What, where, when & how to fit a saddle to a horse 2001

Evidence Based Saddle Fitting What, Where, When & How Do We Measure a Horse for a Saddle

By Robert Ferrand, Inventor WHAT IS EVIDENCE BASED SADDLE FITTING? EVIDENCE BASED SADDLE FITTING is the employment of physics, physiology and peer review clinical research as the basis for understanding saddle fitting and coupling this research with measurement data. By employing three factors: 1. three-dimensional coordinates, 2, a mathematical calibration formula, and 3. a computer interface pressure measurement, a “feedback loop” can be created to precisely define the dynamics of saddle fit.

By first describing the three dimensional measurement coordinates that define the polyform shape of the horse’s back, then employing a mathematical formula to correct for the effect of the rider’s weight relative the horse’s weight, it is possible to determine a more accurate shape of mounted saddle that will provide a superior “FIT”. By then taking the additional step of measuring the actual interface pressure that is exerted by the saddle and rider on to the horse’s back a calibration and or validation of this three-dimensional measurement is also possible, thereby creating a “feedback loop.” providing objective validation. This process is also known as “the scientific method”.

A SADDLE FITTING METHOD THAT CAN APPLY THE SCIENTIFIC METHOD IS 1.

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Observe some aspect of the universe. THREE DIMENSIONAL MEASUREMENTS Invent a description, called a hypothesis. or a mathematical relation A FORMULA Use the formula to make predictions. WEIGHT COMPENSATION FACTOR Test those predictions by experiment INTERFACE PRESSURE MEASUREMENT Repeat steps 3 and 4 until there are no discrepancies FORMULA CALIBRATION

3-D MEASURE HORSE'S BACK

U.S. Patent # 6,334,262

3-D MEASURE SADDLE SHAPE PURCHASE NEW SADDLE OR RESHAPE SADDLE

ENTER # INTO DATABASE 3-D RE-MEASURE HORSE'S BACK

3-D RE-MEASURE SADDLE SHAPE

DETERMINE RE-MEASURE CYCLE TIME

WEIGHT CALIBRATION FORMULA

RIDER LBS.

MATCH FOUND

SORT DATABASE

COMPUTER PRESSURE VERIFICATION PLACE HORSE/SADDLE INTO SERVICE

HORSE LBS.

FAIL

NO MATCH FOUND

REQUISITION ORTHOTIC MADE TO MEASURE

OUTPUT DOCUMENT TO FILE RECORD

PASS

In contrast, to traditional saddle fitting methods, which are based on assumptions that have no scientific basis or supporting measurement data, Evidence Based Saddle Fitting is totally based on physics, physiology, mathematics, and calibrated measurement.

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WHAT IS MEASUREMENT? MEASUREMENT is the dimension, quantity, or capacity determined by measuring.

MEASUREMENT is a qualitative relationship based on a “STANDARD”. Measurement requires a standard unit of measurement.

Many people misunderstand measurement. There are some who believe that the use of a piece of baling wire or flexible curve to be measurement. Unfortunately, until that two-dimensional shape is converted into a series of x and y coordinates it is not measurement, because there are no numerical values that are related to a standard.

There are others who believe that a plaster or plastic form of the horse’s back to be measurement, unfortunately, such polyforms also do not employ numerical values, so measurement is not possible until these coordinates are converted into an array of x, y and z coordinates that relate to an established standard unit of reference.

There is an ancient method, employing an array of rods fit through holes in a plate, which can be adjusted to create a “mirror image” of the shape of the horse’s back. This device can provide the numerical data for x, y and z coordinates, by measuring the length of each individual rod. However. without a standard of reference to determine how these numbers relate to the actual pressure exerted by the saddle and rider on the horse’s back, there can be no measurement. MEASUREMENT REQUIRES A REFERENCE STANDARD. WHAT DO WE MEASURE? The bottom line issue of fitting a saddle to a horse is PRESSURE. If the saddle exerts significant pressure on the tissues of the animal, the animal can be traumatized and in time white hairs and or open sores can develop. Thus, in the final analysis we need to measure the PRESSURE exerted by the saddle and rider on the horse’s back.

Unfortunately, baling wire, plaster casts, plastic forms and rod arrays do not measure that pressure.

The question “What do we measure?” is linked to “What information do we need to properly fit a saddle to a horse?” This question also infers that we have measurement instruments in the first place. So what you measure is linked to what measurement instruments are available to acquire the data. The challenge to measure a saddle on the horse is that the saddle and rider are themselves in the way of determining the three dimensional measurement of the horse’s back.

If you remove the saddle and rider, to be able to have access to measure the threedimensional shape of the horse’s back then you are measuring something different than what occurs when the rider is in the saddle. If you measure one thing and then totally change the equation you really have two different events, but only one measurement. So to accurately measure a saddle with the rider there needs to be a method to correct for this difference. Mathematics provides a technique called CALIBRATION that can correct for such discrepancies.

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The Encyclopedia Britannica defines; the process of calibration of any measuring instrument is the determination of the value of the unit to which the measurements are referred by comparison with a standard unit of the same kind. Thus, the challenge using baling wire, a plaster cast, plastic forms or a rod array for measurement, is that even if these forms are transferred to x, y and z coordinates, these coordinates cannot be calibrated because there is no reference STANDARD to which to calibrate to the actual pressure that is exerted onto the horse’s back.

There are four significant issues relating to saddle measurement. The first, is what actual pressure is exerted on the animal by the saddle and rider? The second issue is what is the three dimensional shape of the animal’s back? The third, is what is the three dimensional shape of the saddle? The fourth, what is the relationship between the actual pressure exerted on the animal and the three-dimensional relationship between the measurement of the horse’s back and measurement of the saddle WITH THE RIDER MOUNTED? The challenge is to create a formula that relates each of the previous measurements into a balanced mathematical equation that can determine the effect of the weight of the saddle and rider on the shape of the horse’s back? To accomplish this task, we need a Two Factor Theory; one measurement device is not enough. To achieve any reasonable accuracy requires at least one measurement device that can measure pressure that can be calibrated to a known reference STANDARD and a second device that can be calibrated to the first device that can measure the three dimensional shape of the horse’s back and corresponding saddle.

A technology is available, consisting of a pressure sensitive pad attached to a computer. The pad contains an array of 256 pressure sensors that measures 24 inches by 32 inches. This instrument can actually be “calibrated” to a known STANDARD of pressure. The individual pressure sensors can be "Calibrated" to a pressure manometer that has been "Calibrated" to another "Calibrated" manometer that was calibrated against a national pressure STANDARD maintained by the National Institute of Standards and Technology, in Washington, DC, IF WE HAVE A REFERENCE “STANDARD” THEN WE HAVE A SCIENTIFICALLY VALID METHOD OF “MEASUREMENT”.

While the sensor array does measure pressure, it does not provide the threedimensional coordinates required to relate the shape of the saddle to the shape of the animal’s back, so the correct saddle can be chosen or adjusted to fit the animal. Such a three dimensional measurement device should provide any array of points that describes the shape of the unloaded horse’s back. Then if we could construct a formula that could adjust for a variety of individual factors we could readjust such a measurement device to describe a new set of numbers, which approximates the shape of the loaded horse and corresponding saddle. Such a device can be constructed by employing transverse linkages as shown below. By employing the computer interface pressure device to calibrate the formula a “feedback loop” is created to validate measurement criteria.

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WHERE DO WE MEASURE? Where we measure is related to where we place the saddle on the horse. There are a number of different theories on saddle placement. When using English saddles there is a tendency for Hunter and Jumpers riders to place the saddle forward, and Dressage riders to place the saddle further back. With Western saddles, many are so large that it is virtually impossible to avoid placing them over the scapula. There are some who argue to keep the scapula free; there are other people who claim it does not matter. Regardless of which saddle position theory you wish to support, the bottom line is that the saddle should be “FIT” to whatever position the saddle is actually going to be ridden, whether it is forward, backward or in-between.

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Technically, the center of the saddle should rest right over the 14th spinal vertebrae, and the rider should be centered above that same point. While this is a great explanation on “exactly where the saddle should be placed”, unfortunately in the real world, it is not easy for an unskilled person to find the 14th spinal vertebrae, much less locate the center of the saddle over that point. So this explains exactly where the saddle should be placed, but it is virtually impossible for most equestrians to use the 14th vertebrae for a reference point.

In 1917 the U.S. Cavalry, published that: there are six axioms in saddle fitting: (1) The withers must not be pinched or pressed upon, (2) The central line of the back must have no pressure put upon it, (3) The shoulder blades must have full and unhampered movement, (4) The loins must not carry weight, (5) The weight must be put upon the ribs through the medium of the muscles covering them, (6) The weight must be evenly distributed over a surface, which extends from the play of the shoulders to the last true rib.

This is a succinct explanation of where to place the saddle, however, while it makes sense to place the saddle behind the scapula, unfortunately, the hunters and jumper riders tend to place the saddle forward for a very good reason, to get the riders weight forward.

When using traditional Western saddles that are 27 inches long, it is virtually impossible to place the Western Saddle behind the scapula because the saddles are so long.

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To make matters more complicated, many horses are asymmetrical, meaning the position of the scapula is not the same from one side to the other, and there is even greater variation from horse to horse and breed to breed. So employing the “scapula� as a reference point is problematic.

The simple solution is to accept whichever saddle placement theory is currently in vogue with that individual rider and using that placement of that saddle for the reference point for measurement. If the saddle is placed on the horse and the position of the front and back of the saddle is marked with chalk or tape, two reference points are established.

If the measurement instruments, themselves, are centered between these two points, then corresponding measurements taken on the horse that can be related to the corresponding contact point on the saddle. This method permits a universally applicable method to measure the horse for a saddle, regardless of whichever saddle placement philosophy is employed.

WHEN DO WE MEASURE? WHEN we need to measure is related to the issue of the saddle and rider being in the way of the measurement itself and the difference between static and dynamic measurement, which in turn relates to understanding the physiological problem we are trying to solve by saddle fitting, in the first place.

There is no way to eliminate the pressure under the saddle, nor is there any need to. There is only a need to understand what the horse's tissues need to remain healthy.

With that knowledge we can learn how to intelligently apply pressure to the horse's back.

Skin and muscle tissue require a constant intermittent flow of blood to remain healthy. In strenuous exercise the muscles require significantly more blood flow to maintain a healthy metabolism. This exchange of oxygen and waste products occurs in the capillary bed.

The saddle fitting problems occur when the saddle causes continuous excessive pressure on the capillaries that exceeds the blood pressure and structural strength of those vessels and the capillary vessels collapse. This collapse leads to the deprivation of oxygen and nutrients brought by fresh blood and the removal of waste products.

CAPILLARY CLOSING PRESSURE IS THE CRITICAL ISSUE IN PREVENTING SADDLE-RELATED TRAUMA AND IMPROVING THE PERFORMANCE OF THE HORSE'S MUSCLES UNDER SADDLE.

In all cases, pressure release is followed by reactive hyperemia and the parts originally starved of arterial blood are instantly flooded with oxygen rich blood. The extent and duration of the blood flow is proportional to the needs of the tissues. The most important issue to remember with tissue trauma is that higher pressures do damage in shorter periods of time. However, even low pressure for long periods of time can do damage

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Tissues do not need a constant flow of blood, but tissues do need a CONSTANT INTERMITTENT FLOW OF BLOOD. This is significant to saddle fit because the fit of the saddle relates to how much time one can ride before causing trauma to the horse.

Obviously if the saddle fits one can ride the horse longer without sustaining damage than a saddle that bridges and causes high pressures.

In the final analysis we need to measure the pressures exerted on the horse dynamically when the horse is in gait. However, as a practical matter that measurement does not provide us the information we need in the saddle shop when we are building the saddle, or at the tack shop trying to choose a saddle that will fit a particular horse.

So again once again, a Two-Factor Theory is required. We need one measurement at one time and a different measurement at another time. First, we need to know the three dimensional (3-D) shape of the animal’s back for a reference position. Secondly, we need a formula to correct for the effect of the rider weight relative to horse weight so that we can make adjustments to the initial 3-D measurements to describe the new shape of the loaded horse’s back in order to choose a saddle. Thirdly, we then can search for a saddle that has the required shape, by placing the device into saddle after saddle, or search a database. Fourthly, the saddle that provides a “3-D Measured Fit” needs to be tested with the rider in the saddle on the horse, first statically, and then dynamically with an interface pressure measurement device, to verify that no errors were introduced into the calibration method or the horse’s conformation or condition requires additional calibration.

The goal of such a interface pressure measurement is to determine that the saddle “REALLY DOES FIT”, which means that we can achieve an even distribution of pressure when the horse is static and that high pressures do not remain in the same place when the horse is in dynamic motion. It is important to remember that we are not trying to eliminate pressure; we are trying to use measurement to control the shape of the saddle in order to be able to control the pressure distribution precisely.

This means that if the saddle does not fit; it “bridges” when the pressures are measured statically as well and dynamically, despite the fact that the horse’s back does move to some degree under the saddle, the higher pressures at the withers remain. This does not permit the intermittent flow of blood that is necessary for the tissues to remain healthy. NOW, IF THE SADDLE DOES “FIT” STATICALLY, WHAT WE WILL FIND IS THAT THE SLIGHT MOVEMENT OF THE HORSE’S BACK WHEN IT IS IN MOTION, WILL CAUSE SLIGHTLY HIGH PRESSURES TO MOVE FROM ONE AREA TO ANOTHER, THROUGHOUT THE SADDLE CONTACT AREA. THIS WILL PROVIDE THE INTERMITTENT FLOW REQUIRED TO MAINTAIN HEALTHY TISSUE.

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HOW DO WE MEASURE? HOW we measure relates to the nature of the measurement instruments themselves, obviously, three-dimensional measurements are taken differently than interface pressure measurements.

One method to acquire three-dimensional measurements of the horses back would be as follows: 1. Be sure that the animal is standing with all four feet square to each other and that the animal’s head is in a normal position when riding.

2. Place the Saddle on the animal and mark the position in the front and the back of the saddle with tape or chalk on the animal’s back 3. Adjust the wings of the measurement device to facilitate measurement 4. Center the measurement device on the animal in the same position that you will put the center of the saddle, meaning centered between the previously marked position of the saddle. Make sure that the wings are adjusted perpendicular to the ground.

5. Adjust the Center wings down so that the bottom edges of the wings have maximum contact with the animal ‘s back.

6. Adjust the wither and loin wings down so that the bottom edges have maximum contact with the animal’s back.

7. Double Check that the faces of the Wings are perpendicular to the ground.

8. Record the Measurements from each of the respective wing (arm) indicia and the arc (link) indicia on the measurement device. The preferred method to measure the Saddle would be: 9. Lift the measurement device off the animal without moving the position of the measurement device.

10. If necessary, adjust wither ((pommel) arc and loin (cantle) arcs of the measurement device using the WCF (Weight Compensation Factor) to compensate for the weight of the rider relative to the weight of the animal using the appropriate formula.

Note: additional factors may require refined formulas. Additional factors affecting saddle fit include the age of the animal, the condition of the animal, the type of saddle, the surface area of the saddle panels, the type of riding and the skill of the rider. Appropriate adjustments can be made using this method to account for additional factors.

11. Turn the measurement device upside down and place the measurement device in the Saddle.

12. Center the measurement device in the center of the saddle, equidistant from the front (pommel or fork) and back (cantle) of the saddle.

13. Use the Saddle Fitting Guide to determine the best possible saddle fit for a particular animal.

The saddle "Fits": if all the wings touch the saddle uniformly.

The saddle "Rocks": if the wither and loin wings do not touch.

The saddle "Bridges": if all the wither and loin wings touch the saddle at the pommel (front) and cantle (back) and do not touch in the center of the saddle.

14. By making an additional measurement employing an interface pressure measurement device, the formula can be calibrated to adjust for additional factors such and age, breeding, or conditioning.

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If the measurement device or computer scan reveals that the saddle is "bridging," causing high pressure on the withers and loin, the measurement of the arc of the saddle can be increased incrementally to permit the saddle to contact the back of the animal and evenly distribute the weight over the entire saddle panel by adjusting incremental rider weight (B) or the incremental animal weight ( Y )

RW – C HW – Z WCF = _______ + _______ B Y Conversely, if the gauge or the computer scan reveals that the saddle "rocks," causing high pressure only on the middle of the back of the animal (no contact on the withers or loin), the arc of the saddle can be decreased to permit the saddle to contact the back of the animal and evenly distribute the weight over the entire saddle panel, by adjusting either the established rider weight ( C ) or the established animal weight ( Z ), The Two Factor Theory includes employing two different measurement instruments, one measurement instrument that measures the three-dimensional shape of the animals back, in conjunction with a formula that can adjust the measurement of the three dimensional shape of the saddle to compensate for the weight of the rider. The second measurement device is then employed to calibrate or verify the accuracy of the 3-D measurement and associated calibration method.

THE "MIRROR IMAGE" CANNOT POSSIBLY FIT! We have all been told over the years, by the expert saddle fitters that you should fit the saddle to the “mirror image” of the horse’s back, because that will distribute the pressure evenly. We are told that we can determine this “fit” for ourselves by placing the saddle on the horse, lifting the skirts or flaps and by running our hand under the saddle, we can “feel” that the panels or bars fit evenly on the horses back. That is the story, now, what is the truth?

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The truth is most equestrians have a number of saddles gathering dust that just do not fit. Most of us go from saddle to saddle, fitting the saddles the way we are told and we never find a saddle that fits. Maybe the saddle fitting experts are wrong.

Maybe the “saddle fitting” problem is that we are all fitting saddles by repeating the same mistake over and over, for centuries.

Let us examine what we have been told with a little bit of common sense. Despite the fact that it is pretty obvious that gravity is a factor everywhere else, we keep trying to fit the saddle without the rider, because as soon as the rider gets in the saddle we cannot “feel” under the saddle.

Then, we step in the saddle and add 150 to 200 pounds and think that it does not matter. Every time I carry a 50-pound sack of grain to the barn, I do think that 200 pounds on the horse has to have a significant effect on the shape of the horse’s back.

Can we possibly find a more reasonable way to fit the saddle to the horse, so we can figure out what the effect of the weight of the rider has on the shape of the horse’s back so we could choose a saddle that fits?

Well, the answer is yes. If we could make a clear plastic structure that we could actually see through, that could simulate the shape of the saddle, so that we could actually see how that shape relates to the shape of the horse’s back, we could test the theory if the “mirror image” does fit the horse when the rider is mounted.

If we place a plastic structure on the horse that we can obviously see for ourselves that does “FIT” the mirror image of the horse, as we have been told to do, and then if we place that structure on the pressure sensitive computer pad on the horse, we should be able to see if it “FITS” when the rider mounts. If it does not fit and it “bridges” we can see that the saddle fitting problem is that the “saddle fitting experts’ have been giving us the wrong advice for many years and it is time to change our strategy.

Testing the “mirror image” theory, we can see that if there is no rider weight: the formula would be: –10 = (0 – 150 ) / 15 + (1000 – 1000 ) / 100. So if we subtract 10 degrees from the wither and loin arc of the measurement of the horse’s back, we should be able to make a plastic structure that is a “mirror image”.

You can see that this “Mirror Image” plastic structure on the left does in fact APPEAR to “FIT” the horse perfectly, as we have been told it should. Notice that you can actually see through the plastic and see that the hair is pressed evenly on the back. Now, if you look at the adjacent computer scan on the right, of the same “Mirror Image” structure on the horse, however, with the additional weight of the saddle and rider, you can see that the horse’s back has been significantly affected by the addition of 225 pounds and the “mirror image” structure actually "BRIDGES".

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Maybe we have identified why we cannot ever find saddles that fit, once again we have been mislead by the experts, and we are ignoring the obviousGRAVITY DOES EXIST AND WEIGHT IS A SIGNIFICANT FACTOR HOW DO WE TEST THE THEORY ?

Now, we can take this experiment one step further and test our formula and see if in fact by correcting for the weight of the rider relative to the weight of the horse, we can actually achieve a better fit. If we achieve a relatively even pressure distribution, maybe we are on to something here.

To test this theory we need some way to make the clear plastic structure in a fashion that it can use the measurements from the measurement device with a direct relationship. This can be done by using the measurement device itself, to be the form on which the plastic structure is actually made. In this manner, the shape of the plastic structure can actually be calibrated, and the formula can be used to precisely change the shape of each plastic structure.

So,

lets put this theory to the test. For this experiment we need,

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a Horse, a Saddle, a Rider, a three-dimensional measurement device, a calibration method to correct for the effect of the weight of the rider, a computer interface pressure measurement instrument, an adjustable form jig to make the test structure, and a clear plastic three-dimensional test structure.

First, we can take the three dimensional measurements of the horse. Now the formula can be simplified into a chart below, which you just match the point where the rider weight and the horse weight cross and just go over to the left and adjust the measurement instrument wither and lion arcs by that amount. This is the simple, quick and easy method.

Adding the 225 pound rider to the equation would be:5 = (225 – 150 ) / 15 + (1000 – 1000 ) / 100. So, if we add 5 degrees to the wither and loin arc of the original measurement of the horse, we should be able to build a structure that would “FIT”. You can see on the right, that the structure APPEARS to “Rock” slightly on the horse’s back, however, if you look at the adjacent computer scan, on the right, with the rider in the saddle you can see that the pressure is relatively even. Bingo, we are on to something here.

So there you have it, “EVIDENCE BASED”” proof that using the three dimensional back shape of the “MIRROR IMAGE” CANNOT POSSIBLY FIT a saddle to a horse. That is the bad news. The good news is we have a modern EVIDENCE BASED verifiable method to fit a saddle to a horse, as well as a structure that can correct for the variations between horse’s backs and saddles.

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In 1908 the British Army Veterinary Service wrote in Animal Management, “Excluding epizootic diseases, it would be difficult to find any cause of inefficiency among army horses equal to that produced by saddle injuries. It has always been so, for the reason that insufficient attention has been paid to the question of prevention, and few realize the extra-ordinary damage which may be inflicted in a very short time by an ill-fitting saddle” A century later, it is time to use the resources of modern science and focus our attention to the question of prevention to protect our animals. Remember, whatever difficulty you may have with mathematics, it was far harder for Albert Einstein, but it did permitted him to solve profound 2 mysteries, remember E = mc . Measurement was a friend to Albert Einstein and it can be a friend to you and your horse as well, and it really is not that hard to do. Saddling a horse is not rocket science, but it does require careful measurement.

Albert Einstein, stated, “Insanity is repeating the same thing over and over and expecting different results” It is time to stop the insanity, because we are abusing our animals by our lack of attention.

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