An introduction to the functional aspects of conformation

By Judy Wardrope

The first in a series of articles which set out different ways to examine a horse’s conformation affects their running style.

An Introduction to the Functional Aspects of Conformation   Judy Wardrope     Why is one horse a sprinter and another a stayer? Why is one sibling a star and another a disappointment? Why does one horse stay sound and another does not? Over the course of the next few issues, we will delve into the mechanics of the racehorse to discern the answer to these questions and others. We will be learning by example, and we will be using objective terminology as well as repeatable measures. This knowledge can be applied to the selection of racing prospects, to the consideration of distance or surface preferences and, of course, to mating choices.     Introducing a different way of looking at things requires some forethought. Questions need to be addressed in order to provide educational value for the audience. How does one organize the information, and how does one back up the information? In the case of equine functionality in racing, which horses will provide the best corroborative visuals?     After considerable thought, these three horses were selected: Tiznow (Horse #1) twice won the Breeders’ Cup Classic (1¼ miles) ; Lady Eli (Horse #2) won the Juvenile Fillies Turf and was twice second in the Filly and Mare Turf (13/8 miles); while our third example (Horse #3) did not earn enough to pay his way on the track. Let’s see if we can explain the commonalities and the differences so that we can apply that knowledge in the future.      Factors for Athleticism      If we consider the horse’s hindquarters to be the motor, then we should consider the connection between hindquarters and body to be the horse’s transmission. Like in a vehicle, if the motor is strong, but the transmission is weak, the horse will either have to protect the transmission or damage it.  According to Dr. Hilary M. Clayton (BVMS, PhD, MRCVS), the hind limb rotates around the hip joint in the walk and trot and around the lumbosacral joint in the canter and gallop. “The lumbosacral joint is the only part of the vertebral column between the base of the neck and the tail that allows a significant amount of flexion [rounding] and extension [hollowing] of the back. At all the other vertebral joints, the amount of motion is much smaller. Moving the point of rotation from the hip joint to the lumbosacral joint increases the effective length of the hind limbs and, therefore, increases stride length.”   From a functional perspective, that explains why a canter or gallop is loftier in the forehand than the walk or the trot.     In order to establish an objective measure, I use the lumbosacral (LS) gap, which is located just in front of the high point of the croup. This is where the articulation of the spine changes just in front of the sacrum, and it is where the majority of the up and down motion along the spine occurs. The closer a line drawn from the top point of one hip to the top point of the other hip comes to bisecting this palpable gap, the stronger the horse’s transmission. In other words, the stronger the horse’s coupling.     We can see that the first two horses have an LS gap (just in front of the high point of the croup as indicated) that is essentially in line with a line drawn from the top of one hip to the top of the opposing hip. This gives them the ability to transfer their power both upward (lifting of the forehand) and forward (allowing for full extension of the forehand and the hindquarters). Horse #3 shows an LS gap considerably rearward of the top of his hip, making him less able to transfer his power and setting him up for a sore back.     You may also notice that all three of these sample horses display an ilium side (point of hip to point of buttock), which is the same length as the femur side (point of buttock to stifle protrusion)—meaning that they produce similar types of power from the rear spring as it coils and releases when in stride. We can examine the variances in these measures in more detail in future articles, when we start to delve into various ranges of motion as well as other factors for soundness or injury.      Factors for Distance Preferences      The hindquarters of Horse #1 and Horse #2 also differ from that of Horse #3 based on the location of the stifle protrusion (not the actual patella, but the visible protrusion that one can watch go through its range of motion as the horse moves). The differences in stifle placement equate with range of motion of the hind leg, stride length and, to some degree, stride rate.     When it comes to the stifle placement for a champion at classic distances, we can see just how far below sheath level Tiznow’s stifle protrusion is and we can equate that to Lady Eli’s as well, even though she doesn’t have a sheath. Horse #3 has a stifle placement that is higher than the other two horses, more in keeping with the placement of a miler (at the bottom of or just below the bottom of the sheath). Sprinters tend to have stifle placement that is above that of milers.     The most efficient racehorses have a range of motion of the forehand that corresponds to the range of motion of the hindquarters. That may seem like stating the obvious, but not all horses have strides that match fore and aft. We have seen those horses that “climb” in the front as well as those that seem to “bounce” higher in the rump. In both cases, a mismatch of strides is often the cause.     For simplicity, let’s say the horse has to generate power from his hindquarters, transfer that power upward and forward through the spine as well as extend his front end at the same stride rate created by the hindquarters for efficiency. He/she has to maintain the same rate in the forequarters and the hindquarters.     One of the things we seldom think about is that horses have to move the front quarters at the same stride rate created by the hindquarters, but they do not necessarily have to be built to have the same stride lengths and turnover rates front and back.     If a horse has to significantly adjust the stride length fore or aft, he/she is likely not going to win in top company, especially racing. And for those horses that can adapt to slight discrepancies, a strong LS placement is paramount.  A car with different sized tires in the front than in the back will travel at a constant speed, but the smaller tires will rotate faster than the larger ones. A horse can’t do that, though; he/she has to compensate to bring the front and rear into the same stride rate.     In a person, the length of the thigh has a major impact on stride length. Now imagine that you have one thigh shorter than the other. How will you run? If you don’t compensate for the difference, you will either fall down or go in circles. Chances are, if you want to travel straight, you will dwell in the air on the short side in order to balance the stride rates. This is what the mismatched horse does, but it is not typically efficient.     When considering the stride length/turnover rate of the horse’s forehand, one must remember that from the top of scapula to knee is all one apparatus. Nothing moves independently. That means that different configurations can have similar results. Conversely, a slight change in humerus length or angle can affect the stride tremendously. For instance, a horse with a short humerus (elbow to point of shoulder) that is considerably angled upward will be much quicker with his turnover rate on the forehand than a horse with the same scapula that has either a longer humerus or one that is not angled as steeply. If a horse has a shorter, quicker range of motion of the forehand, dwelling in the air on the forehand while the hindquarter goes through its range of motion is the most common method of compensation. But, again, a strong coupling is required. Without a strong LS, the horse simply does not attempt to balance its stride in order to maximize range of motion. Such horses just move slower.     If the horse has a shorter stride or quicker turnover rate in front, he’ll often climb with his front end in order to equalize the time it takes to go through the range of motion for each rear stride. It’s not necessarily a bad thing in a jumper, but it is not such a good thing in a racehorse. Many of us have witnessed a horse that climbs in the front, but we may not have attributed it to a difference in turnover rates or stride lengths.     What if the reverse is true and the horse has a shorter stride and quicker turnover rate behind? If the horse has a slower stride rate or longer stride on the forehand, he may choose to dwell in the air for a fraction of a second with his hindquarters. If that is the case, he is not going to be as smooth to ride. He’ll likely pitch the jockey forward and land heavier on his forehand, which is not pleasant and not complimentary to soundness.     Before looking closer at the forequarters for range of motion, it is important to understand that the forehand works as one apparatus—nothing moves independently from top of scapula to point of shoulder to elbow to knee. If the knee rises and comes forward, the forearm follows plus the humerus (elbow to point of shoulder) and the scapula move through corresponding ranges of motion. Likewise, if the top of the scapula rotates rearward, the point of shoulder rises, the elbow comes forward and the forearm is extended and the knee is lifted and moved forward.     Good forelimb movement is characterized by a full range of motion in the swing phase and the stance phase. The latter part of the stance phase is the part of the stride where the horse has rotated his forehand over his front leg and is about to lift that leg from the ground. That is also when the elbow is closest to the ribcage in forward movement. Horses such as #3 have an elbow that could make contact with the ribcage in the latter part of the stance phase (just before the hoof leaves the ground), but they want to avoid that painful collision (almost bone on bone with little padding). How did our sample horse compensate? He built a muscle over his elbow because he has been using it as a brake. He also built muscle on the underside of his neck. Both of these things were meant to lift the hoof off the ground before the elbow struck the ribcage. Again, this does not lead to efficiency of stride.     Length of humerus adds reach, and if that humerus has sufficient rise from elbow to point of shoulder, it does not restrict stride rate. Horses with a short humerus that has a steep rise from elbow to point of shoulder tend to have more knee action than is desired on the track.     Stride length and turnover rate are the two components of speed. Imagine the difference on the clock between two horses of equal stride rate, but one has a longer stride. It may well be the difference between winning and placing out of the money.     In future articles, we will delve into how the variations in length and angle of humerus affect movement plus how tightness of the elbow can impede the rearmost portion of the front stride, thus limiting extension.      Factors for Soundness      Aside from the LS and a few factors in hindquarter construction that we will cover in future articles, one of the best advantages for soundness is lightness of the forehand since speed and weight amplify the forces on a horse’s front legs.     As a means of measuring lightness of the forehand, I use several markers. The first is the pillar of support, which is simply a line extended up and down through the naturally occurring groove in the horse’s forearm. In general one can see how much horse is out in front of that line, but specifically, the further in front of the withers the line emerges, the lighter the horse’s forehand. Additionally, a rise in the humerus adds to lightness, as does a base of neck that is well above the point of shoulder.     All three sample horses share the above traits for lightness. However, where the bottom of the line depicting the pillar of support emerges also plays a role in soundness and longevity. In Horse #1 the line emerges into the rear quarter of his hoof, ideal placement. In Horse #2 it just catches the rear quarter of the hoof, and in Horse #3 it emerges just behind the hoof. Of the three, Horse #3 is at more risk for damage to the suspensory apparatus (bowed tendons and torn ligaments) and is more likely to hit his fetlock on the racing surface. Please keep in mind that where the bottom of the pillar emerges has little to do with length and angle of the pastern. Shocking, but true. More on this in future articles.      Failure or Success      Sometimes it is all in how you analyze the horses and whether you place them where their conformation functions as an asset rather than a detriment. Tiznow proved his championship form at classic distances on dirt. Lady Eli proved her championship form at classic distances on turf. And Horse #3 proved that he was not built to be a successful racehorse.

Tiznow

Lady Eli

Lady Eli

Unnamed horse

Unnamed horse

Why is one horse a sprinter and another a stayer? Why is one sibling a star and another a disappointment? Why does one horse stay sound and another does not? Over the course of the next few issues, we will delve into the mechanics of the racehorse to discern the answer to these questions and others. We will be learning by example, and we will be using objective terminology as well as repeatable measures. This knowledge can be applied to the selection of racing prospects, to the consideration of distance or surface preferences and, of course, to mating choices.

Introducing a different way of looking at things requires some forethought. Questions need to be addressed in order to provide educational value for the audience. How does one organize the information, and how does one back up the information? In the case of equine functionality in racing, which horses will provide the best corroborative visuals?

After considerable thought, these three horses were selected: Tiznow (Horse #1) twice won the Breeders’ Cup Classic (1¼ miles) ; Lady Eli (Horse #2) won the Juvenile Fillies Turf and was twice second in the Filly and Mare Turf (13/8 miles); while our third example (Horse #3) did not earn enough to pay his way on the track. Let’s see if we can explain the commonalities and the differences so that we can apply that knowledge in the future.

Factors for Athleticism

If we consider the horse’s hindquarters to be the motor, then we should consider the connection between hindquarters and body to be the horse’s transmission. Like in a vehicle, if the motor is strong, but the transmission is weak, the horse will either have to protect the transmission or damage it.

According to Dr. Hilary M. Clayton (BVMS, PhD, MRCVS), the hind limb rotates around the hip joint in the walk and trot and around the lumbosacral joint in the canter and gallop. “The lumbosacral joint is the only part of the vertebral column between the base of the neck and the tail that allows a significant amount of flexion [rounding] and extension [hollowing] of the back. At all the other vertebral joints, the amount of motion is much smaller. Moving the point of rotation from the hip joint to the lumbosacral joint increases the effective length of the hind limbs and, therefore, increases stride length.” From a functional perspective, that explains why a canter or gallop is loftier in the forehand than the walk or the trot.

In order to establish an objective measure, I use the lumbosacral (LS) gap, which is located just in front of the high point of the croup. This is where the articulation of the spine changes just in front of the sacrum, and it is where the majority of the up and down motion along the spine occurs. The closer a line drawn from the top point of one hip to the top point of the other hip comes to bisecting this palpable gap, the stronger the horse’s transmission. In other words, the stronger the horse’s coupling.

We can see that the first two horses have an LS gap (just in front of the high point of the croup as indicated) that is essentially in line with a line drawn from the top of one hip to the top of the opposing hip. This gives them the ability to transfer their power both upward (lifting of the forehand) and forward (allowing for full extension of the forehand and the hindquarters). Horse #3 shows an LS gap considerably rearward of the top of his hip, making him less able to transfer his power and setting him up for a sore back.

You may also notice that all three of these sample horses display an ilium side (point of hip to point of buttock), which is the same length as the femur side (point of buttock to stifle protrusion)—meaning that they produce similar types of power from the rear spring as it coils and releases when in stride. We can examine the variances in these measures in more detail in future articles, when we start to delve into various ranges of motion as well as other factors for soundness or injury.

Factors for Distance Preferences

The hindquarters of Horse #1 and Horse #2 also differ from that of Horse #3 based on the location of the stifle protrusion (not the actual patella, but the visible protrusion that one can watch go through its range of motion as the horse moves). The differences in stifle placement equate with range of motion of the hind leg, stride length and, to some degree, stride rate.

When it comes to the stifle placement for a champion at classic distances, we can see just how far below sheath level Tiznow’s stifle protrusion is and we can equate that to Lady Eli’s as well, even though she doesn’t have a sheath. Horse #3 has a stifle placement that is higher than the other two horses, more in keeping with the placement of a miler (at the bottom of or just below the bottom of the sheath). Sprinters tend to have stifle placement that is above that of milers.

The most efficient racehorses have a range of motion of the forehand that corresponds to the range of motion of the hindquarters. That may seem like stating the obvious, but not all horses have strides that match fore and aft. We have seen those horses that “climb” in the front as well as those that seem to “bounce” higher in the rump. In both cases, a mismatch of strides is often the cause.

For simplicity, let’s say the horse has to generate power from his hindquarters, transfer that power upward and forward through the spine as well as extend his front end at the same stride rate created by the hindquarters for efficiency. He/she has to maintain the same rate in the forequarters and the hindquarters.

One of the things we seldom think about is that horses have to move the front quarters at the same stride rate created by the hindquarters, but they do not necessarily have to be built to have the same stride lengths and turnover rates front and back.

If a horse has to significantly adjust the stride length fore or aft, he/she is likely not going to win in top company, especially racing. And for those horses that can adapt to slight discrepancies, a strong LS placement is paramount.

A car with different sized tires in the front than in the back will travel at a constant speed, but the smaller tires will rotate faster than the larger ones. A horse can’t do that, though; he/she has to compensate to bring the front and rear into the same stride rate.

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