The influence of classical dance training on preferred supporting leg and whole body turning bias

Jumping Asymmetries and Risk of Injuries in Preprofessional Ballet

BACKGROUND

Preprofessional ballet dancers are exposed to the risk of injuries, primarily in the lower extremities, with most injuries occurring during jumping and landing activities. Interlimb asymmetry during jumping and landing activities has been associated with the injury risk in adolescent athletes, but this has not been examined in dancers.

PURPOSE

To investigate associations between interlimb asymmetry during a double-leg countermovement jump (DL-CMJ) and single-leg jump (SLJ) and the injury risk in adolescent preprofessional ballet dancers.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Adolescent preprofessional ballet dancers (N = 255) performed 3 DL-CMJs and 3 SLJs on force plates during annual screening. Absolute and directional (separate values for left and right limb dominance) asymmetries in a set of kinetic variables during a DL-CMJ and in jump height during an SLJ were calculated. Each variable was characterized as having "high" or "normal" asymmetry according to the percentage of asymmetry (greater than or less than or equal to, respectively, the mean ± 0.5 SD) based on the present sample. Risk ratios (RRs) and 95% CIs were calculated based on the injury incidence in the subsequent academic year.

RESULTS

Of the 242 dancers that satisfied the inclusion criteria, 128 injuries were observed in the subsequent academic year. In the whole sample, 3 absolute, 7 left limb-dominant, and 1 right limb-dominant kinetic asymmetry in the eccentric, concentric, and landing phases of the DL-CMJ as well as left limb-dominant jump height asymmetry in the SLJ were associated with a significant (P < .001) increase in the injury risk (RR, 1.28-1.69 [95% CI, 1.02-2.37]). Separating by sex, asymmetries in the eccentric and landing phase of the DL-CMJ were not significant in boys, while in girls, RRs for asymmetries in the eccentric and landing phase of the DL-CMJ increased, and SLJ jump height asymmetry was not significant.

CONCLUSION

Higher asymmetries in certain kinetic variables during the DL-CMJ and in jump height during the SLJ were associated with an elevated risk of injuries in elite preprofessional ballet dancers with some sex-specific differences. Associations were mainly identified for high left limb-dominant asymmetry in the takeoff phase, suggesting that the injury risk may be specific to a relative right limb deficit.

Neuropsychological Evidence Underlying Counterclockwise Bias in Running: Electroencephalography and Functional Magnetic Resonance Imaging Studies of Motor Imagery

We aimed to answer the question "why do people run the track counterclockwise (CCW)?" by investigating the neurophysiological differences in clockwise (CW) versus CCW direction using motor imagery. Three experiments were conducted with healthy adults. Electroencephalography (EEG) was used to examine hemispheric asymmetries in the prefrontal, frontal, and central regions during CW and CCW running imagery (n = 40). We also evaluated event-related potential (ERP) N200 and P300 amplitudes and latencies (n = 66) and conducted another experiment using functional magnetic resonance imaging (fMRI) (n = 30). EEG data indicated greater left frontal cortical activation during CCW imagery, whereas right frontal activation was more dominant during CW imagery. The prefrontal and central asymmetries demonstrated greater left prefrontal activation during both CW and CCW imagery, with CCW rotation exhibiting higher, though statistically insignificant, asymmetry scores than CW rotation. As a result of the fMRI experiment, greater activation was found during CW than during CCW running imagery in the brain regions of the left insula, Brodmann area 18, right caudate nucleus, left dorsolateral prefrontal cortex, left superior parietal cortex, and supplementary motor area. In the ERP experiment, no significant differences were found depending on direction. These findings suggest that CCW rotation might be associated with the motivational approach system, behavioral activation, or positive affect. However, CW rotation reflects withdrawal motivation, behavioral inhibition, or negative affect. Furthermore, CW rotation is understood to be associated with neural inefficiency, increased task difficulty, or unfamiliarity.

The Role of Art Expertise and Symmetry on Facial Aesthetic Preferences

Humans, like other species, have a preference for symmetrical visual stimuli, a preference that is influenced by factors such as age, sex, and artistic training. In particular, artistic training seems to decrease the rejection of asymmetry in abstract stimuli. However, it is not known whether the same trend would be observed in relation to concrete stimuli such as human faces. In this article, we investigated the role of expertise in visual arts, music, and dance, in the perceived beauty and attractiveness of human faces with different asymmetries. With this objective, the beauty and attractiveness of 100 photographs of faces with different degrees of asymmetry were evaluated by 116 participants with different levels of art expertise. Expertise in visual arts and dance was associated with the extent to which facial asymmetry influenced the beauty ratings assigned to the faces. The greater the art expertise in visual arts and dance, the more indifferent to facial asymmetry the participant was to evaluate beauty. The same effect was not found for music and neither for attractiveness ratings. These findings are important to help understand how face aesthetic evaluation is modified by artistic training and the difference between beauty and attractiveness evaluations.

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.

Hallux sesamoid fractures in young athletes

Objective: To describe the evaluation, management and recovery time of hallux sesamoid fractures in young athletes.Methods: A retrospective chart review was performed in a large academic teaching institution over a 5-year period (1/1/2010-12/31/2014). All patients with a sesamoid injury were initially included. Excluded were those patients who: 1) did not receive the diagnosis of hallux sesamoid fracture, had a history of prior foot surgery, or had medical records inadequate for analysis, 2) had missing or unclear diagnostic imaging, 3) were age >21 years, or 4) did not report sports participation. Descriptive statistics were employed to analyze the data.Results: Fifty-eight patients (51 females and 7 males) with a mean age of 15.4 years (range: 9-21) were identified with a total of 59 sesamoid fractures. Dancing (37.9%), running (13.8%), and gymnastics (13.8%) were the most common sports reported among these patients. A greater number of fractures were classified as repetitive stress injuries (83.1%), rather than acute traumatic injuries (16.9%). Fractures were treated conservatively in the majority of cases (89.8%), and only six fractures (10.2%) were treated surgically. Most patients (84.7%) were able to return to sports and activities. The average time from diagnosis/start of treatment to pain-free state/cleared to return to sport was 161.4 days.Conclusion: Diagnosis of sesamoid fractures can be challenging, but overall most patients do well with conservative treatment and are able to return to sports and activities. Providers should keep sesamoid fracture in the differential when evaluating patients with pain in the area around the base of the first toe, especially in dancers, gymnasts, and runners. Understanding that the recovery from a sesamoid fracture can be a prolonged process may help patients develop realistic expectations.

Functional muscle asymmetries and laterality in Latin American formation dancers

BACKGROUND

Despite the high popularity of Latin American dance and the specific movement patterns characteristic of this dance discipline, studies on the physical effects of these dance style specific movement patterns are still lacking.

OBJECTIVE

The purpose of the present study is to analyze strength level differences and shortening of relevant muscle groups resulting from formation dance, taking performance standard and gender into consideration. Furthermore, the correlation between the findings of muscle function tests (MFT) and the occurrence of lumbar spine complaints is evaluated.

METHODS

A total of 66 participants (m: n= 31, f: n= 35) volunteered for this cross-sectional study (examination group, n= 39, m: n= 19, f: n= 20). The control group consisted of n= 27 participants (m: n= 12, f: n= 15). Besides isometric maximal strength tests (Digi Max system, mechaTronic), relevant muscle groups were examined for shortenings (hip flexors, hamstrings).

RESULTS

The male participants in dance sport reached a significantly higher strength level in the muscles of the spine region (p= 0.011) than the participants of the control group. The female elite dance athletes developed a significantly higher strength level in the knee flexors on the right side than the dancers of the advanced group (NL) (p= 0.021). At that, muscle shortening were observed that seem to be specific to dance sport. In addition, gender specific differences were observed both in strength levels and in tendency to shortenings.

CONCLUSION

The specific requirements profile of Latin American formation dance seems to produce affects in the form of muscular imbalance on both sides of the body. These differences of muscular status were mainly observed between dance sport competitors and non-dancers rather than between performance levels. Future investigations with higher numbers of participants would be necessary here.

Muscular imbalances and balance capability in dance

Objective

A high unilateral load to the musculoskeletal system is specific for formation dance. Due to the lack of data the aim of this study was the side-related (right – left) analysis of strength- and balance capability subject to injuries, gender and performance standards.

Methods

N = 51 dancers (m: n = 24, f: m = 27) of two performance levels participated in this cross-sectional study. Double-sided tests of the isometric maximal strength of relevant muscle groups and the balance capability were carried out. The tests were supplemented by a self report questionnaire.

Results

Tests of the isometric maximal strength in the elite performance level showed significant differences between either side of the body. As to the balance capability, no significant side-related differences could be found in. Correlations between the strength capability and the injuries could be observed in either group.

Conclusion

The significant strength differences are presumably caused by the right-sided load in the dance-specific movements. The cautious conclusion that movement patterns challenge the stability of either side of the body likewise may be allowed. The increased injury frequency at the muscularly stronger side of the body primarily results from an overload. An additive muscular training should be considered as a preventive measure.

Childrens' left-turning preference is not modulated by magical ideation

The literature on human turning preferences is inconsistent. While the few studies with children below 14 years of age uniformly describe an overall left-turning (counterclockwise) tendency, a recent Internet study with more than 1500 adults found a right-sided (clockwise) bias. We set out to investigate spontaneous turning behaviour in children age 5-3 years and, based on neuropsychiatric work in adults, also explored a potential association with magical thinking. Findings indicated a clear left-turning preference, independent of a participant's sex and handedness. Whether a child responded a question about the existence of extrasensory communication in the affirmative or not was unrelated to direction and size of turning bias and lateral preference. Our results are consistent with a left-sided turning preference reported for children, but in opposition to the clockwise bias recently described in a large-scale study with adults. Whether they point to a maturational gradient in the preferred direction of spontaneous whole-body rotation or rather to a lack of comparability between measures used in observational versus Internet-based studies remains to be further investigated. Regarding a purported association between body turns and magical thinking, our study is preliminary, as only one single question was used to probe the latter.

Differences of ballet turns (pirouette) performance between experienced and novice ballet dancers

PURPOSE

This study investigated the different postural control strategies exhibited by experienced and novice dancers in ballet turns (pirouettes).

METHOD

Thirteen novice and 13 experienced dancers performed ballet turns with dominant-leg support. The peak push force was measured in the double-leg support phase. The inclination angles of rotation axis with respect to vertical axis were calculated in the early single-leg support phase as well as the initiation sequence of ankle, knee, and hip joints on the supporting leg. Moreover, the anchoring index of the head was computed in the transverse plane during turning.

RESULTS

The novice dancers applied a greater push force, an increased inclination angle of rotation axis, and an insufficient proximal-to-distal extension sequence pattern. The novice dancers also had a smaller head-anchoring index compared with experienced dancers, which meant novice dancers were not using a space target as a stability reference.

CONCLUSIONS

A poorer performance in novice dancers could result from higher push force in propulsion, lack of a "proximal-to-distal extension sequence" pattern, and lack of visual spotting for postural stability. Training on sequential initiation of lower-extremity joints and rehearsal of visual spotting are essential for novice dancers to obtain better performance on ballet turns.

Absence of lateral navigational bias in young children

Previous research has shown American adults exhibit a systematic navigational bias to favor moving to the right when locomoting around obstacles and other people. To further investigate how and when the right-side navigational bias develops, the authors tested pre-school and early elementary school aged American children. Children ran down a straight pathway with an object at the center of the end-line. Unlike replicated findings with adults, both pre-school and early elementary school aged children showed no tendency to favor either side of the object. These findings support that the rightward navigation bias found in adults is not present in children up to elementary school, and suggest that the onset of bias occurs during the age range of late elementary or secondary school.

Rotational preference in gymnastics

In gymnastics, most skills incorporate rotations about one or more body axes. At present, the question remains open if factors such as lateral preference and/or vestibulo-spinal asymmetry are related to gymnast's rotational preference. Therefore, we sought to explore relationships in gymnast's rotation direction between different gymnastic skills. Furthermore, we sought to explore relationships between rotational preference, lateral preference, and vestibulo-spinal asymmetry. In the experiment n = 30 non-experts, n = 30 near-experts and n = 30 experts completed a rotational preference questionnaire, a lateral preference inventory, and the Unterberger-Fukuda Stepping Test. The results revealed, that near-experts and experts more often rotate rightward in the straight jump with a full turn when rotating leftward in the round-off and vice versa. The same relationship was found for experts when relating the rotation preference in the handstand with a full turn to the rotation preference in the straight jump with a full turn. Lateral preference was positively related to rotational preference in non-expert gymnasts, and vestibulo-spinal asymmetry was positively related to rotational preference in experts. We suggest, that gymnasts should explore their individual rotational preference by systematically practicing different skills with a different rotation direction, bearing in mind that a clearly developed structure in rotational preference between different skills may be appropriate to develop more complex skills in gymnastics.

Neurocognitive control in dance perception and performance

Dance is a rich source of material for researchers interested in the integration of movement and cognition. The multiple aspects of embodied cognition involved in performing and perceiving dance have inspired scientists to use dance as a means for studying motor control, expertise, and action-perception links. The aim of this review is to present basic research on cognitive and neural processes implicated in the execution, expression, and observation of dance, and to bring into relief contemporary issues and open research questions. The review addresses six topics: 1) dancers' exemplary motor control, in terms of postural control, equilibrium maintenance, and stabilization; 2) how dancers' timing and on-line synchronization are influenced by attention demands and motor experience; 3) the critical roles played by sequence learning and memory; 4) how dancers make strategic use of visual and motor imagery; 5) the insights into the neural coupling between action and perception yielded through exploration of the brain architecture mediating dance observation; and 6) a neuroesthetics perspective that sheds new light on the way audiences perceive and evaluate dance expression. Current and emerging issues are presented regarding future directions that will facilitate the ongoing dialog between science and dance.