral internal rotation between 20 and 50°. 87.3% exhibited a bilateral tibial torsion between 15 and 40°. A bilateral en dehors of 90° was calculated for 25.0%. In 9.1% of those examined, the upper ankle joints presented a dorsiflexion of at least 25°, and in 70.2%, a plantarflexion of at least 70° was seen. In 88.0%, the metatarsophalangeal joint of the great toe was 90° (f) and 80° (m) on both sides. CONCLUSION: The results of this study showed that pre-professional ballet students fulfil many characteristics of adult professional ballet dancers. High values already among young age groups suggest a ballet-specific selection. Nevertheless, not all students fulfil the theoretical "ideal measurements" for professional classical ballet. These anatomical limits should be considered individually in training to protect the growing pre-professional ballet dancer. The high ballet-specific anatomical demands, but especially the large number of students with a low body weight, underline the necessity of mandatory aptitude tests at the beginning and regular check-ups in the course of training to avert compensatory mechanisms and their consequential damage and to screen for eating disorders and disorders of eating behaviour.

How spotting technique affects dizziness and postural stability after full-body rotations in dancers.

Consecutive longitudinal axis rotations are very common in dance, ranging from head spins in break dance to pirouettes in ballet. They pose a rather formidable perceptuomotor challenge - and hence form an interesting window into human motor behaviour - yet they have been scarcely studied. In the present study, we investigated dancers' dizziness and postural stability after consecutive rotations. Rotations were performed actively or undergone passively, either with or without the use of a spotting technique in such an order that all 24 ordering options were offered at least once and not more than twice. Thirty-four dancers trained in ballet and/or contemporary dance (aged 27.2 ± 5.1 years) with a mean dance experience of 14.2 ± 7.1 years actively performed 14 revolutions in passé or coupé positions with a short gesture leg "foot down" after each revolution. In addition, they were passively turned through 14 revolutions on a motor-driven rotating chair. Participants' centre-of-pressure (COP) displacement was measured on a force-plate before and after the rotations. Moreover, the dancers indicated their subjective feeling of dizziness on a scale from 0 to 20 directly after the rotations. Both the active and passive conditions were completed with and without the dancers spotting. As expected, dizziness was worse after rotations without the adoption of the spotting technique, both in active and passive rotations. However, the pre-post difference in COP area after active rotations was unaffected by spotting, whereas in the passive condition, spotting diminished this difference. Our results thus suggest that adopting the spotting technique is a useful tool for dizziness reduction in dancers who have to perform multiple rotations. Moreover, spotting appears most beneficial for postural stability when it involves less postural control challenges, such as when seated on a chair and occurs in situations with limited somatosensory feedback (e.g., from the cutaneous receptors in the feet). However, the unexpected finding that spotting did not help postural stability after active rotations needs to be investigated further in future studies, for example with a detailed analysis of whole-body kinematics and eye-tracking.

Toward Development of a Novel Proprioceptive Trail-Making Test: Comparing Healthy Dancers and Non-Dancers.

There is a pressing need for ecologically valid versions of traditional neuropsychological tests indexing executive function (EF), such as the Trail-Making Task (TMT), that incorporate movement and bodily awareness in healthy participants with varying abilities. We designed a proprioceptive version of the TMT (pTMT) that involved coordinated gross motor movement and proprioceptive awareness to investigate whether this measure of visual attention, task switching, and working memory positively correlated with a computerized version of the TMT (the dTMT). We aimed to establish the initial validity of our proprioceptive TMT (pTMT) by comparing performances on the dTMT and pTMT among a cohort of 36 healthy participants (18 dancers, 18 non-dancers; M age = 22, SD = 5.27; 64% female) anticipating that dancers would express higher intrinsic bodily awareness than non-dancers. Results revealed a mild to moderate but statistically significant positive correlation between dTMT and pTMT completion times [part A: r (36) = .33, p = .04; part B: r (36) = .37, p = .03] and numbers of errors [part B: r (36) = .41, p = .01] across both participant groups. These data suggest partial measurement convergence between these two TMT versions. Relative to non-dancers, dancers exhibited a higher level of performance (likely due to their better proprioceptive ability) through their faster completion times on dTMT-B [t (34) = 3.81, p = .006, d = 1.27] and pTMT-B [t (34) = 2.97, p = .005, d = .99], and their fewer errors on dTMT-B [t (34) = 2.93, p = .006, d = 1.0]. By identifying cognitive differences between these different groups of healthy individuals, our data contribute to both a theoretical understanding and the initial development of gross motor movement-based cognitive assessments, providing a path toward the further refinement of an ecologically valid full-body TMT.

The relationship between postural control and cognitive functioning following Zumba dancing in middle-aged women: A randomized clinical trial.

This study aimed to investigate the effect of 12-week Zumba dancing on postural control and cognitive parameters and the correlations between these parameters in middle-aged women. Thirty-eight women, aged between 50 and 60 years, were randomly allocated to a Zumba group (ZG) or control group. Postural control and cognitive functions [working memory (WM) and reaction time (RT)] were assessed before and after 12 weeks of a Zumba dancing program using a stabilometric force platform, Corsi Block-Tapping Task and Simple RT tests, respectively. The results indicate that ZG showed significantly (p<.01) better balance performances when standing on a stable surface in both visual conditions [firm surface with eyes opened (EO) (20,9%) and eyes closed (EC) (12.3%)]. However, when standing on an unstable surface in both visual conditions (foam surface with EO/EC), the ZG showed no significant improvement in postural control. It seems that the benefits of Zumba on postural control depend on the sensory condition. Besides, 12-week Zumba dancing was not sufficient to significantly enhance cognitive performances (RT/WM) performances. These cognitive performances were related to postural control in challenging conditions and can be considered an effective tool for monitoring postural performances following an intervention program. Clinicians should, therefore, focus on interventions that boost cognitive functions in middle-aged women to achieve optimal postural control, mainly in challenging conditions, in order to prevent the risk and fear of falls as well as the incidence of falling.

Single-Leg Heel Raise Capacity is Lower, and Perceived Ankle Instability is Greater, in Dancers and Athletes With Posterior Ankle Impingement Syndrome.

OBJECTIVE: To compare clinical assessment findings between elite athletic populations with and without a clinical diagnosis of posterior ankle impingement syndrome (PAIS). DESIGN: Cross-sectional case-control study. SETTING: Elite ballet and sport. PARTICIPANTS: Ten male and female professional ballet dancers and athletes with a clinical diagnosis of PAIS and were matched for age, sex, and activity to 10 professional ballet dancers and athletes without PAIS. INDEPENDENT VARIABLES: Posterior ankle pain on body chart and a positive ankle plantarflexion pain provocation test. MAIN OUTCOME MEASURES: Single-leg heel raise (SLHR) endurance test, range of motion testing for weight-bearing ankle dorsiflexion, passive ankle plantarflexion, and first metatarsophalangeal joint dorsiflexion, and Beighton score for generalized joint hypermobility. Participants also completed the Cumberland Ankle Instability Tool (CAIT) questionnaire. RESULTS: The group with PAIS achieved significantly fewer repetitions on SLHR capacity testing ( P = 0.02) and were more symptomatic for perceived ankle instability according to CAIT scores ( P = 0.004). CONCLUSIONS: Single-leg heel raise endurance capacity was lower, and perceived ankle instability was greater in participants with PAIS. The management of this presentation in elite dancers and athletes should include the assessment and management of functional deficits.

Effects of Five Common Preparatory Approaches on Grand Jeté Biomechanics.

Introduction: The grand jeté requires grace and proper biomechanics to produce the iconic glide through the air. Understanding how the preceding choreographed movements affect take-off and flight may influence teaching and training. We sought to examine the effects of 5 common preparatory approaches on grand jeté biomechanics. Methods: One male and 19 female dancers (19.3 ± 1.4 years; 1.61 ± 0.05 m; 58.1 ± 7.3 kg) with 12.5 ± 4.8 years of formal ballet experience performed grand jetés from run, chaine, chasse, assemble, and step-step approaches. Plié angle (deg), vGRF (BW), leap height (m), and leap distance (m) were measured with a motion analysis system and a force plate. One-way repeated measures ANOVAs were conducted to compare variables between approaches and Bonferroni tests were used for pairwise comparisons. Results: Plié depth, vGRF, leap height, and leap distance were all significantly different (P < .001). Plié angles (43.6-68.2 deg) were deepest for the assemble and shallowest for the run. vGRF (2.46-3.81 BW) were greatest for the assemble versus all but the run, and smallest for the chaine. Leap height (0.33-0.41 m) was highest for the run versus the chaine and step-step, but not versus assemble. Height was lowest for the chaine. Leap distance (0.24-1.03 m) was longest for the run and shortest for the assemble. Conclusions: The run approach optimizes the float through the air illusion (high leap height and distance) through applying high vGRF but moderate plié angles. The chasse approach is the next most optimal. The 2-legged assemble requires deeper plié angles to achieve height but produces shorter horizontal distances. Single leg plié training may enhance grand jeté performance and reduce injury risk from approaches such as the run, chaine, chasse, and step-step.Level of Evidence: Level 2.

Dancers Show More Accurate Trunk-Pelvic Joint Angle Reproduction While Wearing a Jacket Augmented With Elastic Bands.

Purpose: The Backalast® compression jacket is intended to improve posture and proprioception of the trunk and shoulder girdle for dancers and dance students during dance training by way of elastic bands in the rear of the garment (which include bands enclosing the inferior thorax). This study was intended to investigate whether there is evidence to support those objectives. Materials and Methods: Fifteen dance students participated (4 male, mean age 19.9 ± 1.4 years old). The dependent variables of trunk-pelvis angle and proximity of trunk axis to global vertical for each participant were measured using optical motion capture before and after the completion of a series of trunk movements. The Helen Hayes model, which we used to represent the trunk, includes the shoulder girdles as part of the trunk. We compared the effect of the type of garment (Backalast® or control compression shirt) worn upon the 2 dependent variables, within-subject with paired t-tests. The order of whether Backalast® or control compression shirt was worn first was alternated between participants. Results: The pre/posttest difference in trunk proprioception as represented by the construct of ability to reproduce trunk-pelvis angle wearing the Backalast® was 0.8° ± 0.8°, but for the control shirt, the difference was 1.8° ± 1.4°, P = .03. The difference between garments in vertical trunk alignment, measured after the series of trunk movements, was not significant. Conclusion: Our findings suggest that the Backalast® can help enhance trunk proprioception when compared to the control compression shirt, although it did not change the angle at which the participants' held their trunks while standing erect (proximity to global vertical).

Differences in Achilles tendon mechanical properties between professional ballet dancers and collegiate athletes utilizing shear wave elastography.

PURPOSE: To report normative stiffness parameters obtained using shear wave elastography in dorsiflexion from the Achilles tendons in asymptomatic professional ballet dancers and compare them with college-level athletes. METHODS: An Institutional Review Board (IRB)-approved study consists of 28 professional ballet dancers and 64 asymptomatic collegiate athletes. The athletes were further subdivided into runner and non-runner disciplines. Shear wave elastography (SWE) measurements were made in maximum ankle dorsiflexion position. RESULTS AND DISCUSSION: Forty-eight (52%) males and 44 (48%) females were examined with an overall mean age of 22.2 (± 3.8 years). There were no significant SWE differences between dominant and non-dominant legs in both groups and comparing spin vs. non-spin leg of ballet dancers (p > 0.05). Ballet dancers had significantly higher short-axis velocity values than runners and non-runners (2.34 m/s increase and 2.79 m/s increase, respectively, p < 0.001). Long-axis velocity was significantly higher in ballet dancers compared to non-runners (by 0.80 m/s, p < 0.001), but was not different between ballet dancers and runners (p > 0.05). Short-axis modulus was significantly higher in dancers compared to runners and non-runners (by 135.2 kPa and 159.2 kPa, respectively, p < 0.001). Long-axis modulus (LAM) was not significantly different in ballet dancers when compared to runners. CONCLUSION: Asymptomatic professional ballet dancers exhibit greater short-axis tendon stiffness compared to athletes and greater long-axis tendon stiffness compared to non-runners but similar to runners. The functional benefit from elevated short-axis stiffness in dancers is not clear but may be related to greater axial loading and adaptations of the tendon matrix.