Introduction
Dancers provide a unique blend of athlete and artist [17], for whom ideal physical attributes are just as important as they are in sport. In addition to their performance, musicality, and technique skills, ballet dancers are selected particularly for their physical qualities amongst other attributes [41]. Ballet students are selected into vocational schools based on their potential talent and physical characteristics [41]. However, incidence of injury in professional companies and in vocational schools remains high [1]
[11]. Howse (1970) advocated for physical screening in ballet students at auditions for the Royal Ballet School. This was based on the premise of reducing injury risk [18]. An audition involves participating in a class where a dancer performs for a panel of experts, and because many companies select dancers from their own schools, it can be assumed that professional ballet dancers set the trend for selection into vocational schools. This study was confined to the physical attributes most desired in elite ballet dancers. This study forms the first part of a Delphi Survey designed to provide information on the requirements to identify professional dancers with lower risks of injury than at present.
Talent identification in aesthetic sports such as gymnastics has been investigated [40] with the conclusion that an appropriate physique in gymnastics for both aesthetic reasons and biomechanical advantages is well known to be important. Such studies have not previously been applied to ballet. Of all dance genres, classical ballet is relatively uniform with a vocabulary that is internationally recognized.
The Delphi technique is a recognised research method that uses a series or round of questionnaires to gather opinions that are continued until a group consensus is achieved [15]
[28]. The technique involves presenting a questionnaire to a panel of preselected, informed individuals or experts to seek their opinion on a particular subject.
In this paper we present and discuss the first round of a Delphi questionnaire in which the physical characteristics most required for classical ballet were obtained, grouped and ranked in order of importance.
Methods
Ethical approval was obtained from the Ethical Committee of University College London and meets the ethical standards for this journal [16].
Study design
Purposive sampling was used to identify an initial panel of international professional company directors, vocational ballet school directors, choreographers, senior teachers, principal dancers, exercise specialists, therapists and doctors. This formed a panel of experts involved in the selection, training and therapeutic treatment of dancers. Purposive sampling is a form of non-probability sampling [9]. Depth and specificity of knowledge and expertise were required and therefore a purposive approach was used to recruit appropriate professionals. Snowball sampling was also used to further increase the size of the panel. This method was helpful to access further, well-informed potential participants not known to the researcher [9]. Colleagues in ballet familiar with the criteria for panel inclusion were requested to distribute the questionnaire.
Data collection
For the first round of the Delphi survey, an anonymous online questionnaire comprising 3 questions was created using Opinio software 7.6.4. Two questions were closed questions, requesting demographic information and profession. The third question was an open-ended question which asked for up to 10 physical attributes expected in today’s elite dancer. The request was ‘Please list up to 10 physical attributes that you think make a great classical ballet dancer’. Although responses were anonymous it was possible for the researcher to see non-responders in order to send reminders via email.
Data analysis
Data was downloaded from Opinio to MS Excel. Demographic and profession data was analysed using descriptive statistics. The open question responses were reviewed and inappropriate recommendations were excluded such as psychological or artistic attributes. The remaining data was coded, thematically analysed and grouped into categories of similar responses by the primary researcher. Thematic analysis is useful when assessing the varied responses to an open-ended question and patterns of similar responses/topics can be grouped allowing the researcher to capture all the data and organise it under distinct headings [7]
[19]. The categories were then reviewed, refined and agreed with 3 members of the research team, HB, JS and AdeM prior to further analysis using descriptive statistics.
Results
Demographics
One hundred and forty-eight participants completed and returned questionnaires. The majority of respondents were physiotherapists and ballet teachers ([Table 1]). Although 6 continents were represented, most of the respondents were from Western Europe and North America ([Table 2]).
Table 1 Professional Background of Participants.
|
Profession
|
Number
|
|
Artistic Director Company
|
14
|
|
Artistic Director School
|
14
|
|
Senior Ballet Teacher
|
44
|
|
Choreographer
|
3
|
|
Principal Dancer
|
8
|
|
Exercise Specialist
|
10
|
|
Physical Therapist
|
46
|
|
Doctor
|
9
|
Table 2 Geographical Location of Participants.
|
Location
|
Number
|
|
Western Europe
|
82
|
|
North America
|
34
|
|
Australasia
|
18
|
|
South America
|
7
|
|
Eastern Europe
|
3
|
|
Africa
|
2
|
|
Asia
|
2
|
Reported physical attributes
Thirty-four attributes were reported. These are listed in thematic groups ([Table 3]). Overall flexibility, overall strength, turnout, body proportions, and foot and ankle flexibility were the most frequently reported.
Table 3 Reported Physical Attributes (ranked by frequency of selection and expressed as a percentage), grouped within each of the broad themes most applicable to ballet.
|
Theme
|
|
Attribute
|
Frequency
|
%
|
|
Flexibility
|
1.
|
Overall flexibility
|
86
|
58
|
|
2.
|
Hip turnout flexibility
|
75
|
50
|
|
3.
|
Foot and ankle flexibility
|
69
|
46
|
|
4.
|
Good pointe position (plantarflexion)
|
21
|
14
|
|
5.
|
High extensions
|
13
|
8.7
|
|
6.
|
Not too hypermobile
|
12
|
8
|
|
7.
|
Good demi plié (dorsiflexion)
|
8
|
5
|
|
8.
|
Hyperextended knee
|
7
|
4.6
|
|
9.
|
Flexible big toe
|
2
|
1
|
|
Strength
|
10.
|
Overall strength
|
85
|
57
|
|
11.
|
Spinal/core strength
|
25
|
16.7
|
|
12.
|
Foot and ankle strength
|
10
|
6.7
|
|
13.
|
Power
|
12
|
8
|
|
14.
|
Ability to jump
|
10
|
6.7
|
|
15.
|
Leg strength
|
4
|
2.6
|
|
16.
|
Upper body strength
|
1
|
0.6
|
|
Coordination
|
17.
|
Coordination
|
34
|
22.8
|
|
18.
|
Balance
|
13
|
8.7
|
|
19.
|
Ability to turn (pirouette)
|
1
|
0.6
|
|
Stability
|
20.
|
Overall stability
|
3
|
2
|
|
21.
|
Spinal stability
|
2
|
1
|
|
22.
|
Shoulder stability
|
2
|
1
|
|
23.
|
Control
|
36
|
24
|
|
Proportions
|
24.
|
Overall good proportions
|
71
|
48
|
|
25.
|
Head/neck
|
35
|
23
|
|
26.
|
Long Legs
|
33
|
22
|
|
27.
|
Long arms
|
17
|
11
|
|
28.
|
Short trunk
|
14
|
9
|
|
29.
|
Height
|
2
|
1
|
|
Aesthetics
|
30.
|
Slimness
|
45
|
30
|
|
31.
|
Leg shape
|
17
|
11
|
|
32.
|
Beauty
|
14
|
9
|
|
Fitness
|
33.
|
Stamina
|
44
|
29.5
|
|
Miscellane-ous
|
34.
|
Eyesight
|
1
|
0.6
|
Discussion
This first round of the Delphi Survey highlights the wide-ranging physical attributes preferred in the ballet dancer today. Thirty-four attributes were recommended. A pragmatic approach was then taken to group these into themes to facilitate a synthesized initial discussion prior to the second round of the Delphi.
Overall flexibility was the most frequently recommended attribute by the expert panel. The demands of ballet technique require dancers to have a greater than normal range of movement at the hip [6]
[14]
[26], spine [29], and foot and ankle [34]. The implications of this are reviewed in detail by Day, Koutedakis and Wyon, 2011 [8]. The authors contend that although this is aesthetically attractive, the risks of injury caused by excessive flexibility may have been overlooked, because some 44% of dancers display hypermobility. However, conventional hypermobility scoring systems are not specifically aimed at dancers and much more research is needed in the area.
Flexibility in dancers is thought to be partly inherited and partly acquired [13]. Inherited characteristics include both the shape of the articulating surfaces of bone and collagen structure [3]
[12]. Additional inherited factors influence range of movement in ballet. External rotation of the hip is further influenced by femoral anteversion angle [2]
[30], acetabular version and depth, and laxity of the anterior iliofemoral ligament [2]. In addition to these inherited traits, range of movement may also be influenced by prolonged static stretching as part of training [13].
‘Hypermobility’, normally understood to be a greater than average range of movement at joints compared to the average population [13], was cited as a desirable feature. Inevitably this overlaps with the more frequent selection of ‘overall flexibility’ as being desirable. The cut point at which flexibility (which more correctly refers to muscle length) becomes ‘hypermobility’ is somewhat arbitrary even when standard scales not applied to dance are used and many respondents may not have appreciated this. However, because many respondents, in their open comments, specified that desired ‘hypermobility’ should not be excessive ([Table 3]), it is probable that the medical community sampled was aware of the greater risk of injury associated with ‘hypermobility’.
Referring to the selected physical attributes in [Table 3], the flexible hip desirable in classical ballet technique is based on ‘turnout’, where the lower limb is externally rotated and the available range of movement in the hip joint is increased [24]. Turnout is qualified as the summation of external rotation of the lower extremities [21]
[24] including contributions from the hip, femur, knee, lower-leg, and foot-ankle complex. Sufficient external rotation at the hip in ballet dancers facilitates control of the lower limb and is thought to reduce the risk of injury [2].
Foot and ankle flexibility and good ‘pointe’ position were often cited as necessary. Ballet dancers weight-bear on extreme ranges of plantar flexion (the en pointe position or ¾ pointe) [34]
[35] in order to execute ballet-specific movements and achieve ideal aesthetics. The fully plantar-flexed position must allow the body weight to descend through the tips of the toes encased in the box of the pointe shoe or ¾ pointe (through the toes and dorsiflexed metatarsophalangeal joints). There is also an important aesthetic element where the plantarflexed foot and ankle continue the length of line of the lower limb. Articulation of the ankle contributes to most of the range of movement, with the remaining contribution from the midfoot [34]. Sufficient weight-bearing dorsiflexion is required to allow the dancer to execute the ‘demi plié’, which allows dancers to execute explosive jumps as well as sustained manoeuvres [5]
[20]. Range of motion here relies on bone shape, soft tissue laxity and neuromuscular tone.
Strength was also frequently reported. The leaps and jumps in ballet demand high muscle torque as well as the balance and postural control required for highly complex moves such as pirouettes. In the past dancers have been considered not as fit or well conditioned as equivalent athletes [23] particularly with respect to strength. However, there has been a movement over the last 5 years to include strength training in dancers’ conditioning [22]. Dowse et al. (2017) advocate for resistance training in dancers, because in their study dynamic balance, lower-body strength and power were improved without affecting artistic or aesthetic components [10].
Core strength and spinal stability, referred to in [Table 3], often come under the term core stability, which is the integration of passive (non-contractile), active (contractile), and neural structures to minimize the effects of external forces and maintain stability [31]. However, this is really a default term applied to all motor control training around the trunk. Core strength, motor control stability and endurance involve different concepts [27]. Injuries to the lower back are high in professional and pre-professional dance [1]
[11] and lack of pelvic stability has been implicated [33]. Impaired core proprioception has also been shown to be predictive of knee injury in female athletes [42]. Further examination of all the components of core stability – core power, strength, endurance and sensory-motor control – is advised in order to understand its multifactorial role in reducing injury and enhancing performance in dancers [31].
Stamina is another attribute important in the elite dancer. This was reported by nearly one-third of respondents. Classical ballet is characterized as a high-intensity, intermittent form of exercise [32]
[38] demanding muscle power reserves for explosive jumps, muscular endurance to maintain high levels of power output, and cardiorespiratory endurance to execute low-intensity exercise. Without these physiological foundations, the dancer is left susceptible to fatigue, and this in turn has an effect on skill and alignment which may increase the risk of injury [38]. Therefore it is believed that enhancing these foundations also enhances aesthetic competence [32] and artistry, and frees the dancer to perform to music, express emotion, and thus captivate an audience.
Motor control and coordination requires an integration of visual, vestibular, and somatosensory information to facilitate accurate positioning and movement of the body in space [36]. Dance training requires the integrity of sensory inputs to coordinate the musculature of the body and to maintain proper alignment while moving through the positions and shapes intrinsic to it [36]
[37].
Physical proportions scored highly in the survey with almost half of the panel highly ranking good proportions. Ballet is demanding in all the above physiological, anatomical, and functional characteristics but remains an art form, and aesthetic attributes are also important. So far, the literature has identified the ideal balletic physique as primarily ectomorphic [25]
[39]. The Vaganova School in St. Petersburg measures and compares lower limb length to trunk length at audition for vocational training in order to attain physical conformity (G. Anthony, personal communication, July 17, 2016). Head and neck proportions as well as slimness are preferred in professional ballet. The slim physique in ballet has been much criticised [4], but lightness and an ability to show “line” in balletic positions are the aesthetic required.
Inevitably there are some weaknesses in this preliminary study. The artistic directors (18% of participants) of companies and schools make the final decisions in recruitment to the profession, but they are supported by their artistic staff of senior ballet teachers (29.7% of the survey panel), who still have a significant influence. Inevitably there will be more teachers than artistic directors. The physiotherapists, doctors and health professionals who participated were all selected because of proven involvement in dance, usually evidenced by their research in dance. Physiotherapists are used in many institutions to screen candidates in support of panel decisions. Their inclusion adds the perspective of injury prevention to the study, and a more detailed future analysis of how the responses of the participating groups differed is planned.
Neither were sex-specific physical attributes studied, although this also could form the basis of an interesting and important future study.
We believe this investigation is the first of its kind to obtain the preferences from those international experts in the profession who select dancers as well as those who care for dancers’ health. It is clear that generalized flexibility takes precedence though specific examples such as hip turnout and foot and ankle flexibility are also sought. However, flexibility can never be separated from strength and control in achieving the range of controlled movement required. Aesthetic requirements were also considered but ranked as less important.
These results will form the basis for further rounds of the Delphi Survey in order to arrive at a consensus. It is hoped this might help guide those who train and those who care for dancers both in performance enhancement and injury risk management.
