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T Licka

Publications and source records attributed to T Licka.

At least 19 recordsLinked to original sources
PubMed2005

Coordination dynamics of the horse-rider system.

The authors studied the interaction between rider and horse by measuring their ensemble motions in a trot sequence, comparing 1 expert and 1 novice rider. Whereas the novice's movements displayed transient departures from phase synchrony, the expert's motions were continuously phase-matched with those of the horse. The tight ensemble synchrony between the expert and the horse was accompanied by an increase in the temporal regularity of the oscillations of the trunk of the horse. Observed differences between expert and novice riders indicated that phase synchronization is by no means perfect but requires extended practice. Points of contact between horse and rider may haptically convey effective communication between them.

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PubMed2004

Influence of the rider on the variability of the equine gait.

The aim of this study was to show that the motion pattern of a well-ridden horse varies less than the motion pattern of an unridden horse. In order to do so, we recorded the motion of two markers, one attached to the dorsal spinous processus of lumbar vertebra L4, the other to the right fore hoof. In total, we measured 21 horses in trot, ridden and unridden, with a fitting and with a non-fitting saddle. After breaking down the entire time series of the three-dimensional motion of the markers into their respective motion cycles, we computed a measure of motion pattern variability for the motion as well as for the derivatives (velocity and acceleration) along each of the three principal dimensions. Two of six variables (velocity and acceleration in the forward direction) displayed a significant discrimination between the ridden and the unridden case, and demonstrated the beneficial effect of a rider on the horse's motion pattern variability. Saddle fit was shown to have also an influence on motion variability: variability of two variables (velocity and of acceleration in forward direction) was significantly lower with a fitting saddle compared to a non-fitting saddle, a third variable (acceleration in the transversal direction) showed a significant difference also. This new method offers an objective evaluation of saddle fit, and a sensitive assessment of the quality of the rider in the moving horse.

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PubMed2004

Influence of rider on lameness in trotting horses.

REASONS FOR PERFORMING STUDY: Equine lameness is commonly evaluated when the horse is being ridden, but the influence of the rider on the lameness has not been documented. OBJECTIVE: To document the effect of 2 riders of different training levels on the vertical movement of the head and croup. METHODS: Twenty mature horses were ridden at trot by an experienced dressage rider and a novice rider, as well as trotted in hand. Kinematic measurements of markers placed on the horse's head and sacral bone were carried out. The asymmetries of the vertical head and sacral bone motion were calculated as lameness parameters and compared with paired t tests. RESULTS: Trotting in hand, 17 horses showed forelimb lameness (1-4/10) and 13 hindlimb lameness (1-2/10). Intra-individually, 11 horses showed significant differences in forelimb lameness and 4 horses showed significant differences in hindlimb lameness when ridden. Over all horses, hindlimb lameness increased significantly under the dressage rider compared to unridden horses. CONCLUSIONS: The presence of a rider can alter the degree of lameness; however, its influence cannot be predicted for an individual horse. POTENTIAL RELEVANCE: In order to evaluate mild lameness, horses should be evaluated at trot both under saddle and in hand. If lameness is exacerbated, a second rider may be helpful; the level of training of the rider should be taken into consideration.

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PubMed2004

Determination of the stiffness of the equine spine.

REASONS FOR PERFORMING STUDY: Mechanical properties of the equine back are the bases for realistic modelling of the back, which is recognised as an important step towards improved understanding of the pathogenesis of equine back conditions. HYPOTHESIS: The stiffness of the equine back depends on the direction of the applied force and on the position of the spine. METHODS: Fourteen dissected spines were tested in a tensile testing machine. In 3 different positions, simulating dorsoventral, laterolateral and dorsoventral-30 degree rotated movement, force was applied on the dorsal spinous process of T12 to reach an excursion of 4 cm in each direction. The normal distribution of the stiffness coefficients was tested with a Kolmogorov-Smirnov test and the stiffness coefficients were compared with paired t tests. RESULTS: Mean +/- s.d. dorsoventral stiffness was 2093 +/- 611 N/m for the nonrotated spine and 2182 +/- 459 N/m for the 30 degree rotated spine. Mean laterolateral stiffness was significantly lower than dorsoventral stiffness at 1454 +/- 156 N/m. CONCLUSIONS: The stiffness of the spine depends on the direction of loading. POTENTIAL RELEVANCE: The stiffness of the spine under loading may be a relevant factor in the development of back disorders.

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PubMed2004

Influence of support boots on fetlock joint angle of the forelimb of the horse at walk and trot.

REASONS FOR PERFORMING STUDY: Support boots are thought to reduce tension on the superficial digital flexor tendon (SDTF) of the horse and are frequently recommended for horses convalescing after tendonitis, but evidence of their effectiveness is conflicting. OBJECTIVE: To document the effects of 4 different types of support boots on fetlock joint angle in comparison to the unprotected fetlock. METHODS: In 26 horses, the kinematics of the forelimb fetlock joint angle was measured at walk and trot on a treadmill when wearing 3 different types of support boots and 1 protective boot, as well as without boots. As outcome parameters, maximum extension of the fetlock joint and the moment at which maximum extension occurred in the stride cycle were determined. RESULTS: At walk, 2 of the support boots reduced the maximum extension significantly by 0.8 and 0.9 degrees, respectively (P<0.05). Additionally, one type of boots also delayed the occurrence of maximal extension within the stride cycle. At trot, all support boots reduced maximum extension significantly by 0.56-1.44 degrees (P<0.01), and the protective boot reduced maximum extension by 0.56 degrees (P<0.05). CONCLUSIONS AND POTENTIAL RELEVANCE: The results demonstrate the effectiveness of support boots in reducing maximum extension of the fetlock, which can be assumed to reduce tension in the suspensory apparatus and SDFT. The delay of the moment of maximal extension may be relevant in reducing dynamic forces. However, it should be noted that the long-term consequences of reduction of maximum fetlock extension are still uncertain. Such a reduction over a prolonged period might negatively affect fibre alignment in the healing tendon.

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PubMed2003

Multifocal eosinophilic enteritis associated with a small intestinal obstruction in a standardbred horse.

A seven-year-old standardbred gelding developed marked signs of colic associated with an acute small intestinal obstruction. Surgical exploration revealed three intramural, circumferential constricting lesions in the small intestine, the two most severe of which were in the jejunum and were resected. The horse was euthanased owing to postoperative complications. Histopathological examination confirmed the diagnosis of idiopathic multifocal eosinophilic enteritis.

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PubMed2001

The influence of lameness on equine stride length consistency.

The aim of this study was to assess the influence of orthopaedic pain on the variation of stride length as a kinematic system-parameter in 21 horses with forelimb lameness. Data were collected while the horses were trotting on a treadmill during a minimum of 12 motion cycles, both before and after intra-articular or perineural anaesthesia. Stride length was assessed for each motion cycle, and the mean and standard deviation were calculated for each condition. Forelimb lameness was documented as percentage of asymmetry of vertical head movement. With significant decrease of forelimb lameness after regional anaesthesia, the SD of stride length increased significantly (+0.35%, P< 0.05). Our results show that in the presence of orthopaedic pain horses keep stride variability low, possibly because the lame horse employs an optimum compensatory mechanism to reduce the pain in the affected limb, and every deviation from this pattern increases pain.

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PubMed2001

Motion pattern of the toelt of Icelandic horses at different speeds.

The toelt of the Icelandic horse is a symmetric 4-beat gait, with alternating single and double support phases. By definition, the duration of the diagonal and ipsilateral stance phases should be similar. The aim of this study was to investigate the stride characteristics of horses ridden at toelt, and to compare these to previous descriptions of this gait. The kinematics of 23 Icelandic horses was measured using the Expert Vision System. Mature and sound horses, used for pleasure riding and/or competitions, were ridden at toelt at 3 different speeds. For each horse, 10 strides were measured at toelting speeds of 2.9 m/s (s.d. 0.28), 3.7 m/s (s.d. 0.29) and 4.7 m/s (s.d. 0.53). Seven horses showed true toelt pattern at one or 2 speeds. At the highest speed, 60% of all motion cycles showed the pattern of 4-beat pace. This investigation shows that the previously described toelt pattern is present only over a narrow speed range, and toelt at extended speed is, in fact, a 4-beat pace or rarely a 4-beat trot.

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PubMed2001

Range of back movement at trot in horses without back pain.

The aim of this study was to establish basic reference data for evaluating 3-dimensional movement of the equine back at the trot. In 22 mature horses without any clinical signs of back pain, the movement of the back was measured during trotting on a treadmill with a system for motion analysis. The position of the markers placed on the head, hooves, skin above the spinous processes of T5, T10, T16, L3 and on 2 of the sacral spines was recorded. The results of all movements were expressed in percent of the horse's height at its withers. At the trot, the maximum lateral movement at the head was 1.72% (s.d. 0.75). At T5 it was 3.15% (s.d. 0.84), at T10 1.99% (s.d. 0.64), at T16 1.85% (s.d. 0.65), at L3 1.89% (s.d. 0.62), at OS1 1.89% (s.d. 0.66) and at OS2 2.21% (s.d. 0.71). The maximum dorsoventral back movement was 4.06% (s.d. 1.14) at the head, 3.93% (s.d. 0.67) at T5, 4.46% (s.d. 0.85) at T10, 4.94% (s.d. 0.77) at T16, 4.91% (s.d. 0.74) at L3, 4.55% (s.d. 0.69) at OS1 and 4.33% (s.d. 0.69) at OS2. The lateral movement of the back at trot is relatively small compared to the movement of the horse's back at stance or at walk, with the marker on T5 showing the widest lateral movement. The dorsoventral movement of the back is larger than the lateral movement, but the differences between single markers are small. The results of this study can be used as a comparison when investigating equine back pain.

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PubMed2001

Evaluation of the EMG activity of the long back muscle during induced back movements at stance.

In this study we investigated the activity of the main back muscle (Musculus longissimus) by surface electromyography (EMG) during induced extension and lateral flexion at stance. Measurements were taken of 15 horses (age 5-20 years, 450-700 kg bwt) without signs of back pain. Reflecting markers were placed on the head, spinous processes of T5, T12, T16, L3 and on 2 of the sacral bones. The surface EMG electrodes were situated on the Musculus longissimus on both sides of the dorsal spinous processes of T12, T16 and L3. In all horses and all movements (extension, lateral flexion to the left and right), the EMG on both sides of the dorsal spinous process of T12 had the highest, and the EMG on both sides of the spinous process of L3, the lowest amplitude (30% of T12). At T16 the amplitude of the EMG signal was 60% of that at T12. There was no time shift between the EMG signals at the different locations (T12, T16, L3). There was a very high correlation between motion and amplitude of the EMG signal of extension, with correlation coefficients of 0.78 at L3, 0.80 at T16 and 0.75 at T12. The correlation of the lateral flexion between amplitude of the EMG and motion was lower, with 0.38 at L3, 0.43 at T16 and 0.39 at T12. This investigation showed that the EMG of the Musculus longissimus during spinal reflexes should be derived on both sides of T12, because this is important for the clinical use of surface EMG.

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PubMed2000

Individual speed dependency of forelimb lameness in trotting horses.

Using a system for motion analysis, linear correlation of speed and forelimb lameness was measured in 16 horses trotting on a treadmill at a minimum of three different trotting speeds. Forelimb lameness was determined as asymmetry of vertical head motion during left and right forelimb stance. In seven horses with a moderate forelimb lameness (head motion asymmetry >40%), lameness increased significantly with trotting speed. In a further seven horses with mild or subclinical forelimb lameness (head motion asymmetry <40%) and in two horses with a moderate forelimb lameness, no significant correlation between speed and motion asymmetry was found. The results indicate that moderate forelimb lameness measured as head motion asymmetry depends on the speed at which the measurements are taken. If head motion asymmetry is measured at two trotting speeds, it can be standardized to any speed within the trotting speed range.

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PubMed1999

Limb locomotion--speed distribution analysis as a new method for stance phase detection.

The stance phase is used for the determination of many parameters in motion analysis. In this technical note the authors present a new kinematical method for determination of stance phase. From the high-speed video data, the speed distribution of the horizontal motion of the distal limb is calculated. The speed with the maximum occurrence within the motion cycle defines the stance phase, and this speed is used as threshold for beginning and end of the stance phase. In seven horses the results obtained with the presented method were compared to synchronous stance phase determination using a force plate integrated in a hard track. The mean difference between the results was 10.8 ms, equalling 1.44% of mean stance phase duration. As a test, the presented method was applied to a horse trotting on the treadmill, and to a human walking on concrete. This article describes an easy and safe method for stance phase determination in continuous kinematic data and proves the reliability of the method by comparing it to kinetic stance phase detection. This method may be applied in several species and all gaits, on the treadmill and on firm ground.

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PubMed1999

Supporting forelimb lameness: clinical judgement vs. computerised symmetry measurement.

The aim of this study was to compare supporting forelimb lameness determined by a motion analysis system with the subjective grading of a trained equine orthopaedic surgeon. Trotting on a treadmill, 29 individuals with a supporting forelimb lameness were measured with the SELSPOT II system and judged by the clinician. The vertical motion of the head was measured, analysed using Fourier transform, and the percentages of symmetry determined. The veterinarian evaluated the lameness and graded it according to a clinical routine. Veterinarian and system for motion analysis assigned the lameness to the same leg in all cases, but the grading of the lameness differed in 6 out of 29 cases. The results of this study indicate that motion analysis can be used as an informative tool supporting the subjective veterinary judgement.

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PubMed1998

Speed dependency of motion pattern consistency.

Treadmills are widely used in equine motion analysis. For the evaluation of the trot of a horse, a trotting speed with low variation between motion cycles is necessary to make the measurements reproducible. The aim of this study is to show how an individual 'optimum' trotting speed for lameness quantification can be determined. In this study, the stability of a horse's gait pattern was evaluated by calculating the standard deviation (S.D.) of motion-cycle speed (MCS). In trot, eighteen horses were analysed at several speeds. The measurements were taken with the ExpertVision System (Motion Analysis Corporation) every 3 km h(-1) (= 0.83 m s(-1)), from the lowest to the highest individual trotting speed. At the different speeds the S.D. of MCS and the asymmetry of the vertical head motion were compared. At the speed where standard deviation was minimum, motion asymmetry was maximum. In twelve horses this optimum speed was situated in the middle of the individual trotting speed range, and in six horses the optimum speed was the maximum speed. The method presented in this study allows the determination of an optimum trotting speed and so contributes to precision and consistency of equine lameness analysis.

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PubMed1998

An objective method for evaluating the flexibility of the back of standing horses.

The spinal movements in maximum arching, dipping and left and right lateral flexion were measured in 10 horses without signs of back pain. A system for motion analysis (Expert Vision System) was used to identify the position of the markers placed on the head, the spinous processes of T5, T10, T16, L3, and on 2 of the sacral spines. By definition, the maximum of the spinal movement was set when the T16 marker reached its maximum deviation from the start position. The difference between start position and maximum position was presented as per cent of the horse's height at the withers. At T16 the mean results for flexion (arching) of the back were 5.9% (s.d.0.9), for extension (dipping) -2.4% (s.d.0.7), for flexion to the left 4.2% (s.d.1.1), and for flexion to the right 5.3% (s.d.1.3).

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PubMed1997

Compensatory movements of horses with a stance phase lameness.

In order to study the mechanism of lameness transfer from fore- and hindlimb lamenesses 2 hypotheses were investigated. Hypothesis 1: Horses with a true supporting limb lameness in one hindlimb show a false supporting limb lameness in the ipsilateral forelimb. Hypothesis 2: Horses with a true supporting limb lameness in one forelimb show a false supporting limb lameness in the contralateral hindlimb. Fourteen horses with fore- or hindlimb lameness were used for this study. Each horse was measured at the trot on a treadmill with standardised speed, before and after diagnostic blocks (9 horses), or with and without induced lameness (5 horses). The head acceleration asymmetry (HAAS) and the sacrum acceleration asymmetry (SAAS) were used for quantification of fore- and hindlimb lameness respectively. Changes were documented by changes of the HAAS or the SAAS. In all 4 horses with a true hindlimb lameness a synchronous false lameness of the ipsilateral forelimb was documented. In 6 of 10 horses with a forelimb lameness a lameness transfer could be assessed according to hypothesis 2. The results of this study show, that horses with a true severe lameness in the forelimb show a false lameness in the contralateral hindlimb, and horses with a true hindlimb lameness show a false lameness in the ipsilateral forelimb. This indicates that the location of the truly lame limb can be deduced from the distribution of 2 lamenesses on a sagittal or diagonal axis.

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