By Robyn Parets
It’s no surprise that ballet dancers, who spend hours rehearsing high impact jumps, experience a high incidence of lower extremity injuries. A new study, however, shows that dancers can reduce loading on lower extremity joints and help reduce injury risk by performing ballet jumps, also called sautés, on a reduced-stiffness floor.
The study, published in September 2015 in the Journal of Dance Medicine & Science by a team of researchers from the Department of Physical Therapy at Missouri State University in Springfield, included 15 female dancers aged 18 to 28 years. All the dancers had at least five years of dance experience and no history of lower extremity injuries, surgeries, or recent pain. They performed sauté jumps on both a reduced-stiffness floor (also called a sprung floor) and a vinyl-covered concrete floor. Investigators measured maximum joint flexion and negative velocities of the ankles, knees, and hips on both types of floors.
The results: Jumping on the reduced-stiffness floor led to decreased maximum joint flexion angles and angular negative velocity in the lower extremity joints compared with performing the same jumps on the concrete floor.
“If a dancer lands a grande jeté, the joints bend, and the lower extremities compress, store energy, and then recoil,” said James Hackney, PhD, PT, associate professor of physical therapy at the university and the study’s lead author. A grand jeté is a type of sauté commonly known as a split jump, where one of the dancer’s legs is stretched out in front of the body and the other is behind.
Jumping on a sprung floor reduces tension on lower extremity muscles and joints, as the reduced-stiffness surface absorbs some of the shock that is experienced by the lower extremities when a dancer jumps on a concrete floor, Hackney said. The findings suggest that dancers rehearsing on a sprung floor might experience a reduction in knee overuse injuries and Achilles tendon injuries.
Only female dancers participated in the study simply because it was easier to recruit women than men, Hackney said.
“I have no reason to think the results would not be the same with men,” he said.
In fact, all ballet dancers have a lifetime injury rate as high as 84%, according to estimates from a study published in the September 2008 issue of Archives of Physical Medicine & Rehabilitation.
Hackney recommends that, to better prepare and train the body for the rigors of ballet jumps, dancers should rehearse mainly on a sprung surface, but also on a harder type of floor. This way the lower extremities are better prepared for either type of surface and less prone to injury, he said.
Training solely on a sprung floor, however, may not help reduce injury risk in dancers who then have to perform on concrete floors, said Jeff Russell, PhD, ATC, assistant professor of athletic training and director of Science and Health in Artistic Performance at Ohio University in Athens. If dancers train on a sprung floor and then spend a week or two performing on a concrete floor, there is a higher chance of an injury while performing, as they aren’t accustomed to the force on the extremities associated with the harder floor, he said.
“These dancers get anxious when they realize they have to dance on a hard surface,” Russell said.
Reduced-stiffness floors are installed at many major ballet companies, but they are expensive and this prohibits many mom-and-pop dance studios and even universities from putting in the flooring systems. It can cost upwards of $50,000, for example, to install a 50-foot by 50-foot reduced-stiffness floor system, Hackney said.
Research backing manufacturer claims that sprung floors can help reduce the risk of injuries could entice dance studios to spend the money on these surfaces.
“Dance is similar to [other] sports in terms of the physical demands on the body,” Hackney said.
Hackney J, Brummel S, Newman M, et al. Effect of reduced stiffness dance flooring on lower extremity joint angular trajectories during a ballet jump. J Dance Med Sci 2015;19(3):110-117.
Hincapie CA, Morton EJ, Cassidy JD. Musculoskeletal injuries and pain in dancers: A systematic review. Arch Phys Med Rehabil 2008;89(9):1819-1829.