Article

The effect of three different head–neck positions on the average EMG activity of three important neck muscles in the horse

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Abstract

The Knowledge of muscle activity in common head–neck positions (HNPs) is a necessary precondition for making judgements on HNPs. The aim of the study was to record the surface electromyography activities of important muscles of the horse’s neck in various HNPs. The electrical activities of the m. splenius, brachiocephalicus and trapezius were recorded on both sides. Five horses, both with and without a rider, were examined in all three gaits on both hands in three different HNPs: a ‘free’ position, a ‘gathered’ (head higher, neck more flexed) position with the noseline in front of the vertical and a ‘hyperflexed’ position. Averages of ten consecutive gait cycles in each HNP were evaluated and compared by standard statistical methods. No difference between ridden and unridden horses could be detected. The m. brachiocephalicus was in the hyperflexed position in all gaits significantly (p < 0.01) more active than in the gathered and free position, which were not significantly different. By contrast, the m. splenius was in the hyperflexed position less active than in the free position (p < 0.02), in which it always showed the highest activity. In walking, the muscle activities in the free and gathered positions deviated significantly (p < 0.01). The m. trapezius was in the hyperflexed posture during walking significantly less active than in the free (p < 0.01) and gathered (p < 0.01) positions with the strongest activities in the free position. Again, the free and gathered positions differed significantly (p < 0.01). In trot, the same pattern occured, although the gathered and hyperflexed positions did not differ significantly. In the canter, the activities of the m. trapezius showed no differences between HNPs. In HNPs with the noseline in front of the vertical, the muscles of the topline (m. splenius, m. trapezius) are activated and trained. In the hyperflexed position, however, a major muscle of the lower topline (m. brachiocephalicus) is activated and trained.

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... These studies recommend the use of a HPF cut-off frequency ≥20 Hz for most applications (Van Boxtel et al., 1998;Van Boxtel, 2001;De Luca et al., 2010). In equine sEMG research, HPF cut-off frequencies of 10 Hz (Harrison et al., 2012), 20 Hz (Hodson-Tole, 2006Crook et al., 2010;Harrison et al., 2012) and 40 Hz (Kienapfel, 2015;Kienapfel et al., 2018) have been reported. No known studies have employed the methods described in human literature to determine the optimal HPF cut-off frequency for equine sEMG signals. ...
... No horse contributed to more than one group. sEMG signals from stance and swing phase were DC offset removed and, in accordance with Kienapfel (2015) and Kienapfel et al. (2018), were HPF using a Butterworth 4th order filter. HPF cut-off frequencies (n ranging between 10 and 80 Hz), were applied to each signal in 10 Hz increments. ...
... A cut-off frequency range of 30-40 Hz is in agreement with previous equine sEMG studies that report using a HPF with a 40 Hz cut-off (Cheung et al., 1998;Kienapfel, 2015;Kienapfel et al., 2018), but do not provide a justification for why this cut-off frequency was chosen. Findings from this study indicate that, while previously employed cutoff frequencies of 10 and 20 Hz (Hodson-Tole, 2006;Crook et al., 2010;Harrison et al., 2012) are more likely to preserve the low-frequency component of the equine sEMG signal, they are not appropriate for completely attenuating the noise components. ...
Article
High-pass filtering (HPF) is a fundamental signal processing method for the attenuation of low-frequency noise contamination, namely baseline noise and movement artefact noise, in human surface electromyography (sEMG) research. Despite this, HPF is largely overlooked in equine sEMG research, with many studies not applying, or failing to describe, the application of HPF. An optimal HPF cut-off frequency maximally attenuates noise while minimally affecting sEMG signal power, but this has not been investigated for equine sEMG signals. The aim of this study was to determine the optimal cut-off frequency for attenuation of low-frequency noise in sEMG signals from the Triceps Brachii and Biceps Femoris of 20 horses during trot and canter. sEMG signals were HPF with cut-off frequencies ranging from 0-80 Hz and were subjected to power spectral analysis and enveloped using RMS to calculate spectral peaks, indicative of motion artefact, and signal loss, respectively. Processed signals consistently revealed a low-frequency peak between 0–20 Hz, which was associated with motion artefact. Across all muscles and gaits, a 30-40 Hz cut-off fully attenuated the low-frequency peak with the least amount of signal loss and was therefore considered optimal for attenuating low-frequency noise from the sEMG signals explored in this study.
... Following on from anatomical dissection studies of post-mortem specimens during passive movement (Clayton and Townsend, 1989a,b;Pagger et al., 2009;Schmidburg et al., 2012), the function of the neck is now being investigated in ever increasing detail. To date, in vivo studies employing skin-based kinematic markers (de Cocq et al., 2009;Clayton et al., 2010Clayton et al., , 2012Elgersma et al., 2010;Zsoldos et al., 2010aZsoldos et al., ,c,d, 2014 and electromyography (Robert et al., 2001(Robert et al., , 2002Wijnberg et al., 2010;Zsoldos et al., 2014;Kienapfel, 2015) are available. In parallel to these studies, modelling of the equine neck has become relevant to answering some research questions not suitable for in vivo or post-mortem investigations, such as the effective cervical intervertebral angles at different neck positions (Elgersma et al., 2010;Zsoldos et al., 2010a,c); this was also pointed out in a review on the function of the equine back . ...
... splenius from its activity pattern and its composition of slow oxidative fibres. Kienapfel (2015) showed that the m. splenius was least active in the unrestricted head/neck position, more active in the maximum flexed head/neck position (cranial neck flexed), and most active in the collected head/neck position (head high, neck flexed, and the nose in front of the vertical). ...
... Obtaining and maintaining a defined head/neck position is a widely recognised prerequisite for most uses of the horse; this has been the reason for several research groups to start investigating such defined head/neck positions about 10 years ago (Rhodin et al., 2005;van Breda, 2006;Weishaupt et al., 2006;de Cocq et al., 2009;Rhodin et al., 2009;Waldern et al., 2009;Elgersma et al., 2010;Wijnberg et al., 2010;Kattelans et al., 2013;Lashley et al., 2014;Kienapfel, 2015). The effect of such head/neck positions on the overall locomotion of the horse has been established in several in vivo studies, and a high head position was found to reduce the dorsoventral ROM of the back in the unridden horse at walk and trot (Rhodin et al., 2005(Rhodin et al., , 2009; this is most likely due to extension in the cranial part and flexion in the caudal part of the thoracolumbar vertebral column (Gómez Álvarez et al., 2006). ...
Article
During both locomotion and body movements at stance, the head and neck of the horse are a major craniocaudal and lateral balancing mechanism employing input from the visual, vestibular and proprioceptive systems. The function of the equine neck has recently become the focus of several research groups; this is probably also feeding on an increase of interest in the equine neck in equestrian sports, with a controversial discussion of specific neck positions such as maximum head and neck flexion. The aim of this review is to offer an overview of new findings on the structures and functions of the equine neck, illustrating their interplay. The movement of the neck is based on intervertebral motion, but it is also an integral part of locomotion; this is illustrated by the different neck conformations in the breeds of horses used for various types of work. The considerable effect of the neck movement and posture onto the whole trunk and even the limbs is transmitted via bony, ligamentous and muscular structures. Also, the fact that the neck position can easily be influenced by the rider and/or by the employment of training aids makes it an important avenue for training of new movements of the neck as well as the whole horse. Additionally, the neck position also affects the cervical spinal cord as well as the roots of the spinal nerves; besides the commonly encountered long-term neurological effects of cervical vertebral disorders, short-term changes of neural and muscular function have also been identified in the maximum flexion of the cranial neck and head position. During locomotion, the neck stores elastic energy within the passive tissues such as ligaments, joint capsules and fasciae. For adequate stabilisation, additional muscle activity is necessary; this is learned and requires constant muscle training as it is essential to prevent excessive wear and tear on the vertebral joints and also repetitive or single trauma to the spinal nerves and the spinal cord. The capability for this stabilisation decreases with age in the majority of horses due to changes in muscle tissue, muscle coordination and consequently muscle strength. Copyright © 2015 Elsevier GmbH. All rights reserved.
... The electrode for the masseter was placed approximately 5 cm cranial to the caudal edge of the mandible (Williams et al., 2014). The electrode for the brachiocephalas was placed in the center of the muscle belly parallel to the muscle fibers as determined by manual palpation of surrounding landmarks and approximately 16 cm cranial to the posterior part of the greater tubercle of the humerus (point of the shoulder) (Kienapfel, 2015;Robert et al., 1998). The electrode for the cervical trapezius was placed parallel to the muscle fibers approximately 6 cm cranial to the proximal end of the spine of the scapula (Robert et al., 1998). ...
... The relationship between signal amplitude and force generation is not always as straightforward as this as it is influenced by a variety of factors (DeLuca, 1997). Despite these limitations, the interpretation of greater ARV in the masseter during sham clipping and social isolation and the brachiocephalas during sham clipping as muscular tension or increased muscle activity seems warranted and similar to conclusions reached by other researchers when interpreting measures of EMG amplitude obtained during dynamic movements (Crook et al., 2010;Kienapfel, 2015;Robert et al., 2010;Zsoldos et al., 2010) The preponderance of literature pertaining to EMG in horses has been undertaken during locomotion, which elicits primarily anisometric, dynamic contractions rather than the isometric, static contractions needed for the most robust interpretation of results (Valentin & Zsoldos, 2016;Williams, 2018). The current study suffers from the same limitation and this should be borne in mind when interpreting the EMG results obtained. ...
Article
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Horses' muscular tension during acute stress remains unexplored. Our aim was to assess muscular, behavioral, cortisol, and hematocrit responses to social isolation (ISO), novel object exposure (NOV), and sham clipping (CLIP). Altered stress responses were expected. Eight mature Standardbred horses (four mares and four geldings) were exposed to acute stressors and a control period (CON) in a balanced, replicated 4×4 Latin Square experimental design with 3 min treatment periods and 10 min washout periods. Surface electromyography collected from the masseter, brachiocephalas, cervical trapezius, and longissimus dorsi was processed to derive average rectified value (ARV) and median frequency (MF) during the initial, middle, and final 30 s of treatments. ARV and MF data were log transformed then analyzed using a mixed model, repeated measures ANOVA along with plasma cortisol and hematocrit. Behavior data were analyzed using a negative binomial distribution mixed model ANOVA. CLIP resulted in greater (p < 0.05) log ARV in the masseter (1.5 + 1.5%, mean + SD) and brachiocepahlas (2.2 + 2.0%) than CON (-1.2 + 1.4%, 0.1 + 1.5%). ISO resulted in greater (p < 0.05) log ARV in the masseter (0.2 + 1.3%) and cervical trapezius (0.6 + 1.3%) than CON (-1.2 + 1.4%, -1.0 + 1.7%). ISO increased (p < 0.05) the total number of stress-related behaviors and hematocrit. No changes in cortisol were observed. We suggest that muscular tension can be used as an indicator of acute stress in horses. Incorporating muscle activity into an array of measurements may provide a more nuanced understanding of stress responses.
... Tokuriki and Aoki [45] and Kienapfel , [46] used fine needle and sEMG respectively to examine equine muscle during riding reporting few differences in muscle activity between the ridden and unridden conditions. Riding was only shown to increase muscle activity levels during ipsilateral hind limb contact in the biceps femoris at walk with a rider compared to without [45], perhaps reflecting the application of the aids and subsequent increased propulsion stimulated by the rider compared to the horses' free gaits on a treadmill. ...
... Riding was only shown to increase muscle activity levels during ipsilateral hind limb contact in the biceps femoris at walk with a rider compared to without [45], perhaps reflecting the application of the aids and subsequent increased propulsion stimulated by the rider compared to the horses' free gaits on a treadmill. Similarly, no differences in EMG profiles have been reported in muscles associated with head and neck flexion when examined using draw reins compared to the same horses when ridden [46]. Unfortunately the studies do not state the experience level of riders used which could be influential [40]. ...
Article
Equine performance research to date has focussed on cardiorespiratory and biomechanical assessment of the horse neglecting the role of muscles. This review considers electromyography (EMG) in the horse, with a specific focus on the role of surface electromyography (sEMG) as a tool to analyse muscle activity in the sports-horse. Three themes have been evaluated in the horse using EMG: muscle recruitment, muscle activity during exercise, and fatigue. Results support kinematic research and add to the knowledge base on how the horse moves. . sEMG is a relatively non-invasive technology requiring clipping which can be used effectively in the ridden horse. Understanding equine locomotion and how muscles responds during different exercises could inform and evaluate training practices used in the sports horse. However, issues exist for example individual variation, accuracy of sensor placement and preventing noise within the EMG signal. Therefore key concepts in research design, data acquisition and processing are explored to inform future studies and to enable reasoned judgements on the validity and reliability of sEMG as a tool to investigate muscle recruitment and activity, and subsequently assess performance in the horse. The high level of inter-subject variance observed in between subjects’ designs combined with differences seen between individuals may preclude reliable comparison of muscle performance between groups of horses. Therefore within subject designs are advised for future sEMG studies. A standardised approach to data collection and analysis conforming to guidance from the human SENIAM database is recommended including consideration of the inherent challenges that present in EMG research.
... As a result, certain techniques commonly used in human sEMG data collection such as obtaining an isometric maximal voluntary contraction (MVC) for the purpose of sEMG data normalisation, are impossible in animals. Despite these challenges, the number of studies on sEMG in animals is steadily growing, with the majority of work having been carried out in equines (Garica et al., 2014;Kienapfel, 2015;St.George and Williams, 2013;Williams et al., 2014;Williams et al., 2013;Zsoldos et al., 2014). The advent of wireless sEMG in particular has been a positive step in opening the doors to research questions which would otherwise have been very difficult to obtain using a wired system in animal populations. ...
... Rollkur). Several studies have demonstrated the effects of head and neck posture on spinal and limb kinematics and ground reaction forces in ridden and unridden horses (Rhodin et al., 2009(Rhodin et al., , 2005Weishaupt et al., 2006), however only one study to date has reported on the influence of head and neck posture on neck muscle activity (Kienapfel et al., 2015). Going forward, future work on assessment of the neuromuscular system using sEMG can provide an evidence base for (or against) equestrian practices often based on tradition alone. ...
Article
The study of muscle activity using surface electromyography (sEMG) is commonly used for investigations of the neuromuscular system in man. Although sEMG has faced methodological challenges, considerable technical advances have been made in the last few decades. Similarly, the field of animal biomechanics, including sEMG, has grown despite being confronted with often complex experimental conditions. In human sEMG research, standardised protocols have been developed, however these are lacking in animal sEMG. Before standards can be proposed in this population group, the existing research in animal sEMG should be collated and evaluated. Therefore the aim of this review is to systematically identify and summarise the literature in animal sEMG focussing on (1) species, breeds, activities and muscles investigated, and (2) electrode placement and normalisation methods used. The databases PubMed, Web of Science, Scopus, and Vetmed Resource were searched systematically for sEMG studies in animals and 38 articles were included in the final review. Data on methodological quality was collected and summarised. The findings from this systematic review indicate the divergence in animal sEMG methodology and as a result, future steps required to develop standardisation in animal sEMG are proposed.
... Becker-Birck et al. found no differences in the behaviour of lunged horses without riders in different HNPs, where the HNPs were achieved with draw reins [21]. The same pattern occurred in the study of Kienapfel [22]. Horses, which were lunged in different HNPs showed subjectively few signs of discomfort in the hyperflexed position. ...
... Riders at these levels supposedly know that riding in a HNP behind the vertical should, according to the FEI-guidelines (''The head should remain in a steady position, as a rule slightly in front of the vertical, with a supple poll as the highest point of the neck, and no resistance should be offered to the Athlete.'' [22]) lead to lower marks for their performance, which may be the reason for them to change the HNP in the competition. Interestingly, according to our results judges appeared to penalize deviations in the HNP from the ideal with lower marks in the lower, but not in the higher classes according to the guidelines. ...
Article
Full-text available
Much controversy exists among riders, and in particular among those practicing dressage, regarding what can be considered an "appropriate" Head-Neck-Position (HNP). The objective was to assess the prevalence of different HNPs in the field, the behavioural reactions of horses during warm-up and competition rides in relation to HNP and the relation between HNP and marks achieved in the competition. Horses (n = 171) were selected during dressage competitions according to their HNP (3 categories based on the degree of flexion), and their behaviour was recorded during 3 minutes each of riding in the warm-up area and in the competition. Scans were carried out on an additional 355 horses every 15 minutes to determine the proportion of each HNP in the warm-up area. Sixty-nine percent of the 355 horses were ridden with their nasal planes behind the vertical in the warm-up area, 19% were ridden at or behind the vertical and only 12% were ridden with their nasal plane in front of the vertical. Horses carrying their nasal plane behind the vertical exhibited significantly (P<0.0001) more conflict behaviours than horses with their nose held in front of the vertical. Horses were commonly presented with a less flexed HNP during competition compared to warm-up (P<0.05). A HNP behind the vertical was penalised with lower marks in the lower (P = 0.0434) but not in the higher (P = 0.9629) competition levels. Horses in higher classes showed more (P = 0.0015) conflict behaviour than those in lower classes. In conclusion, dressage horses are commonly ridden during warm-up for competitions with their nasal plane behind the vertical, and this posture seems to cause significantly more conflict behaviour than HNPs in front of the vertical.
... Recent high profile examples of extreme HNP and the use of Rollkur (also spelled Rollkür), defined as overbending or hyperflexion of the horse's head and neck [5], within training and competition have increased the debate of how horses' HNPs influence their welfare. This combined with advances in technology has seen the scientific community exploring the impact of different HNPs on factors such as equine biomechanics [6,7], muscle activity [8], and equine stress responses [9e11]. ...
Article
The impact of head and neck position (HNP) on horse welfare has received much attention in the scientific literature within the last two decades. Studies have identified physiological and behavioral signs of distress in horses ridden for prolonged time in an HNP with their noseline behind the vertical (BTV), which may compromise their welfare. The objective of this study was to compare potential differences of HNPs shown in horse sales photographs advertised in an Australian horse sales magazine (Horse Deals) from the years 2005 and 2018. In addition, factors potentially impacting HNPs, such as type of tack presented in (e.g., noseband type), riding discipline, and competition experience of the horse, were investigated. The sample population (n = 570) comprised horses ridden with headgear and bit in walk, trot, or canter/gallop, advertised in an Australian horse sales magazine. Issues from April 2005 and October/November 2018 were selected. Head and neck position was categorized as BTV, on the vertical (OV), slightly in front of the vertical (IFV), or extremely in front of the vertical (EIFV; any HNP >30° IFV). Data were analyzed using the chi-squared test and post hoc testing via a multiple regression approach through SPSS and test of proportions via the Z-score calculator for two independent population proportions. Analysis of combined data from years 2005 and 2018 showed 47.0% (n = 570) of the horse sample population were advertised with HNPs BTV. Behind-the-vertical HNP was observed as the predominant HNP (57.8%; n = 268) in the warmblood/eventers/show/performance (WESP) category (P < .0005). In 2005, 53.4% (n = 303) of the sample population were ridden BTV compared with 39.7% (n = 267) in 2018 (P < .001), 12.9% (n = 303) were OV in 2005 compared with 15.0% (n = 267) in 2018 (P > .05), and 10.9% (n = 303) were IFV in 2005 compared with 27.3% (n = 267) in 2018 (P < .0004). These results suggest a positive development with fewer vendors/riders selecting images where the horse’s nose was BTV. However, this may be explained by the larger proportion of horses advertised in the WESP category in 2005 (63.0%; n = 303) versus 2018 (28.5%; n = 267), and the WESP category predominantly comprised of dressage, jumper, and eventing horses. In addition, the reduction of HNPs BTV from 53.4% (n = 303) in 2005 to 39.7% (n = 267) in 2018 could be attributed to the observation that in 2018, a larger proportion of horses were listed in categories that do not require the horses to be worked with a flexed HNP referred to as “on-the-bit” (e.g., western, endurance, Australian sStock horses). The HNP BTV remains preferential by a substantial proportion of the horse-owning public when advertising horses for sale, particularly in disciplines where the horse is worked in a flexed HNP or “on-the-bit.”
... Further, at walk the horse moves with substantially less muscle activity in the lower back and abdomen (Wakeling et al., 2007;Zsoldos et al., 2010), and with larger lateral movement of the body center of mass, compared to trot (Buchner et al., 2000). Maintaining a defined, non-natural, HNP alters neck muscle activity compared to the free position (Kienapfel, 2014), which may affect the coordination between the neck and trunk movements and necessitate increased core muscle tension. Both effects influence the normal gait mechanics of the walk, as evidenced by the finding in this and earlier studies that a restrained HNP decreases stride length at this gait (Gómez et al., 2006;Rhodin et al., 2005;Weishaupt et al., 2006). ...
Article
The debate on proper head and neck positions (HNP) in horse training is lively, but little is known about the biomechanical effects of various HNPs in horses ridden at walk. The aim was to quantify the influence of different HNPs on the kinematics of horses ridden at walk. The standard competition position (HNP2) was compared to a free, unrestrained position (HNP1), more flexed positions (HNP3, HNP4), a raised extended position (HNP5) and a forward-downward extended position (HNP6). An experimental study in seven high-level dressage horses ridden at walk on a treadmill was designed. Kinetic and kinematic measurements were obtained with different HNPs. HNP2 was used as a speed-matched reference. Kinematics were measured from skin-fixed markers recorded by high-speed video cameras. The kinetics of the limbs were measured by the force-measuring instrumentation of the treadmill. In HNP1, compared to HNP2, the lumbar back and the pelvis were more horizontally positioned (more extended), and fore- and hindlimb pro- and retraction increased, with increased caudal rotation of the femur during the second half of hindlimb stance. HNP6 induced similar changes as HNP1, but caused larger increases in forelimb pro- and retraction. In HNP3, HNP4 and HNP5 the pelvis was more angled (less extended) compared to HNP2 at hindlimb midstance, and in HNP3 and HNP4 also in early hindlimb stance. All three HNPs caused increased maximum flexion of the tarsus, stifle and metatarsophalangeal joint during the swing phase. HNP3 and HNP5, but not HNP4, had a decreasing influence on fore- and hindlimb pro- and retraction, and decreased caudal rotation of the femur during the second half of hindlimb stance.The main limitation was that horses were not ridden overground and the number of horses was small. Our conclusion was that changes in head and neck position can markedly affect the horse's movement pattern at walk.
... At the trot, the muscle activity of the M. brachiocephalicus (P = 0.00) and the M. extensor carpi radialis (P = 0.00), the stride length (P = 0.00) and the height of the arc of hoof flight (P = 0.00) increased significantly. This conforms with previous reports: an increase in speed led to an increase in muscle activity of the M. brachiocephalicus [27,28], the long head and the lateral head of the M. triceps [27,29], the M. gluteus medius, the M. tensor fascia lata and the M. longissimus dorsi [29], the M. splenius [29,30], the M. rectus abdominis [29,31] and the M. obliquus externus abdominis [31]. ...
Article
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Background information The present study aimed to investigate the effects of Kinesio Taping on the trajectory of the forelimb and the muscle activity of the M. brachiocephalicus and the M. extensor carpi radialis in horses. 19 horses and ponies of different breeds (body weight: 496±117 kg), gender (8 mares, 10 geldings and 3 stallions) and ages (14.9±6.9 years old) were analysed without Kinesio Tape (“no tape”), with Kinesio Tape (muscle facilitation application on both muscles of both sides, “with tape”) and immediately after Kinesio Taping (“post tape”) through kinematic motion analysis and surface electromyography on a treadmill at the walk (speed: 1.5±0.1 m/s) and trot (speed: 3.1±0.3 m/s). Results The results of the surface electromyography (maximum muscle activity at the walk and trot) and the kinematic motion analysis (maximum stride length and maximum height of the forelimbs flight arc at the walk and trot) showed that there were no significant differences between "no tape", "with tape" and "post tape". Conclusion To sum up, Kinesio Taping on the M. brachiocephalicus and the M. extensor carpi radialis does not affect (in a positive or negative manner) the trajectory of the forelimb or the muscle activity of the M. brachiocephalicus and the M. extensor carpi radialis in horses.
... Its bending moments will assume their greatest values, if the neck is stretched or if acceleration forces are transmitted through the forelimbs, especially in the canter. Both require increased muscle activities, which indeed have been observed by Kienapfel (2015). ...
Article
The activity patterns of trunk muscles are commonly neglected, in spite of their importance for maintaining body shape. Analysis of the biomechanics of the trunk under static conditions has led to predictions of the activity patterns. These hypotheses are tested experimentally by surface electromyography (EMG). Five horses, with and without a rider, were examined in the walk, trot and canter. Footfall was synchronised with EMG by an accelerometer. Averages of ten consecutive cycles were calculated and compared by statistical methods. The start and stop times of the muscle activities of 5–10 undisturbed EMG plots were determined and the averages and standard deviations calculated. In walking, muscle activities are minor. Electromyography (EMG) activity was increased in the m. rectus during the three-limb support. When the bending moments assume their greatest values, for example while the horses' mass is accelerated upward (two times earth acceleration) in the diagonal support phases in trot and canter the m. rectus, connecting the sternum with the pubic bone is most active. The m. obl. externus is most active when the torsional and bending moments are greatest during the same support phases, but not bilaterally, because the forces exerted on one side by the (recorded) m. obl. externus are transmitted on the other side by the (not recorded) m. obl. internus. While the hindlegs touch the ground in the trot and canter, ground reaction forces tend to flex the hip joint and the lumbar spine. Therefore, the vertebral column needs to be stabilised by the ipsilateral m. longissimus dorsi, which in fact can be observed. As a whole, our EMG data confirm exactly what has been predicted by theoretical analysis.
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Head and neck position (HNP) has been identified in literature as important influence on wellbeing. It was investigated in ridden elite dressage horses whether there is a relation between the HNP, ethological indicators and the grading in the warm-up area and in the test. 49 starters (83%) of a Grand-Prix Special (CDIO5 *) as part of the CHIO in Aachen 2018 and 2019 were examined. For each horse-rider pair, HNP (angle at vertical (AT), poll angle (PA), neck angel (NA)) used were analysed as well as conflict behavior for 3 minutes each in warm-up area and test. 6571 individual frames were used. The noseline was carried significantly less behind the vertical in test vs. warm-up (5.43 ° ± 4.19 vs. 11.01 ° ± 4.54 behind the vertical; T = 34.0; p < 0.05). The horses showed significantly less conflict behavior in the test vs. warm-up (123 ± 54 vs. 160 ± 75) (T = 76.00; p < 0.01). In the latter, a smaller PA and more defensive behaviour of the horses was observed compared to the test. A correlation between the grading of test and HNP was found (R = 0.38; p < 0.05). The further the noseline was behind the vertical, the higher was the chance of a good rating. The higher riders were ranked in the “FEI world ranking”, the higher were their marks in the competition (2018: r = -0.69, p < 0.05; 2019: r = -0.76, p < 0.05). Horses of riders higher in world ranking tended to show more unusual oral behaviour (r = -0.30, p < 0.05), and a noseline stronger behind the vertical (r = -0.37, p < 0.05) resulting in a smaller NA (r = 0.43, p < 0.05). This are from the point of view of animal welfare problematic results.
Article
Muscle activities of the major hindlimb muscles have been reported to decrease with fatigue in horses. However, those in other muscles have been scarcely reported. We aimed to quantify fatigue-induced electromyographic changes in head and neck muscles and muscles around the shoulder joints in horses. Surface electromyographic recording of the splenius, brachiocephalicus, infraspinatus, and deltoid muscles was performed on a total of nine healthy Thoroughbred horses. Horses galloped on a treadmill inclined to 3% at a constant speed (12.7-14.6 m/second) to make them fatigued after approximately 5 minutes. They trotted at 3.5 m/second before and after this exercise. Stride frequency, integrated electromyographic values for a stride, and median frequency of the muscle discharge were calculated every 30 seconds. These parameters were compared at the start and end of the gallop exercise for the lead and trailing limbs and while trotting before and after the exercise using a paired t-test. The stride frequency significantly decreased at the end of the gallop (P < .001), whereas it did not change while trotting. Integrated electromyographic values of the splenius and brachiocephalicus muscles in both lead and trailing limbs at the gallop and those of both left and right sides at the trot significantly decreased with fatigue (P < .05), whereas those of infraspinatus and deltoid muscles did not change at either gallop or trot. No changes were observed in median frequency in any muscles with fatigue. These results suggest that splenius and brachiocephalicus muscle activities can be associated with stride frequency and speed.
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Take Home Message-There has been a greater awareness of the role of neck pain and dysfunction in athletic performance across equine disciplines. To better understand how to manage these issues and to differentiate clinical signs of forelimb lameness originating from the lower cervical spine versus the forelimb itself, a working knowledge of structural and functional relationships of the cervical region and cervicothoracic junction is needed.
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The influence of head-neck-positions on the soft tissues of the neck was determined in a selection of various horses. 25 horses of different breeds were induced to assume a number of pre-defined head-neck-positions. This was done with the help of a rope, that was on both sides fixed to a girth and passed through the rings of the bit. The neck was divided into 5 segments and the lengths of those segments were measured in 7 selected positions. Radiographs were taken in a limited number of horses in the different positions to obtain objective, quantitative data about the distances between the spinous processes that make up the withers. The degree of stretching or shortening of the respective segments was determined and correlations were established between the segments. Furthermore, moment arms of a large number of muscles were also determined and it was established whether these structures shortened or were stretched in the various positions. With respect to the hyperflexed or "Rollkur" position, it was concluded that the often made statement that this position would "overstretch" the structures in the neck could not be confirmed, but that data concerning the effects on the withers also could not confirm earlier reports that the position would help in overall ventral flexing of the back. In all flexed positions of the head in relation to the neck, the m. splenius and/or funiculus nuchae exert redirectional forces on the most cranial vertebrae C1, C2, or C3. These do hardly exceed the tensile forces in the muscles and ligaments.
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Pferdeheilkunde 27 358 Pferdeheilkunde 27 (2011) 4 (Juli/August) 358-370 Was bewirkt das Aufrollen des Pferdehalses? -Einflüsse der Halsstellung auf die Dehnung der Weichteile Kathrin Kienapfel und Holger Preuschoft Zusammenfassung 25 Pferde verschiedener Rassen wurden veranlasst, eine Reihe von vorher festgelegten, typischen Kopf-Hals-Stellungen einzunehmen. Zu diesem Zweck wurde ein Seil vom Trensenring der einen Seite durch die Ösen eines Longiergurtes zum Trensenring der anderen Seite geführt. Der Mähnenkamm wurde in 5 Abschnitte unterteilt und die Längen dieser Segmente wurden in 7 verschiedenen Kopf-Hals-Stel-lungen gemessen. Von den Dornfortsätzen der vorderen Brustwirbel, welche den Widerrist bilden, wurden bei 5 Pferden auch Röntgenauf-nahmen angefertigt. Das Ausmaß der Verkürzung oder Dehnung der einzelnen Segmente wurde festgestellt und die Korrelationen zwischen den Segmenten wurden geprüft. Die Hebelarme der Muskeln an der Dorsalseite des Halses wurden für verschiedene Intervertebralgelenke bestimmt und die Dehnung bzw. Verkürzung der Muskeln in den verschiedenenen Kopf-Hals-Stellungen wurde ermittelt. Die häufig aufge-stellte Behauptung, dass die hyperflektierte oder "Rollkur-Position" die Muskeln bzw. die Nackenbänder "überdehnt", kann nicht bestätigt werden. Indessen stimmen die Befunde über den Widerrist auch nicht mit früheren Angaben überein, nach denen die Hyperflexion einen Beitrag zur "Aufwölbung" des Rückens (Ventralflexion des Rumpfes) leisten soll. Bei allen Beugungen des Kopfes gegen den Hals (Beizäu-mung) üben die Muskeln und Bänder des Nackens Umlenkkräfte gegen die kopfnahen Halswirbel (C1, C2, C3) aus. Diese sind nicht viel größer als die Zugkräfte in den Muskeln und Bändern. What effects hyperflexion of the neck? The influence of the head-neck position on stretching of the soft tissue The influence of head-neck-positions on the soft tissues of the neck was determined in a selection of various horses. 25 horses of different breeds were induced to assume a number of pre-defined head-neck-positions. This was done with the help of a rope, that was on both sides fixed to a girth and passed through the rings of the bit. The neck was divided into 5 segments and the lengths of those segments were mea-sured in 7 selected positions. Radiographs were taken in a limited number of horses in the different positions to obtain objective, quantitative data about the distances between the spinous processes that make up the withers. The degree of stretching or shortening of the respective seg-ments was determined and correlations were established between the segments. Furthermore, moment arms of a large number of muscles were also determined and it was established whether these structures shortened or were stretched in the various positions. With respect to the hyper-flexed or "Rollkur" position, it was concluded that the often made statement that this position would "overstretch" the structures in the neck could not be confirmed, but that data concerning the effects on the withers also could not confirm earlier reports that the position would help in overall ventral flexing of the back. In all flexed positions of the head in relation to the neck, the m. splenius and/or funiculus nuchae exert redirectional forces on the most cranial vertebrae C1, C2, or C3. These do hardly exceed the tensile forces in the muscles and ligaments.
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Pferdeheilkunde 27 358 Pferdeheilkunde 27 (2011) 4 (Juli/August) 358-370 Was bewirkt das Aufrollen des Pferdehalses? -Einflüsse der Halsstellung auf die Dehnung der Weichteile Kathrin Kienapfel und Holger Preuschoft Zusammenfassung 25 Pferde verschiedener Rassen wurden veranlasst, eine Reihe von vorher festgelegten, typischen Kopf-Hals-Stellungen einzunehmen. Zu diesem Zweck wurde ein Seil vom Trensenring der einen Seite durch die Ösen eines Longiergurtes zum Trensenring der anderen Seite geführt. Der Mähnenkamm wurde in 5 Abschnitte unterteilt und die Längen dieser Segmente wurden in 7 verschiedenen Kopf-Hals-Stel-lungen gemessen. Von den Dornfortsätzen der vorderen Brustwirbel, welche den Widerrist bilden, wurden bei 5 Pferden auch Röntgenauf-nahmen angefertigt. Das Ausmaß der Verkürzung oder Dehnung der einzelnen Segmente wurde festgestellt und die Korrelationen zwischen den Segmenten wurden geprüft. Die Hebelarme der Muskeln an der Dorsalseite des Halses wurden für verschiedene Intervertebralgelenke bestimmt und die Dehnung bzw. Verkürzung der Muskeln in den verschiedenenen Kopf-Hals-Stellungen wurde ermittelt. Die häufig aufge-stellte Behauptung, dass die hyperflektierte oder "Rollkur-Position" die Muskeln bzw. die Nackenbänder "überdehnt", kann nicht bestätigt werden. Indessen stimmen die Befunde über den Widerrist auch nicht mit früheren Angaben überein, nach denen die Hyperflexion einen Beitrag zur "Aufwölbung" des Rückens (Ventralflexion des Rumpfes) leisten soll. Bei allen Beugungen des Kopfes gegen den Hals (Beizäu-mung) üben die Muskeln und Bänder des Nackens Umlenkkräfte gegen die kopfnahen Halswirbel (C1, C2, C3) aus. Diese sind nicht viel größer als die Zugkräfte in den Muskeln und Bändern. What effects hyperflexion of the neck? The influence of the head-neck position on stretching of the soft tissue The influence of head-neck-positions on the soft tissues of the neck was determined in a selection of various horses. 25 horses of different breeds were induced to assume a number of pre-defined head-neck-positions. This was done with the help of a rope, that was on both sides fixed to a girth and passed through the rings of the bit. The neck was divided into 5 segments and the lengths of those segments were mea-sured in 7 selected positions. Radiographs were taken in a limited number of horses in the different positions to obtain objective, quantitative data about the distances between the spinous processes that make up the withers. The degree of stretching or shortening of the respective seg-ments was determined and correlations were established between the segments. Furthermore, moment arms of a large number of muscles were also determined and it was established whether these structures shortened or were stretched in the various positions. With respect to the hyper-flexed or "Rollkur" position, it was concluded that the often made statement that this position would "overstretch" the structures in the neck could not be confirmed, but that data concerning the effects on the withers also could not confirm earlier reports that the position would help in overall ventral flexing of the back. In all flexed positions of the head in relation to the neck, the m. splenius and/or funiculus nuchae exert redirectional forces on the most cranial vertebrae C1, C2, or C3. These do hardly exceed the tensile forces in the muscles and ligaments.
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Much too tight! On the effects of nosebands The reality of riding in general and equine sports in particular is losing contact with the traditional postulates of the art of horseback riding. Contradictions even occur for example in the way in which nosebands are fixed. Complicate arrangements of superfluous straps and ties induce erroneous interpretations of bitting arrangements. Therefore, the true effects of the most frequently used conventional headgear are demonstrated empirically and tested mathematically. Virtually all conventional and wide-spread, often cited textbooks of riding postulate the horse chewing on the bit. Chewing of course is only possible, if the jaws can be opened to some degree. Exactly this is absolutely impossible if the noseband is too tight. Essential in this context is the tie, which gives least freedom, regardless of where it is placed: above the bit (the “English” arrangement) or below (the “Hannoveranian” arrangement), and regardless of the other, less tight band. Controlling the width of the nosebands is most reliable if done in the conservative way by placing two fingers between the noseband and the nasal bone. This method is less prone to error, than taking the measurement on the ventral side of the lower jaw. The attempt to control the appropriate width of a noseband on the side of the horse s head is complete nonsense. If full occlusion is taken as the starting point, a loosening of the noseband( s) by at least 1 hole is necessary to allow the incisors a distance of one finger s breadth, or the premolars a distance of 12 mm.
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In many equestrian activities a specific position of head and/or neck is required that is dissimilar to the natural position. There is controversy about the effects of these positions on locomotion pattern, but few quantitative data are available. To quantify the effects of 5 different head and neck positions on thoracolumbar kinematics of the horse. Kinematics of 7 high level dressage horses were measured walking and trotting on an instrumented treadmill with the head and neck in the following positions: HNP2 = neck raised, bridge of the nose in front of the vertical; HNP3 = as HNP2 with bridge of the nose behind the vertical; HNP4 = head and neck lowered, nose behind the vertical; HNP5 = head and neck in extreme high position; HNP6 = head and neck forward and downward. HNP1 was a speed-matched control (head and neck unrestrained). The head and neck positions affected only the flexion-extension motion. The positions in which the neck was extended (HNP2, 3, 5) increased extension in the anterior thoracic region, but increased flexion in the posterior thoracic and lumbar region. For HNP4 the pattern was the opposite. Positions 2, 3 and 5 reduced the flexion-extension range of motion (ROM) while HNP4 increased it. HNP5 was the only position that negatively affected intravertebral pattern symmetry and reduced hindlimb protraction. The stride length was significantly reduced at walk in positions 2, 3, 4 and 5. There is a significant influence of head/neck position on back kinematics. Elevated head and neck induce extension in the thoracic region and flexion in the lumbar region; besides reducing the sagittal range of motion. Lowered head and neck produces the opposite. A very high position of the head and neck seems to disturb normal kinematics. This study provides quantitative data on the effect of head/neck positions on thoracolumbar motion and may help in discussions on the ethical acceptability of some training methods.
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Back pain is a common problem, and one contributing factor may be the training method used. The head and neck position plays an important role in the training of horses. However, how different positions affect the back and limb kinematics of the horse is not well described scientifically. It is important to understand how the rider affects the kinematics of the horse during training in order to prevent injury and also to facilitate rehabilitation of a horse with lameness or back dysfunction. The purpose of this thesis was to evaluate the effect of different head and neck positions on the kinematics of the back and limbs of the horse. The horses used in the present studies were privately owned riding horses competing at different levels. The measurements were done with skin-fixed markers and high speed cameras. The markers were placed on the head, neck, back and limbs of the horse. Cameras were positioned around a treadmill and in study III and IV the treadmill was instrumented with a force measuring system. In study I-II, the horses walked and trotted on the treadmill with three different head and neck positions achieved with side and long reins respectively. In study III and IV six positions were evaluated with and without rider. The head and neck position influenced the back and limb kinematics significantly of the horse, especially at walk. The range of flexion-extension movement of the back and the stride length decreased when the neck was restrained in the high position. Even a low position restricted the movement of the back. The different head and neck positions also affected the curvature of the back. With a raised position of the neck the cranial part of the spine was extended while a low position caused a flexion of the spine. The unrestrained horse seems to rely more on the forelimbs for vertical support and use the hind limbs in a more horizontal direction. At walk the stride length and the movement of the pelvis increased, which can be useful for training purposes, while at trot the gait economy is likely improved with a free head and neck position. Extreme elevation of the head and neck caused the most dramatic kinematic changes. Working the horse in this position for a long period of time or at high intensity may therefore lead to transition from training effect to injury. Intervention on the head and neck position can markedly affect the movement pattern at walk, even if the rider’s hand is light enough to allow the horse a normal range of neck movement. At trot the movement pattern is less sensitive to differences in the position at which the head and neck is restrained, as long as not extreme, but the movements differ clearly between restrained positions and free position. The head and neck position also affected the limb kinematics, weight distribution between fore- and hind limbs and thereby the ground reaction forces.
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Ryggömhet är ett vanligt problem hos ridhästar. Orsaken är ofta multifaktoriell men en faktor som kan vara viktig är hur hästen tränas. En vanlig åsikt hos ryttare och tränare är att hästens form, d.v.s. huvud- och halspositionen, påverkar ryggen men detta har aldrig bevisats. Tidigare studier har visat att hästens form påverkar frambenen och att en gramantygel kombinerad med en vanlig tygel kan förskjuta hästens vikt bakåt. Syftet med den här studien var att undersöka hur ryggens rörelse påverkades av tre olika huvud- och halspositioner. De tre olika positionerna var låg, hög (“på tygeln”) samt fri position där hästen gick med halsen framsträckt i valfri höjd. Åtta friska ridhästar ingick i försöket. De försågs med 17 reflektoriska hudmarkörer placerade på huvudet, ovanför tornutskotten längs ryggraden, på bäckenet samt på benen. Hästarna fick skritta och trava på en rullande matta. Huvud-halspositionerna varierades med hjälp av inspänningstyglar fästa till en gjord. Sex kameror registrerade markörernas tredimensionella rörelse. Varje ryggkota kan rotera i tre plan och det ger upphov till tre typer av rörelser: dorsoventral flexion och extension, lateral böjning samt axial rotation. Alla tre typer av rörelse mättes, men endast dorsoventral flexion och extension presenteras här. I skritt minskade rörelsen i ländryggen när hästen spändes in lågt och rörelsen minskade ännu mer när hästen gick på tygeln jämfört med den fria formen. I trav var skillnaden inte så stor förutom vid ryggsegment T10 och T17 där rörelsen minskade när hästen gick på tygeln jämfört med den fria formen. I skritt påverkade inspänningen även steglängden som kortades, mest vid den höga inspänningen men även vid den låga inspänningen. I trav påverkades inte steglängden av huvud- halspositionen. En förklaring till det kan vara att hästen naturligt rör sig olika i skritt och trav. I skritt rör den huvudet mer och en fixering av huvudet medför att rörelsen hämmas. I trav håller hästen huvudet mer stilla och påverkas inte på samma sätt av fixeringen. Tidigare studier visar att steglängden har en direkt inverkan på ryggens rörelse och för att ta reda på om det är ett direkt samband mellan hästens form och ryggens rörelse skulle man behöva ha steglängden konstant. Ett sätt kan vara att tömköra hästen där man kan driva hästen framåt och därigenom kanske påverka steglängden.
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Treadmill locomotion is frequently used for training of sport horses, for diagnostic purposes and for research. Identification of the possible biomechanical differences and similarities between the back movement during treadmill (T) and over ground (O) locomotion is essential for the correct interpretation of research results. To compare the kinematics of the thoracolumbar vertebral column in treadmill and over ground locomotion in healthy horses. Six sound Dutch Warmblood horses trotted on a T and O during 10 s at their own preferred velocity (mean +/- s.d. 3.6 +/- 0.3 m/s T and 3.6 +/- 0.1 m/s O), which was the same in both conditions. Kinematics of the vertebral column was captured by infrared cameras using reflective skin markers attached over the spinous processes of selected vertebrae and other locations. Flexion-extension and lateral bending range of motion (ROM), angular motion pattern (AMP) and intravertebral pattern symmetry (IVPS) of 5 vertebral angles (T6-T10-T13, T10-T13-T17, T13-T17-L1, T17-L1-L3 and L1-L3-15) were calculated. Neck angle, linear and temporal stride parameters and protraction-retraction angles of the limbs were also calculated. The vertical ROM (flexion-extension) was similar in both conditions, but the horizontal ROM (lateral bending) of the lumbar angles T17-L1-L3 and L1-L3-L5 was less during T locomotion (mean +/- s.d. difference of 1.8 +/- 0.6 and 1.7 +/- 0.9 degrees, respectively, P > 0.05). During O locomotion, the symmetry pattern of the lumbar vertebral angles was diminished from 0.9 to 0.7 (1 = 100% symmetry) indicating increased irregularity of the movement (P > 0.05). No differences were found in the basic linear and temporal stride parameters and neck angle. Vertebral kinematics during treadmill locomotion is not identical to over ground locomotion, but the differences are minor. During treadmill locomotion lumbar motion is less, and caution should be therefore taken when interpreting lumbar kinematics.
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Dressage involves training of the horse with the head and neck placed in a position defined by the rider. The best position for dressage training is currently under debate among riders and trainers, but there are few scientific data available to confirm or disprove the different views. To evaluate the kinematic effects of different head and neck positions (HNPs) in elite dressage horses ridden at trot. Seven high-level dressage horses were subjected to kinetic and kinematic measurements when ridden on a treadmill with the head and neck in 5 different positions. Compared to free trot on loose reins the HNP desired for collected trot at dressage competitions increased T6 vertical excursion, increased sacral flexion and decreased limb retraction after lift-off. Further increasing head or head and neck flexion caused few additional changes while an extremely elevated neck position increased hindlimb flexion and lumbar back extension during stance, increased hindlimb flexion during swing and further increased trunk vertical excursion. The movements of the horse are significantly different when ridden on loose reins compared to the position used in collected trot. The exact degree of neck flexion is, however, not consistently correlated to the movements of the horse's limbs and trunk at collected trot. An extremely elevated neck position can produce some effects commonly associated with increased degree of collection, but the increased back extension observed with this position may place the horse at risk of injury if ridden in this position for a prolonged period. Head and neck positions influence significantly the kinematics of the ridden horse. It is important for riders and trainers to be aware of these effects in dressage training.
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It is believed that the head-neck position (HNP) has specific effects on the loading pattern of the equine locomotor system, but very few quantitative data are available. To quantify the effects of 6 different HNPs on forelimb-hindlimb loading and underlying temporal changes. Vertical ground reaction forces of each limb and interlimb coordination were measured in 7 high level dressage horses walking and trotting on an instrumented treadmill in 6 predetermined HNPs: HNP1--unrestrained; HNP2--elevated neck, bridge of the nose in front of the vertical; HNP3--elevated neck, bridge of the nose behind the vertical; HNP4--low and flexed neck; HNP5--head and neck in extreme high position; and HNP6--forward downward extension of head and neck. HNP1 served as a velocity-matched control. At the walk, the percentage of vertical stride impulse carried by the forehand (Iz(fore)) as well as stride length and overreach distance were decreased in HNP2, HNP3, HNP4 and HNP5 when compared to HNP1. At the trot, Iz(fore) was decreased in HNP2, HNP3, HNP4 and HNP5. Peak forces in the forelimbs increased in HNP5 and decreased in HNP6. Stance duration in the forelimbs was decreased in HNP2 and HNP5. Suspension duration was increased in HNP2, HNP3 and HNP5. Overreach distance was shorter in HNP4 and longer in HNP6. In comparison to HNP1 and HNP6, HNPs with elevation of the neck with either flexion or extension at the poll as well as a low and flexed head and neck lead to a weight shift from the forehand to the hindquarters. HNP5 had the biggest effect on limb timing and load distribution. At the trot, shortening of forelimb stance duration in HNP5 increased peak vertical forces although Iz(fore) decreased. Presented results contribute to the understanding of the value of certain HNPs in horse training.
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Computercinemotography is a new method for analyzing the locomotor pattern of horses. Similar to the EKG, the CKG measures time parameters and accelerations not preceptible for the human sense organs with sufficient precission. The accelerations were measured simultanously at the 4 metapodials during a series of about 20 cycles. The measured curves were plotted. Important parameters such as duty factor, phase displacement, and accelerations for impact, lift off and swinging were obtained from smoothened curves. Judgements about the measured curves are based on five criteria: Comparison between right and left side, comparison within the individual, comparison between individuals and biomechanic plausibility. Differences can be quantified numerically. By means of Computercinematography, lameness can be detected and quantified. This paper presents an average horse sampled from 30 representative individuals.
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Since about twenty years sport horses often are ridden extremely overbended(atlantooccipitale flexion), mostly with a deep neck(cervicothoracale flexion), but by some riders or in some situations with an elevated neck(cervicothoracale extension). These head-neck-positions are possible by the natural flexibility of the neck and the head. The described positions differ from the position, the horses choose while moving without restrictions by a rider. Especially corresponding to the way of moving with high demands , the horses take the position of the neck in a medium hight and the nose-forehead-line before the vertical. They properly do that to promote the effect of head and neck for the balance, for breathing and for the perception. Especially the overbending practised in an extreme extent and for a longer time differs from the rules of the national and the international riding organisations. Orthodox interpreters of the riding doctrine turn against the practice of extreme overbending, in these days usually denominated by the terms "Rollkur", "Hyperflexion" oder "LDR (Low, deep, round)". In their view this method not only relinquishes essential principles of training a riding horse but also endangers the well being and the health of the horse. The riding organisations do not take a definite position against overbending. Obviously they are primarly interested not to see diminuished the image of the riders they are looking for and the sport, which they organize and which they are financed by. Still the different experiments, investigations and statements done by veterinarians about the physical and the psychic consequences of the extreme overbending do not show a clear picture. Some veterinarians see the endangering of the health of extensively bended vertebra joints, the hindering of the movements, breathing and perception, just as well detractions from the well beeing, reaching to pain and suffering. Some veterinarians negate the consequences, if the overbending is practised well. From the view of functional morphology and from the view of orthopaedics it is unlikely, that the extreme deviation from the natural disposition of the horse works without consequences. For these views and for the orientation of the training of the horse on his natural dispositions the absence of consequences would be an essential fact. To answer these questions valid and reliable results of further investigations are required.
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We used an opportunistic review of photographs of different adult and juvenile horses walking, trotting, and cantering (n = 828) to compare the angle of the nasal plane relative to vertical in feral and domestic horses at liberty (n = 450) with ridden horses advertised in a popular Australian horse magazine (n = 378). We assumed that horses in advertisements were shown at, what was perceived by the vendors to be, their best. Of the ridden horses, 68% had their nasal plane behind the vertical. The mean angle of the unridden horses at walk, trot, and canter (30.7 ± 11.5; 27.3 ± 12.0; 25.5 ± 11.0) was significantly greater than those of the ridden horses (1.4 ± 14.1; −5.1 ± −11.1; 3.1 ± 15.4, P < 0.001). Surprisingly, unridden domestic horses showed greater angles than feral horses or domestic horses at liberty. We compared adult and juvenile horses in all 3 gaits and found no significant difference. Taken together, these findings demonstrate that the longitudinal neck flexion of the degree desirable by popular opinion in ridden horses is not a common feature of unridden horses moving naturally. Moreover, they suggest that advertised horses in our series are generally being ridden at odds with their natural carriage and contrary to the international rules of dressage (as published by the International Equestrian Federation). These findings are discussed against the backdrop of the established doctrine, which states that carrying a rider necessitates changes in longitudinal flexion, and in the context of the current debate around hyperflexion.
Article
Rollkur, the usually coercively obtained hyperflexion of the horse's neck, is employed as a training method by some dressage riders; however, its use is controversial as it may cause discomfort and adversely affect the horse's welfare. The objectives of this study were to determine: (1) if horses showed differences in stress, discomfort and fear responses as measured by heart rate and behaviour when ridden in Rollkur (R) obtained by pressure on the reins compared to regular poll flexion (i.e. with the nose-line being at or just in front of the vertical; N), and (2) if they showed a preference between the two riding styles when given the choice. Fifteen riding horses were ridden 30 times through a Y-maze randomly alternating between sides. Riding through one arm of the Y-maze was always followed by a short round ridden in R, whereas riding through the other arm was followed by a short round ridden in N. Immediately after the conditioning phase, horses were again repeatedly ridden into the maze; however, riders left it to the horse to decide which arm of the maze to enter. During R, horses moved slower and showed more often behavioural signs of discomfort, such as tail-swishing, head-tossing or attempted bucks (P
The study aimed to investigate the effect of speed and incline on EMG activity in the brachiocephalicus muscle and the long and lateral heads of the triceps brachii muscle. Six horses were exercised on a treadmill at walk (1.7 m s-1), trot (4.0 m s-1) and right lead canter (7.2 m s-1) on a 0 and 8% incline. Kinematics (120 Hz) and electromyography (EMG) (2000 Hz) data were collected simultaneously from the left forelimb of each horse. Significant differences in relation to velocity and incline were identified using two-way ANOVA and post hoc Student–Newman–Keuls tests (P≪0.05). The degree of association between timing of peak EMG intensity and the timing of maximum protraction/retraction angles was assessed using ANCOVA. Increases in velocity led to an increase in stride length and reduction in stride duration. Exercise on the incline increased stance duration and decreased swing duration, while limb protraction/retraction increased. The time of peak EMG activity in the brachiocephalicus was highly related to time of maximum limb retraction (r2=0.84). The time of peak EMG activity in the long head of the triceps brachii was highly associated with time of maximum limb protraction (r2=0.87). Increases in velocity and incline both caused an increase in the intensity of the EMG signal from each muscle. Duration of EMG activity was prolonged in the long head of the triceps brachii muscle and in the brachiocephalicus muscle as velocity increased. Treadmill speed and slope therefore both alter the workload placed on forelimb muscles.
Article
Bringing the head and neck of ridden horses into a position of hyperflexion is widely used in equestrian sports. In our study, the hypothesis was tested that hyperflexion is an acute stressor for horses. Salivary cortisol concentrations, heart rate, heart rate variability (HRV) and superficial body temperature were determined in horses (n = 16) lunged on two subsequent days. The head and neck of the horse was fixed with side reins in a position allowing forward extension on day A and fixed in hyperflexion on day B. The order of treatments alternated between horses. In response to lunging, cortisol concentration increased (day A from 0.73 ± 0.06 to 1.41 ± 0.13 ng/ml, p < 0.001; day B from 0.68 ± 0.07 to 1.38 ± 0.13 ng/ml, p < 0.001) but did not differ between days A and B. Beat-to-beat (RR) interval decreased in response to lunging on both days. HRV variables standard deviation of RR interval (SDRR) and RMSSD (root mean square of successive RR differences) decreased (p < 0.001) but did not differ between days. In the cranial region of the neck, the difference between maximum and minimum temperature was increased in hyperflexion (p < 0.01). In conclusion, physiological parameters do not indicate an acute stress response to hyperflexion of the head alone in horses lunged at moderate speed and not touched with the whip. However, if hyperflexion is combined with active intervention of a rider, a stressful experience for the horse cannot be excluded.
Article
Skeletal muscle activity can be concentric or eccentric, anisometric or isometric and correlation of the equine splenius muscle activity with the movement of its effector joints at walk and trot has not yet been fully characterised. Investigating activity of the splenius muscle together with kinematics of head and cranial neck at walk and trot. Kinematics and surface electromyography were measured in 6 horses (8-20-years-old, 450-700 kg) without signs of neck pain. Markers were placed on left and right crista facialis, and on left and right cervical vertebrae 1 and 3. Head and neck angle was calculated in sagittal and horizontal planes. Electrodes were placed over both splenius muscles at the level of C2. Left and right muscle activity was compared using Student t test for paired samples and correlations calculated using Pearson correlation coefficient. Significance was set at P < 0.05. In all horses, maximum surface electromyography (sEMG) values at the trot were higher than at the walk. The intraindividual differences between maximum and minimum values of the EMG ranged from 45-127 mV in walk and from 154-524 mV in trot. Flexion-extension C1 angle changed by 43° in walk and 27° in trot. For each motion cycle, 2 EMG maxima were found in both gaits, occurring just prior to maximum extension of the C1 angle. Lateral bending at C1 angle changed by 16° in walk and 17° in trot and EMG reached maximum values bilaterally during maximum lateral bending at walk. The splenius muscle reaches maximum activity at the beginning of the forelimb stance phases in trot, indicating functional stabilisation against flexion of the head and neck. Unilateral activity of the splenius muscle representing stabilisation against lateral movement was not found.
Article
Head and neck positions (HNP) in sport horses are under debate in the equine community, as they could interfere with equine welfare. HNPs have not been quantified objectively and no information is available on their head and neck loading. To quantify in vivo HNPs in sport horses and develop o a model to estimate loading on the cervical vertebrae in these positions. Videos were taken of 7 Warmbloods at walk on a straight line in 5 positions, representing all HNPs during Warmblood training and competition. Markers were glued at 5 anatomical landmarks. Two-dimensional angles and distances were determined from video frames for the 5 HNPs and statistically compared (P < 0.05). A new simulation model was developed to estimate nuchal ligament cervical loading at these HNPs. The mean angles were significantly different between the 5 HNPs for the line between C1 and T6 with the horizontal and for the line connecting the facial crest (CF) and C1 with the vertical, while the vertical distance from CF to the lateral styloid process of the radius (PS) was significantly different between all 5 positions (P < 0.05). The estimated nuchal ligament loading appeared to be largest at the origin of C2 for all HNPs, except for the 'hyperextended' HNP5; the 'hyperflexed' HNP4 showed the largest loading values on the nuchal ligament origins at all locations. HNPs can be accurately quantified in the sagittal plane from angles and distances based on standard anatomical landmarks and home-video captured images. Nuchal ligament loading showed the largest estimated values at its origin on C2 in hyperflexion (HNP4). Modelling opens further perspectives to eventually estimate loading for individual horses and thus ergonomically optimise their HNP, which may improve the welfare of the sport horse during training and competition.
Article
In dressage, the head and neck position has become an issue of concern as certain extreme positions may imply a welfare risk for the horse. In man, extension and flexion of the cervical spine cause a decrease and increase in intervertebral foramina dimensions, respectively. However, in horses, the influence of flexion and extension on foramina dimensions and its possible interference with peripheral nerve functioning remains unknown. To determine the effect of ex vivo flexion and extension on intervertebral foramina dimensions in the equine cervical spine. Computed tomography was performed on 6 cadaver cervical spines from adult Warmblood horses subjected to euthanasia for reasons unrelated to cervical spine abnormalities, in a neutral position, in 20 and 40° extension, and in 20 and 40° flexion. Multiplanar reconstructions were made to obtain transverse images perpendicular to the long axis of each pair of intervertebral foramina from C2-T1. Intervertebral foramina dimensions were measured in the 5 positions. Compared to the neutral position, 40° extension caused a decrease in foramina dimensions at segments C4-C5, C5-C6, C6-C7 (P < 0.001) and C7-T1 (P < 0.002); 20° extension caused a decrease in foramina dimensions at segments C5-C6 (P < 0.02), C6-C7 (P < 0.001) and C7-T1 (P < 0.01); 20° flexion caused an increase in foramen length at segment C6-C7 (P < 0.01). Ex vivo extension of the cervical spine causes a decrease in intervertebral foramina dimensions at segments C4-T1, similar to that found in man. In vivo extension of the cervical spine could possibly interfere with peripheral nerve functioning at segments C4-T1. This effect may be even more profound in patients with a reduced intervertebral foramina space, for example in the presence of facet joint arthrosis.
Article
There has been growing interest in training techniques with respect to the head and neck position (HNP) of the equine athlete. Little is known about the influence of HNP on neuromuscular transmission in neck muscles. To test the hypothesis that different HNPs have effect on single fibre (SF), quantitative electromyographic (QEMG) examination and muscle enzyme activity directly after moderate exercise. Seven Warmblood horses were studied using a standard exercise protocol in 5 HNPs: HNP1: unrestrained; HNP2: neck raised; bridge of nose around the vertical; HNP4: neck lowered and considerably flexed, bridge of nose pointing towards the chest; HNP5: neck raised and considerably extended; bridge of nose in front of the vertical; HNP7: neck lowered and flexed; bridge of nose pointing towards the carpus. Mean consecutive difference (MCD) of single muscle fibre potentials and motor unit action potential (MUP) variables (amplitude, duration, area, turns and phases) were recorded in each fixed position directly after exercise at rest using commercial EMG equipment. Muscle enzyme activity was measured before and 4, 6 and 24 h after exercise. Mean consecutive difference in all HNPs was higher than in HNP1 (22 µs, P < 0.001) of which HNP4 was highest with 39 µs compared to 30 µs in HNP2 (P = 0.04); MCD in HNP 5,7 was with 25 µs lower than in HNP 2 and 4 (P < 0.001). Odds ratio for MCD suggestive for conduction delay or block was 13.6 in HNP4 compared to HNP1 (P < 0.001). Motion unit action potential variables followed the same pattern as MCD. Lactate dehydrogenase (LDH) activity increased in HNP4 at 4 h (P = 0.014), 6 h (P = 0.017) and 24 h (P = 0.038) post exercise and in HNP5 and HNP7 at 4 h (P = 0.037; 0.029). HNP4 in particular leads to a higher rise in LDH activity, MCD and MUP variables, indicating that HNPs have effect on variables characterising neuromuscular functionality.
Article
Little is known in quantitative terms about the influence of different head-neck positions (HNPs) on the loading pattern of the locomotor apparatus. Therefore it is difficult to predict whether a specific riding technique is beneficial for the horse or if it may increase the risk for injury. To improve the understanding of forelimb-hindlimb balance and its underlying temporal changes in relation to different head and neck positions. Vertical ground reaction force and time parameters of each limb were measured in 7 high level dressage horses while being ridden at walk and trot on an instrumented treadmill in 6 predetermined HNPs: HNP1 - free, unrestrained with loose reins; HNP2 - neck raised, bridge of the nose in front of the vertical; HNP3 - neck raised, bridge of the nose behind the vertical; HNP4 - neck lowered and flexed, bridge of the nose considerably behind the vertical; HNP5 - neck extremely elevated and bridge of the nose considerably in front of the vertical; HNP6 - neck and head extended forward and downward. Positions were judged by a qualified dressage judge. HNPs were assessed by comparing the data to a velocity-matched reference HNP (HNP2). Differences were tested using paired t test or Wilcoxon signed rank test (P<0.05). At the walk, stride duration and overreach distance increased in HNP1, but decreased in HNP3 and HNP5. Stride impulse was shifted to the forehand in HNP1 and HNP6, but shifted to the hindquarters in HNP5. At the trot, stride duration increased in HNP4 and HNP5. Overreach distance was shorter in HNP4. Stride impulse shifted to the hindquarters in HNP5. In HNP1 peak forces decreased in the forelimbs; in HNP5 peak forces increased in fore- and hindlimbs. HNP5 had the biggest impact on limb timing and load distribution and behaved inversely to HNP1 and HNP6. Shortening of forelimb stance duration in HNP5 increased peak forces although the percentage of stride impulse carried by the forelimbs decreased. An extremely high HNP affects functionality much more than an extremely low neck.
Article
Dynamic nasopharyngeal collapse with upper airway obstruction is an important cause of exercise intolerance in performance horses. Its underlying pathophysiology is not fully understood. We hypothesize that head position affects pharyngeal diameter, and thus head position may be a contributing factor to nasopharyngeal obstruction. Fifteen adult healthy horses were subjected to endoscopy and radiography at rest. The pharyngeal diameter was measured at nine different head and neck positions. The effect of sedation and breathing cycle on the pharyngeal diameter was determined, and the relationship between the head angle and the pharyngeal diameter was analyzed. There was a significant influence of head and neck position on pharyngeal diameter, with head position having the major effect (P < 0.001); neck position was less important, but still significant (P < 0.05). The smallest pharyngeal diameter was found at the dorsal, flexed position, which is a clinically important head position in dressage horses. The largest pharyngeal diameter was found at the extended midway position. At each head level, the pharyngeal diameter decreased with flexing the head and it increased with extending the head. The head angle was not associated with pharyngeal diameter, and neither sedation status nor breathing cycle significantly affected pharyngeal diameter. A decrease in pharyngeal diameter will limit the airflow through the upper respiratory tract, and it may result in turbulence with subsequent dynamic collapse. Head and neck position should therefore be considered a possible contributing factor in horses with suspected nasopharyngeal dysfunction.
Article
The aetiology of temporohyoid osteoarthropathy (THO) is unknown; both primary infectious and degenerative causes have been suggested. There is a significant association between increasing age and severity of temporohyoid joint degeneration. To examine the histopathology of the temporohyoid articulation in aged horses and to compare the appearance of the joint with computed tomography (CT) and peripheral quantitative CT (pQCT). pQCT scans of the temporohyoid articulations were obtained bilaterally from 31 horses (range age 1-44 years) post mortem and images were graded by 2 blinded observers on 2 occasions for the presence of osteophytes, irregularity of the joint surface and mineralisation. Eight heads had been examined previously by CT, with the images similarly graded for the shape and density of the proximal stylohyoid bones, bone proliferation surrounding the joint, mineralisation of the tympanohyoid cartilage and the relationship of the petrous temporal bone to the stylohyoid bone. Sixteen temporohyoid joints were then evaluated histologically. There was significant association between the mean pQCT degeneration score and age (rho = 0.75; P<0.0001), between the pQCT and CT score (rho = 0.63; P = 0.01) and between the degenerative changes identified within each temporohyoid joint within each horse (rho = 0.81; P<0.0001). Age-associated changes included the development of a club shape by the proximal stylohyoid bone, rounding of the synostosis with the petrous temporal bone and extension of osteophytes from the petrous temporal bone to envelope the stylohyoid head and bridge the joint. In no horse was there any evidence of osteomyelitis within the petrous temporal bone, stylohyoid bone or tympanohyoid cartilage. This study provides evidence that age is associated with increasing severity of degenerative changes in the equine temporohyoid joint and that similar changes are commonly found bilaterally. The changes identified appear similar, albeit milder to the changes reported in horses with THO, suggesting that degenerative, rather than infectious causes may underlie the aetiology of THO. Future work should be directed at examining the histopathology of clinical THO cases.
Article
We recorded the electromyographic (EMG) activity of 7 skeletal muscles in the forequarters and 1 in the hindquarters of 6 Thoroughbred horses during overground walking, swimming in a circular pool, and walking and trotting in a water treadmill. Bipolar fine wire electrodes were inserted into the muscles and the EMG signals were recorded using a telemetric system. The splenius exhibited tonic EMG activity during swimming. The brachiocephalicus showed its highest intensity during swimming followed by the walk and trot in the water treadmill and then walking overground. The triceps brachii caput longum had a similar activity pattern to the brachiocephalicus. The brachialis showed only weak EMG activity in all 3 types of locomotion. The extensor digitorum communis had higher intensity of EMG activity in the walk in the water treadmill than in other kinds of locomotion. The flexor digitorum profundus exhibited the most intense EMG activity during swimming. These results indicated that swimming evoked strong EMG activity in the antigravity muscles in spite of reduced gravitational force. Walking in the water treadmill may require more intensified EMG activity of the forelimb than the trot in the same treadmill.
Article
A thorough knowledge of the horse's back and limb movements at different speeds is important in the design of training programmes and the prevention of speed-related injuries. The objective of this study was to investigate changes in muscle activity and kinematics of the trot with increased speed. To evaluate these effects, 4 Saddlehorses were recorded while trotting on a horizontal treadmill at speeds ranging from 3.5-6.0 m/s. The 3-D trajectories of skin markers on the left side of the horse and the dorsal midline of the trunk were established. Electrical activity was obtained simultaneously from 6 muscles using surface electrodes. Ten consecutive strides were analysed for each horse at each of the 5 velocity steps. The increase in speed resulted in a decrease in stride and stance phase duration, increased muscle activity and range of motion of the limbs, but a decrease in back movements. During the stance phase, the limbs appeared more loaded, which resulted in more flexion of the joints and higher excentric muscle activity. During the swing phase, the higher concentric activity of the muscles was responsible for an increased shortening of the limbs. Understanding the effects of speed on equine locomotion is a prerequisite for the development of training programmes.
Article
A common opinion among riders and in the literature is that the positioning of the head and neck influences the back of the horse, but this has not yet been measured objectively. To evaluate the effect of head and neck position on the kinematics of the back in riding horses. Eight Warmblood riding horses in regular work were studied on a treadmill at walk and trot with the head and neck in 3 different predetermined positions achieved by side reins attached to the bit and to an anticast roller. The 3-dimensional movement of the thoracolumbar spine was measured from the position of skin-fixed markers recorded by infrared videocameras. Head and neck position influenced the movements of the back, especially at the walk. When the head was fixed in a high position at the walk, the flexion-extension movement and lateral bending of the lumbar back, as well as the axial rotation, were significantly reduced when compared to movements with the head free or in a low position. At walk, head and neck position also significantly influenced stride length, which was shortest with the head in a high position. At trot, the stride length was independent of head position. Restricting and restraining the position and movement of the head and neck alters the movement of the back and stride characteristics. With the head and neck in a high position stride length and flexion and extension of the caudal back were significantly reduced. Use of side reins in training and rehabilitation programmes should be used with an understanding of the possible effects on the horse's back.
Und was meinen die Pferde dazu? Über das Ausdrucksverhalten von Pferden bei verschiedenen Halsstellungen
  • Kienapfel
Kienapfel, K., 2011: Und was meinen die Pferde dazu? € Uber das Ausdrucksverhalten von Pferden bei verschiedenen Halsstellungen. Pferdeheilkunde 27, 372–380.
Analysis of neck muscle (splenius) activity during jumping by surface videoelectromyography technique
  • C Giovagnoli
  • G Pieramati
  • G Castellano
  • M Reitano
  • M Silvesrrelli
Giovagnoli, C.; Pieramati, G.; Castellano, G.; Reitano, M.; Silvesrrelli, M., 2000: Analysis of neck muscle (splenius) activity during jumping by surface videoelectromyography technique. In: A. Lindner (ed.), The Elite Show Jumper -CESMAS 2000 1st edn. Arno Lindner, J€ ulich, Germany, pp. 57-60.
Eine Untersuchung zum Einfluss der Kopf-Hals-Haltungen auf Gelenkwinkel der Hintergliedmaße mit dem Bewegungsanalysesystem Simi und dem Tekscan ® -HoofTM-System
  • A Kattelans
Kattelans, A., 2012: Eine Untersuchung zum Einfluss der Kopf-Hals-Haltungen auf Gelenkwinkel der Hintergliedmaße mit dem Bewegungsanalysesystem Simi und dem Tekscan â -HoofTM-System. Doktoral Thesis, University Hannover.
Do horses show more stress during riding, lunging or working on a treadmill? Degree Projekt
  • J G Denderen
Denderen, J. G., 2011: Do horses show more stress during riding, lunging or working on a treadmill? Degree Projekt. van Dierendonck, M.; van Dalum, M.; Beekmanns, M.; Christensen, J. W., 2012: Acute stress response of dressage horses ridden in three different heand and neck positions. In: H. Randle, N. Waran, J. Wiliams (eds), Conference Proceedings of the 8th Equitation Science Conference 1st edn. BSAS & Duchy College Print, Edingburgh, UK, p. 62.
Do horses show more stress during riding, lunging or working on a treadmill? Degree Projekt
  • J G Denderen
  • M Van Dierendonck
  • M Van Dalum
  • M Beekmanns
  • J W Christensen
Denderen, J. G., 2011: Do horses show more stress during riding, lunging or working on a treadmill? Degree Projekt. van Dierendonck, M.; van Dalum, M.; Beekmanns, M.; Christensen, J. W., 2012: Acute stress response of dressage horses ridden in three different heand and neck positions. In: H. Randle, N. Waran, J. Wiliams (eds), Conference Proceedings of the 8th Equitation Science Conference 1st edn. BSAS & Duchy College Print, Edingburgh, UK, p. 62.
  • P H Falaturi
Falaturi, P. H., 2001: Computerkinematographie (CKG) als geeignetes Verfahren zur objektiven Bewegungsanalyse-Beschreibung und Ergebnisse. Pferdeheilkunde 1, 30-41.
“Rollkur”, “Hyperflexion” und “LDR” - Die natürliche Kopf-Hals-Haltung des Pferdes und deren Veränderung durch die reiterliche Einwirkung
  • Meyer
Meyer, H., 2010: "Rollkur", "Hyperflexion" und "LDR" -Die nat€ urliche Kopf-Hals-Haltung des Pferdes und deren Ver€ anderung durch die reiterliche Einwirkung. Pferdeheilkunde 26, 388-413.
Das Verhalten von Weidetieren (Pferd, Rind, Schaf und Ziege) bei der Nahrungsaufnahme
  • A Schlunk
Schlunk, A., 2010: Das Verhalten von Weidetieren (Pferd, Rind, Schaf und Ziege) bei der Nahrungsaufnahme. Diploma Thesis, Ruhr University of Bochum, Bochum, Germany.
Computerkinematographie (CKG) als geeignetes Verfahren zur objektiven Bewegungsanalyse- Beschreibung und Ergebnisse
  • Falaturi