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Hilary M. Clayton - One of the best experts on this subject based on the ideXlab platform.

  • an exploration of the influence of diagonal dissociation and moderate changes in speed on locomotor parameters in Trotting horses
    PeerJ, 2016
    Co-Authors: Sarah Jane Hobbs, John E. A. Bertram, Hilary M. Clayton
    Abstract:

    Background. Although the trot is described as a diagonal gait, contacts of the diagonal pairs of hooves are not usually perfectly synchronized. Although subtle, the timing dissociation between contacts of each diagonal pair could have consequences on gait dynamics and provide insight into the functional strategies employed. This study explores the mechanical effects of different diagonal dissociation patterns when speed was matched between individuals and how these effects link to moderate, natural changes in Trotting speed. We anticipate that hind-first diagonal dissociation at contact increases with speed, diagonal dissociation at contact can reduce collision-based energy losses and predominant dissociation patterns will be evident within individuals. Methods. The study was performed in two parts: in the first 17 horses performed speed-matched Trotting trials and in the second, five horses each performed 10 Trotting trials that represented a range of individually preferred speeds. Standard motion capture provided kinematic data that were synchronized with ground reaction force (GRF) data from a series of force plates. The data were analyzed further to determine temporal, speed, GRF, postural, mass distribution, moment, and collision dynamics parameters. Results. Fore-first, synchronous, and hind-first dissociations were found in horses Trotting at (3.3 m/s ± 10%). In these speed-matched trials, mean centre of pressure (COP) cranio-caudal location differed significantly between the three dissociation categories. The COP moved systematically and significantly (P = .001) from being more caudally located in hind-first dissociation (mean location = 0.41 ± 0.04) through synchronous (0.36 ± 0.02) to a more cranial location in fore-first dissociation (0.32 ± 0.02). Dissociation patterns were found to influence function, posture, and balance parameters. Over a moderate speed range, peak vertical forelimb GRF had a strong relationship with dissociation time (R = .594; P 0.05) or speed (R = .223; P = .023). Discussion. The results indicate that at moderate speeds individual horses use dissociation patterns that allow them to maintain trunk pitch stability through management of the cranio-caudal location of the COP. During the hoof-ground collisions, reduced mechanical energy losses were found in hind-first dissociations compared to fully synchronous contacts. As speed increased, only forelimb vertical peak force increased so dissociations tended towards hind-first, which shifted the net COP caudally and balanced trunk pitching moments.

  • stance phase kinematics and kinetics of horses Trotting over poles
    Equine Veterinary Journal, 2015
    Co-Authors: Hilary M. Clayton, Narelle C. Stubbs, Michael Lavagnino
    Abstract:

    SummaryReason for performing study Trotting over poles is frequently used therapeutically to restore swing phase ranges of joint motion. It is not known whether ground reaction forces (GRFs) increase as the swing phase limbs are lifted higher to clear the poles. Higher GRFs might be painful or jeopardise healing of musculoskeletal injuries. Objectives To measure stance phase kinematics and GRFs in the forelimbs and hindlimbs of horses Trotting on level ground, over low poles and over high poles, and to test the hypothesis that Trotting over poles is associated with increases in peak GRFs and impulses in the supporting hindlimb and forelimb compared with Trotting over level ground. Study design Repeated measures experimental study on horses with normal gait. Methods Kinematic and GRF data were collected from 8 horses Trotting on level ground under 3 conditions performed in random order: no poles, low (11 cm) poles and high (20 cm) poles spaced 1.05 ± 0.05 m apart. Spatiotemporal and angular kinematic variables and GRFs were measured during stance. Comparisons among conditions were made using repeated measures ANOVA (P<0.05) with Bonferroni correction for post hoc testing. Results The only GRF component that increased when Trotting over poles was peak forelimb braking GRF. Forelimb vertical and braking impulses increased and the transverse impulse changed from medially to laterally directed. Extension of the metatarsophalangeal and metacarpophalangeal joints did not change. Conclusions The fact that peak vertical forces and extension of the metatarsophalangeal and metacarpophalangeal joints did not increase when Trotting over poles suggests that loading of the musculoskeletal tissues is comparable with that associated with Trotting on level ground in horses with symmetrical movement at trot. The findings support the use of trot poles during rehabilitation from lameness in horses that move symmetrically. The generation of laterally directed forelimb transverse forces suggests that Trotting over poles may recruit the forelimb adductor musculature.

  • swing phase kinematics of horses Trotting over poles
    Equine Veterinary Journal, 2015
    Co-Authors: S. Brown, Michael Lavagnino, Narelle C. Stubbs, L. J. Kaiser, Hilary M. Clayton
    Abstract:

    SummaryReasons for performing study Trotting over poles is used therapeutically to restore full ranges of limb joint motion. The mechanics of Trotting over poles have not yet been described, hence quantitative evidence for the presumed therapeutic effects is lacking. Objectives To compare limb kinematics in horses Trotting over level ground, over low poles and over high poles to determine changes in joint angulations and hoof flight arcs. Study design Repeated measures experimental study in sound horses. Methods Standard motion analysis procedures with skin-fixed reflective markers were used to measure swing phase kinematics from 8 horses Trotting on level ground, over low (11 cm) and high (20 cm) poles spaced 1.05 ± 0.05 m apart. Spatiotemporal variables and peak swing phase joint flexion angles were compared using repeated measures ANOVA (P<0.05) with Bonferroni correction for pairwise post hoc testing. Results Peak heights of the fore and hind hooves increased significantly and progressively from no poles (fore: 13.8 ± 3.8 cm; hind: 10.8 ± 2.4 cm) to low poles (fore: 30.9 ± 4.9 cm; hind: 24.9 ± 3.7 cm) and to high poles (fore: 41.0 ± 3.9 cm; hind: 32.7 ± 4.0 cm). All joints of the fore- and hindlimbs contributed to the increase in hoof height through increased swing phase flexion. The hooves cleared the poles due to increases in joint flexion rather than by raising the body higher during the suspension phases of the stride. Conclusions The increases in swing phase joint flexions indicate that Trotting over poles is effective for activating and strengthening the flexor musculature. Unlike the use of proprioceptive stimulation devices in which the effects decrease over time due to habituation, the horse is required to elevate the hooves to ensure clearance whenever poles are present. The need to raise the limbs sufficiently to clear the poles and place the hooves accurately requires visuomotor coordination, which may be useful in the rehabilitation of neurological cases. The Summary is available in Chinese – see Supporting information.

  • Swing phase kinematics of horses Trotting over poles
    Equine veterinary journal, 2014
    Co-Authors: S. Brown, Michael Lavagnino, Narelle C. Stubbs, L. J. Kaiser, Hilary M. Clayton
    Abstract:

    SummaryReasons for performing study Trotting over poles is used therapeutically to restore full ranges of limb joint motion. The mechanics of Trotting over poles have not yet been described, hence quantitative evidence for the presumed therapeutic effects is lacking. Objectives To compare limb kinematics in horses Trotting over level ground, over low poles and over high poles to determine changes in joint angulations and hoof flight arcs. Study design Repeated measures experimental study in sound horses. Methods Standard motion analysis procedures with skin-fixed reflective markers were used to measure swing phase kinematics from 8 horses Trotting on level ground, over low (11 cm) and high (20 cm) poles spaced 1.05 ± 0.05 m apart. Spatiotemporal variables and peak swing phase joint flexion angles were compared using repeated measures ANOVA (P

  • Stance phase kinematics and kinetics of horses Trotting over poles
    Equine veterinary journal, 2014
    Co-Authors: Hilary M. Clayton, Narelle C. Stubbs, Michael Lavagnino
    Abstract:

    Trotting over poles is frequently used therapeutically to restore swing phase ranges of joint motion. It is not known whether ground reaction forces (GRFs) increase as the swing phase limbs are lifted higher to clear the poles. Higher GRFs might be painful or jeopardise healing of musculoskeletal injuries. To measure stance phase kinematics and GRFs in the forelimbs and hindlimbs of horses Trotting on level ground, over low poles and over high poles, and to test the hypothesis that Trotting over poles is associated with increases in peak GRFs and impulses in the supporting hindlimb and forelimb compared with Trotting over level ground. Repeated measures experimental study on horses with normal gait. Kinematic and GRF data were collected from 8 horses Trotting on level ground under 3 conditions performed in random order: no poles, low (11 cm) poles and high (20 cm) poles spaced 1.05 ± 0.05 m apart. Spatiotemporal and angular kinematic variables and GRFs were measured during stance. Comparisons among conditions were made using repeated measures ANOVA (P<0.05) with Bonferroni correction for post hoc testing. The only GRF component that increased when Trotting over poles was peak forelimb braking GRF. Forelimb vertical and braking impulses increased and the transverse impulse changed from medially to laterally directed. Extension of the metatarsophalangeal and metacarpophalangeal joints did not change. The fact that peak vertical forces and extension of the metatarsophalangeal and metacarpophalangeal joints did not increase when Trotting over poles suggests that loading of the musculoskeletal tissues is comparable with that associated with Trotting on level ground in horses with symmetrical movement at trot. The findings support the use of trot poles during rehabilitation from lameness in horses that move symmetrically. The generation of laterally directed forelimb transverse forces suggests that Trotting over poles may recruit the forelimb adductor musculature. © 2014 EVJ Ltd.

Steven J. Wickler - One of the best experts on this subject based on the ideXlab platform.

  • hindlimb net joint energies during swing phase as a function of Trotting velocity
    Equine Veterinary Journal, 2010
    Co-Authors: Hilary M. Clayton, Steven J. Wickler, Donald F. Hoyt, Edward A. Cogger, Joel L Lanovaz
    Abstract:

    Summary Net joint powers and energies have been described in walking horses during the swing phase of the stride in the fore- and hindlimb (Clayton et al. 2001). During Trotting, swing phase net joint powers have been described in the forelimb but not in the hindlimb. The effects of velocity on power profiles and energy patterns are important in relation to locomotor energetics. The objective of this study was to evaluate velocity-dependent changes in hindlimb net energy profiles of the swing phase during Trotting. Inverse dynamic analysis was used to calculate net joint energies at the hindlimb joints of 6 horses Trotting overground at velocities ranging from 2.27-5.17 m/s. At all velocities, there was net energy generation at the hip and tarsus and net energy absorption at the stifle, fetlock and coffin joints. Velocity-dependent bursts of energy generation at the hip actively protracted the limb in early swing and initiated retraction in late swing. Synchronous with the bursts of energy generation at the hip were velocity-dependent bursts of energy absorption across the stifle that acted to control flexion in early swing and extension in late swing. The distal limb was raised and lowered by velocity-dependent bursts of energy generation that flexed the tarsus in early swing and extended it in late swing. The energy bursts in early swing increased linearly with velocity, whereas the energy bursts in late swing increased as a function of the square or cube of velocity. The results contribute to understanding the mechanisms used to accelerate and decelerate the limbs more rapidly as velocity increases, which is an important consideration in racing and sporting performance.

  • joint work and power for both the forelimb and hindlimb during Trotting in the horse
    The Journal of Experimental Biology, 2006
    Co-Authors: Darren Dutto, Hilary M. Clayton, Donald F. Hoyt, Edward A. Cogger, Steven J. Wickler
    Abstract:

    SUMMARY The net work of the limbs during constant speed over level ground should be zero. However, the partitioning of negative and positive work between the fore- and hindlimbs of a quadruped is not likely to be equal because the forelimb produces a net braking force while the hindlimb produces a net propulsive force. It was hypothesized that the forelimb would do net negative work while the hindlimb did net positive work during Trotting in the horse. Because vertical and horizontal impulses remain unchanged across speeds it was hypothesized that net work of both limbs would be independent of speed. Additionally because the major mass of limb musculature is located proximally, it was hypothesized that proximal joints would do more work than distal joints. Kinetic and kinematic analysis were combined using inverse dynamics to calculate work and power for each joint of horses Trotting at between 2.5 and 5.0 m s –1 . Work done by the hindlimb was indeed positive (consistently 0.34 J kg –1 across all speeds), but, contrary to our hypothesis, net work by the forelimb was essentially zero (but also independent of Trotting speed). The zero net work of the forelimb may be the consequence of our not being able to account, experimentally, for the negative work done by the extrinsic muscles connecting the scapula and the thorax. The distal three joints of both limbs behaved elastically with a period of energy absorption followed by energy return. Proximal forelimb joints (elbow and shoulder) did no net work, because there was very little movement of the elbow and shoulder during the portion of stance when an extensor moment was greatest. Of the two proximal hindlimb joints, the hip did positive work during the stride, generating energy almost throughout stance. The knee did some work, but like the forelimb proximal joints, had little movement during the middle of stance when the flexion moment was the greatest, probably serving to allow the efficient transmission of energy from the hip musculature to the ground.

  • Oxygen consumption (V̇O2) during Trotting on a 10% decline
    Equine veterinary journal. Supplement, 2006
    Co-Authors: Donald F. Hoyt, Steven J. Wickler, S. F. Garcia
    Abstract:

    Although there have been reports of oxygen consumption measurements of horses running on the level and incline, there are no measurements during decline locomotion. This may be due, in part, to the potential for muscle damage produced by eccentric contractions. In man, running on a 10% decline, VO2 decreased by 35% and stride frequency (SF) decreased by 3% when compared to level locomotion. The rate of O2 consumption and SF would be decreased in horses on a 10% decline when compared to the level. Six horses (average 467 +/- 68 kg) were acclimated to Trotting on the level and decline prior to data collection. VO2 under moderate conditions was measured (using open flow respirometry) during Trotting between 2.25 and 4.0 m/sec (at 0.25 m/sec increments) on a treadmill on the level and declined 10%. Stride frequencies were counted manually. VO2 decreased (P<0.009) on the decline by an average of 45% (range 42-47%), and SF was 2.7% slower. The speed at which the minimum Cost of Transport occurs on the decline was faster than on the level. SF was reduced on the decline. No evidence of muscle soreness was noted in response to the downhill running. Downhill Trotting, eccentric exercise, can be done safely in the horse and requires almost half the energetic costs as Trotting on the level. It is not known whether this is the optimum downhill gradient or if the horse adjusts its preferred speed to accommodate downhill Trotting.

  • In vivo muscle function vs speed. II. Muscle function Trotting up an incline.
    Journal of Experimental Biology, 2005
    Co-Authors: Steven J. Wickler, Donald F. Hoyt, Andrew A. Biewener, Edward A. Cogger, Kristin L De La Paz
    Abstract:

    doi:10.1242/jeb.01485 Different locomotor tasks, such as moving up or down grades or changing speed, require that muscles adjust the amount of work they perform to raise or lower, accelerate or decelerate the animal’s center of mass. During level Trotting in the horse, the triceps had shortening strains of around 10.6 % while the vastus shortened 8.1 % during the stance phase. Because of the 250 % increase in metabolic rate in horses Trotting up a 10 % incline which is, presumably, a result of the increased requirement for mechanical work, we hypothesized that muscle strain during Trotting would be increased in both the triceps and the vastus over that observed when Trotting on the level. Because times of contact are similar in level and incline Trotting, we also hypothesized that strain rates of these muscles would be increased, accompanied by an increase in EMG activity. We examined the lateral head of th

  • In vivo muscle function vs speed. II. Muscle function Trotting up an incline.
    The Journal of experimental biology, 2005
    Co-Authors: Steven J. Wickler, Donald F. Hoyt, Andrew A. Biewener, Edward A. Cogger, Kristin L De La Paz
    Abstract:

    Different locomotor tasks, such as moving up or down grades or changing speed, require that muscles adjust the amount of work they perform to raise or lower, accelerate or decelerate the animal's center of mass. During level Trotting in the horse, the triceps had shortening strains of around 10.6% while the vastus shortened 8.1% during the stance phase. Because of the 250% increase in metabolic rate in horses Trotting up a 10% incline which is, presumably, a result of the increased requirement for mechanical work, we hypothesized that muscle strain during Trotting would be increased in both the triceps and the vastus over that observed when Trotting on the level. Because times of contact are similar in level and incline Trotting, we also hypothesized that strain rates of these muscles would be increased, accompanied by an increase in EMG activity. We examined the lateral head of the triceps and the vastus lateralis while Trotting up a 10% incline (5.7 degrees) over a range of speeds. The triceps shortened by 18% compared with 10.6% shortening on the level, and the vastus shortened by 18.5% compared with 8.1% on the level. The increased shortening velocities that were observed in both muscles probably reduced the force that any given set of activated muscle fibers could produce. If this pattern held for other limb muscles that do work to elevate the horse's center of mass on an incline, then a greater volume of muscle would have to be recruited to generate an equivalent force for body support. This was reflected in significant increases in the EMG intensity (IEMG) of both muscles.

David R. Carrier - One of the best experts on this subject based on the ideXlab platform.

  • function of the epaxial muscles in walking Trotting and galloping dogs implications for the evolution of epaxial muscle function in tetrapods
    The Journal of Experimental Biology, 2010
    Co-Authors: Nadja Schilling, David R. Carrier
    Abstract:

    The body axis plays a central role in tetrapod locomotion. It contributes to the work of locomotion, provides the foundation for the production of mechanical work by the limbs, is central to the control of body posture, and integrates limb and trunk actions. The epaxial muscles of mammals have been suggested to mobilize and globally stabilize the trunk, but the timing and the degree to which they serve a particular function likely depend on the gait and the vertebral level. To increase our understanding of their function, we recorded the activity of the m. multifidus lumborum and the m. longissimus thoracis et lumborum at three cranio-caudal levels in dogs while they walked, trotted and galloped. The level of muscle recruitment was significantly higher during Trotting than during walking, but was similar during Trotting and galloping. During walking, epaxial muscle activity is appropriate to produce lateral bending and resist long-axis torsion of the trunk and forces produced by extrinsic limb muscles. During Trotting, they also stabilize the trunk in the sagittal plane against the inertia of the center of mass. Muscle recruitment during galloping is consistent with the production of sagittal extension. The sequential activation along the trunk during walking and galloping is in accord with the previously observed traveling waves of lateral and sagittal bending, respectively, while synchronized activity during Trotting is consistent with a standing wave of trunk bending. Thus, the cranio-caudal recruitment patterns observed in dogs resemble plesiomorphic motor patterns of tetrapods. In contrast to other tetrapods, mammals display bilateral activity during symmetrical gaits that provides increased sagittal stability and is related to the evolution of a parasagittal limb posture and greater sagittal mobility.

  • Function of the extrinsic hindlimb muscles in Trotting dogs.
    Journal of Experimental Biology, 2009
    Co-Authors: Nadja Schilling, Timna Fischbein, Evelyn P. Yang, David R. Carrier
    Abstract:

    SUMMARY The extrinsic appendicular muscles of mammals have been suggested to impose parasagittal torques on the trunk that require recruitment of the oblique hypaxial muscles for stabilization. To determine if the recruitment of the protractors and retractors of the hindlimb are compatible with this hypothesis, we monitored changes in the recruitment of eleven muscles that span the hip joint to controlled manipulations of locomotor forces in Trotting dogs. The results indicate that the primary retractor muscles of the hindlimb produce a small retraction moment at the hip joint early in the support phase during Trotting at constant speed on a level surface. Thus, although the forelimb of dogs appears to function as a compliant strut, the hindlimb functions as a lever early in stance phase. Nevertheless, our results indicate that when dogs run at constant speed on a level surface a primary function of both the retractor and protractor muscles of the hindlimb is to produce swing phase of the limb. When the Trotting dogs did net work in the fore–aft direction, by running uphill or downhill or by resisting a horizontally directed force, recruitment of the protractor and retractor muscles of the hip joint increased or decreased in the anticipated fashion. These observations are consistent with the hypothesis that recruitment of the oblique hypaxial muscles in Trotting dogs function to stabilize the trunk against torques produced by protractor and retractor muscles of the hindlimb.

  • function of the intercostal muscles in Trotting dogs ventilation or locomotion
    The Journal of Experimental Biology, 1996
    Co-Authors: David R. Carrier
    Abstract:

    Although the intercostal muscles play an important role in lung ventilation, observations from fishes and ectothermic tetrapods suggest that their primary function may be locomotion. To provide a broader understanding of the role these muscles play in locomotion, I measured ventilatory airflow at the mouth and activity of the fourth and ninth intercostal muscles in four dogs Trotting on a treadmill. During rest and thermoregulatory panting, activity of the intercostal muscles was associated with inspiratory and expiratory airflow. However, during Trotting, activity of the interosseous portions of the intercostal muscles was correlated with locomotion. When ventilation and stride cycles were not synchronized, activity of the interosseous intercostal muscles stayed locked to the locomotor events and drifted in time relative to ventilation. In contrast, activity of the parasternal portion of the internal intercostal muscles was always associated with inspiratory airflow. These observations suggest that, in dogs, locomotion is the dominant function of the interosseous portions of the intercostal muscles. However, the parasternal intercostal muscles are primarily inspiratory in function.

Nadja Schilling - One of the best experts on this subject based on the ideXlab platform.

  • three dimensional movements of the pelvis and the lumbar intervertebral joints in walking and Trotting dogs
    Veterinary Journal, 2016
    Co-Authors: Martin S Fischer, K Wachs, Nadja Schilling
    Abstract:

    Abstract Current knowledge of the physiological range of motion (ROM) in the canine axial system during locomotion is relatively limited. This is particularly problematic because dogs with back-related dysfunction frequently present for routine consultations. To collect detailed kinematic information and describe the three-dimensional motions of the pelvis and the lumbar spine (i.e. intervertebral joints S1/L7–L2/L1), we recorded ventro-dorsal and latero-lateral X-ray videos of three walking and Trotting dogs and reconstructed their pelvic and intervertebral motions using X-ray reconstruction of moving morphology and scientific rotoscoping. Pelvic roll displayed a monophasic motion pattern and the largest ROM with on average 13° and 11° during walking and Trotting, respectively. Pelvic yaw had the smallest ROM with on average 5° (walk) and 6° (trot). A biphasic pattern was observed for pelvic pitch with a mean ROM of 8°. At both gaits, the greatest intervertebral motions occurred either in S1/L7 or L7/L6. The intervertebral motions were mono- or biphasic in the horizontal and the transverse body planes and biphasic in the sagittal plane. Cranial to L6/5, the ROM tended to decrease from 3° to

  • Compensatory load redistribution in walking and Trotting dogs with hind limb lameness.
    Veterinary journal (London England : 1997), 2013
    Co-Authors: Stefanie Fischer, Alexandra Anders, Ingo Nolte, Nadja Schilling
    Abstract:

    This study evaluated adaptations in vertical force and temporal gait parameters to hind limb lameness in walking and Trotting dogs. Eight clinically normal adult Beagles were allowed to ambulate on an instrumented treadmill at their preferred speed while the ground reaction forces were recorded for all limbs before and after a moderate, reversible, hind limb lameness was induced. At both gaits, vertical force was decreased in the ipsilateral and increased in the contralateral hind limb. While peak force increased in the ipsilateral forelimb, no changes were observed for mean force and impulse when the dogs walked or trotted. In the contralateral forelimb, the peak force was unchanged, but the mean force significantly increased during walking and Trotting; vertical impulse increased only during walking. Relative stance duration increased in the ipsilateral hind limb when the dogs trotted. In the contralateral fore and hind limbs, relative stance duration increased during walking and Trotting, but decreased in the ipsilateral forelimb during walking. Analysis of load redistribution and temporal gait changes during hind limb lameness showed that compensatory mechanisms were similar regardless of gait. The centre of mass consistently shifted to the contralateral body side and cranio-caudally to the side opposite the affected limb. These biomechanical changes indicate substantial short- and long-term effects of hind limb lameness on the musculoskeletal system.

  • Load redistribution in walking and Trotting Beagles with induced forelimb lameness
    American journal of veterinary research, 2013
    Co-Authors: Jalal Abdelhadi, Patrick Wefstaedt, Vladimir Galindo-zamora, Alexandra Anders, Ingo Nolte, Nadja Schilling
    Abstract:

    To evaluate the load redistribution mechanisms in walking and Trotting dogs with induced forelimb lameness. 7 healthy adult Beagles. Dogs walked and trotted on an instrumented treadmill to determine control values for peak and mean vertical force as well as vertical impulse for all 4 limbs. A small sphere was attached to the ventral pad of the right forelimb paw to induce a reversible lameness, and recordings were repeated for both gaits. Additionally, footfall patterns were assessed to test for changes in temporal gait variables. During walking and Trotting, peak and mean vertical force as well as vertical impulse were decreased in the ipsilateral forelimb, increased in the contralateral hind limb, and remained unchanged in the ipsilateral hind limb after lameness was induced. All 3 variables were increased in the contralateral forelimb during Trotting, whereas only mean vertical force and vertical impulse were increased during walking. Stance phase duration increased in the contralateral forelimb and hind limb during walking but not during Trotting. Analysis of the results suggested that compensatory load redistribution mechanisms in dogs depend on the gait. All 4 limbs should be evaluated in basic research and clinical studies to determine the effects of lameness on the entire body. Further studies are necessary to elucidate specific mechanisms for unloading of the affected limb and to determine the long-term effects of load changes in animals with chronic lameness.

  • load redistribution in walking and Trotting beagles with induced forelimb lameness
    American Journal of Veterinary Research, 2013
    Co-Authors: Jalal Abdelhadi, Patrick Wefstaedt, Alexandra Anders, Ingo Nolte, Vladimir Galindozamora, Nadja Schilling
    Abstract:

    Objective—To evaluate the load redistribution mechanisms in walking and Trotting dogs with induced forelimb lameness. Animals—7 healthy adult Beagles. Procedures—Dogs walked and trotted on an instrumented treadmill to determine control values for peak and mean vertical force as well as verticle impulse for all 4 limbs. A small sphere was attached to the ventral pad of the right forelimb paw to induce a reversible lameness, and recordings were repeated for both gaits. Additionally, footfall patterns were assessed to test for changes in temporal gait variables. Results—During walking and Trotting, peak and mean vertical force as well as vertical impulse were decreased in the ipsilateral forelimb, increased in the contralateral hind limb, and remained unchanged in the ipsilateral hind limb after lameness was induced. All 3 variables were increased in the contralateral forelimb during Trotting, whereas only mean vertical force and vertical impulse were increased during walking. Stance phase duration increased...

  • function of the epaxial muscles in walking Trotting and galloping dogs implications for the evolution of epaxial muscle function in tetrapods
    The Journal of Experimental Biology, 2010
    Co-Authors: Nadja Schilling, David R. Carrier
    Abstract:

    The body axis plays a central role in tetrapod locomotion. It contributes to the work of locomotion, provides the foundation for the production of mechanical work by the limbs, is central to the control of body posture, and integrates limb and trunk actions. The epaxial muscles of mammals have been suggested to mobilize and globally stabilize the trunk, but the timing and the degree to which they serve a particular function likely depend on the gait and the vertebral level. To increase our understanding of their function, we recorded the activity of the m. multifidus lumborum and the m. longissimus thoracis et lumborum at three cranio-caudal levels in dogs while they walked, trotted and galloped. The level of muscle recruitment was significantly higher during Trotting than during walking, but was similar during Trotting and galloping. During walking, epaxial muscle activity is appropriate to produce lateral bending and resist long-axis torsion of the trunk and forces produced by extrinsic limb muscles. During Trotting, they also stabilize the trunk in the sagittal plane against the inertia of the center of mass. Muscle recruitment during galloping is consistent with the production of sagittal extension. The sequential activation along the trunk during walking and galloping is in accord with the previously observed traveling waves of lateral and sagittal bending, respectively, while synchronized activity during Trotting is consistent with a standing wave of trunk bending. Thus, the cranio-caudal recruitment patterns observed in dogs resemble plesiomorphic motor patterns of tetrapods. In contrast to other tetrapods, mammals display bilateral activity during symmetrical gaits that provides increased sagittal stability and is related to the evolution of a parasagittal limb posture and greater sagittal mobility.

Donald F. Hoyt - One of the best experts on this subject based on the ideXlab platform.

  • hindlimb net joint energies during swing phase as a function of Trotting velocity
    Equine Veterinary Journal, 2010
    Co-Authors: Hilary M. Clayton, Steven J. Wickler, Donald F. Hoyt, Edward A. Cogger, Joel L Lanovaz
    Abstract:

    Summary Net joint powers and energies have been described in walking horses during the swing phase of the stride in the fore- and hindlimb (Clayton et al. 2001). During Trotting, swing phase net joint powers have been described in the forelimb but not in the hindlimb. The effects of velocity on power profiles and energy patterns are important in relation to locomotor energetics. The objective of this study was to evaluate velocity-dependent changes in hindlimb net energy profiles of the swing phase during Trotting. Inverse dynamic analysis was used to calculate net joint energies at the hindlimb joints of 6 horses Trotting overground at velocities ranging from 2.27-5.17 m/s. At all velocities, there was net energy generation at the hip and tarsus and net energy absorption at the stifle, fetlock and coffin joints. Velocity-dependent bursts of energy generation at the hip actively protracted the limb in early swing and initiated retraction in late swing. Synchronous with the bursts of energy generation at the hip were velocity-dependent bursts of energy absorption across the stifle that acted to control flexion in early swing and extension in late swing. The distal limb was raised and lowered by velocity-dependent bursts of energy generation that flexed the tarsus in early swing and extended it in late swing. The energy bursts in early swing increased linearly with velocity, whereas the energy bursts in late swing increased as a function of the square or cube of velocity. The results contribute to understanding the mechanisms used to accelerate and decelerate the limbs more rapidly as velocity increases, which is an important consideration in racing and sporting performance.

  • joint work and power for both the forelimb and hindlimb during Trotting in the horse
    The Journal of Experimental Biology, 2006
    Co-Authors: Darren Dutto, Hilary M. Clayton, Donald F. Hoyt, Edward A. Cogger, Steven J. Wickler
    Abstract:

    SUMMARY The net work of the limbs during constant speed over level ground should be zero. However, the partitioning of negative and positive work between the fore- and hindlimbs of a quadruped is not likely to be equal because the forelimb produces a net braking force while the hindlimb produces a net propulsive force. It was hypothesized that the forelimb would do net negative work while the hindlimb did net positive work during Trotting in the horse. Because vertical and horizontal impulses remain unchanged across speeds it was hypothesized that net work of both limbs would be independent of speed. Additionally because the major mass of limb musculature is located proximally, it was hypothesized that proximal joints would do more work than distal joints. Kinetic and kinematic analysis were combined using inverse dynamics to calculate work and power for each joint of horses Trotting at between 2.5 and 5.0 m s –1 . Work done by the hindlimb was indeed positive (consistently 0.34 J kg –1 across all speeds), but, contrary to our hypothesis, net work by the forelimb was essentially zero (but also independent of Trotting speed). The zero net work of the forelimb may be the consequence of our not being able to account, experimentally, for the negative work done by the extrinsic muscles connecting the scapula and the thorax. The distal three joints of both limbs behaved elastically with a period of energy absorption followed by energy return. Proximal forelimb joints (elbow and shoulder) did no net work, because there was very little movement of the elbow and shoulder during the portion of stance when an extensor moment was greatest. Of the two proximal hindlimb joints, the hip did positive work during the stride, generating energy almost throughout stance. The knee did some work, but like the forelimb proximal joints, had little movement during the middle of stance when the flexion moment was the greatest, probably serving to allow the efficient transmission of energy from the hip musculature to the ground.

  • Oxygen consumption (V̇O2) during Trotting on a 10% decline
    Equine veterinary journal. Supplement, 2006
    Co-Authors: Donald F. Hoyt, Steven J. Wickler, S. F. Garcia
    Abstract:

    Although there have been reports of oxygen consumption measurements of horses running on the level and incline, there are no measurements during decline locomotion. This may be due, in part, to the potential for muscle damage produced by eccentric contractions. In man, running on a 10% decline, VO2 decreased by 35% and stride frequency (SF) decreased by 3% when compared to level locomotion. The rate of O2 consumption and SF would be decreased in horses on a 10% decline when compared to the level. Six horses (average 467 +/- 68 kg) were acclimated to Trotting on the level and decline prior to data collection. VO2 under moderate conditions was measured (using open flow respirometry) during Trotting between 2.25 and 4.0 m/sec (at 0.25 m/sec increments) on a treadmill on the level and declined 10%. Stride frequencies were counted manually. VO2 decreased (P<0.009) on the decline by an average of 45% (range 42-47%), and SF was 2.7% slower. The speed at which the minimum Cost of Transport occurs on the decline was faster than on the level. SF was reduced on the decline. No evidence of muscle soreness was noted in response to the downhill running. Downhill Trotting, eccentric exercise, can be done safely in the horse and requires almost half the energetic costs as Trotting on the level. It is not known whether this is the optimum downhill gradient or if the horse adjusts its preferred speed to accommodate downhill Trotting.

  • In vivo muscle function vs speed. II. Muscle function Trotting up an incline.
    Journal of Experimental Biology, 2005
    Co-Authors: Steven J. Wickler, Donald F. Hoyt, Andrew A. Biewener, Edward A. Cogger, Kristin L De La Paz
    Abstract:

    doi:10.1242/jeb.01485 Different locomotor tasks, such as moving up or down grades or changing speed, require that muscles adjust the amount of work they perform to raise or lower, accelerate or decelerate the animal’s center of mass. During level Trotting in the horse, the triceps had shortening strains of around 10.6 % while the vastus shortened 8.1 % during the stance phase. Because of the 250 % increase in metabolic rate in horses Trotting up a 10 % incline which is, presumably, a result of the increased requirement for mechanical work, we hypothesized that muscle strain during Trotting would be increased in both the triceps and the vastus over that observed when Trotting on the level. Because times of contact are similar in level and incline Trotting, we also hypothesized that strain rates of these muscles would be increased, accompanied by an increase in EMG activity. We examined the lateral head of th

  • In vivo muscle function vs speed. II. Muscle function Trotting up an incline.
    The Journal of experimental biology, 2005
    Co-Authors: Steven J. Wickler, Donald F. Hoyt, Andrew A. Biewener, Edward A. Cogger, Kristin L De La Paz
    Abstract:

    Different locomotor tasks, such as moving up or down grades or changing speed, require that muscles adjust the amount of work they perform to raise or lower, accelerate or decelerate the animal's center of mass. During level Trotting in the horse, the triceps had shortening strains of around 10.6% while the vastus shortened 8.1% during the stance phase. Because of the 250% increase in metabolic rate in horses Trotting up a 10% incline which is, presumably, a result of the increased requirement for mechanical work, we hypothesized that muscle strain during Trotting would be increased in both the triceps and the vastus over that observed when Trotting on the level. Because times of contact are similar in level and incline Trotting, we also hypothesized that strain rates of these muscles would be increased, accompanied by an increase in EMG activity. We examined the lateral head of the triceps and the vastus lateralis while Trotting up a 10% incline (5.7 degrees) over a range of speeds. The triceps shortened by 18% compared with 10.6% shortening on the level, and the vastus shortened by 18.5% compared with 8.1% on the level. The increased shortening velocities that were observed in both muscles probably reduced the force that any given set of activated muscle fibers could produce. If this pattern held for other limb muscles that do work to elevate the horse's center of mass on an incline, then a greater volume of muscle would have to be recruited to generate an equivalent force for body support. This was reflected in significant increases in the EMG intensity (IEMG) of both muscles.