The Biology of Dance

Ballet is one of those things that just can’t really be categorized. It straddles the line between an art and a sport, blending an eye for visually beautiful movements with the body that supplies the physical power necessary. In fact, the rigid technique requires dancers to be even more aware of their bodies than the average person, making some knowledge of anatomy and biology necessary for the profession. In today’s BioBeyond, we’re going to talk a little bit about the biology of dance.

Transcript

Episode 3: The Biology of Dance

0:45 Ballet is one of those things that just can’t really be categorized. It straddles the line between an art and a sport, blending an eye for visually beautiful movements with the body that supplies the physical power necessary. In fact, the rigid technique requires dancers to be even more aware of their bodies than the average person, making some knowledge of anatomy and biology necessary for the profession. In today’s BioBeyond, we’re going to talk a little bit about the biology of dance. 

1:11 Let’s start with a brief summary of the art form. Ballet is a well-established art that dates all the way to the 15th century Italian Renaissance, then spread to France and gained popularity in the court of King Louis XIV. (Louis The Fourteenth). Narrative ballets, long stories told entirely through dance, really began in the 19th century Romantic period. This period was when pointe work began, which is a technique in ballet that involves standing on the tips of the toes, aided by special shoes that support the foot. Modern ballet in the United States is codified by George Balanchine’s neoclassical ballets, which often had no story and focused only on the dancing. 

1:56 Pointe work, which began in the 19th century, has become much more prominent in the current time. This technique requires extensive training to achieve and a dancer must meet certain parameters in order to begin pointe training. Firstly, their feet must be developed enough that they will not be damaged by the intense training, meaning that dancers under eleven years old should not begin pointe training. They must have experience and be taking many ballet classes a week to keep up their performance, and they must master correct positions, as having the incorrect placement en pointe can lead to injury. 

2:29 Scientifically, pointe work also requires a great deal of hard work and criteria. Pointe shoes apply force that is twelve times the body weight to the foot, triple the amount when wearing technique shoes. Pointe work requires extreme plantarflexion, or movement where the top of the foot points away from the leg. In fact, professional ballerinas have an average ankle flexion of 113 degrees, over double the standard range of motion. In an analysis of which young prospective dancers were accepted into dance education, it was found that enrolled students had a more equal length of the lower extremities and had more flexible hips and ankles than the rejected students. 

3:10  Ballet doesn’t only affect the muscles and bones of dancers. Even proper breathing is necessary to coordinate movement as a professional ballet dancer. In a study, motion capture was used to evaluate the kinematics of dancers’ breathing, and it was found that dancers use an optimized breathing strategy that increases the air volume of a breath. Optimized breathing was previously discovered in swimmers and yoga practitioners. Dancers have poor aerobic capacities compared to other athletes, since ballet is so focused on technique that it cannot be executed with the same intensity as sports with simpler movements such as running. 

3:50 The physical readiness of a dancer’s body isn’t the only component to performance en pointe. The pointe shoe, in actuality, is also an intricate invention that works to allow the dancer to rise on their toes. The shoe distributes the weight under the arch and around the toes so that the dancer can remain en pointe. The very bottom of the shoe, where the toes go, is called the box, and is usually made out of layers of paper and glue–NOT wood, as commonly thought. The sole, or shank, may have varying flexibility, but it should be stiff in order to support the dancer’s weight. Likewise, the vamp is the part of the shoe that extends from the box to cover the top of the foot. As dancers use their shoes, they will conform to the feet, in a process called “breaking-in”. New shoes are uncomfortable to dance in, then reach a sweet spot over the process of breaking in. However, pointe shoes do not last forever, and eventually reach a part where the box is too soft to adequately support the dancer. This is called a “dead” shoe. 

4:55 The state of pointe shoes actually affects  the biomechanics of ballet dancers. In a recent study, it was shown that lower extremity biomechanics and muscle activity change between trials of new and dead pointe shoes. In the study, dancers were asked to execute the steps relevé, rising en pointe, and arabesque, extending one leg out behind them. Sway area, peak ankle moment, and muscle activity of the tibialis anterior and medial gastrocnemius were observed in the study, as these are often risk factors for injuries. Reflective markers and electrodes were used to observe the data. The results showed that dancers swayed significantly more in dead pointe shoes, as well as showed that it was more physically demanding on the muscles. 

5:42 In addition, a second study that investigated pointe shoe deterioration focused on foot and ankle kinematics. This study focused on bourrées, which are fast walks en pointe, and focused on using worn pointe shoes instead of dead ones. These were somewhat broken in, but not fully dead. Reflective markers and video recording were again used to measure the data. The worn shoe showed a greater plantarflexion and mid-foot flexion. This could cause excessive stress of the ligaments in the foot, creating a greater risk of injury. However, the toe box of these shoes was relatively unaltered, resulting in no change on peak force or stability. These two studies show, together, that it is important to watch the deterioration of a pointe shoe and replace the shoe when it gets too dead to continue due to risk of injury. 

6:30 Ballet comes with a risk of injury by default, as the nature of it pushes the body’s natural limits. Overuse injuries are common to ballet dancers, such as at the big toe joint, as dancers are expected to have far more flexibility for full releve onto demipointe. It is possible for dancers to sickle to compensate if they do not have enough flexibility for the position, resulting in injury. (Sickling is when the foot is aligned too far to one side instead of being straight in a position). Many stress fractures in ballet dancers occur in metatarsals, the bones just before the toes, since this is where most of the weight is focused in demi pointe and pointe work. All injuries may be exacerbated or more likely to happen if a dancer is not exercising proper technique or alignment, or if they are not warmed up. Dancers are also very likely to experience sprained ankles, achilles tendonitis (swelling of the achilles tendon), and plantar fasciitis (inflammation of tissue on the bottom of the foot). 

7:42 Now: Hello, it’s the person behind this podcast. I know that I’m usually speaking about scientific studies in the passive voice for this podcast, but this topic is actually pretty personal for me, since I do ballet with pointe work. I have personally experienced plenty of ballet injuries. These include straining my adductor, experiencing repeated tendinitis in my ankles, and plantar fasciitis. I can trace most of these injuries back to me pushing myself too hard without warming up beforehand, or not being careful about my technique (for example, sickling my feet). So it really is important to properly warm up and execute proper technique, not just for ballet, but for every type of physical activity. 

8:20 Talking about ballet isn’t an urgent public health crisis or even something many people will relate to. But today, we dove into some scientific aspects of ballet that, in my opinion, are really interesting to know about, and I hope you learned something new from it. 

Sources
1, Altmann, C., Roberts, J., Scharfbillig, R., & Jones, S. (2019). Readiness for en pointe work in young ballet dancers are there proven screening tools and training protocols for a population at increased risk of injury? Journal of Dance Medicine & Science, 23(1), 40–45. https://doi.org/10.12678/1089-313x.23.1.40

2, A brief history of ballet - illustrated by Pittsburgh Ballet Theatre. Pittsburgh Ballet Theatre. (2020, September 15). Retrieved November 20, 2022, from https://www.pbt.org/learn-and-engage/resources-audience-members/ballet-101/brief-history-ballet/

3, Common ballet injuries and how to prevent them. Common Ballet Injuries and How to Prevent Them: Phoenix Foot and Ankle Institute: Foot and Ankle Specialists. (n.d.). Retrieved November 20, 2022, from https://www.phoenixfai.com/blog/common-ballet-injuries-and-how-to-prevent-them

4, Criteria to begin pointe work (13 point checklist). Washington University Orthopedics. (n.d.). Retrieved November 20, 2022, from https://www.ortho.wustl.edu/content/Patient-Care/3496/Services/Physical-Medicine-and-Rehabilitation-Musculoskeletal/Performing-Arts-Program/Criteria-for-Pointe-Work.aspx

5, How a pointe shoe works . Gaynor Minden - Pointe Shoes. (2017, May 7). Retrieved November 20, 2022, from https://dancer.com/ballet-info/about-pointe-shoes/how-a-pointe-shoe-works/

6, Khan, K., Brown, J., Way, S., Vass, N., Crichton, K., Alexander, R., Baxter, A., Butler, M., & Wark, J. (1995). Overuse injuries in classical ballet. Sports Medicine, 19(5), 341–357. https://doi.org/10.2165/00007256-199519050-00004

7, Rodrigues, I. M., Bernardina, G. R., Sarro, K. J., Baroni, G., Cerveri, P., & Silvatti, A. P. (2017). Thoracoabdominal breathing motion pattern and coordination of professional ballet dancers. Sports Biomechanics, 18(1), 51–62. https://doi.org/10.1080/14763141.2017.1380223