Dynamic pressure effect on horse and horse rider during riding

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<ul><li><p>ORIGINAL ARTICLE</p><p>Dynamic pressure effect on horse and horse rider during riding</p><p>Graeme Nicol Graham P. Arnold </p><p>Weijie Wang Rami J. Abboud</p><p> International Sports Engineering Association 2014</p><p>Abstract Horse riding predisposes to degenerative spinal</p><p>injury to both rider and horse. This study evaluated the</p><p>dynamic pressure exerted on horse and horse rider. The</p><p>main comparison investigated was how the flocking</p><p>(cushioning) material of a saddle affected the pressure</p><p>exerted on both. Six horse riders and one horse were used</p><p>to conduct this study. The Pliance horse saddle and seat</p><p>pressure testing systems, designed by NovelGmBH, were</p><p>used for this study. Pressure recordings were carried out</p><p>from a saddle fitted with wool then again following its</p><p>conversion to air flocking. Both flocking materials were</p><p>tested during a variety of different gait settings using two</p><p>pressure mats to record the pressures firstly being exerted</p><p>onto the horse and secondly onto the rider. This study was</p><p>the first carried out to examine the pressure exerted on</p><p>horse and rider. Results found that both the mean peak</p><p>pressure (MPP) and mean pressuretime integral (PTI)</p><p>exerted on the rider increased by as much as 21.9 and</p><p>22 %, respectively, following conversion to air flocking. In</p><p>contrast, the air flocking saddle exerted a lower MPP and</p><p>PTI on the horse by as much as 25.3 and 26.6 %, respec-</p><p>tively. This study has shown that air flocking reduces the</p><p>pressure exerted on the horse; however, it has also indi-</p><p>cated that it increased the pressures exerted on the rider. As</p><p>a result of our study, further research needs to be conducted</p><p>to determine the most appropriate material to flock a saddle</p><p>with.</p><p>1 Introduction</p><p>There is a higher incidence of cervical and lumbar</p><p>degenerative spondyloarthropathy in experienced horse</p><p>riders [1]. Degenerative changes are produced by a com-</p><p>bination of mechanisms. The riders posture causes the</p><p>muscles in the back to contract to balance the spine and</p><p>prevent injury, which leads to large compressive forces</p><p>being produced resulting in greater pressure placed on the</p><p>intravertebral discs and facet joints. The extension moment</p><p>is increased further due to positioning of the arms and</p><p>tensile force exerted by the reins. Ground reaction force</p><p>(GRF) is another contributing factor. It is an equal and</p><p>opposite force to the force exerted by the rider on the</p><p>saddle. These forces applied repetitively over time may</p><p>lead to injuries such as degeneration of joints, lower back</p><p>pain and fatigue fractures [2]. Saddle cushioning material</p><p>may directly affect the GRF and in so doing may reduce the</p><p>extent of degenerative changes seen in the spine. The</p><p>saddle cushioning material may not reduce the compressive</p><p>forces produced by the riders posterior back muscles</p><p>directly. However, it could indirectly as performance</p><p>problems as a result of high pressure points affecting the</p><p>horse causes the horse to pull on the reins harder exhibiting</p><p>more erratic movements, which in-turn will result in a</p><p>larger balancing force being required by the musculoskel-</p><p>etal system [3].</p><p>Saddle-fit is a recognised factor in the pathogenesis of</p><p>equine back problems [4], localised pressure concentra-</p><p>tions, regularly exerting pressures up to 29.8 kPa [3]. This</p><p>is greater than the capillary closure pressure in both skin</p><p>and muscle which is 4.66 kPa. When a horse carries a</p><p>78 kg rider its limbs experience an additional dynamic load</p><p>excluding the weight of the rider of up to 380 N [5]. This</p><p>induces an overall extension of the equine spine, which</p><p>G. Nicol G. P. Arnold W. Wang R. J. Abboud (&amp;)Department of Orthopaedic and Trauma Surgery, Institute of</p><p>Motion Analysis and Research, TORT Centre, Ninewells</p><p>Hospital and Medical School, University of Dundee,</p><p>Dundee DD1 9SY, Scotland, UK</p><p>e-mail: r.j.abboud@dundee.ac.uk</p><p>Sports Eng</p><p>DOI 10.1007/s12283-014-0149-z</p></li><li><p>contributes to soft tissue injuries, crowding and overriding</p><p>of the dorsal spinous processes kissing spine syndrome</p><p>[6, 7]. In the transverse plane, the rider induces a desta-</p><p>bilising effect during the trot and gallop on the equine</p><p>spine.</p><p>The equine spine displays three types of movement:</p><p>dorsoventral flexionextension, axial rotation and lateral</p><p>bending [8, 9]. The saddle is placed over the region of the</p><p>spine with the greatest amount of axial rotation and axial</p><p>bending in the mid-thoracolumbar spine at the level of</p><p>11th/12th thoracic intervertebral joints [9].</p><p>No research has thus far been conducted to evaluate the</p><p>shock attenuating properties of the materials used to</p><p>manufacture saddles. In addition no research has been</p><p>conducted to discover the magnitude of the force exerted</p><p>on riders whilst riding. This study set out to help discover</p><p>these missing pieces of information.</p><p>2 Methods</p><p>2.1 Subjects</p><p>Six experienced riders were selected as volunteers for this</p><p>study as it has been found that the particular level of rider</p><p>training can influence any interaction with the saddle [10].</p><p>Riders selected were of varying heights and weights</p><p>(Table 1). Six were recruited as although each of the riders</p><p>had similar riding abilities, each individual brought their</p><p>own unique riding style. The horse was 17 hands high</p><p>(approximately 1.7 m), in regular training hence did not</p><p>find the study physically strenuous. The study was</p><p>approved by the University Research Ethics Committee in</p><p>consultation with the Home Office inspector for projects</p><p>conducted on animals.</p><p>2.2 Pliance system</p><p>Pliance system (Novel GmBH Munich, Germany) was</p><p>used to record the pressures under the saddle as it has</p><p>previously produced repeatable results [7, 11]. This</p><p>pressure measurement system consists of a pressure mat</p><p>containing 256 sensors that is situated under the saddle.</p><p>The seat sensor mat originally designed to measure the</p><p>pressures exerted on a cyclist was adapted to measure</p><p>the pressure between the rider and the saddle, see Fig. 1.</p><p>This used similar pressure sensors and technology to that</p><p>of the Pliance saddle system which has also been</p><p>proven to give repeatable results [12]. The data collected</p><p>from the two mats were synchronised in real time via</p><p>the adaptor and control box which was carried on</p><p>the riders back in a specially designed harness, see</p><p>Fig. 2. The recorded data were then sent via a Bluetooth</p><p>radio transmitter to a computer to show the overall</p><p>pressure distribution above and below the saddle during</p><p>riding.</p><p>Table 1 Horse rider demographics</p><p>Identification number Gender Weight (kg) Height (m)</p><p>1 Female 51 1.64</p><p>2 Female 54 1.67</p><p>3 Male 76 1.79</p><p>4 Male 83 1.82</p><p>5 Male 89 1.90</p><p>6 Male 112 1.89</p><p>Fig. 1 a Pliance horse saddle sensor mat, b Pliance saddle seatsensor mat</p><p>Fig. 2 a Synchronisation control box, b Pliance saddle seat sensormat, c Pliance horse saddle sensor mat</p><p>G. Nicol et al.</p></li><li><p>Pliance creation of any masks was used to differ-</p><p>entiate areas on both pressure mats allowing different areas</p><p>of the horse and rider to be analysed individually. A mask</p><p>was created to investigate the three naturally created areas</p><p>of pressure on the horse, see Fig. 3. The areas displayed</p><p>represent the left and right sides of the saddle in contact</p><p>with the horse. The different areas include the rear section</p><p>of the saddle areas 1 and 2, the front (wither area) areas 3</p><p>and 4, and the region in contact with the shoulder areas 5</p><p>and 6. This is displayed alongside the saddle for a clearer</p><p>understanding, Fig. 3. To examine the pressure exerted on</p><p>the rider whilst riding, the seat pressure mat recorded the</p><p>pressure experienced through the left and right side of the</p><p>saddle, areas 7 and 8, Fig. 4.</p><p>2.3 Testing protocol</p><p>A standardised test protocol was used when each rider</p><p>tested the saddle. Pressure readings were recorded firstly</p><p>when the horse was stationary. The horse was then ridden</p><p>on one lead, i.e. the right at a walk, trot and canter</p><p>allowing measurements to be taken for each gait before</p><p>the process was repeated on the alternate lead. On com-</p><p>pletion of the test, the pressure was again measured while</p><p>stationary to ensure the measurement was equal to the</p><p>pre-test recording. The procedure was carried out three</p><p>times by each rider on two separate days. The same</p><p>saddle was then converted from traditional wool flocking</p><p>to air flocking and the testing protocol was repeated as</p><p>before.</p><p>2.4 Gait analysis</p><p>Each horse gait is distinctly different and hence it was</p><p>important that each be tested independently. Data were</p><p>recorded along a 35-m straight line eliminating pressure</p><p>variations due to turning. Recordings were first taken</p><p>during walking, this being a four-beat gait cycle. Over the</p><p>35-m straight line, 20 four beat gait cycles were analysed.</p><p>This was performed by all six riders three times on two</p><p>separate days and equated to 720 four beat gait cycles both</p><p>before and after conversion of the saddle from wool to air</p><p>flocking.</p><p>The trotting gait which is a two-beat gait cycle was</p><p>recorded in two ways; firstly, readings were taken during a</p><p>rising trot (where the rider rises from the saddle and sits</p><p>once per gait cycle). The horse whilst trotting produced 13</p><p>two-beat gait cycles along the 35-m straight line. Again all</p><p>six riders performed this three times on two separate days.</p><p>In addition, recordings were collected whilst the rider had</p><p>their period of sitting at the time the near and subsequently</p><p>the off horse fore leg was in contact with the ground. This</p><p>was felt important to exclude any asymmetry in the horse</p><p>musculature as horses, similar to humans, have a favoured</p><p>side in effect being right or left sided. This resulted in twice</p><p>the number of recordings along the 35-m straight line being</p><p>conducted which equated to a total of 936 two-beat gait</p><p>cycles both before and after conversion of the saddle from</p><p>wool to air flocking.</p><p>Secondly, the saddle was tested during a sitting trot</p><p>(where the rider stays seated on the saddle). The horse</p><p>Fig. 3 Horse saddle mask andsaddle</p><p>Fig. 4 Horse rider saddle mask</p><p>Dynamic pressure effect on horse and horse rider</p></li><li><p>completed 13 two-beat gait cycles along the 35-m straight</p><p>line. However, as the rider stays seated this halved the</p><p>number of gait cycles analysed to 468 compared to the</p><p>rising trot as the rider is always seated as this is a sym-</p><p>metrical gait cycle.</p><p>Recordings were then taken at a canter which is a three-</p><p>beat gait cycle. During this gait, the horse completed 7</p><p>three-beat gait cycles along the 35-m straight line. This was</p><p>performed by all six riders three times on both the right and</p><p>left lead on two separate days producing 504 three-beat</p><p>cantering gait cycles both before and after conversion of</p><p>the saddle from wool to air flocking.</p><p>2.5 Ensuring fair testing</p><p>Throughout the experiment the same 35-m straight was</p><p>used and each rider wore the same riding equipment. The</p><p>same pressure measuring equipment was used throughout</p><p>the experiment and the recordings were taken in the same</p><p>manner. The pressure readings of each rider were recorded</p><p>on two separate days so an average figure was used for</p><p>comparison. All data recorded were done by the same</p><p>individual throughout the experiment.</p><p>2.6 Statistical methods</p><p>Statistical analysis was carried out using SPSS (version 16).</p><p>Data were reported using descriptive parameters, e.g. mean,</p><p>standard error of mean, the number of samples/trails. All data</p><p>collected had a normal distribution (i.e. a skewness value less</p><p>than twice its standard error) and were analysed using paired</p><p>t test to evaluate whether the two groups of data were sig-</p><p>nificantly different. The significant level was set as 0.05.</p><p>3 Results</p><p>Both the flocking materials in the study were investigated</p><p>for mean peak pressure (MPP) and mean pressuretime</p><p>integral (PTI). The pressures exerted on the horse were</p><p>examined, this being mat areas 16, Fig. 3 and then the</p><p>pressures exerted on the rider, this being mat areas 7 and 8,</p><p>Table 2 Analysis by walking: mean peak pressure (kPa)/mean pressuretime integral (kPa s)</p><p>Mean peak pressure (kPa) Mean pressuretime integral (kPa s)</p><p>Mean Std. error mean Sig. (2-tailed) Mean Std. error mean Sig. (2-tailed)</p><p>Area 1</p><p>M1 before 6.2969 0.83654 0.010 81.6922 10.41466 0.00</p><p>M1 after 5.2781 0.64249 58.9397 7.75408</p><p>Area 2</p><p>M2 before 6.17 0.788 0.312 78.8042 10.17058 0.117</p><p>M2 after 6.38 0.797 68.6842 9.45244</p><p>Area 3</p><p>M3 before 5.0686 0.64958 0.679 73.7778 9.38862 0.002</p><p>M3 after 4.9536 0.66520 57.3731 7.66478</p><p>Area 4</p><p>M4 before 5.8797 0.76449 0.006 83.3122 10.46677 0.000</p><p>M4 after 4.9994 0.65204 58.3411 8.23727</p><p>Area 5</p><p>M5 before 3.5303 0.47002 0.374 61.1558 7.60999 0.000</p><p>M5 after 3.4028 0.46997 43.5783 5.97066</p><p>Area 6</p><p>M6 before 4.1442 0.56487 0.037 67.1547 8.69758 0.000</p><p>M6 after 3.5764 0.48208 44.2694 6.21012</p><p>Area 7</p><p>M7 before 21.7589 0.83766 0.042 310.7022 12.54486 0.528</p><p>M7 after 23.8769 1.22292 326.8172 20.43892</p><p>Area 8</p><p>M8 before 26.9903 0.67276 0.823 390.4375 12.07008 0.032</p><p>M8 after 26.7819 0.97526 350.5539 19.75618</p><p>G. Nicol et al.</p></li><li><p>Fig. 4. The results of MPP and PTI are displayed in</p><p>Tables 2, 3, 4 and 5.</p><p>3.1 Walking gait: horse saddle mat</p><p>Comparing the flocking materials whilst the horse walked,</p><p>areas 1 and 2 represent the pressures exerted on the back left</p><p>and right side of the horses back. In area 1 (left back), the</p><p>MPP and the PTI were both found to be lower following</p><p>conversion of the saddle to that of air flocking. There was a</p><p>statistical difference in PTI with a reduction of 22.8 kPa s,</p><p>which is equal to a reduction of 27.9 %, following conver-</p><p>sion to air flocking. There were no statistically significant</p><p>differences in area 2 (right back) for either MPP or PTI.</p><p>In areas 3 and 4, which represent the left and right front</p><p>of the saddle, respectively, over the wither region, the MPP</p><p>and the PTI recorded are higher for the wool flocking</p><p>material than that of the air flocking. The difference in</p><p>MPP was not statistically significant; however, a statistical</p><p>difference was recorded in both areas 3 and 4 when</p><p>examining PTI. In area 3, the PTI was reduced by 22.2 %</p><p>from 73.78 to 57.4 kPa s and in area 4 the PTI was reduced</p><p>by 30 % from 83.31 to 58.34 kPa s.</p><p>In areas 5 and 6, which, respectively, examined the</p><p>region covering the left and right shoulders of the horse, a</p><p>larger MPP and PTI were again recorded using the wool</p><p>flocking material. This was discovered to be statistically</p><p>significant when looking at the PTI in both of these areas.</p><p>In area 6, the PTI reduced by 34 % from 67.15 to</p><p>43.58 kPa s, in area 5 it reduced by 28.78 % from 61.15 to</p><p>43.58 kPa s.</p><p>3.2 Walking gait: rider saddle mat</p><p>There was little variation and no statistically significant</p><p>differences when comparing the MPP and PTI exerted on</p><p>the rider whilst at a walk. This possibly resulted from</p><p>minimal movement encountered by the region of the rider</p><p>in contact with the saddle during the walking gait.</p><p>3.3 Trotting gait: horse saddle mat</p><p>There was no significant difference in area 1 for either MPP</p><p>or PTI. In area 2, however, there was an unexpected increase</p><p>in both MPP and PTI following conversion to air flocking.</p><p>The MPP increased by 16.6 % from 5.13 to 5.98 kPa and the</p><p>PTI increased by 14.3 % from 35.3 to 40.32 kPa s.</p><p>I...</p></li></ul>

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