A study conducted at the University of Colorado Boulder (CU-Boulder) shows that when rounding curves, Paralympic sprinters who use left transtibial prostheses are slowed more than athletes who use right transtibial prostheses. Athletes with left-leg prostheses who sprinted in the inside lane of an indoor track ran about 4 percent slower than athletes with right-leg prostheses. Based on that, the researchers estimated a 0.2 second difference in an outdoor 200-meter race.
Participants included 11 Paralympic sprinters from the United States and Germany who use transtibial prostheses, as well as six sprinters without amputations. The Paralympic sprinters in the study wore their own customized, J-shaped, carbon fiber running blade prostheses. All participants were timed and filmed running on a straight section of an indoor oval track, running on the curve counterclockwise (standard protocol for track and field races), and running the curve clockwise. The athletes were filmed with a high-speed video camera that recorded their motions at a rate of 210 frames per second.
All participants ran slower on curves compared with straight running, but with different kinematics. The able-bodied cohort ran 1.9 percent slower clockwise compared with counterclockwise, and they reduced stride length and frequency in both curve directions compared with straight running. Sprinters with an amputation ran 3.9 percent slower with their affected leg on the inside of the curve compared with the outside of the curve, and they also reduced stride length in both curve-running directions but reduced stride frequency only on curves with the affected leg on the inside.
The research indicates the performance of Paralympic sprinters was impaired by their reduced ability to generate enough force with their left-leg prostheses while running counterclockwise on the inside of a track curve, said CU-Boulder research associate Paolo Taboga, PhD, chief study author. The athletes had a shorter stride frequency and longer contact time between the blade and the track surface, and were not able to compensate by using more rapid leg-swing times, he said.
“What surprised me the most was the large effect that running on the inside lane of [the] curve had on these elite Paralympic sprinters,” said Taboga. “A 4 percent reduction in speed during a competitive sprint event could mean the difference between a gold medal and no medal at all.”
Taboga suggested that in order to make the Paralympic sprint races more fair, the sprinters with left lower-limb amputations running on a curve should be allowed to run in the outside lanes. The study was published March 15 in the Journal of Experimental Biology.
Editor’s note: This story was adapted from materials provided by the University of Colorado Boulder.