Chiropractic effects on stride parameters and heart rate during exercise in sport horses

BACKGROUND

Equine veterinarians performing chiropractic treatments are frequently asked to evaluate and treat sound horses to improve their performance and address pain associated with the axial skeleton. Studies describing the effects and mechanisms of chiropractic treatments in horses without overt lameness are scarce.

OBJECTIVES

This study aimed to evaluate the effect of chiropractic treatments on stride rate, length, symmetry, heart rate and rider-perceived quality of the ridden work in sport horses.

STUDY DESIGN

A blind randomised controlled trial with crossover design.

METHODS

Thirty-eight horses ridden in the hunter-jumper discipline were enrolled. Exercise tests were recorded before and after chiropractic or sham treatment while horses were wearing a fitness tracker. Stride length, rate and symmetry, heart rate and the perceived quality of the ridden work were compared.

RESULTS

There was a difference in the qualitative assessment of the ridden work by riders between treatments (odds ratio 33.8, 95% CI [4.68, 458.71], p < 0.01). Stride length, rate, symmetry and heart rate were not different between treatments.

MAIN LIMITATIONS

The quantitative outcomes measured may not be sensitive enough to detect changes that improve the ridden work. Terrain, weather and rider were not standard across horses making small changes difficult to detect.

CONCLUSIONS

Riders participating in a blind randomised controlled trial perceived a positive effect of chiropractic treatments on the quality of the ridden work. There were no differences in stride length, stride rate, stride symmetry or heart rate. The mechanisms, indications and potential benefits of chiropractic treatments in horses need further study.

Riders' Effects on Horses-Biomechanical Principles with Examples from the Literature

Movements of the horse and rider in equestrian sports are governed by the laws of physics. An understanding of these physical principles is a prerequisite to designing and interpreting biomechanical studies of equestrian sports. This article explains and explores the biomechanical effects between riders and horses, including gravitational and inertial forces, turning effects, and characteristics of rider technique that foster synchronous movement with the horse. Rider symmetry, posture, and balance are discussed in the context of their relationship to rider skill level and their effects on the horse. Evidence is presented to support the feasibility of improving equestrian performance by off-horse testing followed by unmounted therapy and exercises to target the identified deficiencies. The elusive quality of harmony, which is key to a true partnership between riders and horses, is explored and described in biomechanical terms.

Static pelvic posture is not related to dynamic pelvic tilt or competition level in dressage riders

Static assessment and grouping of riders by competition level are prevalent in equestrian coaching practice and research. This study explored sagittal pelvic tilt in 35 competitive dressage riders to analyse the relationship between static and dynamic postures and assess the interaction of competition level. Riders were assessed using optical motion capture on a riding simulator at halt and in walk, trot, and left and right canter. Mean, minimum and maximum pelvic tilt, and range of motion (ROM) were measured as the pitch rotation of a rigid body formed by markers placed on the rider's left/right anterior and posterior superior iliac spines and sacrum, averaged over six time-normalised strides. Three key results emerged: (1) there are correlations between the rider's mean pelvic tilt in simulated walk, trot and canter, but not at halt; (2) mean pelvic tilt values are not significantly influenced by competition level (p = 0.233); and (3) the minimum and maximum pelvic tilt values illustrate individual strategies between gaits. Therefore, results from static assessment and grouping of riders by competition level should be interpreted with caution. Riders should be assessed as individuals, during dynamic riding-specific tasks, to understand their postural strategies.

Evaluating Overall Performance in High-Level Dressage Horse-Rider Combinations by Comparing Measurements from Inertial Sensors with General Impression Scores Awarded by Judges

In the sport of dressage, one or more judges score the combined performance of a horse and rider with an emphasis on the technical correctness of the movements performed. At the end of the test, a single score is awarded for the 'general impression', which considers the overall performance of the horse and rider as a team. This study explored original measures that contributed to the general impression score in a group of 20 horse-rider combinations. Horses and riders were equipped with inertial measurement units (200 Hz) to represent the angular motion of a horse's back and the motions of a rider's pelvis and trunk. Each combination performed a standard dressage test that was recorded to video. Sections of the video were identified for straight-line movements. The videos were analyzed by two or three judges. Four components were scored separately: gaits of the horse, rider posture, effectiveness of aids, and harmony with the horse. The main contributor to the score for gaits was stride frequency (R = -0.252, p = 0.015), with a slower frequency being preferred. Higher rider component scores were associated with more symmetrical transverse-plane trunk motion, indicating that this original measure is the most useful predictor of rider performance.

Trunk Kinematics of Experienced Riders and Novice Riders During Rising Trot on a Riding Simulator

Asymmetry of horses and humans is widely acknowledged, but the influence of one upon the other during horse riding is poorly understood. Riding simulators are popular for education of beginners and analysis of rider biomechanics. This study compares trunk kinematics and saddle forces of 10 experienced riders (ER) and 10 novice riders (NR) performing rising trot on a simulator. Markers were placed on the 4th lumbar (L4) and 7th cervical (C7) spinous processes, and both acromion processes. Displacements in three axes of motion were tracked using 10 high-speed video cameras sampling at 240 Hz. Displacement trajectories at L4 and C7 were similar between both groups, displaying an asymmetrical butterfly pattern in the frontal plane, which reversed when changing diagonal. Comparison between groups, NR displayed greater vertical displacement and higher saddle impact forces at L4 (P = .034), greater amplitude of medio-lateral displacement on the right diagonal between C7 and L4, and on the right diagonal while seated they rotated left (acromion processes) while the ER rotated right. Within group comparison demonstrated that on the right diagonal both groups produced significantly greater medio-lateral displacement at L4, and NR displayed significantly greater medio-lateral displacement between C7 and L4. On the left diagonal NR produced significantly greater vertical displacement and higher saddle impact forces. The findings of this study suggest that ER were more stable, symmetrical, and had lower impact force on the saddle. These issues could be addressed in beginners using a simulator to avoid unnecessary stresses on horses.

Static postural differences between male and female equestrian riders on a riding simulator

This study aimed to compare static posture of male and female riders on a riding simulator. Ten female and five male riders underwent a 5 min standardised exercise programme on the simulator, they were then videoed for 10 s from each the left, right, and rear views whilst stationary on the simulator. Two-dimensional kinematic analysis of the videos showed that male riders had a more neutrally positioned pelvis in the sagittal plane (median left: 6.47°, right: 5.24°) with females demonstrating a posterior pelvic tilt (L: 14.04°, R: 13.55°). Females showed significantly greater pelvic obliquity (median female: 1.99°, male: 0.73°), trunk lean (F: 1.60°, M: 0.43°), and shoulder tilt (F: 1.79°, M: 0.57°) in the frontal plane, demonstrating an overall greater postural asymmetry. Previous studies of elite riders have shown a more anteriorly rotated pelvis to be more desirable. Symmetry of riding position is favourable as it allows movements to be performed with ease and ensures even force distribution through the saddle to the horse. Male riders may therefore have a biomechanical advantage over females when it comes to maintaining a desirable riding position. This research should now be extended to study riders on the horse in motion.

Breast biomechanics, exercise induced breast pain (mastalgia), breast support condition and its impact on riding position in female equestrians

Breast biomechanics, exercise-induced breast pain (EIBP) and performance effects in female athletes are established. Wearing sports bras during exercise reduces breast movement and EIBP. Despite the prevalence of female equestrians, little investigation of breast movement during horse riding exists, yet excessive breast movement, embarrassment and EIBP are reported. Breast movement relative to the torso is linked to EIBP, associated with magnitude and direction of forces generated. Equestrians may experience novel breast and upper-body movement patterns in response to large vertical excursions of the horse. This study aimed to establish relative vertical breast displacement (RVBD), EIBP and positional changes in three support conditions: ‘no support’, ‘low support’ and ‘high support’. Thirty-eight female equestrians rode a Racewood™ Equine Simulator in each breast support condition in medium walk, medium trot (sitting) and medium canter. Trials were filmed and analysed using Quintic® Biomechanics V29. Significant reductions in RVBD (P<0.001) and EIBP (P<0.001) were identified with increased breast support in all gaits. In medium trot (sitting) a significant reduction in range of movement (ROM) of shoulder-elbow-wrist (P<0.001) was seen from low to high support. ROM of torso-vertical angles were reduced from no support to low support (P<0.001) and further by high support (P<0.001). This reduction in ROM was significantly greater in large breasted riders (cup size DD-FF) (n=21) (P<0.001) compared to small breasted (cup size AA-D) (n=17). These results suggest that appropriate breast support positively impacts EIBP and riding position in female riders possibly enhancing performance. As RVBD and reported EIBP were not wholly comparative with results in female runners, further research is warranted to establish breast movement in equestrianism in three dimensions.

Ergonomic assessment of work-related musculoskeletal disorder and its determinants among commercial mini bus drivers and driver assistants (mini bus conductors) in Nigeria

Introduction

Work-related musculoskeletal disorder (WMSD) is a leading causes of occupational injury and disability among drivers and workers in the transport industry. This study evaluated the ergonomically assessed WMSD and its determinants among Nigerian commercial mini bus drivers (BD) and mini bus conductors (BC)

Method

A total of 379 participants (BD = 200, BC = 179) were purposively sampled for this exploratory cross-sectional study. Participants’ WMSD and work related variables were respectively assessed using the standardized Nordic questionnaire and a content-validated, Driving Work Station Assessment (DWSA) form. Data were analyzed descriptively and inferentially using chi-square and logistic regression. The level of significance was set at α = 0.05.

Results

The participants were aged between 20 and 66 years, with a mean age of 33.26±10.76years (BD = 38.42±10.22years, BC = 27.50±8.13years); most of whom consumed alcohol (84.4%) and experienced severe job stress (73.4%). There was a high prevalence (95.8%; BD = 94.5%, BC = 97.8%) of WMSDs, the lower back (66.8%) and upper back (54.1%) had the highest regional prevalence of WMSD. The BC (BC vs BD) had significantly (p<0.05) higher prevalence of Neck (47.7% vs 21.5%) and upper back (80.4% vs 30.5%) WMSDs. Conversely, the BD (BD vs BC) had significantly (p<0.05) higher prevalence of low-back (85.0% vs 46.4%), knee (25.0% vs 9.5%), elbow (11.5% vs 3.9%), and wrist (10.5% vs 3.4%) WMSD. There was a significant association between WMSD and each of work duration (X² = 11.634, p = 0.009), work frequency (X² = 8.394, p = 0.039), job dissatisfaction (X2 = 10.620, p = 0.001) and job stress (X² = 16.879, p = 0.001). Working beyond 4days/week (OR = 10.019, p = 0.001), job dissatisfaction (OR = 1.990, p = 0.031), constrained working postures (OR = 5.324, p = 0.003) and fatigue (OR = 4.719, p = 0.002) were the predictors of WMSD.

Conclusion

Job stress, work duration and work frequency, posture and fatigue are important determinants of WMSDs among mini bus drivers and their assistants in Nigeria. Ergonomics training intervention for this population is recommended.

Guidelines for the Measurement of Rein Tension in Equestrian Sport

Rein tension is relatively easy to measure, and the resulting data are useful for evaluating the interaction between horse and rider. To date, there have been a number of studies using different transducers, calibration methods and analytical techniques. The purpose of this paper is to make recommendations regarding the collection, analysis and reporting of rein tension data. The goal is to assist users in selecting appropriate equipment, choosing verified methods of calibration, data collection and analysis, and reporting their results consistently to facilitate comparisons between different studies. Sensors should have a suitable range and resolution together with a fast enough dynamic response, according to the gait, speed and type of riding for which they will be used. An appropriate calibration procedure is necessary before each recording session. A recording frequency of 50 Hz is adequate for most rein tension studies. The data may be analyzed using time-series methods or by extracting and analyzing discrete variables chosen in accordance with the study objectives. Consistent reporting facilitates comparisons between studies.

Footedness and Postural Asymmetry in Amateur Dressage Riders, Riding in Medium Trot on a Dressage Simulator

This study explored the relationship between footedness and postural asymmetry in equestrian riders. 28 female riders completed the Waterloo Footedness Questionnaire- Revised (WFQ-R), giving a score for footedness. They then took part in a test on a riding simulator where measures of saddle force, stirrup force, and degree of lateral tilt of the pelvic, trunk, and shoulder segments were taken over a period of 20 seconds in trot. Symmetry indices were calculated for stirrup force and saddle force. There were no significant correlations between WFQ-R score and any of the measures of postural symmetry. Only a very small number (n=3) participants showed a marked footedness, with the majority of the sample being classed as 'mixed footed' based on test scores. This, coupled with data loss for some participants in each of the parameters, means direct comparison of footedness groups was difficult. However, the variation of asymmetry in the mixed footed group supports the idea that footedness does not have a significant impact on the rider's posture. There was a correlation between trunk lean and stirrup force symmetry index (r=0.537, P=0.021) showing the trunk leaned towards the side of higher stirrup force. There was a significant negative correlation between pelvic obliquity and shoulder tilt (r= -0.481, P=0.023) with 59% of the sample showing pelvic obliquity and shoulder tilt in opposite directions. The findings indicate that there is little effect of footedness on postural asymmetries in the rider. Research should now consider other causal factors to support riders to become more symmetrical.

Relationships between the Rider's Pelvic Mobility and Balance on a Gymnastic Ball with Equestrian Skills and Effects on Horse Welfare

Riders need core stability to follow and guide the horse's movements and avoid giving unintended or conflicting signals. This study evaluated the rider's performance of exercises on a gymnastic ball with on-horse performance and indicators of stress in the horse. Twenty experienced riders were scored performing three exercises on a gymnastic ball and for quality and harmony when riding based on evaluation of video recordings in which conflict behaviours were evident. The horse's heart rate and number of conflict behaviors during the riding test and cortisol levels after completion of the test were measured. The rider's ability to roll the pelvis from side-to-side on a gymnastic ball was highly correlated with ability to circle the pelvis on the ball and with quality and harmony during riding. However, pelvic roll and riding quality and harmony showed a trend toward a negative correlation with balancing skills on the ball. It appears that the ability to actively move the pelvis is more relevant to equestrian performance than static balancing skill. Horses ridden by riders with better pelvic mobility and control showed significantly fewer conflict behaviors. On the contrary, high scores for balancing on the gymnastic ball were negatively correlated with the horses' working heart rates, suggesting a less energetic performance. Pelvic control and mobility may be predictive for equestrian skills and riding harmony.

Asymmetries of horses walking and trotting on treadmill with and without rider

BACKGROUND

Left-right movement symmetry is a highly desirable characteristic in sport horses.

OBJECTIVES

This study compared movement symmetry in well-trained dressage horses in unridden and unrestrained position and ridden in a dressage frame, and investigated possible associations between gaits.

STUDY DESIGN

Experimental study.

METHODS

Seven sound, high-level dressage horses were measured at walk and sitting trot on a treadmill at several speeds under two conditions: with and without rider. Left-right differences in stance duration, stance protraction and retraction based on longitudinal hoof positions, ipsilateral limb tracking, minimum and maximum vertical positions of the dorsal spinous processes of the sixth thoracic (T6), third sacral vertebrae (S3) and wing of atlas, and vertical ground reaction forces were calculated and analysed in mixed models.

RESULTS

At walk, five body variables indicated increased asymmetry in the ridden condition compared with unridden condition: forelimb stance duration (unridden/ridden left-right differences 9 vs 13 ms; P = .008), forelimb stance protraction (P = .004), stance retraction (P = .001) and first force peak (P = .003), and hindlimb stance retraction (P = .01). At trot, six body variables were more asymmetrical in the ridden condition: forelimb stance duration (2.5 vs 3.8 ms, P = .004); hindlimb stance protraction (P < .0001) and retraction (P = .01), T6 minimum (4 vs 6 mm, P = .001), T6 maximum (9 vs 11 mm, P = .01) and S3 maximum (6 vs 12 mm, P < .001). Five variables had significant associations between asymmetries at walk and trot, but only three demonstrated a positive slope.

MAIN LIMITATIONS

A limited number of horses and riders were studied. Measurements were performed on a treadmill.

CONCLUSIONS

High-level horses moved slightly more asymmetrically when ridden in a dressage frame than in the unridden condition.

The Effect That Induced Rider Asymmetry Has on Equine Locomotion and the Range of Motion of the Thoracolumbar Spine When Ridden in Rising Trot

There is a paucity of evidence on the effect that rider asymmetry has on equine locomotion. The aim of this study was to evaluate the effect of rider asymmetry on equine locomotion by using a novel approach to induce rider asymmetry. Ten nonlame horses were recruited for this study. Joint center markers were used to capture 2D kinematics (Quintic Biomechanics) of the horse and rider and horses were equipped with seven inertial sensors positioned at the fifth (T5) and eighteenth (T18) thoracic vertebrae, third lumbar (L3) vertebra, tubera sacrale (TS), and left and right tubera coxae. Rider asymmetry was induced by shortening the ventral aspect of one stirrup by 5 cm. Kinematic data were compared between conditions using a mixed model with the horse defined as a random factor and stirrup condition (symmetrical stirrups and asymmetrical stirrups) and direction (inside and outside) defined as fixed factors. Data from riders where the right stirrup was shortened were mirrored to reflect a left stirrup being shortened. To determine differences between conditions, a significance of P ≤ .05 was set. On the rein with the shortened stirrup on the outside: an increase in lateral bending range of motion (ROM) at T5 (P = .003), L3 (P = .04), and TS (P = .02), an increase in mediolateral displacement at T5 (P = .04), T18 (P = .04), and L3 (0.03) were found. An increase in maximum fetlock extension was apparent for both the front (P = .01) and hind limb (P = .04) on the contralateral side to the shortened stirrup; for the asymmetrical stirrup condition on the rein with the shortened stirrup on the inside: an increase in flexion-extension ROM at T5 (P = .03) and L3 (P = .04), axial rotation at T5 (P = .05), and lateral bending of T5 (P = .03), L3 (P = .04), and TS (P = .02). Asymmetric rider position appears to have an effect on the kinematics of the thoracolumbar spine. These findings warrant further investigation to understand the long-term impact this may have on equine locomotor health.

Saddle and stirrup forces of equestrian riders in sitting trot, rising trot, and trot without stirrups on a riding simulator

Studies into horse-saddle-rider interaction demonstrate that increased vertical forces on the horse’s back are potentially damaging to the musculoskeletal system, and any practice that could lead to this warrants investigation. The contribution of the stirrups in stabilising the bodyweight of the rider, and the effect of riding without stirrups on force distribution to the horse, has yet to be fully described in the literature. The current study therefore aimed to compare saddle and stirrup forces in three conditions; sitting trot, rising trot, and sitting trot without stirrups on the riding simulator. Fourteen amateur female riders of mean age 34.6±10 years participated in the study and 20 s of data were collected for saddle and stirrup force across the three conditions. Mean and peak forces were extracted from the data for total force under the whole saddle, left and right sides of the saddle separately, left and right stirrups, and both stirrups combined. Peak vertical saddle forces were significantly higher in sitting trot without stirrups than with (P=0.011). Higher mean and peak saddle forces were seen on the right-hand side in all conditions (P<0.001) and there was an overall tendency for higher left stirrup forces in both sitting and rising trot with this being significant for peak force in sitting trot (P=0.039). The higher forces recorded when trotting without stirrups indicate that the stirrups play an important role in controlling the vertical acceleration of the rider in relation to the horse, however further studies are needed on live horses before any specific recommendations can be made regarding training practices. Asymmetrical saddle forces have a potentially negative effect on the horse and future research should also aim to identify the underlying causes of these patterns of rider asymmetry to improve both horse welfare and performance.

A preliminary study investigating functional movement screen test scores in female collegiate age horse-riders

The functional movement screen (FMS) is an easily administered and non-invasive tool to identify areas of weakness and asymmetry during specific exercises. FMS is a common method of athlete screening in many sports and is used to ascertain injury risk, but has to be used within an equestrian population. The aim of this study was to establish FMS scores for female collegiate age (18-26 years) riders, to inform a normative data set of FMS scores in horse riders in the future. Thirteen female collegiate horse riders (mean ± standard deviation (sd); age 21.5±1.4 years, height 167.2±5.76 cm, mass 60.69±5.3 kg) and 13 female collegiate non-riders (mean ± sd; age 22.5±2.1 years, height 166.5±5.7 cm, mass 61.5±4.9 kg) were assessed based on their performance on a 7-point FMS (deep squat, hurdle step, in-line lunge, shoulder mobility, active straight leg raise, trunk stability and rotary stability). The mean composite FMS scores (± sd) for the rider group was 14.15±1.9 and for the non-riders was 13.15±1.77. There was no statistically significant difference in median FMS composite scores between the rider and non-rider groups (Mann-Whitney U test, z=-1.249, P=0.223). However, 46% of riders and 69% of non-riders scored ≤14, indicating that a non-rider is 1.5 times (odds ratio) more likely to be at increased risk of injury compared to riders. Collegiate female riders scored higher than the non-rider population, but lower than seen in other sports suggesting some riders may be at risk of injury. Riders’ FMS scores demonstrated asymmetric movement patterns potentially limiting left lateral movement. Asymmetry has a potential impact on equestrian performance, limiting riders’ ability to apply the correct cues to the horse. The findings of such screening could inform the development of axillary training programmes to correct asymmetry pattern and target injury prevention.

Rein tension in novice riders when riding a horse simulator

This study reports tension in the left and right reins when riding a horse simulator that moved only in the sagittal plane. The objective was to determine whether asymmetries in rein tension of novice riders at the rising trot, canter, and halt were present, and if so, to investigate their relationship with the rider’s handedness. The experimental hypothesis was that rein tension would be higher on the side of the rider’s non-dominant hand. 22 novice riders (19 right-handed; 3 left-handed) rode a horse simulator at halt, rising trot and canter. Rein tension was recorded in both reins at a sampling rate of 1000 Hz for 8 s at each gait. The variables measured in rising trot and canter were minimal and maximal tension, the change between minimal and maximal values and mean tension per step at rising trot or per stride at canter. At halt only mean tension during the 8 s recording was measured. Comparisons between right and left reins and between right-handed and left-handed riders were made using mixed models. The results showed no asymmetries in mean tension at halt. In rising trot and canter all significant differences involved higher tension in the right rein regardless of handedness of the riders. During rising trot the minimum was higher in the right rein over all riders and both the mean and maximal values were higher in the right rein in left-handed riders. In canter left-handed riders had higher mean tension in the right rein. All recorded asymmetries had higher tension in the right rein compared with the left and they were more prevalent in left-handed riders which implies higher tension in the non-dominant hand. Rein tension patterns were not symmetrical on the left and right sides and asymmetries in left-handed riders were not mirrored in right-handed riders.