using gait analysis to assess racing performance: a case study

We were asked recently to assess a 3 year old filly, who had been racing well but whose trainer felt wasn't quite living up to her full potential. There were no soundness or health issues identified by her veterinarian.

We initially assessed her using the inertial motion units to measure symmetry. She measured within normal limits in both the forelimbs and hindlimbs.

She was in fact one of the most symmetrical horses that we have ever measured! We next assessed her using high-speed video and 2D kinematic analysis. She again measured quite symmetrically comparing joint range of motion between the left and right limbs, suggesting that there were unlikely to be any underlying soundness issues.

It was when we looked closely at her stride characteristics that we were able to identify some things that may have been limiting her performance.

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​1. Diagonal Advanced Limb Placement

This refers to the placement of diagonal forelimb and hindlimb in trot and canter. The USDF's Glossary of Judging Terms defines it as being when the “hooves of a diagonal pair of limbs (in trot or canter) do not contact the ground at the same moment."

We found that the:

• Left forelimb lands 30 m/s before the right hindlimb
• Right forelimb lands 10 m/s before the left hindlimb

 
This demonstrates a negative diagonal advanced placement (each forelimb lands before its diagonal hindlimb pair). In dressage horses we know from research that a positive diagonal advanced placement (hindlimb landing 20-30m/s before forelimb) is important for propulsion of the hindquarters. While this has not yet been studied in racehorses, we hypothesised that a similar limb placement pattern would be important for propulsion in the racehorse, and thus performance. This is something we hope to study further in racehorses to examine the effect on performance.

At the trot, you can see that the left forelimb has hit the ground before the right hindlimb.

The left hindlimb hits the ground first. Next comes the phase of the gait cycle where the diagonal pair of limbs (left forelimb and right hindlimb) in theory hit the ground at the same time. Here you can see that the left forelimb has hit the ground first before the right hindlimb.

Now the right hindlimb has hit the ground, before the next phase of the gait cycle, which is the right forelimb contacting the ground.

The final phase of the gait cycle, the suspension phase.

Upon performing a physiotherapy assessment, we found that this horse had some loss of muscle bulk in her hindquarters, particularly the right hindlimb, along with some pain response around the pelvic region. She had a tendency to overuse the muscles in the shoulder and lower neck region to pull herself along rather than really push from behind.

2. Stride Frequency
 
In a study of thoroughbred racehorses tested at maximal speed, the best performers were found to have a stride frequency of 2.81 strides/sec at the gallop. Stride frequency is positively correlated with performance – ie the best performers have higher stride frequencies. We found that this horse had a stride frequency of 1.9 strides/second. 


3. Ground Contact Duration
 
Ground contact duration is defined as the time elapsed between the non-lead hindlimb contact and the lift off of the lead forelimb, expressed as a percentage of the total stride duration.
 
In a study of thoroughbred racehorses tested at maximal speed, horses that won short distance races (<1400m) were found to have a longer relative ground contact duration (68%). Long distance winners had shorter ground contact durations (58%).  Sprinters tend to have higher stride frequencies but longer ground contact durations to give more time for propulsion.
This horse (a sprinter) had a ground contact duration of 69% which is similar to top performing sprinters.

Looking at parameters such as these were really useful for the trainer to know, as several studies have found that stride parameters such as frequency and duration can be influenced by training. Based on these findings, the trainer of this horse was able to make any adjustments to her training as he felt appropriate. We also put in place an exercise program which focused on improving her hindquarter strength and symmetry. Not long after this was put in place this horse had 2 great runs, placing a very close second in both races!

This type of analysis is not just beneficial to racehorses, but for horses of all disciplines. Please feel free to get in touch to discuss in more detail how we can use gait analysis to assess your horse's performance.