Science in brief: Interactions between the rider, the saddle and the horse
The horse-saddle-rider interface was the topic of discussion at an international workshop held at
the Animal Health Trust in Newmarket in February 2012. The workshop was organized under
the auspices of the Saddle Research Trust, which is a charitable organization dedicated to
supporting the generation of scientific knowledge about the influence of the saddle on horse and
rider performance. It was chaired by Dr. Sue Dyson, Head of Clinical Orthopedics at the AHT,
and facilitated by Dr. Pat Harris, Waltham Equine Studies Group. The specific objectives were to
evaluate the current state-of-knowledge regarding the horse-saddle-rider interaction and then to
discuss how research should logically progress towards a better understanding of this complex
issue. The speakers included representatives from several of the research groups that are
focusing on the effect of the saddle and rider on equine health and performance. The saddlery
industry was well represented, together with riders, trainers and other professionals involved in
equine care and performance. Attendees from the technological sector also provided valuable
input into the discussions. The format involved a series of state-of-the-art talks on different
aspects of the rider-saddle- horse interface that served as a starting point for the discussions.
The first speaker was Anne Bondi, a member of the University of Sunderland Equestrian Study
Group, who talked about the evolution of modern day saddles. She addressed the design and
function of different parts of the saddle in relation to comfort and performance of horse and rider.
Her introduction set the stage for the talks that followed by drawing attention to some of the
difficulties in simultaneously accommodating the needs of both human and equine athletes.
In the next presentation Dr. Sue Dyson shared her clinical observations on the complexities of
the diagnostic procedure when evaluating a possible role of the saddle and/or rider in cases that
are presented for clinical evaluation of lameness, back pain or other performance problems. In
her examination of these cases, Dr. Dyson often evaluates the horse under saddle and, in
addition to watching the horse ridden by its usual rider, may also have it ridden by another rider
who is known to have a symmetrical position in the saddle. Comparison of the saddle position
and symmetry with the two riders may point to a primary problem in the way the horse has been
ridden and trained. Furthermore, an intrinsically unbalanced or asymmetrical rider position may
contribute to the development of equine back pain. However, when the saddle consistently slips
to the same side with different riders, it may reflect an ill-fitting saddle or hind limb lameness. If
the lameness is resolved by nerve blocks and the saddle slip is abolished, this indicates a direct
causal relationship. Dr. Dyson has observed that saddle slip is consistently present in as many
as 50% of horses with hind limb lameness in spite of the fact that these horses usually have
symmetrically-developed back musculature. Dr. Dyson’s insights show that the horse is
sometimes the source of problems that are manifest as asymmetries in the position of the
saddle and/or rider.
Dr. Lars Roepstorff from the Swedish University of Agricultural Sciences in Uppsala, Sweden
drew attention to some of the problems inherent in the use of pressure mapping technology to
measure forces and pressures on the horse’s back. Different measurement systems are based
on different types of sensors that vary in their characteristics and thus would not be expected to
produce identical results. The sensors are temperature sensitive and degrade over time
necessitating recalibration at intervals that vary between systems [1,2]. The lack of a “gold
standard” for measuring pressure on the horse’s back is a serious drawback and interpretation
of information from the pressure mat is hampered by not having a generally-accepted method of
dealing with the spatial and temporal variability of the resulting data. Even though current saddle
pressure measurement systems and analytic procedures are less than perfect, this does not
disqualify their use. However, researchers need to be cognizant of the limitations and take these
into account both in the design of their studies and in the interpretation of the data.
Dr. Roepstroff also talked about some innovative techniques for measuring and evaluating rider
position based on inexpensive inertial sensors of the type used in WII video games. When these
sensors are applied to the rider’s pelvis and trunk, they show how the rider’s movements are
coordinated in different gaits. The reasonable cost of the sensors makes this a promising
system for field use.
The effect of the rider was addressed by Dr. Narelle Stubbs, a human and equine
physiotherapist from the McPhail Equine Performance Center at Michigan State University,
USA. She discussed the effects of limb dominance and leg length asymmetries on the rider’s
motor function and position in the saddle. In the majority of right handed people there is a
common lumbopelvic pattern that alters the rider’s position from "perfect neutral". The left leg is
often longer, more open, and more dynamically stable than the right leg (diagonal dominance)
due to relative neuromuscular dominance of the hip extensors including the gluteals. The right
leg is more flexed at the hip due to over-activity and shortening of the hip flexors, predominantly
iliopsoas, which rotates the right ilium anteroventrally and elevates the rider's right ischium and
posterior ilium from the saddle. The right leg often appears a little shorter and externally rotated
compared to the left leg. In addition to their natural asymmetries, many riders also suffer from
the effects of musculoskeletal trauma, which is an occupational hazard in equestrian sports. Dr.
Stubbs showed examples of the value of proprioceptive stimulation techniques, such as the use
of kinesiotape, in helping a rider to become more aware of postural problems and to ride more
symmetrically. This talk concluded by showing preliminary results of a series of studies of rider
postural control and balance that are being conducted using equipment designed to study the
effects of low back pain in people. In addition, she showed some ultrasonographic images of the
activation of the abdominal musculature in riders assessed to have good and poor postural
control of the trunk when riding. It was clear from the information presented by Dr. Stubbs that
rider asymmetries are common and can be a causative or contributory factor in the horse-
saddle-rider asymmetry conundrum.
Dr. Christian Peham, Head of Movement Science at the Veterinary School at the University of
Vienna in Austria, summarized a series of peer-reviewed papers from his laboratory on the
horse’s back, saddle fit and rider dynamics. He showed that, when the tree width of a saddle is
appropriate for the shape of the horse’s back, the force is distributed along the length of the
panels. With a narrow tree, pressure is concentrated at the front and back of the panels with an
unweighted area in the middle of the panels (bridging). The saddle tends to be high in front and
low at the back, which tips the rider’s position backwards. When the tree is too wide, the
pressure is concentrated on the inner edge of the panels close to the horse’s spine and the
pommel tends to be too low thus tipping the rider forwards . If a saddle is basically the correct
size for a horse but not a perfect fit, the use of a saddle pad may improve the horse’s comfort.
Research published by Dr. Peham’s group has shown that a reindeer fur pad can reduce the
maximal total force by distributing the load more evenly throughout the duration of the stride .
If the saddle tree is too wide, however, the use of a pad is liable to increase the maximal total
force and local pressures . Dr. Peham also illustrated the effects of different rider positions in
the saddle on the forces transmitted to the horse’s back. For example, when riding side saddle,
the weight is always distributed asymmetrically . When riding astride at trot, the loading on
the horse’s back is highest for sitting trot, intermediate for rising trot and lowest in a two-point
seat. The rising trot and two-point seat show a temporal redistribution of forces with a lowering
of peak values . The information presented by Dr. Peham provided further evidence of the
complexity of the interaction between rider, saddle and horse.
The last speaker was Prof. Hilary Clayton, Director of the McPhail Equine Performance Center
at Michigan State University, USA. Her talk focused on techniques for analyzing the horse-
saddle-rider interaction. She emphasized the importance of using techniques and equipment
that have been proven to be valid and reliable for the purposes for which they are being used. A
good example of this is the electronic saddle pressure mat. To date only one brand of pressure
mat has been shown to be valid and reliable for measuring interface pressure between the
saddle and the horse’s back [1,2]. It is likely that some of the other pressure mats on the market
would also be valid for this purpose if tested appropriately, but there are also mats that have
insufficient sensor density to accurately measure total force or pressure distribution. All of the
pressure mats that are currently used to measure saddle pressure are limited by the fact that
they only measure the force component applied perpendicular to the sensors. Shear forces that
are not measured by the mat may contribute to friction rubs and the development of saddle
sores. Three-dimensional sensors are available but at the present time they are too expensive
for this application. Pressure profiles are open to misrepresentation and/or misinterpretation
since the same pressure scan can be made to look very different by changing the range of
pressure within each coloured band. Furthermore, forces and pressures change according to
the phase of the stride at which they are recorded, especially in gaits that have a suspension
phase. Therefore, when evaluating a still image it is important to know the ranges of pressure
represented by the different coloured bands and the stage of the stride that is depicted.
Unscrupulous manipulation of these two factors can misrepresent a saddle or a rider’s
performance. Prof. Clayton provided some practical tips on interpreting forces and pressures
on the horse’s back and described the results of a study by researchers from Zurich University
in Switzerland in which pressure levels on the horse’s back were correlated with the presence of
clinical lesions and dry spots underneath the saddle that are indicative of areas of local
ischaemia . These data are being applied to set threshold values for acceptable pressure
levels beneath a saddle.
Dr. Pat Harris facilitated the next phase of the workshop which involved an open and frank
discussion of the information that had been presented with emphasis on the major issues in
saddle design and saddle fitting as well as the assessment of saddle fit and treatment of the
consequences of poor saddle fit. A list of research topics was generated related to the horse,
rider and saddle and attendees cast votes to determine which topics would be revisited the next
day. The following morning, each participant was assigned to one of four discussion groups led
by Dr Rachel Murray, Head of Equine Orthopaedic Research at the Animal Health Trust; Dr
Charlotte Nevison, Director of Equine Research at Anglia Ruskin University, Cambridge; Wayne
Channon, Secretary General of the International Dressage Riders Club; and Karen Coumbe,
from the Bell Equine Clinic, Kent. The groups discussed the research topics that received the
most votes the previous day then reconvened to compare notes on each topic. These
brainstorming sessions brought forth some interesting and insightful ideas and suggestions; the
sheets prepared by the groups are being analyzed to seek recurring themes among different
groups that will guide future research efforts.
Overall, this was an interesting and stimulating workshop. The interaction among professionals
who deal with rider asymmetry patterns, practical saddle fitting issues, and clinical evaluation of
equine lameness or back pain brought greater awareness of the complexity of the problem and,
perhaps, a degree of frustration at the lack of validated techniques and to evaluate the horse-
saddle-rider interface. It is clear that we do not have a gold standard of measurement and that
some of the challenges faced by researchers cannot be solved with the equipment and
techniques that are currently available. Participants agreed that there are unlikely to be easy
solutions and, although the existing technology is imperfect, researchers should continue their
investigations with full recognition of these limitations.
Hilary M. Clayton, BVMS, PhD, DACVSMR, MRCVS
Mary Anne McPhail Dressage Chair in Equine Sports Medicine
Large Animal Clinical Sciences
College of Veterinary Medicine
Michigan State University
East Lansing, MI 48824-1314
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