An analysis of the foot in turnout using a dance specific 3D multi-segment foot model

Cueing Dancers to "Externally Rotate From the Hips" Improves Potentially Injurious Ankle Joint Angles and Contact Forces During a Demipointe Ballet Position

Introduction: The demipointe dance position puts the ankle at high risk of overuse injury and posteromedial ankle pain due to increased ankle valgus forces. Previous work has shown that creating lower limb external rotation intrinsic to demipointe with hip external rotation reduces foot pronation that causes ankle valgus stress. Therefore, the purpose of this work was to examine long axis rotation kinematics of the hip, knee, and ankle as well as the ankle joint contact forces in demipointe to better understand the biomechanical impact(s) of the specific cue to increase hip external rotation in this position. Methods: Three-dimensional motion capture and force plate data were collected from 23 contemporary or ballet pre-professional dancers (age: 19.94 ± 1.34 years) who each performed 3 dancer-selected (DS) demipointe positions and 3 demipointes with the cue to "externally rotate from the hips." Results: The cue to increase hip external rotation resulted in significantly increased hip external rotation angle [DS: 37.5; 9.42° (median; interquartile range), Cued: 39.9; 10.8°, P < .0001)] and significantly reduced ankle eversion angle (DS: 8.13; 11.4°, Cued: 7.77; 10.3°, P = .023). However, total turnout angle was also significantly decreased (DS: 75.8; 7.91°, Cued: 75.4; 7.73°, P < .0001), which is undesirable for proper esthetic performance of demipointe. Total ankle joint force remained unchanged, but ankle eversion force was significantly reduced (DS: 15.3; 4.18 %bodyweight (BW), Cued: 14.7; 4.99 %BW, P < .0001) with use of the cue. Discussion/Conclusion: Utilization of a cue to increase hip external rotation was successful in increasing hip contribution to turnout angle and reducing injurious ankle eversion force. Further coaching using this cue may allow dancers to produce these advantageous mechanics while maintaining turnout angle.

The time-continuous association between turnout and axial joint moments in the competitive Irish dance 'fly' landing

Turnout is a key technical and aesthetic element in competitive Irish dance involving external rotation of the lower limb and must be sustained during landings. 'Forced' turnout, aided by floor friction rather than active hip rotation, is likely to result in large internal rotation moments at the knee and ankle, which may increase the risk of injury. The aim of the current study was to establish the relationship between the hip and ankle external rotation vector field and maximum internal rotation moments of the ankle and knee. Thirteen (12 female) competitive Irish dancers performed 10 flys (common Irish dance leap) onto a force plate while being recorded by a ten-camera motion capture system. Time-continuous data were analysed over the duration of landing using statistical parametric mapping (SPM). A positive correlation (p < 0.05) was found between the hip-ankle turnout vector field and maximum ankle internal rotation moments throughout most of the landing. Post-hoc analyses showed that hip external rotation contributed the most to the maximum ankle internal rotation moment (p < 0.05). Increasing hip turnout during landing could reduce internal rotation moments, assuming hip turnout brings the thigh and foot axial orientation more in line with each other.

Hallux valgus in preprofessional adolescent dancesport athletes: Prevalence and associated training factors

BACKGROUND

This study aimed to determine the risk factors of hallux valgus angle among preprofessional adolescent dancesport athletes.

METHODS

A total of 275 athletes, (73 males and 202 females) aged between the ages of 11 and 18 years, participated in this study. A cross-sectional questionnaire was used to survey their demographic characteristics (sex and age), training information (starting age, weekly training time, and athletic career [number of years of training at this specific dancesport school]), and measured their height and weight. The hallux valgus angle was measured based on foot photographs. The chi-square test was used to compare the difference with prevalence of hallux valgus between male and female athletes. A normal distribution test was performed, and based on the test results, unpaired t-test and multiple logistic regression were conducted to identify training factors for the hallux valgus in this cohort.

RESULTS

Chi-square test showed higher prevalence of hallux valgus in female elite adolescent dancesport athletes than males. The t-test results did not show any significant differences between the hallux valgus group and non-hallux valgus groups with start age, athletic career, and weekly training time. Multiple logistic regression analysis with hallux valgus as the dependent variable revealed that the female sex was a strong predictor of a higher prevalence of hallux valgus (odds ratio [OR]: 3.954, 95% confidence interval 95% CI: 2.193-7.131, and p < 0.001). Weekly training time was also entered into the multiple logistic regression model (OR: 1.033, 95% CI: 1.001-1.067, and p = 0.041).

CONCLUSIONS

Our findings revealed that the prevalence of hallux valgus in adolescent dancesport athletes was higher in females than in males. Longer weekly training time was also a risk factor for hallux valgus. Training factors should be considered in preventive programs for elite adolescent dancesport athletes, and special attention should be paid to female athletes.

Foot and Ankle MRI Findings in Asymptomatic Professional Ballet Dancers

Background

Previous research in sport populations has demonstrated that abnormal magnetic resonance imaging (MRI) findings may be present in individuals without symptoms or known pathology. Extending this understanding to ballet, particularly in relation to the foot and ankle, is important to guide medical advice given to dancers.

Purpose

To assess foot and ankle MRI scans in asymptomatic ballet dancers focusing on bone marrow edema and the posterior ankle and to investigate whether these MRI findings would become symptomatic within 1 year.

Study Design

Case series; Level of evidence, 4.

Methods

In total, 31 healthy dancers (62 feet/ankles; 15 male and 16 female; age, 26.5 ± 4.3 years) who were dancing in full capacity were recruited from an elite professional ballet company. Orthogonal 3-plane short tau inversion recovery imaging of both feet and ankles was obtained using 3T MRI and the images were reviewed using a standardized evaluation form by 2 musculoskeletal radiologists. Injuries in the company were recorded and positive MRI findings were assessed for correlation with any injuries requiring medical attention during the subsequent 12 months.

Results

A total of 51 (82%) of the 62 feet and ankles had ≥1 area of bone marrow edema. The most common locations of bone marrow edema were the talus (n = 41; 66%), followed by first metatarsal (n = 14; 23%). Os trigonum and Stieda process were seen in 5 (8%) and 8 (13%) ankles, respectively. Among them, 2 os trigona showed bone marrow edema. Fluid in the anterior and posterior talocrural joints and the subtalar joint was observed in 48%, 63%, and 63% of these joints, respectively. Fluid around foot and ankle tendons was observed, with the most prevalent being the flexor hallucis longus tendon (n = 13; 21%). Two dancers who had positive findings on their MRI subsequently developed symptoms during the next 12 months.

Conclusion

Positive MRI findings are commonplace in the foot and ankle of asymptomatic professional ballet dancers. The majority do not result in the development of symptoms requiring medical attention within 12 months. Careful interpretation of MRI findings with the dancer's clinical picture is required before recommending activity modification or further intervention.

The vertical mobility of the first tarsometatarsal joint during demi-plié with forced turnout in ballet dancers

The forced turnout has a perceived risk of development of hallux valgus (HV) in ballet dancers. We determined how the forced turnout affects the sagittal mobility of the first tarsometatarsal (TMT) joint, which is one of the pathogenic factors of HV development. Seventeen female ballet dancers (body mass index: 18.2 ± 1.8 kg/m2) were included and performed demi-plié in control, functional turnout, and forced turnout conditions. Ultrasound imaging synchronized with a three-dimensional motion analysis system was used for measuring the vertical locations of the first metatarsal and medial cuneiform (MC) to evaluate the first TMT joint mobility. Plantar displacement of MC and the first TMT joint mobility in the forced turnout were the greatest among the 3 conditions. Multiple regression analysis indicated that the greater extent of the forcing angle might increase the displacement of MC and the first TMT joint mobility. Evaluating the sagittal mobility of the first TMT joint in the forced turnout can assist in understanding the association between inappropriate techniques including the forced turnout and HV development in ballet dancers. Since the excessive mobility of the first TMT joint is a factor in HV development, the acquirement of adequate active turnout may have the potential to prevent HV development in ballet dancers.

Sensing Technology for Assessing Motor Behavior in Ballet: A Systematic Review

Background

Human performance in classical ballet is a research field of growing interest in the past decades. Technology used to acquire data in human movement sciences has evolved, and is specifically being applied to evaluate ballet movements to better understand dancers’ profiles. We aimed to systematically review sensing technologies that were used to extract data from dancers, in order to improve knowledge regarding the performance of ballet movements through quantification.

Methods

PubMed, MEDLINE, EMBASE, and Web of Science databases were accessed through 2020. All studies that used motor control tools to evaluate classical ballet movements, and possible comparisons to other types of dance and sports movements were selected. Pertinent data were filled into a customized table, and risk of bias was carefully analyzed.

Results

Eighty studies were included. The majority were regarding classical ballet and with pre-professional dancers. Forty-four studies (55%) used two or more types of technology to collect data, showing that motion capture technique, force plates, electromyography, and inertial sensors are the most frequent ways to evaluate ballet movements.

Discussion

Research to evaluate ballet movements varies greatly considering study design and specific intervention characteristics. Combining two or more types of technology may increase data reliability and optimize the characterization of ballet movements. A lack of studies addressing muscle–brain interaction in dancers were observed, and given the potential of novel insights, further studies in this field are warranted. Finally, using quantitative tools opens the perspective of defining what is considered an elite dancer.

The Impact of Hallux Valgus on Adolescent Ballet Dancer Balance and Health-Related Quality of Life Scores

BACKGROUND

It is well-known that hallux valgus (HV) alters foot biomechanics. In different populations, HV and postural stability has been studied, but HV and the adolescent ballet dancer has not been studied. The aims of this study were to explore the effect of HV on adolescent ballet dancers' balance and to assess the health-related quality of life (HRQOL) of adolescent ballet dancers with HV.

METHODS

Female ballet dancers aged 8 to 16 years were screened prospectively and divided into two groups: those with HV (group 1) and those without HV (group 2). The HV diagnosis was made clinically. The groups were compared according to balance parameters and HRQOL questionnaires.

RESULTS

In group 1 (n = 31) and group 2 (n = 24), the mean age was 11.6 years and 12.2 years, respectively. Mean first metatarsophalangeal angle was 13.4° (range, 10°-15°) in group 2 and 19.8° (range, 16°-25°) in group 1. A statistically significant difference was found according to the nonparametric Mann-Whitney U test results in the comparison of HV angle between groups. According to Spearman rho correlation analysis, it was determined that the increase in HV angle caused deterioration in the flamingo static balance test (r = 0.552; P = .019). No significant relationship was found between HRQOL questionnaires and the presence of HV (P > .05).

CONCLUSIONS

Adolescent ballet dancers experience static balance impairment due to HV angle increase. Clinical measurement of HV and application of balance parameters made easy without need of set ups to perform evaluation with high numbers of participants in concordance with the literature.

Optimization Simulation of Dance Technical Movements and Music Matching Based on Multifeature Fusion

Music and dance videos have been popular among researchers in recent years. Music is one of the most important forms of human communication; it carries a wealth of emotional information, and it is studied using computer tools. In the feature engineering process, most present machine learning approaches suffer from information loss or insufficient extracted features despite the relevance of computer interface and multimedia technologies in sound and music matching tasks. Multifeature fusion is widely utilized in education, aerospace, intelligent transportation, biomedicine, and other fields, and it plays a critical part in how humans get information. In this research, we offer an effective simulation method for matching dance technique movements with music based on multifeature fusion. The initial step is to use music beat extraction theory to segment the synchronized dance movements and music data, then locate mutation points in the music, and dynamically update the pheromones based on the merits of the dance motions. The audio feature sequence is obtained by extracting audio features from the dancing video's accompanying music. Then, we combine the two sequences to create an entropy value sequence based on audio variations. By comparing the consistency of several approaches for optimizing dance movement simulation trials, the optimized simulation method described in this research has an average consistency of 87%, indicating a high consistency. As a result, even though the background and the subject are readily confused, the algorithm in this research can keep a consistent recognition rate for more complicated dance background music, and the approach in this study can still guarantee a certain accuracy rate.

Type of Turnout and Injury Rates in Elite Dancers: A Critically Appraised Topic

Clinical Scenario: Dancers commonly stand in hip external rotation due to the esthetics that ballet requires. Increased external rotation is desired which leads dancers to find ways to compensate to increase their external rotation, an action known as compensated turnout. Dancers commonly rotate at the tibiofemoral joint and/or the talocrural joint to increase external rotation of the entire lower body, placing increased stress on these joints. This critically appraised topic focuses on the relationship between types of turn out and lower-extremity injury in dancers. Clinical Question: In elite dancers, does compensated, anatomical, or functional turnout influence lower-extremity injuries? Summary of Key Findings: Three studies met the inclusion criteria and were included in the analysis. One study demonstrated a relationship between compensated turnout and traumatic injuries, low back pain, and number of injuries in modern dancers. Greater compensated turnout in dancers was associated with a greater number of injuries. Two studies showed no relationship between anatomical or functional turnout and injuries in dancers. Clinical Bottom Line: Based on 3 level 2b studies, there is level C evidence to suggest that increased compensated turnout is associated with increased traumatic lower-extremity injuries, low back pain, and number of injuries in university modern dancers compared with dancers with a reduced angle of compensated turnout. This relationship was not found between anatomical or functional turnout and lower-extremity injuries in elite dancers. Strength of Recommendation: There is weak evidence to suggest that compensated turnout, but not anatomical or functional turnout, is related to lower-extremity musculoskeletal injury. More research is needed to study compensatory mechanisms in a broader range of dancers and the relationship to lower-extremity injury.

In Pursuit of the Perfect Dancer's Ballet Foot. The Footprint, Stabilometric, Pedobarographic Parameters of Professional Ballet Dancers

This work aims to assess footprint parameters in a group of professional ballet dancers and to determine the correlation between the aforementioned parameters and lateralization, stabilometric parameters, pedobarographic parameters and work environment conditions. A group subjected to tests consisted of 44 elite professional ballet dancers and the reference group was composed of 44 students. The test of balance and thrust under feet involved 30 s-long free standing with open eyes on a podographic platform. The research-related analysis was concerned with footprint parameters (foot length and width, Clarke angle, and Weissflog index), stabilometric parameters (path length and ellipse field, mean value of the velocity and deflection of the displacement of the center of the foot pressure on the ground) and pedobarographic parameters (percentage thrust on the right, left foot as well as the front and rear part the foot). Statistically significant differences between the groups were observed in relation to the stabilometric parameters, the percentage pressure of the left forefoot and the right heel, as well as the value of the Clarke angle (p ≤ 0.05). The longitudinal arch of the foot and the width of the foot in ballet dancers are not dependent on the total and professional career duration and weekly training volume.

Four meta-analyses across 164 studies on atypical footedness prevalence and its relation to handedness

Human lateral preferences, such as handedness and footedness, have interested researchers for decades due to their pronounced asymmetries at the population level. While there are good estimates on the prevalence of handedness in the population, there is no large-scale estimation on the prevalence of footedness. Furthermore, the relationship between footedness and handedness still remains elusive. Here, we conducted meta-analyses with four different classification systems for footedness on 145,135 individuals across 164 studies including new data from the ALSPAC cohort. The study aimed to determine a reliable point estimate of footedness, to study the association between footedness and handedness, and to investigate moderating factors influencing footedness. We showed that the prevalence of atypical footedness ranges between 12.10% using the most conservative criterion of left-footedness to 23.7% including all left- and mixed-footers as a single non-right category. As many as 60.1% of left-handers were left-footed whereas only 3.2% of right-handers were left-footed. Males were 4.1% more often non-right-footed compared to females. Individuals with psychiatric and neurodevelopmental disorders exhibited a higher prevalence of non-right-footedness. Furthermore, the presence of mixed-footedness was higher in children compared to adults and left-footedness was increased in athletes compared to the general population. Finally, we showed that footedness is only marginally influenced by cultural and social factors, which play a crucial role in the determination of handedness. Overall, this study provides new and useful reference data for laterality research. Furthermore, the data suggest that footedness is a valuable phenotype for the study of lateral motor biases, its underlying genetics and neurodevelopment.

Correlation between degree of hallux valgus and kinematics in classical ballet: A pilot study

Hallux valgus is a serious medical concern for classical ballet dancers. Although it is well-known that progression of hallux valgus is related to inappropriate movement techniques in classical ballet, the kinematic relationship between the degree of hallux valgus and ballet techniques has not been substantiated. To develop proper training methods that prevent progression of hallux valgus, this study aimed to investigate the relationship between the degree of hallux valgus and movement techniques in classical ballet. Seventeen female classical ballet dancers at the advanced college-level participated in this study. Kinematic analysis of standing and plié in the first position was conducted via video capture technique. The Pearson product-moment correlation analysis was performed to examine the degree of hallux valgus and the following three kinematic variables: (1) the extent to which turnout is forced by other joints in the lower extremity than the hip joint, (2) the direction difference between the knee and toe in the transverse plane, and (3) the pelvis obliquity angle. Among these kinematic variables, we found a significant correlation between the hallux valgus angle and the pelvis obliquity angle during plié (P = .045). The greater the hallux valgus angle, the greater the retroversion of the pelvis, a result which was contrary to our prediction. We present the first evidence that the degree of hallux valgus correlates with kinematics in a very basic technique of classical ballet.

On the track of the ideal turnout: Electromyographic and kinematic analysis of the five classical ballet positions

The turnout of the lower extremities is the major component of the classical ballet positions (CPs) and correctly is initiated in the hips. The aim of this research was to determine the differences in the electromyographic and kinematic variables in the five CPs in ballet students with greater and lesser amount of passive hip external rotation (HER). A group of 14 female pre-professional ballet dancers 11–16 years of age participated in the study. Based on the amount of passive HER, participants with higher values made up greater rotation group (n = 7) whereas those with lesser values formed lesser rotation group (n = 7). Electromyographic activity of 14 muscles from right side of the trunk and right lower extremity was recorded with the surface electrodes while subjects were standing in all five CPs (CP1-CP5). The external rotation of the hips, knees and feet were recorded with the motion capture system. The kinematic differences between the groups were revealed in asymmetric positions CP4 and CP5 where foot progression angle was significantly lesser in forward than backward setting only in lesser rotation group. In lesser rotation group the ankle and back muscles were more engaged in CPs while abdominal and hip muscles less when compared with greater rotation group. This finding suggests that in the group with lesser passive HER the mechanism of forced turnout was employed. The most remarkable finding in our work was that various electromyographic patterns can be observed between groups in all CPs, while kinematic differences may be marked only in asymmetric positions.