Ground reaction forces and knee mechanics in the weight acceptance phase of a dance leap take-off and landing

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.

The effects of eccentric training on hamstring flexibility and strength in young dance students

The objective of this research is to examine the impact of eccentric training on hamstring flexibility and strength in young dancers during the concluding stages of their foundational dance training program. A total of 24 female, second-year dance students from Hebei Normal University were selected as participants. They were divided into three distinct groups: Nordic hamstring exercise and single-leg deadlift group (NHE&SLD), forward bending exercises and standing leg lift group (FBE&SLL), and a control group (CG). The study was designed around a 6-week training regimen. An isokinetic dynamometer was used to measure seated knee flexor-extensor strength, while electronic goniometry was employed to measure hamstring flexibility in the supine position. Paired sample t-tests were conducted within each group, and one-way analysis of covariance (ANCOVA) was utilized for comparisons between groups. In the NHE&SLD group, significant disparities were observed in both concentric (T = - 5.687, P = 0.001) and eccentric (T = - 3.626, P = 0.008) hamstring strength pre and post-intervention. The pre-intervention dominant leg concentric strength test values significantly influenced the post-intervention outcomes (F = 5.313, P = 0.001, η2 = 0.840). Similarly, the pre-intervention dominant leg eccentric strength test values impacted the post-intervention results (F = 4.689, P = 0.043, η2 = 0.190). Following the intervention, the NHE&SLD group displayed marked changes in the active straight leg raising angle on both left (T = - 4.171, P = 0.004) and right (T = - 6.328, P = 0.001) sides. The FBE&SLL group also revealed significant changes in the active straight leg raising angle on both left (T = - 4.506, P = 0.003) and right (T = - 4.633, P = 0.002) sides following the intervention. The pre-intervention left leg concentric strength test value significantly influenced the post-intervention outcomes (F = 25.067, P = 0.001, η2 = 0.556). Likewise, the pre-intervention right leg eccentric strength test value significantly influenced the post-intervention results (F = 85.338, P = 0.01, η2 = 0.810). Eccentric training can better enhance the flexibility and strength of hamstring muscles in dance students. Traditional stretching training significantly improves the flexibility of the hamstring muscles. Eccentric training has more training benefits than traditional stretching training. It is recommended for dance students to use eccentric training when increasing hamstring flexibility and strength.

Comparisons of musculoskeletal injuries among three different modalities of Taekwondo (Kyorugi, Poomsae, and Shibum): a one-year follow-up prospective epidemiologic study

The purpose of the study was to report the injury rates and characteristics (body location, type, mechanism, and severity) of musculoskeletal injuries in Kyorugi, Poomsae, and Shibum. A total of 137 Korean collegiate Taekwondo players - Kyorugi (n = 44), Poomsae (n = 46), and Shibum (n = 47) - were prospectively studied in 2019. Injury rates per 1,000 athlete-exposures (AEs) and time-exposures (TEs) during training and competition were calculated. Additionally, body location, type, mechanism, and severity of injury were analysed. The highest injury rate was recorded in Poomsae (172.0/1,000 AEs and 79.5/1,000 TEs) followed by Kyorugi (47.1/1,000 AEs and 25.9/1,000 TEs) and Shibum (57.5/1,000 AEs and 17.0/1,000 TEs). The frequently injured body location was the thigh (Kyorugi = 17%; Poomsae = 25%; Shibum = 18%). The common injury types were muscle cramps/spasms in Kyorugi (33%) and Poomsae (59%), and sprain in Shibum (41%). The common injury mechanisms were gradual onset in Kyorugi (40%) and Shibum (49%), and non-contact trauma in Poomsae (91%). Regarding the severity, the number of days from the injury onset to recovery > 1 week were higher in the order of Kyorugi (78%), Shibum (54%), and Poomsae (28%). Our data provide preliminary evidence that different injury prevention strategies should be applied to each modality of Taekwondo.

The Effect of Foot Position and Lean Mass on Jumping and Landing Mechanics in Collegiate Dancers

The purpose of this study was to investigate the effects of foot positioning and lean mass on jumping and landing mechanics in collegiate dancers. Thirteen dancers performed 3 unilateral and bilateral vertical jumps with feet in neutral and turnout positions. Dual-energy x-ray absorptiometry scans, jump height, vertical stiffness, and joint stiffness were assessed for relationships between foot positions. Jump heights were greater in right compared with left limb (P = .029) and neutral compared with turnout (P = .020) during unilateral jumping. In unilateral landing, knee stiffness was greater in turnout compared with neutral (P = .004) during the loading phase. Jump height (P < .001) was significantly increased, and vertical stiffness (P = .003) was significantly decreased during bilateral jumping in neutral compared with turnout. Significantly increased hip stiffness during the attenuation phase was observed in neutral compared with turnout (P = .006). Left-limb lean mass was significantly less than the right limb (P < .05). Adjustments for bilateral jumping were focused on hip stiffness, whereas there was a slight shift to knee strategy for unilateral jump.

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.

Comparison of Tibial Geometry, Density, and Strength in College-Aged Female Eumenorrheic Dancers, Gymnasts, and Runners: A Peripheral Quantitative Computed Tomography Study

INTRODUCTION

Weightbearing activities such as gymnastics, soccer, weightlifting, and running have often been used as benchmarks in skeletal research since they have been shown to promote densitometric and geometric benefits. In comparison with other sports, there is a paucity of information in relation to dance and its osteogenic potential.

OBJECTIVE

This study aimed to compare tibial geometry, density, and strength in college-aged dancers versus gymnasts and runners.

METHODS

A total of 60 trained eumenorrheic collegiate-aged female dancers (n = 11), gymnasts (n = 11), runners (n = 19), and sedentary controls (n = 19) were included in the study. Bone measurements, including total area (ToA), volumetric (total vBMD) and cortical density (CoD), compressive bone strength (BSI), and polar strength stress index (SSIp) of the dominant limb, were assessed using peripheral quantitative computed tomography (pQCT) at the distal and proximal tibia (4% and 66% of limb length).

RESULTS

No significant differences in ToA, CoD, CoA, and total vBMD were found between dancers and the comparison athletes at the measured sites. In addition, strength indices (BSI and SSIp) at the distal and proximal sites were similar between the dancing and both athlete groups.

CONCLUSION

Results suggest dance elicits similar structural adaptations at the tibia compared to benchmark high-impact and repetitive impact sports; thus, indicating dance, in its various forms, can have a positive effect on important bone variables that influence density and strength. These adaptations may potentially delay or prevent bone fragility later in life. Future studies should compare individual styles of dance separately, longitudinally, and include other important lower (e.g., hip) and upper body (e.g., radius) sites to further identify which forms provide the greatest osteogenic benefits.

Movement quantity and quality: How do they relate to pain and disability in dancers?

Objective

This field-based study aimed to determine the association between pre-professional student dancers’ movement quantity and quality with (i) pain severity and (ii) pain related disability.

Methods

Pre-professional female ballet and contemporary dance students (n = 52) participated in 4 time points of data collection over a 12-week university semester. At each time point dancers provided self-reported pain outcomes (Numerical Rating Scale as a measure of pain severity and Patient Specific Functional Scale as a measure of pain related disability) and wore a wearable sensor system. This system combined wearable sensors with previously developed machine learning models capable of capturing movement quantity and quality outcomes. A series of linear mixed models were applied to determine if there was an association between dancers’ movement quantity and quality over the 4 time points with pain severity and pain related disability.

Results

Almost all dancers (n = 50) experienced pain, and half of the dancers experienced disabling pain (n = 26). Significant associations were evident for pain related disability and movement quantity and quality variables. Specifically, greater pain related disability was associated with more light activity, fewer leg lifts to the front, a shorter average duration of leg lifts to the front and fewer total leg lifts. Greater pain related disability was also associated with higher thigh elevation angles to the side. There was no evidence for associations between movement quantity and quality variables and pain severity.

Discussion

Despite a high prevalence of musculoskeletal pain, dancers’ levels of pain severity and disability were generally low. Between-person level associations were identified between dancers’ movement quantity and quality, and pain related disability. These findings may reflect dancers’ adaptations to pain related disability, while they continue to dance. This proof-of-concept research provides a compelling model for future work exploring dancers’ pain using field-based, serial data collection.

Countermovement Jump and Drop Jump Performances Are Related to Grand Jeté Leap Performance in Dancers With Different Skill Levels

ABSTRACT

Blanco, P, Nimphius, S, Seitz, LB, Spiteri, T, and Haff, GG. Countermovement jump and drop jump performances are related to grand jeté leap performance in dancers with different skill levels. J Strength Cond Res 35(12): 3386-3393, 2021-Thirty-five classical ballet dancers were chosen to investigate relationships between the grand jeté leap, countermovement jump (CMJ), and drop jump (DJ) and establish whether the magnitude of the relationship between these tests differed across 3 skill levels. Subjects (male: n = 11 and female: n = 24) were divided into 3 groups: novice (n = 12; age: 16.6 ± 1.5 years; height: 1.7 ± 0.1 m; body mass: 58.0 ± 13.0 kg), semiprofessional (n = 13; age: 20.0 ± 1.6 years; height: 1.7 ± 0.1 m; body mass: 64.1 ± 10.5 kg), and professional (n = 10; age: 23.8 ± 3.5 years; height: 1.8 ± 1.2 m; body mass: 63.3 ± 14.7 kg). Grand jeté leap height, followed by CMJ and DJ vertical displacement, was assessed. Significant relationships were found between the grand jeté, CMJ (r = 0.77, p = 0.001) and DJ (r = 0.76, p = 0.001). After a Fisher's r-z transformation, professional dancers and novice dancers showed greater r-value differences in CMJ (r2 - r1 = 0.27) compared with novice (r2 - r1 = 0.17) and semiprofessional dancers (r2 - r1 = 0.11), indicating larger strength of CMJ to grand jeté relationship in professionals. The grand jeté leap showed large to very large correlations with CMJ and DJ within groups. These common performance tests were determined to be practical and efficient methods for assessing the jumping ability of dancers. As dance skill increased, larger correlations were observed, suggesting that dancers with superior ballet skills may be more likely to use their underpinning physical capacities to jump higher within the context of ballet-specific jumping.

Analysis of foot structure in young recreational female ballet dancers

Study aim: The human foot is an essential element of the locomotor system. It plays a key role in both the dynamics and the statics of the whole lower limb. The normal structure of the foot determines its mechanical function. During growth and formation of the foot structure, sport activity plays an important role.

The aim of this study was to analyse the structure of the foot in ballet dancers aged 6 to 14 years compared with a clinical reference peer group that did not do ballet.

Material and methods: The study involved 120 girls aged 6 to 14 years (mean age 9.6, sd. 2.4). Sixty of them formed the study group of ballet dancers, and the other 60 formed the reference group. To conduct the measurements, the computer podoscope CQ-ST produced by the CQ Elektronik System, connected to a portable computer, was used.

Results: A few differences were found between the foot structure in young female ballet dancers and their peers. A statistically significant difference was found in the hallux valgus α angle. The left foot of the examined ballet dancers was found to have a larger hallux valgus. A statistically significant correlation was found between the length of time of ballet training and the increase in the α angle values of the left foot and the right foot in the ballet group.

Conclusions: Ballet dancing in childhood may increase the risk of developing hallux valgus, with the tendency of worsening with training time.

The effects of both jump/land phases and direction on Achilles tendon loading

BACKGROUND

Athletes in jumping and running sports have a high incidence of Achilles tendon (AT) injuries. We compared AT loading during jumping and landing phases in anteroposterior (AP) and mediolateral (ML) directions.

METHODS

Sixteen males (age: 21.6±1.8 years, height: 178.4±6.4 cm, weight: 76.4±11.2 kg) performed single leg AP and ML jump-landings during both propulsive (jump) and braking (land) phases. Inverse dynamics and static optimization were used to determine muscle forces. AT cross sectional area was measured with ultrasound. AT force was divided by cross sectional area to determine stress while strain was determined from previous data. Two-way repeated measures analysis of variance (α=0.05) compared several variables (vertical ground reaction force (VGRF), ankle and knee angle, ankle joint muscle moment arm, external ankle moment arm, AT tendon force, stress, and strain) between movements (jump-landings) and directions (AP/ML).

RESULTS

AT loading was higher during jump than land in the ML compared to AP direction. VGRF was higher during land versus jump with no direction effect (AP/ML). An interaction showed a higher VGRF during the AP land and ML jump. The ankle joint moment arm was lower in jump and AP direction at peak tendon stress. External ankle moment arm at peak tendon stress was higher in jump and ML direction with an interaction. A larger external ankle moment arm occurred in ML but the change was less in the jump.

CONCLUSIONS

Higher tendon loading occurred during the jump and ML direction. This may provide insight into both injuries and rehabilitation efforts.

Lower Leg Morphology and Stretch-Shortening Cycle Performance of Dancers

Greater levels of bone ultimate fracture load, bone stress–strain index, muscle cross-sectional area, and maximal voluntary isometric plantarflexion (MVIP) strength of the lower leg may be adaptations from chronic exposure to stretch-shortening cycle (SSC) actions. Dancers, a population that habitually performs SSC movements primarily about the ankle joint, may serve as a novel population to gain broader understanding of SSC function. A total of 10 female collegiate dancers and 10 untrained controls underwent peripheral quantitative computed tomography scans of both lower legs and performed MVIPs, countermovement hops, and drop hops at 20, 30, and 40 cm on a custom-made inclined sled. Dancers had greater right and left ultimate fracture load values and significantly (P ≤ .05) greater left leg stress–strain index than controls. Dancers had significantly larger right and left muscle cross-sectional area and MVIP values and hopped significantly higher during all hopping conditions in comparison with controls. Average force–time and power–time curves revealed significantly greater relative force and power measurements during the concentric phase for all hopping conditions in dancers when compared with controls. This investigation provides evidence that dance may be a stimulus for positive muscle and bone adaptations, strength levels, and enhanced SSC capabilities.

Differences in lower limb biomechanics between ballet dancers and non-dancers during functional landing tasks

OBJECTIVES

To determine the differences in the lower limb landing biomechanics of adolescent ballet dancers compared to non-dancers when performing a hop and a stop jump task.

DESIGN

Cross-sectional.

SETTING

Laboratory.

PARTICIPANTS

Thirteen adolescent female ballet dancers (11.8 ± 1.1 years) and 17 non-dancers (10.9 ± 0.8 years) performed hop and stop jump tasks.

MAIN OUTCOME MEASURES

Vertical ground reaction force, and three-dimensional ankle, knee and hip joint angles and moments during the landing phase.

RESULTS

Dancers displayed greater sagittal plane joint excursions during the hop and stop jump at the ankle (mean difference = 22.0°, P < 0.001, 14.8°, P < 0.001 respectively), knee (mean difference = 18.1°, P = 0.001, 9.8°, P = 0.002 respectively) and hip (stop jump task; mean difference = 8.3°, P = 0.008). Dancers displayed a larger hip extensor moment compared to non-dancers (P < 0.001) during the stop jump task only. Dancers also took longer to reach peak vGRF and jumped three times higher than non-dancers (P < 0.001) during the stop jump task. No difference in peak vGRF between groups was displayed for either task.

CONCLUSIONS

Adolescent dancers demonstrate a transfer of landing technique to non-ballet specific tasks, reflective of the greater jump height and sagittal plane joint excursions. This landing strategy may be associated with the low rate of non-contact ACL injuries in female dancers.

Unravelling Motor Learning Processes in Theater Performers

Theater performers, more than common actors, experience high physical loadings. This study aimed at analyzing the motor behavior of novice performers (dancers/actors who were introduced to the acting method of Jan Fabre) by investigating the kinematics of a physical acting exercise in a prospective study. Two measurement sessions were organized: before and after the novice performers (N = 13) took part in seven workshops. Total body kinematics were registered using a three-dimensional motion capture system. Using a principal component analysis, six factors were disseminated out of 30 kinematic parameters: Pelvic Motion, Speed of Progression, Lower Limb Position, Foot Motion, Lower Limb Motion, and Trunk Posture. Although no main effect of training was found for any of the factors (.429 < p < .964), Trunk Posture showed a higher consistency after the workshops. This study succeeded in providing insights in the motor behavior of theater performers and revealed recognizable features of motor learning.

An Approach to Ballet Dance Training through MS Kinect and Visualization in a CAVE Virtual Reality Environment

This article proposes a novel framework for the real-time capture, assessment, and visualization of ballet dance movements as performed by a student in an instructional, virtual reality (VR) setting. The acquisition of human movement data is facilitated by skeletal joint tracking captured using the popular Microsoft (MS) Kinect camera system, while instruction and performance evaluation are provided in the form of 3D visualizations and feedback through a CAVE virtual environment, in which the student is fully immersed. The proposed framework is based on the unsupervised parsing of ballet dance movement into a structured posture space using the spherical self-organizing map (SSOM). A unique feature descriptor is proposed to more appropriately reflect the subtleties of ballet dance movements, which are represented as gesture trajectories through posture space on the SSOM. This recognition subsystem is used to identify the category of movement the student is attempting when prompted (by a virtual instructor) to perform a particular dance sequence. The dance sequence is then segmented and cross-referenced against a library of gestural components performed by the teacher. This facilitates alignment and score-based assessment of individual movements within the context of the dance sequence. An immersive interface enables the student to review his or her performance from a number of vantage points, each providing a unique perspective and spatial context suggestive of how the student might make improvements in training. An evaluation of the recognition and virtual feedback systems is presented.

Increasing plantarflexion angle during landing reduces vertical ground reaction forces, loading rates and the hip's contribution to support moment within participants

The ankle joint's role in shock absorption during landing has been researched in many studies, which have found that landing with higher amounts of plantarflexion (PF) results in lower peak vertical ground reaction forces and loading rates. However, there has not yet been a study that compares drop landings within participants along a quantitative continuum of PF angles. Using a custom-written real-time feedback program, participants adjusted their ankles to an instructed PF angle and dropped onto two force platforms. For increasing PF, peak ground reaction force and peak loading rate during weight acceptance decreased significantly. The hip's contribution to peak support moment decreased as PF at initial contact increased up to 30°. The ankle and knee contributions increased over this same continuum of PF angles. There appears to be no optimal PF angle based on peak ground reaction force and loading rate measurements, but there may be an optimum where joint contributions to peak support moment converge and the hip moment's contribution is minimised.

Dancers with patellar tendinopathy exhibit higher vertical and braking ground reaction forces during landing

Dancers are exposed to the effects of repetitive jumping and leaping as are other athletes that tend to develop patellar tendinopathy. Greater vertical ground reaction forces occur during landing from a dance leap than during takeoff and during other common athletic activities. The purposes of this study were: (1) to compare the landing ground reaction force profiles of participants with and without clinically diagnosed patellar tendinopathy, and (2) to determine the strength of the relationship between landing angle, and braking impulse. Eighteen elite pre-professional dancers (12 healthy, 6 with patellar tendinopathy; both groups 50% male) performed sauts de chat for kinetic and kinematic analysis. Dancers with patellar tendinopathy demonstrated greater peak vertical ground reaction force and impulse (36% and 15% greater, respectively). Dancers with patellar tendinopathy demonstrated greater peak braking ground reaction force and impulse (82% and 126% greater, respectively). Landing angle explained 67% of the braking impulse. Dancers with patellar tendinopathy exhibited greater vertical and braking impulses than healthy dancers. Braking impulse was strongly correlated with landing angle. While there was no difference between groups in landing angle, dancers with patellar tendinopathy exhibited greater braking impulse than their non-tendinopathic counterparts, even at similar landing angles.

Dancers with achilles tendinopathy demonstrate altered lower extremity takeoff kinematics

STUDY DESIGN

Controlled laboratory study using a cross-sectional design.

OBJECTIVES

To analyze lower extremity kinematics during takeoff of a "saut de chat" (leap) in dancers with and without a history of Achilles tendinopathy (AT). We hypothesized that dancers with AT would demonstrate different kinematic strategies compared to dancers without pathology, and that these differences would be prominent in the transverse and frontal planes.

BACKGROUND

AT is a common injury experienced by dancers. Dance leaps such as the saut de chat place a large demand on the Achilles tendon.

METHODS

Sixteen female dancers with and without a history of AT (mean ± SD age, 18.8 ± 1.2 years) participated. Three-dimensional kinematics at the hip, knee, and ankle were quantified for the takeoff of the saut de chat, using a motion analysis system. A force platform was used to determine braking and push-off phases of takeoff. Peak sagittal, frontal, and transverse plane joint positions during the braking and push-off phases of the takeoff were examined statistically. Independent samples t tests were used to evaluate group differences (α = .05).

RESULTS

The dancers in the tendinopathy group demonstrated significantly higher peak hip adduction during the braking phase of takeoff (mean ± SD, 13.5° ± 6.1° versus 7.7° ± 4.2°; P = .046). During the push-off phase, dancers with AT demonstrated significantly more internal rotation at the knee (13.2° ± 5.2° versus 6.9° ± 4.9°; P = .024).

CONCLUSION

Dancers with AT demonstrate increased peak transverse and frontal plane kinematics when performing the takeoff of a saut de chat. These larger displacements may be either causative or compensatory factors in the development of AT.