Hartpury Student Research Journal

Home » Issue 1 (Summer 2015) » Project Articles » Evaluation of rider asymmetry during sitting trot at fast and slow speeds

Evaluation of rider asymmetry during sitting trot at fast and slow speeds

Author Names:  Sadie Kent (BSc (Hons) Equestrian Sports Science) and Kirsty Lesniak

 

Abstract

Asymmetry has been reported to be performance limiting in many sports and is perceived to limit performance within equestrian sports, however research into rider asymmetry is currently limited. The purpose of this investigation was to assess rider asymmetry during sitting trot by identifying inconsistencies between joint angles on the left and right sides of the riders and to determine whether the speed of the trot influenced the degree of rider asymmetry. Fifteen female riders (age 18-22 years, =21.5 years ±0.71, body mass 67±9.42kg, height 169.9±5.5cm) were analysed, all of whom rode a minimum of five times per week and held a competitive record. One camera filmed the posterior view of the rider during the fast and slow trot speeds of trot simulated by a Racewood Riding Simulator. Seven angles of the upper body, trunk and lower limbs were measured using Dartfish 5.5. Wilcoxon signed ranks tests revealed that the left shoulder was positioned lower (P<0.05) than the right during slow sitting trot. For both fast and slow sitting trot, the right ankle joint was positioned lower than the left (P<0.05). Results also indicated a significant difference between slow and fast sitting trot (P<0.05) for the hip angles on the right side of the riders. Thus the results indicated that the slower trot speed produced greater asymmetry within this population. The present study suggests that common asymmetric postures occur within riders and that the speed of the gait influenced the degree of asymmetry. Further research into this field is required to enhance knowledge into determining factors for rider asymmetry, the effect on performance and horse and rider welfare.

 

1.0 Introduction

Horse riding is a unique sport where the rider guides and controls the horse through their position and physical signals which they create with their body (Münz, Eckardt and Witte, 2013; Lovett et al., 2005). The dynamic relationship between horse and rider is complex and many factors of the horse-rider dyad can influence performance (Williams, 2013; Zetterqvist et al.,2008; Lagarde et al 2005; Visser et al., 2003; Wipper, 2000).

One performance limiting factor of the horse and rider system is rider asymmetry (Nevison and Timmis, 2013; Longhurst and Lesniak, 2013; Symes and Ellis, 2009). Asymmetry has been reported to be performance limiting in numerous sports including cycling (Yanci and Arcos, 2014), endurance running (Yanci and Arcos, 2014), short track speed skating (Hesford et al., 2012), football (Stewart et al., 2010) and tennis (Ellenbecker et al, 2009.)

Hinnenmann and Baalen (2004) state that laterality occurs in all levels of rider; with riders being commonly referred to as being “crooked” or “collapsed in the hip”. However rider asymmetry has received minimal attention within the literature (Nevison and Timmis, 2013; Symes and Ellis, 2009). If research could identify common postural asymmetries in riders, then coaching techniques could be developed to help coach riders to a correct, symmetrical position, in turn improving performance (Symes and Ellis, 2009). Training programmes off the horse could also be developed to help reduce on-horse laterality.

If a rider is asymmetrical then in addition to hindering the horse’s balance and straightness, instructional signals could be misinterpreted by the horse, causing confusion and welfare implications (Nevison et al.,2013; Nevison and Timmis, 2013; Symes and Ellis, 2009). Training problems deemed as behavioural problems, could in fact be the result of rider postural asymmetry (Nevison and Timmis, 2013).  Rider injury and back pain may also occur as a result of postural asymmetry and could lead to back pain in the horse, through repeated uneven forces being applied (Nevison and Timmis, 2013).  Over time this could contribute to injury and pathology (Nadeau, 2006; Dyson, 2002). Therefore it is important to research rider asymmetry further so that the findings can be practically applied to try and decrease the incidence of rider asymmetry and subsequent injury.

The aim of this investigation was therefore to answer the following research questions:

  1. Does postural asymmetry occur within this sample?
  2. What body segments most commonly demonstrate postural asymmetry?
  3. Does the speed of the trot influence the degree of rider asymmetry?

The objectives of this investigation were to:

  • Analyse video footage of the riders in sitting trot at fast and slow speeds using Dartfish motion analysis software.
  • To compare the left and right angles for each rider.
  • To compare the angles for each rider in fast and slow speeds.
  • To determine whether common asymmetrical postures occur.

The study hypotheses were as follows:

  • Null Hypothesis: There will be no significant difference between the left and right sides of the rider and no relation to the speed of the gait.
  • Alternative Hypothesis: There will be a prevalence of asymmetry between the left and right sides of the rider within the population which will also be related to the speed of the gait.

 

2.0 Methodology

2.1 Research Design

A quantitative research design was used to try and asscertain whether aysmmetry of the rider occurs within fast and slow sitting trot. This is because quantititative data analysis concerns the collection of numerical data, which is an objective measure from which comparisons can be drawn (Punch, 2014; Bryman, and Bell, 2011).

 

2.2 Data Collection

2.2.1 Sampling

The method of convenience sampling was used (Price and Murnan, 2004; Mays and Pope 2000; Marshall, 1996) to target Hartpury College Students. It is important to note that convenience sampling is not usually representative of the whole popoulation, therefore the results found using convenience samples cannot be generalised to the whole population (Price and Murnan, 2004). Female riders aged 18-25 years old who held a competitive record were targeted; therefore the results of the data can be applied to other female riders of a similar age with similar experience. A stipulation for inclusion in the study was that riders had no medically known anatomical discrepancies.

 

2.2.2 Study population

The sample size consisted of fifteen female riders age 18-22 years old (=21.5 years ±0.71). The mean body mass of the riders was 67kg (± 9.42kg). The riders’ mean height was 169.9cm (±5.5cm). The riders who participated in the data collection rode a minimum of five times per week and all held a competitive record. Riders were free from injury at the time of the study. All riders completed a handedness questionnaire prior to participating in the study, and all riders were right hand dominant.

 

2.2.3 Data Collection

The data used in this study was retrospectively collected data. The data collection occurred at Hartpury College, Gloucester in the winter of the 2010-11 academic year. Preceding data collection, a pilot study was conducted. The pilot study determined that riders preferred to perform rising trot before sitting trot. Thus to ensure rider comfort, adaptations were made to the sequence of gaits compared to the original. Adjustments to the camera positions were also made to ensure a complete field of view was provided.

 

2.2.4 Marker Placement

Based on prior research into posture (Normand et al., 2007) and rider posture (Symes and Ellis, 2009; Lovett et al., 2005), twenty-one anatomical marker position points were chosen and positioned to allow analysis of the joint angles of the riders. The positions of the markers are shown in Table 1 and Plate 1. The anatomical markers were positioned upon the riders by the same chartered physiotherapist. This ensured that the markers were positioned correctly. To allow for easy positioning and to minimise movement of the markers due to displacement of clothing, all riders wore vest tops and leggings. Anatomical markers were positioned upon the cranio-caudal line of the mechanical horse at the point of the tail, behind the saddle, in front of the saddle (withers) and the poll.

 

KentPlate1

Plate 1: Anatomical marker positioning

 

Table 1: The position of anatomical markers

Anterior view Posterior view Left and Right lateral views
Forehead Bottom of riders hat Tragus
Suprasternal notch Seventh cervical vertebrae Acromial angle of the arm
Base of the sternum Second thoracic vertebrae Trochlear notch
Anterior superior illiac spine Fifth lumbar vertebrae Capitate
Anterior femoral condyle Inferior angle of the scapula Iliac crest
Toe Central posterior calcaneus Lateral femoral Condyle
Greater trochanter
Fifth metatarsal phalangeal joint
Lateral Malleoulus

 

2.2.5 Recording Equipment

Four digital cameras (Sony DCR-SR190E) were located to show the anterior and posterior views of the rider and the lateral views from each side. These cameras were positioned on tripods at a height of 136mm and 470mm from the horse. A fifth camera was positioned above the rider, 345cm above the horse. The five cameras filmed 50-60 frames per second. Only the data recorded from the posterior view camera was analysed within the current investigation.

 

2.2.6 Data Capture

The weight and height of the riders was taken. Whilst the rider was led in the supine position, the chartered physiotherapist measured the riders’ leg length from the anterior superior iliac spine to the medial malleolus; leg length discrepancy was subsequently calculated from these measurements. All riders mounted the Racewood Riding Simulator and participated in a standardised  five minute warm up to acclimatise to the motion of the mechanical horse. All riders chose stirrup lengths that were comfortable for them and these lengths were checked to ensure that they were equal. All riders rode the Racewood Riding Simulator. Horse riding simulators vary to riding a live horse and give the rider a different sensation (Yamaguchi and Iguchi, 2014) therefore each rider had a two minute period to acclimatise to the mechanical horse before commencing filming and data collection . All riders rode in the same saddle (Wintec synthetic dressage saddle). Quinn and Bird (1996) state that different saddle types can also alter rider position.

Riders were briefed before filming commenced. The riders were filmed for five minutes at the gaits of walk, slow trot, fast trot, slow canter and fast canter. Ten variations of rider position and horse gait were followed, as seen in Table 2; the rider rode in each variation for thirty seconds.

 

Table 2: Gait sequence within data collection

Time Duration (s) Gait Rider Position
30 Walk Sitting
30 Slow trot Sitting
30 Fast trot Sitting
30 Slow canter Sitting
30 Fast Canter Sitting
30 Fast Canter Light Seat
30 Slow Canter Light seat
30 Fast trot Rising
30 Slow trot Rising
30 Walk Sitting

 

2.3 Data Analysis

Dartfish motion analysis software version 5.5 was used to draw down angle measurements from the video footage of the riders in sitting trot at fast and slow speeds.  Symes and Ellis (2009) state that since the trot is a symmetrical pace then only slight variations in shoulder displacement should be noted if the rider is actually symmetrical. The Racewood Riding Simulator was designed to be symmetrical; whereas, horses have been found to show mild asymmetry (Symes and Ellis, 2009; Murphy and Arkins, 2008; McGreevy and Rogers, 2005), therefore the use of the mechanical horse eliminates any effect of horse laterality. Previous research using the trot has been completed, thus comparisons could be drawn (Peham et al., 2010; De Cocq et al., 2010; Symes and Ellis, 2009; Terada et al., 2006).

Seven angles were chosen to measure (see Table 3) based on angles in view from the posterior view camera and previous research (Longhurst, 2011; Kang et al., 2010; Symes and Ellis, 2009). The method of analysing rider asymmetry within the rider was adopted from Symes and Ellis (2009). A straight line was drawn along the horse’s cranio-caudal line from the marker at the point of the horse’s tail, through the marker on the back of the saddle, extending along the midline of the rider through the median sagittal plane (Line A). A straight line was drawn using Dartfish between the left and right markers for each of the corresponding angles (Line B). Therefore the two lines A and B bisect one another, splitting the area into four quadrants (see Figure 1). The centres of the markers were selected and the angles from the centre of the marker to the intersection between line A and line B were calculated using Dartfish. The markers were magnified to increase the accuracy in choosing the centre of the markers. Should the rider be symmetrical then the angle would be identical for each side.

 

Table 3: Angles measured to intersection between lines A and B

Angle Left Side Right Side
1 Point of shoulder-Acromion Point of shoulder-Acromion
2 Inferior angle of the scapula Inferior angle of the scapula
3 Point of elbow-Olecranon Point of elbow-Olecranon
4 Hips Hips
5 Knee-Lateral femoral Condyle Knee-Lateral femoral Condyle
6 Ankle-lateral malleoulus Ankle-lateral malleoulus
7 Toe-Fifth metatarsal joint Toe-Fifth metatarsal joint

 

Measurements of the rider’s position for each angle were taken at three different intervals within the video footage, the highest point of the stride, the lowest point of the stride and the middle point of the stride. These intervals were randomly sampled. No measurements were taken in the first ten seconds of the gait, to allow the rider time to become accustomed to the new gait. The mean was calculated from the three measurements for each rider.

 

KentFigure1

Figure 1: How the angles were calculated for the angle joint

 

2.4 Statistical Analysis

Statistical Analysis was performed using SPSS. Statistical tests for normal distributions are not sensitive enough on samples of less than 30 observations (Ghasemi and Zahediasl, 2012; Mohd Razali and Bee Wah, 2011; Dytham, 2011). Therefore it was assumed that the data was not normally distributed. Results were analysed using the Wilcoxon’s signed ranks test. The Wilcoxon signed ranks test compared the means for each angle for the left and right side in both fast sitting trot and slow sitting trot. The Wilcoxon signed ranks test also compared the means for the left side in fast and slow sitting trot and the means for the right side in fast and slow sitting trot.

 

2.5 Ethical Considerations

The data used was retrospectively collected data from a project that has been pre-approved by the Hartpury College ethics committee. At the time of data collection, all participants were asked to read a participation information sheet. All participants completed a participant permission form and informed consent was collected from all participants. The subjects also had the right to withdraw from the study at any time and understood what was to be measured in the study.

The participants remain completely anonymous. All data was kept in a secured file and all “data protection principles” were adhered to in line with the Data Protection Act 1998.

 

3.0 Results

3.1 Descriptive Statistics

For angles 1, 2, 3, 4, and 5, all 15 riders were analysed for both fast and slow trot. Due to being unable to follow the markers for the movement pattern, less riders were analysed for fast and slow trot for angles 5 (N=12, N=11 respectively), 6 (N=10, N=9 respectively) and 7 (N=12). Table 4 shows the angles measured for each corresponding number.

 

Table 4: Angle number and corresponding anatomical area measured

Angle Anatomical point measured
1 Point of shoulder-Acromion
2 Inferior angle of the scapula
3 Point of elbow-Olecranon
4 Hips
5 Knee-Lateral femoral Condyle
6 Ankle-lateral malleoulus
7 Toe-Fifth metatarsal joint

 

The largest difference between the angles measured on the left and right side occurred during fast trot in angle 2 (=91.34 ± 3.3, =89.00±2.93 respectively; Table 4). The least difference between the angles measured on the left and right side occurred during slow trot in angle 5 (=90.14±1.65, =90.02±1.81 respectively). The descriptive statistics for the difference between the mean angles measured on the left and right side for all riders are shown in Figure 2.

 

Table 5: The difference between the mean left and right angles

Angle Fast Trot Slow Trot
1 2.32 1.48
2 2.34 1.88
3 1.34 0.54
4 -0.21 0.37
5 -0.16 0.12
6 -3.02 -2.15
7 -1.02 -1.23

KentFigure2

Figure 2: Mean values for the left and right sides of each angle

 

3.2 Statistical Analysis

3.2.1 Left vs right

The results from the Wilcoxon signed ranks test demonstrated that for angles 2, 3, 4, 5 and 7 there was no significant difference between the left and right sides of the riders (P>0.05). However for angle 1 there was a significant difference between the left and right sides of the riders during slow sitting trot (P=0.041) and for angle 6 there was a significant difference for fast sitting trot (P=0.017) and slow sitting trot (P=0.038) (see Table 5). For angle 1 in slow sitting trot the means were 91.03 (±1.79) and 89.55 (±2.7) for the left and right sides respectively. For angle 6 during fast sitting trot the mean angles were 88.23 (±1.2) and 91.25 (±1.15) for the left and right sides respectively and for slow sitting trot the mean angles were 89.54 (±3.32) and 91.69 (±1.63) respectively.

 

Table 6: Number of riders and statistical differences for each angle

Number of Riders P Value
Angle Fast Trot Slow Trot Fast Right-Fast Right Slow Right-Slow Left Slow Left-Fast Left Slow Right-Fast Right
1 15 15 0.173* 0.041* 0.443 0.172
2 15 15 0.182 0.164 0.470 0.775
3 15 15 0.191 0.570 0.589 0.118
4 15 15 0.776 0.156 0.244 0.025*
5 12 11 0.937 0.790 0.475 0.533
6 10 9 0.017* 0.038* 0.678 0.373
7 12 12 0.209 0.108 0.266 0.656

* =Significance P<0.05

 

3.2.2 Slow Vs Fast

The results from the Wilcoxon signed ranks test demonstrated that for angles 1, 2, 3, 5, 6 and 7 there was no significance difference between slow sitting trot and fast sitting trot between the left and right sides of all of the riders (P.0.05). However for angle 4 there was a significant difference (P=0.025) between slow sitting trot (=90.19±2.51) and fast sitting trot (90.41±2.08) for the angles on the right side of the riders.

 

4.0 Discussion

4.1 Results

Previous research into rider asymmetry is limited and only preliminary results have been published (Symes and Ellis, 2009). The aim of this study was to investigate whether postural asymmetry occurs, and if so in which body segments and to determine if the speed of the trot influences rider asymmetry. Anecdotally, riders should have a symmetrical posture that is identical on either side of their body (Quint and Toomey, 1988). Therefore since trot is a symmetrical gait, if the rider is symmetrical then no discrepancies between angles should exist (Symes and Ellis, 2009; Weishaupt et al., 2009; Clayton 1997, Clayton, 1994). Within the present study discrepancies between the left and right sides occurred, however significant differences did not occur for all angles.

 

4.1.1 Upper Body Position

The findings of the present study that during slow sitting trot the left shoulder is positioned lower (=91.03±1.79) than the right shoulder (=89.55±2.7), differ from the findings of Symes and Ellis (2009) who found the right shoulder to be lower in all gaits except right canter. These differences could occur due to 17 different horses being used by Symes and Ellis (2009) and since horses exhibit laterality, the asymmetries could be transferred to or compensated for by the riders (Symes and Ellis, 2009; Murphy and Arkins, 2008; McGreevy and Rogers, 2005). The riders in the present study rode a Racewood Riding Simulator in order to eliminate any effect of horse laterality. Hobbs et al., (2014) found competition riders exhibited a larger mean standing acromion process height on the right, which supports the findings of the present study. However these results are atypical as Kendall et al., (1983) states that in the majority of people, usually the non-dominant shoulder is positioned higher than the dominant shoulder.

Longhurst (2011) investigated the discrepancies between joint angles of each rider during sitting trot from the lateral views using the same data from the present study. Since only the rear view was taken into account in the present study, parallels can be drawn from the results of Longhurst to create a more holistic observation of what occurred in the sample population. A highly significant difference (P≤0.001) in the absolute angle of the upper arm was found, with the right hand side angles being larger than those on the left; thus suggesting that the elbow on the right side was bought further back. The results also indicated that the right shoulder and hip were rotated towards the right about the transverse axis (Longhurst, 2011). The rotation of the right shoulder correlates to the higher positioning of the right shoulder as found in the present study. Increased strength is usually demonstrated on the dominant side (Gluck et al., 2008; Bohannon, 2003). Since the participants in this study are right hand dominant, it can be suggested that the motion patterns observed are compensatory patterns due to the rider having a weaker non-dominant left side. Thus the greater strength in the dominant right side allows the rider to stay in a more upright posture, whereas the weaker left side collapses lower. The compensatory pattern of the right elbow retraction could be so that it is closer to the body’s centre of mass, because this moves the body into a more stable position (Stapley et al., 1999).

It is important to note that tasks associated with the care and management of horses are often performed by riders on a daily basis. These tasks (e.g. mucking out, sweeping and heavy lifting) require bending and rotation and most people have a preferred, dominant side on which they wish to perform these tasks (Pummel et al., 2008). Sadeghi et al. (2000) highlights that usually the dominant limb is used for mobilisation and the non-dominant limb is used for support. Thus the repetitive motions used to perform these tasks can lead to muscular adaptations, potentially resulting in asymmetrical muscular development (Bagesteiro and Sainburg, 2002; Watkins et al., 1996). Since the population in this study are right hand dominant, muscle hypertrophy on the right could provide an explanation for the higher point of shoulder angle exhibited on the right.

 

4.1.2 Lower Body Position
The findings of the present study show that the right ankle joint was positioned significantly lower than the left ankle in both fast (P=0.017) and slow trot (P=0.038). These results indicate that the right ankle was held in greater dorsi-flexion (see Figure 3) than the left ankle, thus resulting in a lower position.

KentFigure3

Figure 3: Dorsi-flexion of the foot (Rowe et al, 2013)

 

These findings concur with the results of Longhurst (2011) who found a decreased absolute angle of the right lower leg, suggesting greater dorsi-flexion of the right ankle. Asymmetries of both dorsi-flexion and plantar flexion have been reported with weight bearing (Rabin et al, 2015) and without weight bearing (Ferrario et al, 2007) within the general population. Therefore asymmetries of dorsi-flexion that occur in riders off the horse could be transferred when on the horse, thus causing asymmetry when riding. However it is important to note that the foot position in the stirrup plays an important role. Although not measured in the present study, it was observed that variation between feet positioning in the stirrups occurred, with some riders having their toes pointing more laterally than others. The foot position in the stirrups would alter the angles calculated for the ankle and the toe. Anecdotally the correct foot position denotes that the toe of the foot should rest on the stirrup with the toe pointing cranially and the heel toward the ground (Ceroni et al., 2007). However currently no research exists to validate this positioning and riders commonly ride with differing foot positions therefore future research is needed into foot position in the stirrup and its effect on rider performance.

An improvement to the present study would have been to measure and compare the angles of the lowest point of the riders’ foot, to determine if one leg was being positioned lower than the other. This would have helped to establish if the lower right ankle joint was due to the right leg being positioned lower or if it was due to ankle and foot position. It is important to note that less riders were analysed for the ankle angle during fast and slow trot (N=10, N=9 respectively) because some riders reached a point of asymmetry where the left leg was positioned further forwards and the markers were unable to be followed for the movement pattern. The findings of Longhurst (2011) that the left leg is positioned further forwards than the right corresponds to this. Thus because for some riders the markers couldn’t be followed for the knee, ankle and outside toe, this could potentially account for why a significant difference in the discrepancies between angles wasn’t found for the knee and outside toe.

 

4.1.3 Influence of Speed

The findings of the present study show that speed appears to influence rider asymmetry. A greater occurrence of rider asymmetry was found in slow trot than in fast trot; also for the hips on the right side, there was a significant difference between slow sitting trot (=90.19±2.51) and fast sitting trot (90.41±2.08). The findings could be due to that fact that the mechanical horse feels different to a live horse (Yamaguchi and Iguchi, 2014) and anecdotally the slow trot on the mechanical horse is reported to feel more like a passage as opposed to trot. Thus the sensation provided by the mechanical horse would feel unusual for the rider compared to normal trot, which is likely to increase the incidence of asymmetry.

To present there is no literature into the influence of speed on rider asymmetry. Data suggests that an increased velocity causes the rider to produce a greater force amplitude on the horse’s back (Bogisch et al., 2008). Therefore it is suggested that the velocity of the horse affects rider motion pattern, however further research is needed to quantify the effect of speed on rider position. Robert et al., (2001) demonstrated that in the horse, increased trotting speed produced increased and continual muscle activity of the trunk muscles. The increased activities of the trunk muscles in the horse are likely to influence the pressure distribution under the saddle and have effects that could transfer to the rider. This thus supports that speed is likely to influence rider asymmetry.

 

4.2 Implications for the Industry

The results of this study indicate that a common area for rider asymmetry is within the shoulders, as supported by previous literature (Hobbs et al., 2014; Longhurst, 2011; Symes and Ellis, 2009) and the ankle joint. Further information into rider asymmetry and particularly of the lower limbs is required to identify common postural asymmetries. This in turn would enable coaches to develop techniques to coach riders to ride in a correct, symmetrical position, consequently enhancing performance (Symes and Ellis, 2009). Training programmes off the horse could be implemented in an attempt to decrease asymmetric movement patterns on the horse (Nevison and Timmis, 2013; Douglas et al., 2012). Preliminary research by Nevison and Timmis (2013) suggests that physiotherapy intervention could also reduce rider asymmetry.

It is speculated that reductions in rider asymmetry would have positive effects on rider welfare (Douglas et al., 2012; Symes and Ellis, 2009). This is because underlying rider asymmetry could predispose riders to injury and back pain, a common occurrence in riders (Nevison and Timmis, 2013; Symes and Ellis, 2009; Kraft et al., 2007). Reductions in rider asymmetry would also have a positive influence on horse welfare as rider asymmetry could cause signals to be misconstrued and subsequently misunderstood by the horse (Nevison et al.,2013; Nevison and Timmis, 2013; Symes and Ellis, 2009). This could lead to training and behavioural issues (Nevison and Timmis, 2013; Symes and Ellis, 2009). Asymmetric rider movements can produce asymmetric loading of the horse which could induce back pain in the horse (Byström et al, 2009). Thus over time this could contribute to the incidence of injury and pathology (Nadeau, 2006; Dyson, 2002).

 

4.3 Limitations of the study

4.3.1 Sample Population

A limitation of the present study is that the sample population is small (n=15), thus making it harder to extrapolate the findings to the wider rider population. However similar studies within this field have used comparable sample populations, for example the preliminary study of Symes and Ellis (2009) (n=17) and Baxter et al (2014) (n=10).

 

4.3.2 Type of horse

Although use of the Racewood Riding Simulator reduced external variables such as the effect of horse laterality, horse riding simulators differ to riding a live horse and provide the rider with a different sensation (Yamaguchi and Iguchi, 2014). Anecdotally, riding the mechanical horse is considered to be less strenuous than riding a live horse. Research suggests that the type and behaviour of the horse affects rider energy expenditure (Devienne and Guezennec, 2000). Fatigue, a variable not considered in the present study, is more likely to occur on a live horse and could also influence rider asymmetry. It is important to recognise that asymmetry on the mechanical horse may not occur to the same degree as when riding a live horse, since muscular efforts are likely to be higher on a live horse; thus the results of the present study may not be as pronounced as if the rider was riding a live horse. Prior research has reduced external variables by using one horse (Lovett et al, 2005). Research has found that rider pelvis tilt is correlated to horse pelvis tilt, with 85% occurring in the same direction (Brown and Cunliffe, 2014). Therefore it is suggested that horse asymmetry can be transferred to and adopted by the rider. In conclusion there are benefits and drawbacks to using both a live horse and a mechanical horse when assessing rider asymmetry, thus future research should encompass a combination of both approaches.

 

4.4 Implications for future research

Further research into this area is required to enhance knowledge into rider posture and its effect on performance.

 

4.4.1 Effect of gait on rider asymmetry

The present study only investigated sitting trot during fast and slow speeds. Further research into other gaits is needed to determine how the gait and speed of gait affects rider asymmetry. For example, the canter is typically an asymmetric gait, with a leading leg (Clayton, 1994) however on the Racewood Riding Simulator, the canter is symmetrical, thus eliminating the effect of the asymmetric gait. Further research could assess the asymmetry of a live horse compared to a simulated horse to see what effect, if any the leading leg has on rider asymmetry. Since rising trot produces asymmetric loading of the horses’ back, additional research into the effect of rising trot on rider asymmetry could also be conducted (Roepstorff et al, 2009).

 

4.4.2 Effect of Handedness

The results from this study suggest that rider handedness influences rider asymmetry. Associations between right hand dominance and right trunk axial rotation have been made (Baxter et al., 2014), nonetheless further research is necessary to establish whether causality exists between rider handedness and rider asymmetry. Since research suggests around 90% of the normal population exhibit a right hand preference (Carpes et al., 2010; Cuk et al., 2001) if causality does exist between rider handedness and rider asymmetry, it would greatly influence the type of common asymmetrical posture that occurs.

 

4.4.3 Lateral Movements

Preliminary research into rider asymmetry during shoulder-in has been completed (Baxter et al., 2014) and found that right axial rotation occurs throughout. However the effect that the asymmetry has on the movement is yet to be determined. Further research into rider asymmetry and its effect on other lateral movements such as half pass is warranted to enhance knowledge and consequently improve performance.

 

4.4.4 Other areas of interest

When investigating rider asymmetry on a mechanical horse, a bird’s eye view would provide further insight into rider asymmetry. A bird’s eye view coupled with lateral views and posterior or anterior views would provide a holistic observation of rider asymmetry.

 

5.0 Conclusion and Applications

The purpose of this study was to investigate whether postural asymmetry occurs, if so, in which body segments and if the speed of the trot influences rider asymmetry. The null hypothesis suggested that there would be no significant difference between the left and right sides of the rider and no relation to the speed of the gait.

Asymmetry has been reported to be performance limiting in many sports and is anecdotally suggested to limit performance within equestrian sports, however research into rider asymmetry is currently limited.

The present study suggests that common asymmetric postures occur within riders in the shoulder and ankle, with the left shoulder being held lower than the right and the right ankle joint positioned lower than the left. These results may be connected to the handedness of the rider. The results of this study also suggest that the speed of the gait influenced the degree of asymmetry, with the slow sitting trot corresponding to increased asymmetry.

The findings of this study are important to the wider equine industry in relation to increasing performance, developing coaching techniques, horse and rider welfare and the relationship between asymmetry and rider and horse injury. Further research into this field is required to enhance knowledge into determining causal factors for rider asymmetry, particularly the effect of gait and handedness on rider asymmetry. The effect on performance and horse and rider welfare and the relationship between asymmetry and injury should also be investigated further. The enhancement of knowledge within this area would help improve performance within equestrian sports.

 

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Bogisch, S., von Peinen, K., Wiestner, T., Roepstorff, L., van Weeren, R. and Weishaupt, M., (2008) Influence of speed on the horse–rider interaction and resulting saddle forces at walk and trot. Cabourg, 6th International Conference on Equine Locomotion.

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