I was grateful to be able to watch the replay of the Saddle Research Trust 4th International Conference, which was presented online on 11th December 2021. Here I share with you some of my learnings from the conference. Find out more about the Saddle Research Trust, and see the proceedings from previous conferences, at www.saddleresearchtrust.com.
There are many systems and techniques available to give objective measures for saddle fitting, and in this presentation Russell discusses how useful some of these might be. An objective measure uses some kind of validated technique to give specific measurements, as opposed to subjective measurements, which
One of the cheapest and most accessible objective measurements in terms of saddle fitting is the flexicurve ruler. This is used to measure the curve of the back muscles. The flexicurve ruler has been shown to be a reliable method of measuring changes in the shape of the back muscles, with an accuracy of +/- 2mm. Several studies have used the flexicurve ruler as an objective measurement. For example, it’s been shown that there’s a decrease in the size of the back muscles at T13 in a wide saddle and a decrease at T18 in a narrow saddle. There’s an increase at T13 after a vibration session, and an increase at T13 after 30 minutes of exercise in a correctly fitted saddle.
However, researchers are now questioning whether the changes measured by the flexicurve ruler are due to the muscle dimensions, or due to changes in the horse’s posture. For example, Dr MacKechnie-Guire described a horse where there was a change in height of 1cm at T8 after 30 minutes of exercise. When the pre and post exercise flexure measurements were superimposed with the change in height of the vertebra taken into account, it seems there was no change in muscle dimensions. More data is being analysed.
Another study that Dr MacKechnie-Guire and his team carried out, using a flexicurve ruler to measure horses’ backs every hour for 8 hours, showed that back dimensions change over time within the individual horse. Also, they found that the height of the horse, particularly at T18, changed through the day. He pointed out that we might need to take into account the time of day, or the activity the horse has been dong before being measured (for example, stabled, turnout, ridden), when we are interpreting the data from the flexicurve ruler measurements.
The next objective measurement that Dr MacKechnie-Guire discussed was pressure mapping. The pressure mat is a pad that sits under the saddle, with multiple sensors, measuring peak and mean pressures. The pressure mat must be calibrated, and has been validated in terms of measurements of pressure under the saddle. The repeatability of the pressure mat after the saddle and mat has been removed is fair to good for the back quadrants, but poor for the front quadrants and for peak stress distribution. This means that it’s essential that the positioning of the mat and the saddle is carefully controlled.
Also, it’s important to link data from pressure mapping with video footage, as changes in pressure can happen with things like a shift in rider balance, or the horse tripping or sneezing, for example. Aspects such as speed, direction, surface and weather can have an effect on the pressure distribution. All of these things need to be taken into account, and care should be taken in interpreting results as these systems become more widely available.
Thermography is a system that many of us have come across. Veterinary infrared imaging measures the emitted thermal radiation from the skin’s surface. Thermography has been used in studies that have looked at left / right asymmetry, front / back pressure, and more. However, there may have been assumptions made, such as high pressure leading to hyperthermic patterns (increased temperature), and severe muscle spasm being represented by hypothermic patterns (decreased temperature). It’s also potentially assumed that a correctly fitting saddle should give a symmetrical heat pattern.
Dr MacKechnie-Guire and his team recently investigated this. Measurements were taken in four horses using thermography, pressure mapping, and inertial measurement units, with the same rider throughout. They took measurements at baseline, immediately after 20 minutes lungeing, immediately after a standardised ridden exercise, and at one hour after exercise. The horses were lunged, then ridden, and data collected in rising trot, seated canter, and a two point seat.
Results from the thermography showed that the temperatures of the horse’s back increased after lungeing, and maintained the increase in temperature after riding. This should be taken into account when interpreting findings. Pressure mapping shows that a saddle that is too narrow or too wide, according to industry guidelines, will create increased pressure under the front of the saddle. In this study, thermography did not show these patterns, and therefore is perhaps not representative of saddle fit.
Using inertial measurement units, Dr MacKechnie-Guire and his team have shown that the movement of the horse’s back becomes more symmetrical when the rider is in a two point seat, compared to the horse working in hand, or the rider trotting on the correct or incorrect diagonal.
Video analysis is becoming easier with the use of smart phones, and there are various apps available now which can be very helpful in terms of assessing saddle fit. With all of these options, it’s important to understand the technology that’s being used, and to interpret the findings with caution.
You can find more information on Dr MacKechnie-Guire’s work, and join one of his many fascinating webinars, at www.centaurbiomechanics.co.uk.
Find out more about the Saddle Research Trust, and see the proceedings from previous conferences, at www.saddleresearchtrust.com.
© Sue Palmer, The Horse Physio, 2021
Treating your horse with care, connection, curiosity and compassion