Research shows that world-beating sprinter Usain Bolt has an uneven stride, raising intriguing questions around asymmetry in the most athletic of animals — horses — and what it actually means for performance.
Improving technology has in recent years allowed the collection of accurate and objective data on the movement of horses through the use of accelerometers.
It has resulted in a number of studies pointing to a high prevalence of asymmetry and lameness in horses, both of which often went unrecognized by owners.
The latest findings by researchers at Southern Methodist University in Dallas, Texas, who investigated Bolt’s running style, raise a raft of fresh questions on what potential impact asymmetry has on performance, given that the world-record-breaking Bolt has secured the 100m and 200m sprint doubles at the last three Olympics — performances that unquestionably make him the greatest sprinter of all time.
The research into Bolt’s stride was carried out by biomechanics expert Peter Weyand and his colleagues Andrew Udofa and Laurence Ryan, whose findings have been discussed in a New York Times story published today.
The researchers in the university’s Locomotor Performance Laboratory first reported in June that Bolt, who is nearing retirement, may have an asymmetrical running gait.
While not noticeable to the naked eye, Bolt’s potential asymmetry emerged after the researchers dissected race video to assess his pattern of ground-force application — literally how hard and fast each foot hits the ground. To do so, they measured the “impulse” for each foot.
Analysis thus far suggests that Bolt’s mechanics may vary between his left leg and his right.
They found that his right leg appeared to strike the track with 13 percent more peak force than his left leg. With each stride, his left leg stays on the ground about 14 percent longer than his right one.
The existence of an unexpected and potentially significant asymmetry in the fastest human runner ever would help scientists better understand the basis of maximal running speeds.
Experts generally assume asymmetry impairs performance in human runners and horses.
Udofa has said the observations raise the immediate scientific question of whether his lack of symmetry represented a personal mechanical optimization that made Bolt the fastest sprinter ever, or existed for reasons yet to be identified.
Initial findings from the study were presented last month at an international biomechanics conference in Germany.
In horses, the picture is equally intriguing, complicated by the need to distinguish between what may be lameness issues and asymmetry.
Research published earlier this year found that movement imbalances in a straight line trot were found to be remarkably widespread among 222 warmblood horses considered by their owners to be sound. The findings raised the question as to whether asymmetry was just a normal part of being a horse, or was it a case of owners failing to pick up the smaller signs of lameness?
The researchers acknowledged: “It is not known to what extent these asymmetries are related to pain or to mechanical abnormalities.”
A study published last year on newborn foals found that horses can suffer from pelvic symmetry, even at a young age.
A British study of 60 polo ponies, reported in 2015, found that a large proportion had asymmetries. In all, 60 percent to 67 percent of the horses were classified with movement asymmetry outside published guideline values for either the forelimbs, hindlimbs, or both.
Research published in 2015 found that asymmetric movement induced when lunging a horse may not necessarily be the same in both directions.
Riders have not been immune from scrutiny in this field of research. A study that used innovative body suits used by movie makers and the video game industry found that all 12 riders assessed by the researchers showed some asymmetry in the saddle.