RIDER ASYMMETRY RESEARCH
|Researchers from Hartpury University in Gloucestershire and Bishop Burton College in East Yorkshire recently collaborated on a project to investigate whether footedness had an impact on rider asymmetry.|
|Tracy Bye, this month’s Guest Editor, holds an MSc in Equine Science and is a BHS Coach in Complete Horsemanship. Tracy was a Lecturer in Equine Science at Bishop Burton College for eight years and is now working towards her Ph.D. in the School of Sport, Health and Exercise Science at Loughborough University, focussing on rider biomechanics.||Victoria Lewis is a Senior Lecturer at Hartpury University and Programme Manager for the BSc. (Hons) Equestrian Sports Coaching. She is a BHS Level 5 Performance Coach and sits on the Executive Committee for the International Group for Equestrian Qualifications. She has developed a research interest in performance, biomechanics and rider injuries by combining her academic experience in sports medicine and her own coaching and riding experience at the international level in show jumping and eventing.|
|Footedness is defined as having a preferred foot for particular tasks, such as kicking a ball or hopping on one leg. As the majority of the population is right-handed, children are generally encouraged to learn new tasks, such as writing or using a knife and fork, in a right-handed manner. The same cannot be said of footedness, so footedness can provide a better representation of an individual’s movement patterns in sporting activities such as riding.|
Riders are expected to sit in the centre of the saddle and to have symmetrical posture and movement so as to influence the horse to move symmetrically and to use its body to the best effect. This is rarely the case, however, and several studies have shown the presence of rider asymmetry measured via kinematics (looking at posture and joint angles) and kinetics (looking at forces under the saddle, in the stirrups, and down the reins). Whilst several previous studies have looked at ways of improving rider asymmetry, none have really investigated the potential underlying causes.
Twenty-eight riders took part in the study over two weekends; one at Bishop Burton College and one at Nottingham Trent University. All of the riders had to meet certain criteria to take part; they were all female, aged 18-60yrs, had no current injury of any type, no previous injury to the pelvis or hips (which may have affected their seat), and had to be competent at British Dressage Preliminary or Novice level.
To start with all riders completed the 10 questions ‘Waterloo Footedness Questionnaire’. This is a questionnaire that has been previously validated in sports studies. It asks things such as ‘With which foot would you kick a ball towards target straight in front of you?’ and ‘If you had to balance on a rail on one leg which leg would you use?’. Participants then chose an option from ‘right always’, ‘right usually’, ‘no preference’, ‘left usually’, and ‘left always’. The questionnaire aims to determine which is the ‘mobilizing’ limb and which is the ‘stabilizing’ limb. The mobilizing limb is the leg that you are more likely to use for movement tasks, like kicking a ball; the stabilizing limb is the leg that you are balancing on while the movement task is happening.
|Rider on one of the simulators that were used for the study. This image shows a different set of markers that can be used when analyzing posture from the side view.|
|The ridden test was conducted on a riding simulator to make sure that the ‘horse’ being used for the trial was itself symmetrical and wouldn’t affect the results. The riders had white joint markers placed on their backs for later analysis, and pressure mats were fitted under the saddle and on both stirrups to record forces at the horse-rider interface. Each rider was mounted on the simulator and undertook a four-minute warm-up: one minute in the walk, two in trot, and one in canter. Riders were then assessed in sitting trot; 20 seconds of data were recorded from the saddle and stirrup pressure sensors, and 20 seconds of slow-motion video was captured from the rearview using a high-speed camera.|
|The image on the left shows the location of the markers on the rider’s spine, pelvis, and shoulders. The one on the right shows how these markers were joined up by the software to follow the movement of each section. The pelvis and shoulder segments were compared to a horizontal line, and the trunk to a vertical line to work out an angle for ‘tilt’.|
|Findings: Footedness and Posture|
The Waterloo Footedness Questionnaire gives a score on a scale from -20 to +20. People who score between -7 and -20 are considered to be left-footed (left foot mobilizing and right foot stabilizing), those that score +7 to +20 are classed as right-footed and people scoring -6 and +6 are considered to be mixed-footed. The average score in the group was +4. Three participants were classed as right-footed, the rest were mixed-footed. No one scored the -7 or lower required to allocate left footedness.
Three different angle measurements were taken from the slow-motion video, which corresponded to the amount of left or right tilt of the pelvis, shoulders, and trunk when viewed from the back. These values were tracked throughout the 20 seconds of recording and then an average was taken for each rider in each measure. You expect the angle of tilt to change as the rider moves with the horse, but in a rider that is moving perfectly symmetrically, the average would be 0o because they would tilt by the same amount to the left and to the right and these would cancel each other out.
Only 36% of participants showed an average trunk tilt of 1o or greater, however, this increased to 64% for a pelvic tilt of 1o or greater, and 82% of riders showed an average shoulder tilt of 1o or greater. There were no correlations between scores on the Waterloo Footedness Questionnaire and the average tilt of the trunk, pelvis, or shoulders. This indicates no relationship between footedness and rider posture.
|Findings: Footedness and Forces|
Total forces were measured in each stirrup separately. The area under the saddle was split into left and right sides using the analysis software for the pressure mat, so separate force measurements could be taken for each side of the saddle. A calculation was then conducted to get an asymmetry index for stirrups and an asymmetry index for the saddle. The symmetry index is a measure of the percentage difference in force between the left and right sides. A positive number means the force is higher on the right-hand side, a negative number means the force is higher on the left-hand side. The average symmetry index for the saddle force was +41% and the range was +21% to +68%. The average symmetry index for the stirrup force was -7% and the range was -55% to +30%. There were no correlations between scores on the Waterloo Footedness Questionnaire and the symmetry index for either the saddle or the stirrups. This indicates no relationship between footedness and the forces at the horse-rider interface.
|Findings: Movement Patterns|
Relationships were seen between some of the different measures of posture and force. There was a significant positive correlation between trunk tilt and stirrup force symmetry index. This means that as a rider tilted to one side the stirrup force on that side increased. The saddle force however did not appear to be affected by trunk tilt. There was a significant negative relationship between pelvic tilt and shoulder tilt, meaning that as the pelvis tipped one way the shoulders tended to tip the other way. Almost 60% of riders in the sample showed this movement pattern, which is commonly described as the ‘collapsed hip’.
|The left-hand image shows a symmetrically seated rider from the rearview on a riding simulator, the right-hand image demonstrates the ‘collapsed hip’ with pelvis deviating to the right and shoulders tilting to the left.|
|Conclusions and Applications|
|This research suggests that laterality, as measured by footedness, has very little impact on the symmetry of a rider’s position, or the symmetry of the forces they transmit to the horse. A large range of asymmetries was seen in individuals in the mixed-footed group. For example, the average pelvic tilt angle ranged from -3o (tilt left) to +3.5o (tilt right). This means that factors are affecting the symmetry of posture and weight-bearing, other than footedness. Other things to note are that a large proportion of the riders studied showed evidence of a collapsed hip, and there was a tendency to counteract body lean (trunk tilt) by putting more weight in one stirrup. These are examples of compensatory movement patterns, which are like ‘quick fixes’ to rebalance the rider without addressing the original problem. For example, if a rider’s pelvis is asymmetrical and tilting one way, tilting the shoulders in the opposite direction helps to bring the rider’s centre of mass back to the middle of the horse. This reduces the chances of falling off, but it doesn’t help the rider sit straighter as the body has found a way to ‘get away with an asymmetrical pelvic posture. Over time these compensatory movement patterns can become more and more embedded and get more difficult to correct. If laterality is not the cause of rider asymmetry, researchers need to consider some other factors such as previous injury, back pain, training effects, or a combination of these.|
Surveys of horse riders have found that 50-80% report having back pain. The higher numbers are in groups that compete at higher levels or have been riding for a greater number of years. Back pain has previously been linked with asymmetry of the back muscles in cricketers. In research comparing the posture of riders of different experience levels, the riders that were more experienced showed greater asymmetry. Also, many other studies have shown that riders’ postural symmetry can be improved fairly easily with interventions such as core stability training and physiotherapy. This appears to indicate that hours in the saddle is exacerbating any asymmetry, potentially through repetition of asymmetric posture, back pain, or a combination of the two. These ideas provide a basis for future studies into rider posture and asymmetry.
|Take Home Messages|
Riders have a tendency to sit asymmetrically, which can present problems for performance, horse welfare, and for the riders themselves due to links with back pain. These asymmetries don’t seem to be linked to laterality and they tend to get worse as riders spend more hours in the saddle and compensatory movement patterns become more established. This indicates that rider asymmetry may be linked to training effects. The human brain will prioritize safety over posture, so if a rider has a tight or weak area, such as an asymmetrical pelvic posture, the body will adapt to keep the rider secure on the horse, regardless of what this looks like. Future research into these movement patterns could help to develop training protocols that better support riders to become straighter, more balanced, and more effective in the saddle.