225 research outputs found

    Balance strategies used in passage

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    An exploration of strategies used by dressage horses to control moments around the center of mass when performing passage

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    Background Locomotion results from the generation of ground reaction forces (GRF) that cause translations of the center of mass (COM) and generate moments that rotate the body around the COM. The trot is a diagonally-synchronized gait performed by horses at intermediate locomotor speeds. Passage is a variant of the trot performed by highly-trained dressage horses. It is distinguished from trot by having a slow speed of progression combined with great animation of the limbs in the swing phase. The slow speed of passage challenges the horse’s ability to control the sagittal-plane moments around the COM. Footfall patterns and peak GRF are known to differ between passage and trot, but their effects on balance management, which we define here as the ability to control nose-up/nose-down pitching moments around the horse’s COM to maintain a state of equilibrium, are not known. The objective was to investigate which biomechanical variables influence pitching moments around the COM in passage. Methods Three highly-trained dressage horses were captured by a 10-camera motion analysis system (120 Hz) as they were ridden in passage over four force platforms (960 Hz). A full-body marker set was used to track the horse’s COM and measure balance variables including total body center of pressure (COP), pitching moments, diagonal dissociation timing, peak force production, limb protraction–retraction, and trunk posture. A total of twenty passage steps were extracted and partial correlation (accounting for horse) was used to investigate significant (P < 0.05) relationships between variables. Results Hindlimb mean protraction–retraction correlated significantly with peak hindlimb propulsive forces (R = 0.821; P < 0.01), mean pitching moments (R = 0.546, P = 0.016), trunk range of motion, COM craniocaudal location and diagonal dissociation time (P < 0.05). Discussion Pitching moments around the COM were controlled by a combination of kinematic and kinetic adjustments that involve coordinated changes in GRF magnitudes, GRF distribution between the diagonal limb pairs, and the moment arms of the vertical GRFs. The moment arms depend on hoof placements relative to the COM, which were adjusted by changing limb protraction–retraction angles. Nose-up pitching moments could also be increased by providing a larger hindlimb propulsive GRF

    The role of biomechanical analysis of horse and rider in equitation science

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    Equestrian sports are unique in that they involve the participation of two athletes that differ greatly in morphology yet are able to move together harmoniously; experienced riders not only move in phase with the horse, they can even improve the consistency of the horse’s movements. The motion of the horse imposes perturbations on the rider that differ in magnitude and direction according to gait. In faster gaits where suspension phases are present, the rider must accommodate greater vertical and horizontal accelerations of the horse’s trunk through three-dimensional movements of their axial body segments. The rider, in turn, can improve the horse’s performance through correct training, or cause it to deteriorate through faults in the rider’s position or incorrect application of the aids. This review addresses the current state of knowledge of the biomechanics of the horse-rider interaction, with reference to the ways in which the emerging field of equitation science can help to improve equine welfare by enhancing rider awareness of horse behaviour and movement, as well as the impact of the rider on the horse

    Ground reaction forces in collected trot and passage

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    Development of a method to identify foot strike on an arena surface: application to jump landing

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    Foot strike can be difficult to determine using kinematics alone, particularly when studying equine activities on more compliant surfaces, so this study was done with the aim of developing and validating a method to determine foot strike on an arena surface that can be used in conjunction with kinematics alone, and of applying the method in the context of measuring foot strike during jump landing on an arena surface. A low-cost contact mat was developed. The timing of the contact mat switching ‘on’ was compared to the timing of a force platform onset of 20 N, load and loading rate at foot strike. Two groups of 25 participants were used in two separate studies to validate the contact mat: the first measured the difference in timing with respect to two different activities (running and stepping down from a box), and the second measured the difference in timing with respect to 1- and 2-cm depths of an arena surface during running. In a third study, the mat was used to measure leading limb foot strike of six horses during jump landing, and these data were compared to kinematics from a palmar marker on the hoof wall. All data were recorded at 500 Hz. A consistent difference in delay was found between the mat and force platform onset, and as a result, no significant differences (P>0.05) in timing delay between different loading rates or depths were found. During jump landing, foot strike (determined from the mat) occurred after the vertical velocity minima and the acceleration maxima for the hoof marker, but it occurred before the point where the rate of vertical displacement began to reduce. In conclusion, further work is needed to enhance these techniques, but these preliminary results indicate that this method may be effective in determining foot strike for field-based applications

    Effects of barefoot and minimally shod footwear on effective mass - implications for transient musculoskeletal loading

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    The purpose of this investigation was to explore the effects of barefoot and minimally shod footwear on effective mass, and determine the implications that this has for transient loading during running. Fifteen male runners ran at 4.0 m/s in five different footwear conditions (barefoot, running trainer, Nike-free, Inov-8 and Vibram five-fingers). Kinematics were collected using an 8 camera motion capture system and ground reaction forces via an embedded force platform. Effective mass was examined using impulse-momentum modelling. Differences between footwear were examined using one-way repeated measures ANOVA and linear regression was used to determine the association between effective mass and instantaneous loading rate. The findings showed that effective mass was significantly larger in the barefoot (11.47 %BW), Nike-free (9.81 %BW), Inov-8 (12.10 %BW) and Vibram five-fingers (8.84 %BW) compared to the running trainer (6.86 %BW). Furthermore, instantaneous loading rate was significantly larger in the barefoot (347.55 BW/s), Nike-free (178.76 BW/s), Inov-8 (369.93 BW/s) and Vibram five-fingers (339.37 BW/s) compared to the running trainer (133.18 BW/s). It was also revealed that there were significant positive associations between effective mass and the instantaneous rate for each footwear; barefoot (R2=0.60), Nike-free (R2=0.53), Inov-8 (R2=0.80), Vibram five-fingers (R2=0.52) and running trainer (R2=0.40). The findings from the current investigation indicate that effective mass has key implications for the generation of transient forces and also that running barefoot and in minimally shod footwear may place runners at increased risk from impact related injuries compared to the traditional running shoes

    Three-dimensional kinematic correlates of ball velocity during maximal instep soccer kicking in males

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    This is an Accepted Manuscript of an article published by Taylor & Francis Group in European Journal of Sport Science, on 23 April 2014, available online at: https://www.tandfonline.com/doi/abs/10.1080/17461391.2014.908956.Achieving a high ball velocity is important during soccer shooting, as it gives the goalkeeper less time to react, thus improving a player's chance of scoring. This study aimed to identify important technical aspects of kicking linked to the generation of ball velocity using regression analyses. Maximal instep kicks were obtained from 22 academy-level soccer players using a 10-camera motion capture system sampling at 500 Hz. Three-dimensional kinematics of the lower extremity segments were obtained. Regression analysis was used to identify the kinematic parameters associated with the development of ball velocity. A single biomechanical parameter; knee extension velocity of the kicking limb at ball contact Adjusted R(2) = 0.39, p ≤ 0.01 was obtained as a significant predictor of ball-velocity. This study suggests that sagittal plane knee extension velocity is the strongest contributor to ball velocity and potentially overall kicking performance. It is conceivable therefore that players may benefit from exposure to coaching and strength techniques geared towards the improvement of knee extension angular velocity as highlighted in this study.Peer reviewedFinal Accepted Versio

    Ground reaction forces of elite dressage horses in collected trot and 1 passage

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    In this study, sagittal plane ground reaction forces (GRFs) in ridden elite dressage horses performing ‘collected trot’ and in ‘passage’ over ground were determined. In-ground force plates captured GRF data from four Dutch Warmblood and four Lusitano horses ridden by their trainers. At least three stance phases were analysed for forelimbs and hind limbs per horse. The variables extracted were vertical and longitudinal (braking, propulsive) force maxima, their times of occurrence and the respective impulses for forelimbs and hind limbs. Lusitanos had lower vertical impulses than Dutch warmbloods in collected trot. Across all horses, passage had larger vertical impulses than collected trot in the forelimbs and hind limbs. Propulsive impulse increased in the hind limbs in passage. Prolonged stance durations in passage contributed to higher vertical impulses that are needed to increase the vertical excursions of the centre of mas

    A simple method of equine limb force vector analysis and its potential applications

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    Background Ground reaction forces (GRF) measured during equine gait analysis are typically evaluated by analyzing discrete values obtained from continuous force-time data for the vertical, longitudinal and transverse GRF components. This paper describes a simple, temporo-spatial method of displaying and analyzing sagittal plane GRF vectors. In addition, the application of statistical parametric mapping (SPM) is introduced to analyse differences between contra-lateral fore and hindlimb force-time curves throughout the stance phase. The overall aim of the study was to demonstrate alternative methods of evaluating functional (a)symmetry within horses. Methods GRF and kinematic data were collected from 10 horses trotting over a series of four force plates (120 Hz). The kinematic data were used to determine clean hoof contacts. The stance phase of each hoof was determined using a 50 N threshold. Vertical and longitudinal GRF for each stance phase were plotted both as force-time curves and as force vector diagrams in which vectors originating at the centre of pressure on the force plate were drawn at intervals of 8.3 ms for the duration of stance. Visual evaluation was facilitated by overlay of the vector diagrams for different limbs. Summary vectors representing the magnitude (VecMag) and direction (VecAng) of the mean force over the entire stance phase were superimposed on the force vector diagram. Typical measurements extracted from the force-time curves (peak forces, impulses) were compared with VecMag and VecAng using partial correlation (controlling for speed). Paired samples t-tests (left v. right diagonal pair comparison and high v. low vertical force diagonal pair comparison) were performed on discrete and vector variables using traditional methods and Hotelling’s T2 tests on normalized stance phase data using SPM. Results Evidence from traditional statistical tests suggested that VecMag is more influenced by the vertical force and impulse, whereas VecAng is more influenced by the longitudinal force and impulse. When used to evaluate mean data from the group of ten sound horses, SPM did not identify differences between the left and right contralateral limb pairs or between limb pairs classified according to directional asymmetry. When evaluating a single horse, three periods were identified during which differences in the forces between the left and right forelimbs exceeded the critical threshold (p < .01). Discussion Traditional statistical analysis of 2D GRF peak values, summary vector variables and visual evaluation of force vector diagrams gave harmonious results and both methods identified the same inter-limb asymmetries. As alpha was more tightly controlled using SPM, significance was only found in the individual horse although T2 plots followed the same trends as discrete analysis for the group. Conclusions The techniques of force vector analysis and SPM hold promise for investigations of sidedness and asymmetry in horses

    Posture flexibility and grip strength in horse riders

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    Since the ability to train the horse to be ambidextrous is considered highly desirable, rider asymmetry is recognized as a negative trait. Acquired postural and functional asymmetry can originate from numerous anatomical regions, so it is difficult to suggest if any is developed due to riding. The aim of this study was therefore to assess symmetry of posture, strength and flexibility in a large population of riders and to determine whether typical traits exist due to riding. 127 right handed riders from the UK and USA were categorized according to years riding (in 20 year increments) and their competition level (using affiliated test levels). Leg length, grip strength and spinal posture were measured and recorded by a physiotherapist. Standing and sitting posture and trunk flexibility were measured with 3-D motion capture technology. Right-left differences were explored in relation to years riding and rider competitive experience. Significant anatomical asymmetry was found for the difference in standing acromion process height for a competition level (-0.07±1.50 cm Intro/Prelim; 0.02±1.31 cm Novice; 0.43±1.27 cm Elementary+; p=0.048) and for sitting iliac crest height for years riding (-0.23±1.36 cm Intro/Prelim; 0.01±1.50 cm Novice; 0.86±0.41 cm Elementary+;p=0.021). For functional asymmetry, a significant interaction was found for lateral bending ROM for years riding x competition level (p=0.047). The demands on dressage riders competing at higher levels may predispose these riders to a higher risk of developing asymmetry and potentially chronic back pain rather than improving their symmetry
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