Physics of dance
Gemma Aldana ’16 loves to dance. Open to all styles, she doesn’t discriminate. She can shake her hips and wave her arms with the best of them, but her favorite moves require a little more poise.
“My mom thought that a summer of ballroom dance lessons would go toward our general education, and maybe make up for her not being able to drive us to ballet lessons when we were younger,” says Aldana, who continues taking lessons when she can.
However, the foxtrot and waltz are not Aldana’s only passions. She loves science as well. In fact, she loves science so much that she is having trouble deciding between a major in physics or biochemistry.
So, what’s a science-loving dancer to do?
Well, as Aldana and her lab partner Annie Oyler ’15 have found out during their 10 weeks as Anderson Research Scholars, they can join physics professor Melanie Lott ’04 in studying the biomechanics of dance.
In a continuation of Lott’s Ph.D. dissertation, the group has been collecting data on how a dancer balances during a pirouette, a full turn on the front foot.
“We’re looking at what kind of movements make dancers effective,” says Aldana, who is on the premed track at Denison.
In a perfectly balanced state, says Lott, the center of mass (CM) is directly over the base of support. If any sort of movement displaces the CM, gravity exerts a force that pushes the body off balance. So people learn to regain balance without thinking about it.
The same goes for dancers. However, their process for correction is more complicated because pirouettes corrupt the systems that usually keep us balanced, like our vision, inner ear, and sensors in our joints and muscles. The question for Lott and her crew then became, “How is it that dancers can rotate through many revolutions and correct for imbalance all at the same time?”
To study this, the trio set up a mobile lab including six 3D cameras, three laptops, and 70 luminescent markers (made out of material similar to stop signs).
Volunteer dancers are prepped with the markers before turning in front of the cameras, which flash infrared light to capture the reflection of the markers and translate the movement into a 3D image on the computer.
Oyler, a physics major from Louisville, Ky., then looks at the angles of joints while Aldana locates the CM of the body and the base of support on the floor.
“Dancers have to be strong and erect but a little fluid too. They have to be able to correct their balance slightly so they don’t fall, but their corrections can’t be easily noticed according to the rules of ballet,” says Aldana, who is working with Oyler to investigate what kind of joint movements create an acceleration of the center of mass over the center of pressure for their final poster.
While dancers from Columbus’ BalletMet were consulted for the project, the majority of their data was gathered from a trip to Shuffles Dance Studio in Little Rock, Ark., where they worked for four days with six dancers from Ballet Arkansas and the studio’s pre-professional program.
While the volunteers helped them collect data, Aldana likes to think that the exchange goes both ways.
“We help dancers. Not only does it help us understand the way that humans move, but it will help dancers use their bodies better, which will prevent injury and help them become better turners,” she says. The hope is that teachers will one day incorporate their techniques and findings in order to better educate their dancers.
With the biomechanics of dance being a relatively new field, however, the connections between studios and researchers have been somewhat slow. But Aldana believes that they are on the cusp of something big.
“In Arkansas we met a dancer who just graduated high school and wanted to continue to dance but didn’t want to go professional. She came all four days we were there and by the end she was thinking about looking into studying biophysics of dance herself. It’s like we’re blazing a new trail and introducing new options,” she says.