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Kinetics of jump landing in agility dogs
Abstract
A recent survey reported an increased risk of injury in dogs participating in agility, a competitive canine sport involving different jumping activities. The aim of this study was to quantify the kinetic parameters during jump landing for commonly used obstacle types. It was hypothesised that with increasing obstacle height, the vertical force and vertical and accelerative horizontal impulse will increase as a result of a lengthened aerial phase, a more acute landing angle and the need to convert potential into forwards kinetic energy. Simultaneous kinetic and kinematic data were recorded from 11 competition agility dogs jumping over obstacle combinations of different height and inter-obstacle distance. Speed and landing angle of the second of the two consecutive jumps were successfully controlled by obstacle height and distance between obstacles. Statistical analysis showed differences between obstacles for peak vertical force, vertical impulse and accelerative horizontal impulse (increasing values with more acute landing angles). Extremely high peak vertical force was observed in the forelimbs (4.5 times bodyweight) when landing from a hurdle jump at high speed. Further detailed studies into the consequences for internal limb structures are warranted in order to clarify how this might be related to injury.
... Our aim was to identify which demographic, training, and competition variables were associated with the injury risk specifically in Border Collies. We hypothesized that jumping at higher jump heights would be associated with an increased injury risk, based on previous biomechanical studies [11,12]. We also hypothesized that Border Collies with handlers who had competed at the national/international level would be associated with an increased injury risk, based on previous injury risk factor studies [4]. ...
... One study demonstrated that dogs significantly alter their jump kinematics as the jump height increases, particularly once the height of the jump increases over 125% of the height of the dog at the withers [12]. Another found that the peak vertical force in the forelimbs was higher with higher obstacles [11]. Conversely, a recent study showed no decrease in landing forces when the jump height was decreased from 20 inches to 16 inches [15]. ...
... Since these studies primarily used Border Collies, as well as some Border Collie crosses, it is unknown how specific these kinematic and kinetic changes are to Border Collies and how much variation there is between breeds. These changes in kinematics and increased peak vertical forces in dogs jumping above shoulder height could potentially contribute to repetitive stress injuries, particularly in the shoulder, which is the most injured anatomic region [1,11,12]. However, if all breeds have similar changes in kinematics and kinetics during jumping, this may not explain the increase in the injury rate in the Border Collie breed compared to other breeds. ...
Simple Summary
Injuries in agility dogs are common. Border Collies are the most common dog breed participating in agility and their reported injury rate is notably higher than that of other breeds. Understanding the risk factors for injury allows for improved education and awareness and the development of injury prevention strategies, as well as improved management plans post-injury. Our aim was to identify which demographic, training, and competition variables were associated with the injury risk specifically in Border Collies. An increased risk of injury in Border Collies was associated with the following factors: the height of jumps relative to the shoulder height, the number of competitions at the national level, the age at the beginning of elbow height jumping, and the number of weekends spent competing during the year. Other factors associated with the injury risk included the age at the beginning of backside jumps, the acquisition of the dog from a breeder, and the age of the handler. These data provide valuable information about the possible risk factors for injury in Border Collies and highlight the need for prospective studies on injuries in agility dogs and the relationships between injuries and the breed, conformation, and genetics.
Abstract
Border Collies are the most common breed in agility and their reported injury rate is much higher than that of other breeds. We aimed to identify demographic, training, and competition variables associated with the injury risk for this breed. We hypothesized that higher jump heights and competition at national/international levels would increase the injury risk. Data were collected from an internet-based survey. A logistic regression model was built using backward selection. There were 934 Border Collies in the sample, with 488 reporting an injury. The jump height relative to the shoulder height was associated with injury, with dogs jumping noticeably above or below shoulder height more likely to report a history of injury. Other identified risk factors included the number of weekends spent competing/year, the number of competitions at the national level, the age when starting elbow height jumps and backside jumps, the acquisition of the dog from a breeder, and the age of the handler. Factors associated with prolonged injury (>3-month duration) were the age when starting elbow height jumps and having a veterinary assistant as a handler. Border Collies jumping above shoulder height had an increased risk of injury. However, those jumping below shoulder height were also at a higher risk, which could have been due to reverse causality. Similarly, the observed associations regarding differences based on the number of trial weekends/year may have been impacted by reverse causality as well. The increased risk of injury with elbow height jump training at <10 months of age may indicate that the repetitive impact of jump training prior to skeletal maturity negatively influences musculoskeletal development. These data provide valuable information for further prospective studies.
... 10,11 The dietary program can also have an influence on the metabolic factors related to work-related hyperthermia in dogs. 12,13 These factors should be considered when developing a management plan for athletic and working dogs. ...
... Grade 4 refer to complete tears of either muscle or tendon. In veterinary medicine, a 3-grade system of classification is generally applied [12,13,14]. Grade I (mild grade) strains show intact muscle function, with focal oedema or haemorrhage and less than 5%of the muscle involved [12]. ...
... Grade III (severe grade) strains involve significant fascial tearing, muscle fibre disruption, and significant oedema or haemorrhage [12]. Grade I injuries are rarely noted or diagnosed, asides from athletic or performance animals, and generally resolve with appropriate rest in <1 week [12,13,14]. Ultrasonography is commonly used for diagnosis of muscular trauma in dogs. ...
Proceedings 47th annual ECVSMR congress
... Literature also reports that most injuries occurred during obstacle performance during competition, with most injuries (16.9-36.5%) occurring when traversing the bar jumps, which are the most numerous obstacles on any agility course (3,5). ...
... Little research has evaluated the kinetics of impact associated with jumps of variable heights used in agility competitions. A limited study of 11 agility dogs evaluating the effect of different jump obstacles on approach speed and landing angle, found that increased vertical forces occurred during the hurdle (vertical) jump compared to the broad (horizontal) jump (5). A recent study assessed the impact of static jumping on landing forces, and found a significant difference in peak vertical forces when landing from a box set at different heights (7). ...
... In support, other studies found that as the height of the obstacle decreases, there is an increase in speed and shallower landing angles of the forelimbs (5, 10). Pfau et al. reported peak vertical force of 4.5 times body weight when landing at a high speed (5). Further, when jump heights were not changed, but distances between jumps was increased, there was an increase in speed coupled with shallower landing angles (11, 12). ...
Objective
The objective of this study was to evaluate the effects of jump height on the landing forces of dogs.
Animals
Client-owned Border Collies experienced in agility competition, n = 9.
Procedures
The study involved client owned border collies with the same AKC standard jump height of 20 inches and preferred height of 16 inches. Standard height is based upon the height of the dog at the withers, with preferred height referred to as reduction in jump height by one level due to injury or age. An AKC regulation bar jump was placed over a previously validated pressure sensitive walkway (PSW). The peak force (%BW) and peak contact pressure (kPa) of the leading and trailing forelimbs were evaluated for all dogs.
Results
There was no significant difference in landing force between the two jump heights for either peak force as a percentage of body weight or peak contact pressure when evaluated in both leading and trailing forelimbs.
Conclusions and clinical relevance
Our findings demonstrated no significant difference in active landing forces of peak contact pressure and peak force on the forelimbs of dogs when jumping at a standard jump height vs. a preferred jump height when controlling for velocity in dogs performing a single running bar jump. These results suggest that the recommendation of decreasing jump height for older animals or injured animals may not provide a significant decrease in the impact on the forelimbs. It is likely that other factors contribute to the total forelimb kinematics picture during competition. Veterinarians and trainers should consider additional ways to decrease impact for canine athletes as they recover from injury.
... Wider canine kinematic research suggests that peak landing force is higher when landing over an upright hurdle than running or landing over a long jump for dogs (14). On landing following a simulated jump from a car boot, peak ground force increased as the height of the platform increased (15). ...
... There is a paucity of research on the impact of scale height on landing forces and apparent joint angulation of dogs on landing after traversing the scale. This contrasts with the discipline of dog agility, where research has identified specific kinematic and ground reactive force alterations in participating dogs (8,9,14,23). The height of scale used in working dog trials may thus have ramifications for physical health of dogs participating in this discipline. ...
... However, dogs <25 kg showed no significant changes in PVF at any of the heights. Pfau et al. (14) highlighted very high peak vertical force in the forelimbs of dogs (25 N/kg per foot) when landing from hurdle jumps at speed. This was not observed in the present study, although Pfau and colleagues examined border collie dogs of up to 19 kg, which was the weight category in which we found greatest variation despite less variability in bodyweight (dogs <25 kg 21.5 ± 2.4 kg, dogs >25 kg 29.2 ± 4.3 kg). ...
Working trials is a canine discipline that originated from police and military dog work. One aspect of working trials competition is for a dog to “scale” a 6ft high wooden wall. Concern has been raised in other canine disciplines that landing forces after traversing jumps may lead to soft tissue injuries. There is a paucity of research into the impact of scale height on peak vertical landing force (PVF) in dogs participating in working trials. The aim of this work was to determine whether an alteration in scale height impacts PVF and apparent joint angulation on landing. Twenty-one dogs who regularly competed in working trials traversed the scale at three different heights; 6ft (full height), 5.5ft and 5ft. Changes in PVF, apparent carpal and shoulder joint angulation and duration of landing were analyzed using general linear mixed models. Dogs weighing >25 kg had greater PVF at 6ft than at 5ft (p < 0.05). There was no effect of scale height on PVF in dogs <25kg. Duration of landing was longer at 5ft than 5.5ft (p < 0.001) and 6ft (p < 0.001). Apparent carpus angle on landing was smaller at 6ft than 5ft (p < 0.05) and 5.5ft (p < 0.05) for dogs <25 kg. Apparent carpus angle on landing did not differ at any height for dogs >25 kg (p > 0.05). Apparent shoulder angle was not affected by scale height for any dogs (p > 0.05). There was considerable variation in the study population, but this research indicates that when the scale height was lowered to 5.5ft dogs had reduced PVF and less compressed joint angles on landing. When the scale height was lowered to 5ft they altered their traversing style and greater compression and increased PVF was seen. Evidence-based approaches to canine working trials are important to ensure minimum impacts on physical health and welfare of participating dogs, in terms of risk of injury in both competition and training. Based on these findings it is recommended that the maximum height of the scale is reviewed for training and competitive purposes, to ensure minimal impacts on the health of competing dogs, while maintaining the level of competitive challenge.
... Furthermore, work by Carter et al. [17] identified changes in peak vertical landing force and joint angulation in dogs traversing different heights in the working trials scale obstacle. Beyond the work of Pfau et al. [7], to the authors' knowledge, there is no research on the impact of spread jumps on agility dogs, and there is no publicly available research on the impact of the length of long jump on dogs regularly competing in working trials. ...
... Pfau et al. [7] highlighted greater loading on the front limbs than rear limbs of agility dogs after clearing the long jump and research into injury risk of dogs competing in flyball has highlighted the forelimb as the predominant point of injury [14,15]. The front limbs were the areas of focus for this piece of research. ...
... Previous research has indicated that dogs will alter joint angles to reduce the impact of force when landing [7]. Our findings support this concept. ...
Simple Summary
Working trials is a competitive canine discipline based on work originating from military and police dog work. Working trials competitions include dogs clearing a 9 ft long jump. Jumping over hurdle jumps or long jumps has the potential to cause injuries to the front limbs of dogs, and different jump heights can cause changes to landing forces and the angle of joints on landing. Little is known about the impact of the 9 ft long jump on landing force and joint angles in dogs. In this study, we aimed to determine whether altering the length of the long jump impacted dogs’ landing forces or joint angles. There was no relationship between the length of long jump and landing forces or joint angulation on landing, however, the greatest joint compression was observed on landing after traversing 9 ft. The dogs showed lots of individual variability. We recommend further research is undertaken to examine this individual variability and the effect of training and experience in working trials participants, to enable evidence-based recommendations for those training and competing dogs in working trials.
Abstract
Working trials is a competitive canine discipline based on work undertaken by military and police dogs. A 9 ft long jump is a key component of the discipline. Research into landing forces and joint angulation in other canine disciplines has highlighted the potential for the occurrence of soft tissue injuries, predominantly in the front limbs. There is a paucity of work into the impact of spread/long jumps on joint angulation and peak vertical force (PVF) on landing, and limited research on working trials dogs generally. This study aimed to determine whether altering the length of the long jump impacted PVF and apparent joint angulation upon landing. 21 dogs regularly competing in working trials cleared the long jump at three lengths: 9 ft (full length), 8 ft, and 7 ft. The impact of altered long jump length on the PVF, apparent shoulder and carpus angulation, and duration of landing, were analysed using general linear mixed models. There was no significant relationship between the length of the long jump and PVF or joint angulation on landing (p > 0.05). Greatest joint compression was observed on landing after clearing 9 ft. Individual variability in landing joint angulation, PVF and force distribution of the left and right front limbs on landing was observed across all three experimental lengths. We recommend further research is undertaken to examine individual variability and the effect of training and experience in working trials participants, to provide evidence-based recommendations for training people and competing dogs in this discipline.
... As seen in a previous study (Pfau et al., 2011), pressures were higher in trot than in walk, but relatively balanced in comparison to force, highlighting the breeds ability to distribute bodyweight evenly at the two gaits measured, albeit trot does increase both force and pressure on the forelimbs. PFz at walk and trot was not collected during the study, however it would be expected that as stride length increases from walk to trot stance time decreases, increasing PFz, which has been noted as up to 125% of bodyweight in the forelimbs, and 85% of bodyweight in the hindlimbs (Holler et al., 2010;Weigel et al., 2005). ...
... During a lengthier approach, the animal would be more able to optimise body position, with a greater energy release from elastic structures contributing to the power needed to clear the jump (Gregersen and Carrier, 2004). The method of jumping used in this study led to a relatively sharp incline and decline angle at both take-off and landing, as well as causing the animal to maintain proflexion of the hindlimbs to clear the obstacle, all of which may result in different loading patterns and higher joint moments than seen in previous studies using higher approach speeds, which would allow for a flatter trajectory (Pfau et al., 2011). Upon landing it was also observed that although the elbow and shoulder flexed upon impact, momentum, and the dog's eagerness to turn towards its handler meant it effectively rolled over the axis of the shoulder joint, limiting both flexion but potentially increasing GRFs as the centre of mass shifted cranially, as well as increasing torsion forces through the forelimbs. ...
... Existing research has shown that upon landing one forelimb follows the other whilst ensuring that sufficient horizontal velocity is retained, allowing the hind limbs to clear the jump, but creating asymmetrical limb loading (Meershoek et al., 2010;Söhnel et al., 2020). The resulting rotation at the forelimb upon landing would also mean ground reaction force vectors may be misaligned with the limb, suggesting GRF moments could be counteracted by higher internal forces (Pfau et al., 2011). Further investigation is needed to fully understand the relationship between kinematics and kinetics of jump landing, and if dogs use additional strategies such as abduction/adduction of the limb to reduce rotational forces. ...
Many police dogs do not reach their expected retirement age as they are no longer able to cope with the physical demands of the job. Annual licensing requires police dogs to complete a series of agility tasks, including jumping and negotiating an A-frame obstacle, both of which are associated with higher injury rates in canine agility competitors. This study sought to measure conformational, kinematic, and kinetic parameters of actively employed police German Shepherd Dogs (GSDs), whilst completing a 55 cm jump hurdle, and a standard A-frame. Each dog completed three repetitions of each obstacle and was also recorded at both walk and trot. Contact pressures and forces were measured, whilst joint kinematics were recorded using reflective markers and a high-speed camera. Results found that static hip angle was significantly correlated with hip flexion at trot, during jump suspension and at the apex of the A-frame. Stifle and hock flexion were greatest during the suspension phase of jump (56.98±11.710° and 54.51±17.430°). Shoulder and elbow flexion were greatest at the apex of A-frame (104.34±16.744° and 75.72±20.804°), whilst carpal extension was highest upon landing from the jump (125.77±7.071°). Peak vertical force (PFz) when normalised for body mass (BM) increased when landing from A-frame (14.28 N/kg BM) as opposed to landing from the jump obstacle (12.055 N/kg·BM). Our results show that increased range of motion (ROM) is required during both jumping and negotiation of A-frame compared to walk and trot, but more significantly, greater forces are incurred upon landing from the A-frame than compared to jumping. It was also observed that dogs were subject to high degrees of torsion in the distal limbs upon landing from the A-frame due to trained behaviours. We conclude that use of agility equipment generates greater forces through the musculoskeletal system and requires a greater ROM than what is experienced at walk and trot, which may contribute to early retirement ages in police dogs.
... In allowing dogs to jump unaided out of vehicles, owners may be inadvertently predisposing their dogs to the development of musculoskeletal pathologies. Some studies have explored the biomechanics of competitive jump landings in dogs [11][12][13][14] ; however, minimal quantitative canine studies investigating the effects of jump landing exist when investigating static start jump-downs. Given the paucity of research in this area, it is important to consider the biomechanical implications of jumping from a stationary position from a range of heights. ...
... A capture rate of 500 Hz and a time period of 10 seconds were used to ensure effective data collection. 13 Non-slip rubber matting was placed over the force plate and the surrounding area to ensure that dogs did not slip on landing. Two-dimensional video recording (Canon EOS 600D, 1280×720, 60 fps) of each trial took place to enable confirmation of the validity of trials. ...
... If on the acclimatisation jump a dog did not land in the middle of the force plate, the platform was then moved forwards or backwards in increments of 0.01 m for a second acclimatisation jump. 13 The range of distances used was from 0.26 to 0.47 m (mean 0.38±0.05). Once a successful trial was observed, this counted as part of data collection and subsequent trials continued with the same configuration. ...
Many dog owners allow their pets to jump out of a car boot; however, to date, there has been no study that has investigated whether this places dogs at risk of injury. The aim of this study was to investigate the relationship between height and peak vertical ground reaction force (vGRF) in static start jumps. Fifteen healthy adult dogs performed three jumps from a platform that represented common vehicle boot sill heights (0.55, 0.65, 0.75 m), landing on a single force platform. Kinetic data (mediolateral (Fx), craniocaudal (Fy) and vertical (Fz)) were normalised for body weight and analysed via a one-way repeated analysis of variance (ANOVA) and pairwise post hoc tests with a Bonferroni correction applied. There was a significant difference in peak forelimb vGRF between both the 0.55 m (27.35±4.14 N/kg) and the 0.65 m (30.84±3.66 N/kg) platform (P=0.001) and between the 0.65 and 0.75 m (34.12±3.63 N/kg) platform (P=0.001). There was no significant difference in mediolateral or craniocaudal forces between the heights examined. These results suggest that allowing dogs to jump from bigger cars with a higher boot sill may result in augmented levels of loading on anatomical structures. Further research is required to investigate the kinematic effects of height on static jump-down and how peak forelimb vGRF relates to anatomical loading and subsequent injury risk.
... In canine agility athletes, the forelimb, and specifically the shoulder, is the most common site of injury (1,2,4,11). The forelimbs carry 60% of a dog's body weight during the stance phase, and are subject to high peak vertical forces when landing from a jump (12). In addition, when landing from a jumping turn, the forelimbs experience higher lateral forces compared to the hindlimbs (13). ...
... Jump height has been associated with increased injury risk (3). Obstacle height and the distance between obstacles has also been demonstrated to affect speed and landing angle (12). In addition, jump angle and landing angle may alter biomechanical forces. ...
Agility is a rapidly growing canine performance sport worldwide, yet the literature is sparse regarding the impact of ground substrate on performance and injury. Approximately 1/3 of dogs participating in agility trials will experience a performance-related injury. The impact of ground material has been well-documented in racing greyhounds, equine athletes, and humans, but has been minimally investigated in agility dogs. In this retrospective, cross-sectional study, 300 respondents (handlers, owners, and trainers) of 308 agility dogs completed an online survey regarding their dog's training and competition regimen, history of injury, perceived association between injury and substrate and/or agility obstacle, markers of decreased performance (MDPs) observed on different substrates, and changes to routine following injury. 35.7% of dogs sustained a training injury (TI) and 11.2% sustained a competition injury (CI). The most commonly reported sites of injury were the shoulder (TI: 33.9%, CI: 25.4%), forelimb digits (TI: 14.7%, CI: 11.9%) and iliopsoas muscle (TI: 11.9%, CI: 13.6%). Dogs most commonly trained on natural grass (85.3%), artificial turf (50.8%), and dirt (34.5%). Significantly fewer MDPs were observed on natural grass than any other substrate except dirt. Significantly more MDPs were noted on rubber mat compared to natural grass, artificial turf, dirt, sand, or foam mat. Rubber mat had the highest Incidence Proportion (IP) (32.0%) of TI and was perceived to be related to TI in 87.5% of cases. Obstacles perceived to be associated with injuries included jumps (TI: 37.5%, CI: 27.8%), contacts (TI: 29.7%, CI: 22.2%), weaves (TI: 11.9%, CI: 13.9%), and tunnels (CI: 25.0%). Overall, agility dogs were perceived to perform best on natural grass and dirt, while rubber mat was associated with injury and decreased performance. Respondents were willing to make significant alterations to their dog's routine due to a perceived association between substrate, injury, and performance. Further prospective studies are needed to assess the impact of substrate composition and maintenance, and inform evidence-based recommendations to maximize performance and minimize performance-related injury in agility dogs.
... Jumping a lower jump height is thought to exert less force on the developing bones and joints, and therefore be less likely to cause developmental musculoskeletal conditions or injury. While biomechanical studies have shown that increasing jump height increases peak vertical force upon landing with the forelimbs, and increases angulation of the scapulohumeral and sacroiliac joints, no studies have correlated the kinematic and kinetic findings with injury development or risk (17,18). Based on the findings of this survey, it does not appear that starting jumping at a lower jump height when younger is protective of injury. ...
... Jumping 2-4" and jumping >4" above the height of the withers was associated with an increased risk of injury. This finding may be due to the increased neck angulation, lumbar spine extension and shoulder flexion as jump height increases, as well as the increased peak vertical force with higher jump heights and steeper landing angles (18,19). Further studies are needed to prospectively evaluate effect of jump training on musculoskeletal development and injury incidence, as well as the association of altered kinetics and kinematics of increasing jump height and injury development. ...
Objective: To describe risk factors associated with training and competition in relation to frequency and severity of injuries experienced by agility dogs.
Procedures: An internet-based survey collected data on competition level variables and training level variables. The primary outcome was history of any injury and a secondary outcome considered history of severe injury (injury lasting > 3 months). Logistic regression was used to estimate associations and final models were obtained via backward selection to identify the strongest associations within variables.
Results: There were 4,197 dogs included in this analysis. Injury was reported for 1,737 (41.4%) dogs and severe injury was reported for 629 (15.0%). In the model with competition level factors, jumping 4” (OR: 1.50) or 2–4” (OR: 1.31) over shoulder height compared to jumping 0–2” lower and competing at national events was associated with increased injury risk, while competing 6+ times on rubber matting was associated with lower risk (OR: 0.62). Training level variables associated with injury risk were age starting jump, teeter, and weave training, with the highest risk observed for dogs starting jump training between 3 and 18 months but starting weave and teeter training after 18 months of age.
Conclusion and Clinical Relevance: Many variables thought to be associated with injury risk were not significant in the final model. Starting jump training at an earlier age was associated with greater risk of injury relative to starting after 18 months. It is possible that the high impact of jump training before skeletal maturity may increase the risk of injuries or musculoskeletal conditions. The increased risk of injury in dogs that jump 2–4, or 4+ inches higher than shoulder height may be due to increased biomechanical forces during takeoff and landing. Faster dogs may be at higher risk of injury; handlers planning competition around big events or competing at the national level are likely to have faster dogs, and may be less likely to compete on rubber matting. These data provide valuable current insight into the possible effects that training and competition variables may have on injury risk in agility dogs.
... United Stated Dog Agility Association (n ¼ 272, 54.4%), Canine Performance Events (n ¼ 194, 38.8%), United Kennel Club (n ¼ 94, 19.8%), North American Dog Agility Council (n ¼ 65, 13.0%), Dogs on Course in North America (n ¼ 10, 2.0%), Teacup Dogs Agility Association (n ¼ 4, 0.8%), or other (n ¼ 63, 12.6%). ...
... In addition, the forelimbs are loaded asymmetrically upon landing. This may further exacerbate pre-existing orthopaedic conditions and contribute to degeneration over time, 19 and may be speculated to cause a higher rate of shoulder injuries in this population of agility dogs. Higher loads and faster loading may also fatigue muscles more quickly. ...
Objective The aim of this study was to identify risk factors for an agility dog becoming injured during its career. We hypothesized that certain factors involved with the training, competition, age, sex, age of neuter, body condition, and management could be associated with the risk for injury.
Study Design The outcome of interest in this cross-sectional survey design was injury versus no injury, and an initial univariable analysis screening was performed. All variables with a p-value of less than 0.20 in univariable analysis were entered into a multivariable logistic regression model. Manual backward stepwise removal was performed until remaining variables had a p-value of less than 0.05.
Results Five-hundred responses were included in the analysis. In the final multivariable model adjusting for all other variables, breed, age, age at neuter, and level of competition remained associated with injury in the study population.
Conclusion These findings support existing literature on the predispositions for injury with certain breeds and competition level. Our study further suggests, however, that there is a need to better understand how health decisions earlier in life may affect the prevalence for injury in the agility competitor, particularly regarding age at neutering and age of the competitor.
... The authors also suggest that galloping dogs' forelimbs do not bear peak vertical forces and have a larger decelerating impulse. This is opposite, when considering kinetics in jumping dogs (Pfau et al. 2011), where an accelerating impulse was recorded by the authors in forelimbs with even larger forces compared to that during galloping. ...
... This is because stochastic values for robustness analysis are based on a singular value of mean and standard deviation. However, this is subject to variability as locomotion performed by dogs not only varies between individual dogs but also with an uncommon gait such as jump landing (Pfau et al. 2011) or impact that develop higher dynamic impulses compared to those presented in Figure 7.3. Therefore, a further examination for reliability will enable an engineer in computing such rare event probabilities. ...
Additive manufacturing (AM) has almost taken over the traditional manufacturing market due to its ability to fabricate complex parts with reduced lead times. This has radically reduced a number of post-processing and finishing procedures that used to follow up after initial part production, thus making AM an economic platform for fabrication. In regard to metal AM processing, Electron Beam Melting (EBM) is an active technology that employs Ti-6Al-4V ELI (Titanium alloy) for the production of bespoke medical implants. This is primarily for two reasons: firstly, the biocompatibility of the metal that makes it suitable for the production of implants; and secondly, corresponding to the high melting point of the alloy, EBM can easily acquire these temperatures necessary for fabrication. Despite these advantages offered by EBM AM process, a major challenge lies in the determination of failure modes associated with these bespoke implants. This is because each implant geometry is fabricated for single-time use only, and this induces patient-specific uncertainties that need to be addressed during the design phase of each implant.
Therefore, this research encompasses several factors, including consistency of EBM manufacturing process, anisotropy in anatomical structures, variability in boundary conditions and static/dynamic response of implants, through probabilistic numerical analysis. Simulation for robustness through Finite Element (FE) analysis facilitated in quantifying the failure probability associated with each implant design. The methodology developed in this research was assessed across seven retrospective studies; the approach proved viable in computing the failure probability for all distinct implant scenarios. A low probability of failure was simulated for implants that are operational to date, and the approach successfully simulated a high probability of failure for the retrospective failed implant. The researcher believes that with the employment of suitable tools for data acquisition and manipulation, this methodology can be integrated for any weight-bearing implant to determine the robustness and risk associated with the preliminary design.
... The combination of kinetics (evaluation of the forces that generate movement) and kinematics (description of movement) is possible when data are measured simultaneously, resulting in a more complete analysis of the canine march [5]. For this analysis, data from both combined analyzes have been used [11], kinetic [9], [17] and kinematic [1], [18], in order to complement information on the analysis and verification of results. ...
... This change is because quadruped dogs have more time to reposition their limbs, which causes a limb to start applying propulsion forces while it is still holding [11]. For the calculation of the horizontal component (cranialcaudal force) a relationship between the vertical and horizontal forces of several studies made on Force Plates has been obtained and presented below on Table I. [3], [11], [13], [17] The result of this relationship is an estimated coefficient of: ...
... Hurdle height has been shown to affect vertical peak force and landing angle (Pfau et al., 2011) and joint angles of the forelimb and hindlimb at take-off (Birch and Le sniak, 2013). The type of obstacle and the distance between them influences the peak vertical force, the vertical momentum, the accelerating horizontal momentum during landing (Pfau et al., 2011), the speed and the jumping distance (Birch et al., 2015). ...
... Hurdle height has been shown to affect vertical peak force and landing angle (Pfau et al., 2011) and joint angles of the forelimb and hindlimb at take-off (Birch and Le sniak, 2013). The type of obstacle and the distance between them influences the peak vertical force, the vertical momentum, the accelerating horizontal momentum during landing (Pfau et al., 2011), the speed and the jumping distance (Birch et al., 2015). Furthermore, the peak vertical force depends on the breed of dog (Yanoff et al., 1992). ...
A considerable body of work has examined the dynamics of different dog gaits, but there are no studies that have focused on limb dynamics in jumping. Jumping is an essential part of dog agility, a dog sport in which handlers direct their dogs through an obstacle course in a limited time. We hypothesized that limb parameters like limb length and stiffness indicate the skill level of dogs. We analyzed global limb parameters in jumping for 10 advanced and 10 beginner dogs. In experiments, we collected 3D kinematics and ground reaction forces during dog jumping at high forward speeds. Our results revealed general strategies of limb control in jumping and highlighted differences between advanced and beginner dogs. In take-off, the spatially leading forelimb was 75% (P<0.001) stiffer than the trailing forelimb. In landing, the trailing forelimb was 14% stiffer (P<0.001) than the leading forelimb. This indicates a strut-like action of the forelimbs to achieve jumping height in take-off and to transfer vertical velocity into horizontal velocity in landing (with switching roles of the forelimbs). During landing, the more (24%) compliant forelimbs of beginner dogs (P=0.005) resulted in 17% (P=0.017) higher limb compression during the stance phase. This was associated with a larger amount of eccentric muscle contraction, which might in turn explain the soft tissue injuries that frequently occur in the shoulder region of beginner dogs. For all limbs, limb length at toe-off was greater for advanced dogs. Hence, limb length and stiffness might be used as objective measures of skill.
... Fore-and hindlimbs contributed equally to the increase in total vertical impulse produced during take-off with no change in weight distribution between fore-and hindlimbs. Around 53% of the total vertical impulse was produced by forelimbs at all bar heights, which is similar to previous reports of 55-56% in take-off to agility jump (bar height 90% of wither height) and 56-58% in galloping dogs [16,[19][20][21]. ...
Sport-related injuries have been reported to occur in around one-third of agility dogs. Higher bar height in competitions has been shown to increase odds of an injury. This study evaluated the effect of bar height on the kinetics and kinematics at take-off to a bar jump. Forces from fore- and hindlimb pairs were measured with force plates. A three-dimensional motion capture system was used to measure sagittal joint kinematics of the shoulder, elbow, carpus, hip, stifle, and tarsal joints, as well as limb coordination, trunk horizontal velocity, take-off distance, and take-off angle. Data were collected for 17 Border Collies at three different bar heights: 80%, 100%, and 120% of wither height. A linear mixed model was used for statistical analysis. At higher bar height, decelerative impulses were greater and accelerative impulses decreased along with greater vertical impulses from forelimb and hindlimb pairs (p<0.001). Post-hoc analyses revealed differences between all three bar heights (p<0.01), except for forelimb decelerative impulse, which did not differ between 80% and 100% heights. Sagittal range of motion was greater, through increased peak flexion or extension, at 120% bar height than at lower bar heights (p<0.05) in almost all measured limb joints. The only exceptions were leading forelimb shoulder and elbow joints and leading hindlimb hip joint. With increasing bar height, the horizontal velocity of trunk decreased (p<0.001), and take-off angle became steeper (p<0.001), with all bar heights differing from each other (p<0.01). Temporal synchronicity between trailing and leading limbs increased and craniocaudal distance decreased in forelimbs (p<0.05) and hindlimbs (p<0.01) as bar height increased. Increased vertical and decelerative impulses, as well as the greater peak flexion and extension angles of joints, may indicate greater load on the tissues at higher bar heights, which could explain the increased odds of injury at higher bar heights in agility dogs.
... Pressure-sensitive walkways (PSW) measure temporospatial (TPS) and ground reaction forces (GRF) information about all four limbs and multiple gait cycles (18). PSWs have been used to characterize the TPS and GRFs in different populations of dogs under various conditions (19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30). ...
Objective
The objective of this study was to investigate the effects of cavaletti pole height on temporospatial (TPS) and ground reaction force (GRF) variables as compared to a walking gait in healthy dogs.
Animals
A total of 25 client-owned dogs were included in this study.
Procedures
This study used client-owned dogs to explore the effects of cavaletti pole height on TPS and GRF variables. Dogs were first walked over a validated pressure-sensitive walkway (PSW) and then walked over the PSW over which six cavaletti poles were set. Cavaletti pole height was initially set at 2 inches and then increased incrementally to 4 inches, 6 inches, and 8 inches. TPS and GRF variables were obtained for all dogs walking across a PSW without cavaletti poles and at each cavaletti height. TPS variables were then compared to those obtained at a normal walking gait.
Results
Increasing cavaletti height resulted in significant decreases in walking gait velocity and the number of gait cycles per minute. Conversely, significant increases in gait cycle duration (duration of one complete cycle of gait, which includes the time from the initial contact of one paw to the subsequent contact of the same paw) and gait time (duration to walk the total distance on the PSW) were noted. Increases in stance time, normalized maximum force, and normalized vertical impulse were observed.
Conclusion and clinical relevance
Cavaletti height does influence TPS variables in healthy dogs at a walking gait. The effects were most notable with regard to velocity. Due to the lack of consistent velocity for all cavaletti heights, no conclusions can be drawn regarding the effect of cavaletti height on ground reaction forces. Further investigation is needed to elucidate whether it is the velocity, cavaletti height, or combination of both that impacts ground reaction force variables. When selecting cavaletti pole heights for a therapeutic exercise program, an increase in cavaletti height results in a slower walking gait.
... The various vertical ground reaction loads based on previous studies are as follows; walk (6.5 N/kg), trot (10.4 N/kg), and hurdle jump (45 N/kg) (Oosterlinck et al., 2010, Pfau et al., 2011. All the surgical methods were able to withstand the one-time walk and trot. ...
... Surprisingly, this observation was also common in the present study for dogs completing the dog walk, with a large percentage of dogs jumping from the down ramp of the obstacle rather than running off it. The act of jumping higher agility obstacles has been associated with more acute landing angles and an increase in peak vertical forces [11,12] when landing, which may serve as another source of stress on the joints leading to injuries while completing the a-frame and dog walk obstacles. Given the similarities observed between the two obstacles, further studies regarding paw placement styles of dogs completing the a-frame may be of interest to determine if there is a large amount of variability in paw placement occurring that could contribute to its association with injury and how it compares to the variability seen in dogs completing the dog walk obstacle. ...
The objective of this study was to describe paw placement patterns for canine athletes completing the dog walk obstacle during canine agility trials. It was hypothesized that dogs would demonstrate defined sets of paw placement patterns as they complete the dog walk obstacle and that those could be classified based on end contact behavior. Videos of 296 dogs attempting the dog walk obstacle at the 2021 UK Agility International (UKI) US Open were reviewed online. Data observed from video evaluation included front and rear limb paw placement across the dog walk and time to complete the obstacle. Results showed a high variability in obstacle performance. Mean time to complete the entire obstacle was 2.26 seconds (sd = 1.03). Mean and median completion times were qualitatively similar across all height classes. A slight majority of dogs hit the up ramp with their right foot first indicating running on their left lead (n = 185, 63%) with some variation observed between heights. Likewise, a slight majority (58%) of dogs hit the down ramp with their right front foot first (151/262). Given the high variation in completion times and paw placements, we could not identify clear patterns of dog walk performance. The large amount of variation observed with the dog walk obstacle suggests a need for future studies to employ alternative methods for objective gait analysis and to strategically select dogs to reflect the large variety in obstacle performance observed here.
... Anthony et al. of injury in agility dogs (CULLEN et al., 2013). Research has shown that the most common sites of injury in agility dogs are the shoulders, back and digits and that injuries are most likely to be soft tissue in nature (KERR et al, 2014;LEVY et al., 2009).It is also believed that the greater the forces experienced by the limbs and the more acute the joint angles, the greater the strain placed upon the dog's body leading to a higher risk of injury (PFAU et al., 2011). Because the dog walk is, according to agility injuries surveys (CULLEN et al., 2013;LEVY et al., 2009), one of the of the obstacles most implicated in injuries in agility dogs, and there is no study of the biomechanical demands of this obstacle negotiation, this study has been devised to elucidate some of these aspects. ...
The injury rate in agility dogs is relatively high compared to the general population. No study to date has considered the biomechanical effects of the dog walk obstacle in agility trials, highlighting a research need. This study assessed forelimb joint kinematics and peak ground reaction forces (PVF) over a dog walk agility obstacle and correlate with experience. Ten (n = 10) dogs were filmed running across a Kennel Club (KC) standard dog walk for kinematics analysis. Two pressure sensors were secured to the (1) dog walk contact area at exit and (2) ground at the end of the dog walk (landing area) for kinetics analysis. Forelimb joints angles and PVF at the contact zone at the walk exit and landing were analysed. A key finding is that the way a dog will move across the obstacle changes depending on their level of experience, with experienced dogs showing faster obstacle negotiation and increased flexion of the elbow joint compared to inexperienced competitors. Higher speeds over the dog walk also resulted in significantly increased elbow joint flexion. Another important finding is that PVF at landing are higher is dogs that are faster and also in dogs performing running technique in comparison to stopped technique. Overall, dog walk obstacle created more forelimbs joint flexion and similar PVF in comparison with previously studied agility contact obstacles which leads us to conclude that further research is required to ascertain the long term health implications for dogs used in agility trials.
... Higher jump heights have been shown to increase peak vertical force and landing angles, with forces in the forelimbs incurring up to 4.5 times the bodyweight. 22 Both jump height and distance between jumps have been shown to affect joint angulation, speed, and jump trajectory. [23][24][25][26][27] The correlation between these biomechanical alterations and injury remains unknown. ...
Agility is a physically demanding sport, and injuries are common. An understanding of the common clinical presentations, frequent injuries, and risk factors for injury is critical when seeing this population of patients in practice. Shoulder injuries and other soft tissue injuries including iliopsoas muscle strains are commonly seen. The Border Collie seems to be at higher risk of developing agility-related injuries. The key to rehabilitation of the agility dog is accurate and expedient diagnosis of the injury, which often involves advanced diagnostics such as musculoskeletal ultrasound, arthroscopy, and/or MRI.
... Humans can cross obstacles by controlling the trajectory of their bodies as well as the amount of foot force. Furthermore, animals can perceive ground information through the visual and tactile systems and then plan movement trajectories according to the size and location of obstacles [36,37]. The animal control of body trajectory and foot force is what the robot should learn in order to improve motion performance. ...
Legged animals can adapt to complex terrains because they can step or jump over obstacles. Their application of foot force is determined according to the estimation of the height of an obstacle; then, the trajectory of the legs is controlled to clear the obstacle. In this paper, we designed a three-DoF one-legged robot. A spring-loaded inverted pendulum model was employed to control the jumping. Herein, the jumping height was mapped to the foot force by mimicking the jumping control mechanisms of animals. The foot trajectory in the air was planned using the Bézier curve. Finally, the experiments of the one-legged robot jumping over multiple obstacles of different heights were implemented in the PyBullet simulation environment. The simulation results demonstrate the effectiveness of the method proposed in this paper.
... Most performed limb amputations are total limb amputations and associated with the aggravation of an animal's concomitant orthopedic joint angles go from 48 • to 191 • [39]. However, bone angles regarding the ground are not typically assessed [33,40]. ...
Simple Summary
Currently, more owners look for offering a better quality of life to their pets. In fact, the complete limb amputation seems to be the last option considered by pet owners in surgeries to save their pets’ lives. Although this field is under development in veterinary medicine, we believe that 3D-printed implants for this market sector will improve the advancement in its research by reducing production costs. This would allow the pet owners to select this solution without large expenses, allowing at the same time, advances in this field. For this purpose, mechanical tests have been carried out on implants printed in a high-performance plastic that resembles the resistance of metals—that are traditionally used in veterinary surgery—and the properties of dogs’ bones as well. The results obtained have confirmed that the implants could withstand the dog weight in its different gaits, although further comparative studies on the effect of rotation forces applied during the animal’s change of direction (evaluated at different paces) are required to confirm their suitability.
Abstract
Exo-endoprosthesis is a limb salvage procedure poorly described for animals, as only expensive metal devices have been used so far. Currently, additive manufacturing (AM) can make this type of implant affordable by exploring a wide new range of materials. However, safety factors should be considered and could be related to kinetic and kinematic studies of canine natural gaits. The suitability of a novel inner part of an exo-endoprosthesis manufactured by fuse deposition modeling (FDM) was assessed for long canine bones with an elliptical medullary canal. Polyether ether ketone (PEEK) was the material used as an alternative to metal for veterinary traumatology. Poisson’s ratio of 3D-printed PEEK material and ex vivo mechanical tests of the customized endoprosthesis were performed for the evaluation. The customized endoprostheses had promising outcomes for the radii of 20 kg dogs. Quasistatic mechanical tests of bone-inserted endoprostheses—pure compression tests—reached a maximum force of 1045.0 ± 78.0 N. In fatigue tests, the samples reached 500,000 cycles without failure or detriment to their quasistatic results. These outcomes surpass the natural weight-bearing of dogs, even during a galloping pace. Furthermore, torque tests with different adhesives were performed to obtain reference data for future assessments comparing with natural dog movements.
... Jumping has frequently been suggested as a possible cause of injury for agility athletes, and hesitancy to jump is often one of the first symptoms described after an iliopsoas injury (23)(24)(25)(26)(27)(28). Iliopsoas injury has been postulated to result from microtrauma from repetitive jumping, but jumping frequency (based on number of runs per day), age at which jump training was started, and the heights of jumps were not associated with odds of iliopsoas injury in this study. ...
Objective
To describe risk factors associated with demographics, training, and competition for iliopsoas injury in dogs participating in agility competitions, as well as describe owner reported treatment and return to sport following injury.
Procedures
An internet-based survey of agility handlers collected risk factor data for dogs participating in agility. Owners were asked questions about demographics, training, and competition as well as injury treatment and recovery if applicable. Associations between variables of interest and iliopsoas injury were estimated with logistic regression. The final risk factor model was built via modified backward selection, with all variables in the final model showing significant associations at p < 0.05.
Results
Of the 4,197 dogs in the sample, 327 (7.8%) reported iliopsoas injury. The final model identified six risk factors for iliopsoas injury. A higher risk of iliopsoas injury was observed for the Border Collie breed, dogs with handlers who are veterinary assistants, dogs competing on dirt, dogs competing on artificial turf 6+ times a year, and dogs that trained with the 2 × 2 method for weave poles. Dogs that were not acquired with agility in mind were observed to have a decreased risk of injury. Factors like number of competition days and jump height were not significantly associated with risk of iliopsoas injury. Owners sought veterinary care for 88% of dogs with iliopsoas injury, including specialty care for 63%. Treatment most often included rest, home rehabilitation, formal rehabilitation, and/or oral medications. Most dogs (80%) were able to return to sport within 6 months, while 20% were out for longer than 6 months, or retired.
Conclusion and Clinical Relevance
Iliopsoas injury can necessitate a significant amount of time off from training and competition, and even lead to retirement of dogs competing in agility. Some of the risk factors identified in this study can inherently not be modified (breed, intended use, and handler profession), but can be taken into consideration for injury prevention strategies. Competition and training risk factors that can be modified, such as weave training, may help to inform guidelines for best practices in management of the agility athlete.
... Bockstahler et al. [15] demonstrated that peak vertical force and vertical impulse increased in the forelimbs and decreased in the hind limbs in dogs retrieving objects at weights between 0.5 to 4 kg. Furthermore, the height of jumping obstacles has been found to affect joint angles and stress on the joints during landing [59,60]. Recent research on post-exercise cooling methods [25] and hydration strategies [26] have also been presented and require adherence by dog handlers and organizers of trials and competitions. ...
Dog trials and competitions involve various sport disciplines, e.g., obedience, agility, working dog trials and rally obedience. Dog handlers navigate their dogs through physically and mentally demanding tasks. The purpose of this study was to gain a better understanding of barriers and facilitators to canine health promotion and injury prevention described by dog handlers. Methods: Qualitative inductive content analysis was applied to systematically organize and interpret narrative data from 654 respondents’ answers to open-ended questions in an anonymous online inquiry. Results: Two categories, with seven sub-categories, emerged from the analysis: (1) Challenges in applying the regulations in dog trials and competitions, and (2) Implementation of animal welfare and canine well-being approaches. Respondents described the challenges in applying regulations in dog trials and competitions and lack of scientific research as barriers to their intent to prevent injuries in their dogs. Implementation of animal welfare and canine well-being approaches were described as facilitators. Conclusion: The findings imply that the stakeholders continuously need to work on bridging possible gaps between the canine welfare criteria and the scientific and empirical knowledge in canine sports and performance medicine.
... To our knowledge, there are no studies showing that larger dogs have superior jumping abilities to smaller dogs. Although lower relative fence heights have been associated with increased speed [30,31], and smaller dogs had a lower competition speed than larger dogs. Lower speed and lower mass result in lower kinetic energy, and thus, smaller risk of damage in case of collision. ...
Knowledge regarding training, competition, and management routines of agility dogs is lacking. Through a retrospective online questionnaire, Finnish owners and handlers of 745 competition-level agility dogs provided information on training routines and management of these dogs during one year free of agility-related injuries. Competition routines were collected from the national competition results database. Most dogs trained agility 1–2 times a week, with a median active training time of 18 min a week. Dogs competed in a median of 2.1 runs per month at a speed of 4.3 m/s. Common field surfaces were different types of artificial turfs and dirt surface. Warm-up and cool-down were established routines, and 62% of dogs received regular musculoskeletal care. Moreover, 77% of dogs underwent conditioning exercises, but their frequency was often low. Additionally, dogs were walked for a median of 1.5 h daily. Pearson’s chi-squared and Kruskal–Wallis tests were used to evaluate the association between a dog’s competition level and training and competition variables. A dog’s competition level was associated with competition (p < 0.001) and training frequency (p < 0.001); dogs at higher levels compete more but train less than dogs at lower levels. This study provides information on training, competition, and management routines of competing agility dogs.
... In contrast, men land with a semi-flexed knee, and this position is more suitable for shock absorption and energy transfer throughout the pelvic limb [113,142,145]. In veterinary medicine, changes of direction and landing from high altitudes represent a risk, especially for dogs participating in agility and disc dog competitions [146][147][148][149]. Even dogs not engaged in specific sports can exhibit a traumatic CrCL rupture during a jump or run. ...
Cranial cruciate ligament (CrCL) rupture is one of the most common orthopaedic conditions in veterinary medicine. CrCL plays a fundamental role in the stability and biomechanics of the femoral-tibio-patellar joint, and its incorrect functionality severely impacts on the quality of life of patients. In dogs, the structural weakening of this joint due to the progressive degeneration of the ligament is the most accredited etiopathogenetic hypothesis in relation to the dog signalment (breed, sex and age) and the stifle joint conformation. In humans, this injury is often traumatic and generally occurs during sporting activities. CrCL rupture can be managed conservatively or surgically, and decisions regarding treatment are due to numerous factors: the patient’s age and health, the degree of stifle instability, and cost. Physiotherapy protocols play an important role in rehabilitation, with similar goals in humans and dogs: pain management, physiological articular range of motion recovery, periarticular and core muscle strengthening, and proprioceptive deficit correction. Physiotherapy, even if often neglected in veterinary medicine, is mandatory for the recovery of the correct functionality of the injured limb and for the return to normal daily and sporting activities.
... Running agility course often consists of bursts of activity and direction changes for both handlers and dogs which potentially places a physical demand on both humans and canines. As a consequence, physical training could be beneficial for all levels of handlers and dogs, from those competing at high levels to those training recreationally, in order to improve performance and reduce the risk of injury (Pfau et al., 2011). In other sports characterized by aerobic activity with sudden direction changes (e.g., soccer), physical training including aerobic, and strength training are useful for the prevention of non-contact-related injuries and for increasing sport performance, even in individuals participating in recreational level activities (Gamble, 2013;Klugl et al., 2010;Monajati et al., 2016;Stone & Kilding, 2009). ...
Participation in dog agility may strengthen the bond between dog owners and their dogs and provide a reason for increasing physical fitness, thus increasing physical activity behavior. The purpose of this study was to compare physical activity levels (performed both with their dogs and without their dogs) of agility trainers with non-agility trainers, and to examine factors associated with physical activity using Self-Determination Theory (SDT) and dog responsibility (i.e., the sense of responsibility for the wellbeing of one’s dog). Dog owners (n = 280) completed an online survey that examined the relationship between participation in dog agility and (a) physical activity (performed with or without a dog), and (b) motives for physical activity, behavioral regulation, and dog responsibility using multiple regression analyses and analyses of covariance (ANCOVAs). Agility trainers indicated significantly higher total weekly minutes of moderate-to-vigorous physical activity with a dog (p < 0.05), but lower weekly levels of physical activity without a dog compared with non-agility trainers. ANCOVAs indicated that agility trainers showed higher competence motives (p < 0.01), and social motives (p < 0.05) compared with non-agility trainers. Multiple regression analyses indicated that the SDT constructs and dog responsibility accounted for 23% of the variance in physical activity with a dog in the overall sample, but that no significant differences were found in these relationships when agility trainers compared with non-agility trainers through moderation analyses. In conclusion, dog owners who train their dogs in agility may accumulate more physical activity with their dogs but less physical activity without their dogs compared with other dog owners. Dog agility trainers may indicate more self-determined and intrinsic motives for physical activity with a dog compared with non-agility trainers.
... Notwithstanding the many informative and inspiring studies of legged animal performance, e.g. [26,27,121,158,167,183,214], we have not been able to find any previous formalization of the notion of legged agility suitable for comparing robots of different morphologies and different sizes over different tasks. Perhaps the most common measure for acceleration and leaping used in the legged biology literature is specific power (watts per kilogram taken over a gait cycle of leg power output relative to leg muscle mass or body mass) [155,182,183,220] but it is not scale invariant as we observe in Chapter 3.5. ...
How does a robot's body affect what it can do? This thesis explores the question with respect to a body morphology common to biology but rare in contemporary robotics: the presence of a bendable back. In this document, we introduce the Canid and Inu quadrupedal robots designed to test hypotheses related to the presence of a robotic sagittal-plane bending back (which we refer to as a "spine morphology"). The thesis then describes and quantifies several advantages afforded by this morphological design choice that can be evaluated against its added weight and complexity, and proposes control strategies to both deal with the increase in degrees-of-freedom from the spine morphology and to leverage an increase in agility to reactively navigate irregular terrain. Specifically, we show using the metric of "specific agility" that a spine can provides a reservoir of elastic energy storage that can be rapidly converted to kinetic energy, that a spine can augment the effective workspace of the legs without diminishing their force generation capability, and that -- in cases of direct-drive or nearly direct-drive leg actuation -- the spine motors can contribute more work in stance than the same actuator weight used in the legs, but can do so without diminishing the platform's proprioceptive capabilities. To put to use the agility provided by a suitably designed robotic platform, we introduce a formalism to approximate a set of transitional navigational tasks over irregular terrain such as leaping over a gap that lend itself to doubly reactive control synthesis. We also directly address the increased complexity introduced by the spine joint with a modular compositional control framework with nice stability properties that begins to offer insight into the role of spines for steady-state running. A central theme to both the reactive navigation and the modular control frameworks is that analytical tractability is achieved by approximating the modes driving the environmental interactions with constant-acceleration dynamics.
... Kimura et al. (1979) stated that difference in mass on the fore and hind limbs for quadrupedal mammals when standing reflected the distribution of foot force during locomotion. Biomechanical studies have approximated the mass distribution in standing mammals for examinations of ground reaction forces and energy changes during walks, trots and gallops (Alexander, Maloiy, Hunter, Jayes, & Nturibi, 1979;Lee, Bertram, & Todhunter, 1999;Pfau, de Rivaz, Brighton, & Weller, 2011;Usherwood, Williams, & Wilson, 2007;Witte, Knill, & Wilson, 2004). ...
Dogs have been bred for different sizes and functions, which can affect their locomotor biomechanics. As quadrupeds, dogs must distribute their mass between fore and hind legs when standing. The mass distribution in dogs was studied to determine if the proportion of supported mass on each limb couplet is dependent on body size. A total of 552 dogs from 123 breeds ranging in size from Chihuahua to Mastiff were examined. Each dog was weighed on a digital scale while standing, alternating foreleg, and hind leg support. The overall “grand” mean proportion of mass on the forelegs to the total mass was 60.4% (range: 47.6–74.4%). The data set indicated no significant change in the ratio with total mass but there was a significant difference by sex. When separated into American Kennel Club categories, no group was notably different from the grand mean or from each other, but when sex was also considered, there was a significant difference that was not specifically discerned by post hoc analysis. The mean for female Hounds was notably below the grand mean. For clades based on genetics, the mean for European origin mastiffs was notably greater than the grand mean and significantly different from UK origin herders and coursers. The mass of the head, chest, and musculature for propulsion could explain the mass support differential. Mass distribution and terrestrial locomotion in dogs shows substantial variation among breeds.
... Our study did not find an association between relative dog size (<12 vs. >12 kg), jump height, and injury; thus, it is likely that the described changes in joint angles are clinically unimportant during flyball activity. Another study found significant increases to ground reaction forces of up to 4.5 times body weight of the landing forelimbs when a dog lands a jump at high speeds (14). Based on these prior findings one could suppose that faster average flyball course times would be associated with injury risk which was not evident in our study. ...
Background: Injury risk in canine sprinting sports, such as greyhound racing and agility, have been previously documented through various surveys. Flyball, another sprinting canine sport with similar athletic requirements to agility, has yet to be assessed for factors associated with injury. The aim of this study was to determine injury prevalence and assess for risk factors for injury in flyball dogs.
Methods: Survey data from 375 flyball participants was collected and analyzed. Data collected included patient-specific variables, equipment use, training/competition practices, and injury occurrence and localization. Univariate analysis was utilized for all variables of interest, followed by backwards nominal logistic regression to identify variables associated with increased risk of injury, with a p < 0.05 defined as significant.
Results: Thirty-nine percent of dogs incurred at least one injury with 172 injuries reported. Injuries to the limbs were common (30.8% affecting forelimbs, 25.6% affecting hindlimbs), with the paw or nail the most frequently reported injured area (19.2%). Only protective wrap use and age were significantly associated with injury in the final nominal regression model (p < 0.01). A biphasic injury rate with more injuries in younger dogs was observed, and injuries peaked by 6 years of age. Use of carpal wraps was positively associated with increased injury risk.
Conclusions: These findings suggest an association between younger dogs and greater risk of injury, as well as identify a need to further investigate the utilization of wraps and potential association between injury risk among flyball participants.
... the vertical ground reaction forces of dogs jumping and reported that higher obstacle heights and acute landing angles caused an increase in the peak vertical force (PVF). 8,9 These studies posed concern for agility owners, and Members of the Australian National Kennel Council (ANKC) proposed a reduction in the angle of incline of the A-frame to reduce injuries they believe are associated with this contact obstacle; however, this proposal was rejected (Proposed change 6.7 presented to Western Australian branch of the ANKC: K. Kelly, 27/03/2014). ...
Objective The main purpose of this study was to investigate the effect of a decrease in the A-frame angle of incline on the vertical and cranio-caudal ground reaction forces observed in a homogeneous cohort of agility dogs during entrance and contact with the A-frame.
Materials and Methods A crossover study design was applied to eight large breed dogs to compare the vertical and cranio-caudal ground reaction forces entering the A-frame at three angles of incline: 40° (standard), 35° and 30°. The peak vertical force, passive impact peak, peak propulsive force, peak braking force, the time point (percentile) in the stance phase at which these events occurred and the proportion of time for limb contact spent in braking (% braking) and propulsion (% propulsion) were examined.
The variables measured from three trials at each incline were evaluated for a significant effect of A-frame angle with height and velocity included as covariates.
Results The peak propulsive force and the % propulsion were significantly higher at the 40° angle of incline compared with 30° (p = 0.013, p = 0.0165 respectively) and the % braking was significantly lower at the 40° angle of incline compared with 30° (p = 0.0165). There was no significant effect of A-frame angle on the vertical ground reaction forces measured.
Clinical Significance Compared with 30° incline, ascent up the A-frame at a 40° incline requires a higher propulsive force and extended time in propulsion to maintain forward movement and convert potential energy into forward kinetic energy.
... The aim of animal physiotherapy treatment is minimizing the neuromuscular dysfunctions, and, in turn, preventing the pathological lesions within the dog's locomotor apparatus. This effect is obtained through active movement of soft tissues, relaxation of antagonist muscles, post-isometric relaxation of muscles (Landrum et al. 2008, Pfau et al. 2011, SiniScaLchi et al. 2014. The underlying purpose of active mobilization (kinesiotherapy) is the stimulation of blood circulation, and, consequently, stimulation of metabolism, the increase of temperature in the active area, preparing the motor structures for dynamic reactions. ...
Agility competition is a discipline of canine sports in which dogs complete the obstacle course in specific order racing against the clock. The aim of this study was to estimate the impact of applied manual therapy techniques on the movement parameters of dogs. The movement of the dogs was characterised on the basis of 5 parameters, i.e.: walk, trot, gallop, flexibility and mobility and was assessed with the use of quality point scale. The study covered the assessment of movement parameters of 36 dogs, in canine discipline-agility, during two sporting seasons. The animals were assessed in categories: Small, Medium, Large. Assessment of parameters was carried out before the beginning of sporting dog competition and again after the end of three-month season of competitions. In the following year there were animal physiotherapy manual treatments implemented. Treatments included passive and active exercises, so called mobilizations, massages, thermal therapy, vibration training and sensomotoric exercises. In Small, Medium and Large category the highest average point values were attributed to walk feature, whereas the lowest values were attributed to trot. Dogs whose height at the withers was up to 35 cm were characterized by proper traction of movement in gait, correct dynamics of takeoff while jumping and were given high marks for completing slalom obstacle. The lowest average value for flexibility feature was recorded for dogs in Large category. Manual therapy techniques applied systematically reinforce dog's anatomical structures of skeletal system, reduce muscle tension and increase the intensity of metabolism.
... The aim of animal physiotherapy treatment is mini- mizing the neuromuscular dysfunctions, and, in turn, preventing the pathological lesions within the dog's locomotor apparatus. This effect is obtained through active movement of soft tissues, relaxation of antagonist muscles, post-isometric relaxation of muscles (lAnDruM et al. 2008, PFau et al. 2011, siniscAlcHi et al. 2014). The underlying purpose of active mobilization (kinesiotherapy) is the stimulation of blood circulation, and, consequently, stimulation of metabolism, the increase of temperature in the active area, preparing the motor structures for dynamic reactions. ...
There is a systematic increase in the number of traffic accidents involving both domestic and free-living animals. It was found that the largest number of animals dies in May and at the turn of October and November. It is estimated that only every fourth driver reports a police collision in Poland. In some cases, wounded animals are slaughtered and their meat is used for consumption. In connection with road accidents involving animals, it is crucial for the law enforcement authorities to determine the actual state of affairs in order to assess the proper course of the collision. The paper presents comprehensive legal and veterinary aspects of the discussed issues. The own analysis was also made according to the number of the road incidents in Poland with the participation of animals.
... Any one of a theoretically infinite number of trajectories could be used to pass over the obstacle with minimum adequate clearance; only a single unique trajectory, however, would minimise overall mechanical energy. Both horses and dogs use jump trajectories that differ depending on the size and shape of the obstacle being traversed (Pfau et al., 2011;Birch et al., 2016;Lewczuk et al., 2007), suggesting that they might have the capacity to control take-off to follow an energetically optimum trajectory. ...
It is generally accepted that animals move in a way that minimises energy use during regular gait and there is evidence that the principle might extend more generally to locomotor behaviour and manoeuvres. Jumping during locomotion is a useful manoeuvre that contributes to the versatility of legged locomotion and is within the repertoire of many terrestrial animals. We describe a simple ballistic model that can be used to identify a single unique trajectory of the body's centre of mass that minimises the mechanical work to initiate a jump, regardless of the approach velocity or take-off position. The model was used to show that domestic dogs (Canis lupus familiaris) demonstrate complex anticipatory control of locomotor behaviour by systematically using jump trajectories close to those that minimised the mechanical energy of jumps over raised obstacles. It is unclear how the dogs acquired the complex perception and control necessary to exhibit the observed behaviour. The model may be used to investigate whether animals adopt energetically optimised behaviour in any similarly-constrained ballistic task.
Background
Flexible tunnels are the second most common obstacle on all dog agility courses, surpassed only by jumps. There has been a lot of debate and concern regarding risk factors associated with slips, falls and delayed exits (unseen slips, missteps, trips, falls). However, only one study was found which focused on the tunnel-related injuries, and it relied on handler reporting and did not consider base rates of the risk factors. As such, it is currently unknown which risk factors are statistically predictive of incidents. This study addresses this gap.
Methods
Observational data from local, regional, national and international agility competitions (between June 30, 2023, to September 22, 2024) were collected from various agility organizations and countries by a team of researchers who are also judges and/or coaches within the sport. Tunnel, equipment, competition and course attributes, ground type and conditions along with tunnel incidents (slips, falls, and delayed exits) were recorded. Correlation, regression analyses, and chi-squared tests of independence were conducted to identify the relevant factors associated with incident rates.
Results
The data included 563 tunnels (75.0% were incident free), with 30,418 tunnel performance observations (1.552% were incidents). The identified factors associated with incidents include tunnel characteristics (equipment specifications, shape on course), type and density of fixtures, course design (shape in design, angle of approach), ground and conditions. Their association with incident occurrence will be further detailed below.
Discussion
Several previously assumed risk factors were relevant; however, some were not supported, and additional new factors were identified. Implications for future research and for organizations, judges, trial hosts, and competitors are discussed.
There are no regulations for the flyball box angulation, which ranges from 45° to 89°. As such at present, the box turn is deemed to represent the greatest injury risk to competitors. The aim of this study was to understand the influence of box angle on kinematic variables during a flyball turn, by comparing dogs turning on three different angulations of flyball box (45°, 60° and 83°) to allow for recommendations to be made regarding the most appropriate box design in terms of limiting risk of injury across the sport, to increase both wellbeing and safety for competitors. Turning on a 45° box generates significantly more flexion in the forelimbs and carpus, whereas turning on an 83° box generates greater degrees of extension in the elbow, shoulder, hock and stifle. What our 3D analysis has shown is that the relationship between box angle and the physical demands placed on the dog are complex, and related mainly to asymmetrical nature of the sport, and as such no one angle may be more or less suitable for training and competition, but the 60° seems to be a mid-ground, whereas direction of turn may be fundamental in generating the potential for injury.
OBJECTIVE
To investigate whether a humeral intracondylar fissure (HIF) alters bone strain in the French Bulldog humerus, we developed a quantitative CT-based 3-D finite element (FE) model for virtual mechanical testing. We hypothesized that higher strains would be seen in the intracondylar region and lateral epicondylar crest if there was a HIF.
METHODS
Patient CT scans from 3 (n = 3) French Bulldogs were selected. Dog 1 had a closed distal physis and no HIF. Dog 2 had an open distal humeral physis but no HIF. Dog 3 had an open distal physis and a HIF. A 3-D FE model was built for FE analysis, and pressure was applied to the humerus over the region that contacts the radial head.
RESULTS
The maximum principal bone strain patterns differed in each of the models. A path of strain concentration mimicking the typical pattern of a lateral condylar fracture was only found in dog 3. Maximum principal strain exceeded 1% in parts of the lateral epicondylar crest in all 3 dogs.
CONCLUSIONS
We developed a patient-specific, quantitative CT-based 3-D FE model for virtual mechanical testing. We accepted our hypothesis. Strain concentration occurred in the intracondylar region and along the lateral epicondylar crest only when a HIF was present.
CLINICAL RELEVANCE
The presence of a HIF in French Bulldogs elevates maximum principal bone strain in this region and alters its path in an FE model, which suggests an increased risk of a lateral humeral condylar fracture.
Objective
To understand relative frequency of adverse health events, defined as injuries or infectious diseases, in dogs participating in agility and to determine health research priorities of agility dog owners.
Procedures
An internet-based questionnaire distributed to agility dog owners included items related to experiences with infectious diseases and injuries in agility dogs, reasons for retirement of dogs from competition, and ranking of health research priorities. Frequencies of infectious diseases in US geographic regions were compared with Chi-square tests. Research priority rankings were determined as median and interquartile range (IQR) for each topic. Rank-based tests (Kruskal Wallis and Mann-Whitney) compared rankings between participants in different agility organizations, between veterinarian and non-veterinarian competitors, and between respondents who had competed in national championship events and other respondents.
Results
There were 1,322 respondents who had competed in canine agility in the previous 6 months, with those respondents reporting a median time competing in the sport of 13 years (IQR = 8–20 years); 50% of respondents had competed in at least one national championship agility event in the preceding 5 years. Overall, 1,015 respondents (77%) indicated that one or more of their dogs had been injured and approximately one-third (n = 477, 36%) indicated that one or more dogs had likely acquired one or more infectious diseases as a result of agility activities. Specific types of infectious diseases acquired varied by geographic region in the US. Research priority rankings were similar regardless of preferred agility organization or respondent experience. The highest-ranking research topics were identification of risk factors for specific types of injuries, improvements in equipment and understanding of safe course design, and physical conditioning programs to prevent injury.
Conclusions and clinical relevance
Agility competitors prioritize research in areas that advance understanding of injury prevention in their dogs. Research priorities are nearly uniform among competitors regardless of their preferred agility organization or level of experience, providing a strong rationale for agility organizations to collaborate in research initiatives that improve safety and well-being for dogs competing in the sport. There has been little published research focusing on the high-priority research areas identified by competitors.
Simple Summary
Dog agility is a canine sport that has gained popularity among pet owners in recent decades. Because of the high-performance level, injuries to dogs competing in this sport are becoming frequent. The need for better knowledge of the anatomy of the structures involved in athletic movements is an essential starting point for correctly managing agility-related injuries. The aim of this paper was to investigate the ultrasonographic anatomy of the carpal joint, creating a baseline reference for the Border Collie, which is the breed most utilised in agility competitions. The data acquired could be of use in future studies regarding sport-induced injuries in the canine carpus.
Abstract
Recent literature has demonstrated that high-resolution ultrasonographic anatomy of the canine carpus is possible; however, only the structures of the dorsal face were described. The aims of this prospective study were: (1) to describe the normal ultrasonographic appearance of the carpal tendons in sporting Border Collies; (2) to measure the height, length, and thickness of the tendon at the radial ulnar notch level in order to create a baseline reference for the breed, and (3) to describe a standardised protocol to ultrasonographically evaluate the carpal faces and visible tendinous structures. A pilot study based on ten cadaveric front limbs was used to identify the structures. A subsequent clinical phase of the study using twenty-six Border Collies was recorded. The tendons of the Extensor Carpi Radialis, Extensor Digitorum Communis, and Extensor Digitorum Lateralis were identified and followed from the tenomuscular junction to the distal insertion on the dorsal face of the digits. On the lateral face, the tendon of the Extensor Carpi Ulnaris was recognised and followed. On the palmar face, the two heads of the Flexor Carpi Ulnaris tendon ending on the accessory carpal bone, the adjacent Flexor Digitorum Superficialis tendon, and the deep and medially located Flexor Digitorum Profundus tendon were seen and followed. The Flexor Carpi Radialis and the Abductor Pollicis Longus tendons were seen in the medial carpal face. The ulnar notch of the radius was used as the measurement and starting point of the ultrasonography. These data could be used as a standard reference in the case of chronic overuse and trauma-induced changes in the canine carpus.
The aim of conditioning is to remodel body tissues in preparation for the physical demands of activity. Body tissues need strength to produce and withstand the forces generated during movement. Body tissues remodel in response to load, for example, training can remodel and increase the size of tendons, but this takes time. Training does more than just strengthening tissues; it also improves tissue response to exercise and recovery time. The National Sports Medicine Institute in the United Kingdom states "regular exercise increases muscle tone, facilitates good circulation, improves strength, agility and flexibility and improves the rate of waste product disposal."
Objective: To describe the frequency and types of injuries experienced by dogs competing and training in agility and identify breed and geographic differences in frequency and types of injuries.
Sample: Surveys completed by owners of 4,701 dogs.
Procedures: The study involved an internet-based survey. Participants were asked whether their dog had ever had an injury that kept it from participating in agility for > 1 week and, if so, to identify the location and type of injury.
Results: Owners of 1,958 (41.7%) dogs reported that their dogs had experienced an injury. The most common injury locations were the shoulder region (n = 589 [30.1% of all dogs with an injury]) and iliopsoas muscle (380 [19.4%]). The percentage of Border Collies sustaining an injury (549/1,052 [51.9%]) was significantly higher than percentages of other breeds. Percentage of dogs that sustained an injury varied by country, with the highest percentage reported in Australia (93/174 [53.4%]) and lowest percentage reported in the US (1,149/2,889 [39.8%]).
Conclusions and clinical relevance: Results suggested that, among dogs competing and training in agility, injuries to the shoulder region were substantially more common than injuries in other anatomic locations, with iliopsoas muscle injuries second most common. The frequency and types of injuries varied among breeds and geographic regions. Findings may help guide clinical evaluations when agility dogs are seen in clinical practice for performance issues or lameness. Further studies regarding regional differences in injury rates are required.
Objective
To compare the axial biomechanical properties of intracondylar humeral osteotomies fixed with 4.5 mm transcondylar positional or cortical lag screws.
Study design
Ex vivo study.
Sample population
Paired humeri from 21 canine cadavers.
Materials and methods
An intracondylar osteotomy was created on each humerus to mimic an intracondylar fissure. Paired humeri were randomly assigned to fixation with a positional or a lag screw. All specimens were radiographed postinstrumentation to document proper screw placement. Axial load was applied to the distal articular surface of the trochlea at a rate of 1 mm/s until a 40% decrease in load was measured. Specimens were assessed for mode of failure with visual inspection and radiographs.
Results
Stiffness (1236.7 ± 181 N/mm vs. 1050.8 ± 265 N/mm), yield load (3284.3 ± 1703 N vs. 2071.1 ± 740 N), and maximum load (7378.0 ± 1288 vs. 5793.7 ± 2373 N) were greater in constructs fixed with a positional rather than a lag screw (p = .0008, .044, and .040, respectively).
Conclusion
In our model, mechanical properties were improved when the transcondylar osteotomy was stabilized with a 4.5 mm positional screw rather than a lag screw.
Clinical significance
This ex vivo study suggests that a transcondylar lag screw and positional screw are not biomechanically equal. Additional in vivo studies are need to help with clinical decision making when prophylactically treating HIF.
This study analyses three additively manufactured canine implants designed for angular limb deformity correction procedure through probabilistic numerical analysis. These implants have produced excellent results in-vivo and are operational to-date. Therefore, this study uses finite element analysis in conjunction with statistical analysis in order to further validate these implants from a numerical perspective. Due to uncertainties associated with boundary conditions for a bespoke implant geometry, the analyses in this study were conducted on a range of input values. An interrogation of these parameters through sensitivity analysis enabled in identifying the vital inputs. These inputs were then employed to conduct robustness analysis in order to determine the mean value of stress on which these implants ideally operate. These mean values were then compared with the associated safety and failure limit to obtain the probability of reaching these limits through different reliability techniques. A low probability of failure computed from numerical analysis in combination with the continued performance of these implants, suggests a successful integration of the methodology in the design phase of bespoke implants.
Simple Summary
Hurdle jumping is part of the increasingly popular canine agility competition. Although the jumping characteristics of agility dogs have been examined in recent years, there is currently a lack of data related to the suspension phase. The purpose of the present study was to investigate the biomechanics of the suspension phase of the agility jump and to analyze the kinematic differences in dogs with different jumping abilities. Two groups of dogs competing at different skill levels and assessed as excellent jumpers and less-skilled jumpers, respectively, were analyzed and compared. Excellent jumpers showed longer and faster jumps with flatter jump trajectories than less-skilled jumpers. In less-skilled jumpers, the distance in front of the hurdle was notably greater than the distance behind it, while the difference between these two distances was less in excellent jumpers. Length and duration of the jump, maximal height of the jumping trajectory, take-off and landing distances to the hurdle, time of occurrence of maximal jump height, and time of change in back orientation essentially defines the suspension phase of the agility jump. This study presents preliminary evidence that the kinematic characteristics of hurdle clearance are different in excellent jumper dogs and in less-skilled jumper dogs.
Abstract
Although the jumping characteristics of agility dogs have been examined in recent years, there is currently a lack of data related to the suspension phase. The purpose of the present study was to investigate the biomechanics of the suspension phase of the agility jump and to analyze the kinematic differences in dogs with different jumping abilities. Two groups of dogs of the same height category (large dogs) competing at different skill levels and assessed as excellent jumpers (n = 4) and less-skilled jumpers (n = 3), respectively, were analyzed and statistically compared. Excellent jumpers showed longer and faster jumps with flatter jump trajectories than less-skilled jumpers. In less-skilled jumpers, the distance in front of the hurdle was notably greater than the distance behind it, while the difference between these two distances was less in excellent jumpers. Length and duration of the jump, maximal height of the jumping trajectory, take-off and landing distances to the hurdle, time of occurrence of maximal jump height, and time of change in back orientation essentially defines the suspension phase of the agility jump. This study presents preliminary evidence that the kinematic characteristics of hurdle clearance are different in excellent jumper dogs and in less-skilled jumper dogs.
To determine whether participation in dog agility has an impact on canine arousal and welfare, this study aimed firstly to identify the effect of the competition context on arousal changes experienced by dogs, as distinct from purely physical participation in agility, and secondly to assess the handlers’ ability to recognize this. Behaviors indicative of changes in arousal were recorded for twenty dogs immediately before completion of both a competition and a training run, whilst the accuracy of handlers’ observations of their dogs’ behavior was examined via questionnaire. Whilst a moderate number of behaviors presented with greater frequency or duration in competition, the total number of different arousal behaviors performed was higher for dogs in competition (p < 0.01). Context had a relatively modest effect on the level of arousal of agility dogs, with a greater number of behaviors indicating increased arousal in competition. Such increased arousal may adversely influence the success of dog-handler partnerships in competition. In both contexts, handlers observed fewer behaviors than their dogs performed and this finding may have implications for dog welfare.
The injury rate in agility dogs is relatively high compared to the general population. No study to date has considered the biomechanical effects of the dog walk obstacle in agility trials, highlighting a research need. The aim of this study was to test for correlation between dog age, weight, speed, contact training method and agility experience and forelimb joint angulation and peak ground reaction forces (GRFs) over this obstacle. Dogs were filmed running across a Kennel Club (KC) standard dog walk whilst wearing reflective markers attached to specific anatomical points. A Tekscan Comformat and a Tekscan Walkway pressure mat were secured to the dog walk contact area and the ground at the end of the dog walk respectively. Joint angulation and peak forelimb GRFs were recorded and analysed. A key finding is that the way a dog will move across the obstacle changes depending on their level of experience, with experienced dogs showing increased flexion of the elbow joints and decreased extension of the carpus compared to inexperienced competitors. Higher speeds over the dog walk also resulted in significantly increased elbow joint flexion. Increased joint angulation and higher GRF’s are associated with a higher risk of injury.
Objective The aim of this study was to develop an in vitro biomechanical protocol for canine cementless hip arthroplasty that represents physiological gait loading (compression and torsion) and to evaluate if three alternative implant designs improve fixation compared with the traditional collarless, tapered stem in the clinically challenging case of moderate canal flare index.
Study Design Twenty-four (six/group) laboratory-prepared canine constructs were tested using a simulated gait and overload (failure) protocol. Construct stiffness, failure load/displacement and migration were measured as outcome variables.
Results Simulated gait loading did not show any significant differences between implant types for peak displacement, peak rotation, torsional stiffness, subsidence or inducible displacement. The collared and collarless stem groups were stiffer in compression compared with the collarless with a lateral bolt and short-stem groups. Increasing the loading above simulated gait showed significant reductions in compressive and torsional stiffness for all implant constructs. Despite the reductions, the short-stem group showed significantly higher stiffness compared with the other three groups.
Conclusion Peak failure loads (compressive and torsional) in this study were approximately four to seven times the simulated gait loading (430 N, 1.6 Nm) regardless of implant type and highlight the importance of limiting activity level (trotting, jumping) following hip replacement in the postoperative period and during the osseointegration of the implant.
The application of qualitative analysis techniques, currently used in sports biomechanics, may help equine biomechanics researchers identify the most appropriate directions for future research. This paper reviews existing qualitative biomechanical models that could be relevant to equine jumping research. The deterministic model approach1 is identified as the most appropriate. This approach is used to derive deterministic models suitable for equine jumping evaluation. The horse's jump can be broken down into five discrete parts_— approach, take off, suspension, landing and departure. Each of these parts has specific determining factors, which have either a mechanical or a mathematical relationship. These models may be used to assist horse trainers identify and implement appropriate strategies for improvement in jumping horses.
The work done during each step to lift and to reaccelerate (in the forward direction) and center of mass has been measured during locomotion in bipeds (rhea and turkey), quadrupeds (dogs, stump-tailed macaques, and ram), and hoppers (kangaroo and springhare). Walking, in all animals (as in man), involves an alternate transfer between gravitational-potential energy and kinetic energy within each stride (as takes place in a pendulum). This transfer is greatest at intermediate walking speeds and can account for up to 70% of the total energy changes taking place within a stride, leaving only 30% to be supplied by muscles. No kinetic-gravitational energy transfer takes place during running, hopping, and trotting, but energy is conserved by another mechanism: an elastic "bounce" of the body. Galloping animals utilize a combination of these two energy-conserving mechanisms. During running, trotting, hopping, and galloping, 1) the power per unit weight required to maintain the forward speed of the center of mass is almost the same in all the species studied; 2) the power per unit weight required to lift the center of mass is almost independent of speed; and 3) the sum of these two powers is almost a linear function of speed.
The storage and recovery of elastic strain energy in muscles and tendons increases the economy of locomotion in running vertebrates. In this investigation, we compared the negative and positive external work produced at individual limb joints of running dogs to evaluate which muscle-tendon systems contribute to elastic storage and to determine the extent to which the external work of locomotion is produced by muscles that shorten actively rather than by muscles that function as springs. We found that the negative and positive external work of the extensor muscles is not allocated equally among the different joints and limbs. During both trotting and galloping, the vast majority of the negative work was produced by the two distal joints, the wrist and ankle. The forelimb produced most of the negative work in both the trot and the gallop. The hindlimb produced most of the positive work during galloping, but not during trotting. With regards to elastic storage, our results indicate that the forelimb of dogs displays a greater potential for storage and recovery of elastic energy than does the hindlimb. Elastic storage appears to be more important during trotting than during galloping, and elastic storage appears to be more pronounced in the extensor muscles of the distal joints than in the extensor muscles of the proximal joints. Furthermore, our analysis indicates that a significant portion of the external work of locomotion, 26 % during trotting and 56 % during galloping, is produced by actively shortening muscles. We conclude that, although elastic storage of energy is extremely important to the economy of running gaits, actively shortening muscles do make an important contribution to the work of locomotion.
Dynamic gearing is a mechanism that has been suggested to enhance the performance of skeletal muscles by maintaining them at the shortening velocities that maximize their power or efficiency. We investigated this hypothesis in three domestic dogs during trotting and galloping. We used ground force recordings and kinematic analysis to calculate the changes in gear ratio that occur during the production of the external work of locomotion. We also monitored length changes of the vastus lateralis muscle, an extensor muscle of the knee, using sonomicrometry in four additional dogs to determine the nature and rate of active shortening of this muscle. During both trotting and galloping, the gear ratios of the extensor muscles of the elbow, wrist and ankle joints were relatively constant early in limb support, but decreased rapidly during the second half of support. The gear ratio at the hip exerted an extensor moment initially, but decreased throughout limb support and became negative midway through support. This pattern of decreasing gear ratio during the second half of support indicates that dynamic gearing does not maximize muscle power or efficiency at the elbow, wrist, hip and ankle joints. In contrast, the extensor muscles of the shoulder and knee joints exhibited an increase in gear ratio during limb support. In two dogs, the vastus lateralis muscle shortened at a relatively constant rate of 3.7-4 lengths s-1 during intermediate-speed galloping. This pattern of increasing gear ratio and constant velocity of muscle shortening at the knee joint is consistent with the hypothesis of dynamic gearing. Given the amount of work done at the knee and shoulder joints of running dogs, dynamic gearing may contribute to the economy of constant-speed running and may be important to integrated limb function.
During quadrupedal trotting, diagonal pairs of limbs are set down in unison and exert forces on the ground simultaneously. Ground-reaction forces on individual limbs of trotting dogs were measured separately using a series of four force platforms. Vertical and fore-aft impulses were determined for each limb from the force/time recordings. When mean fore-aft acceleration of the body was zero in a given trotting step (steady state), the fraction of vertical impulse on the forelimb was equal to the fraction of body weight supported by the forelimbs during standing (approximately 60 %). When dogs accelerated or decelerated during a trotting step, the vertical impulse was redistributed to the hindlimb or forelimb, respectively. This redistribution of the vertical impulse is due to a moment exerted about the pitch axis of the body by fore-aft accelerating and decelerating forces. Vertical forces exerted by the forelimb and hindlimb resist this pitching moment, providing stability during fore-aft acceleration and deceleration.
Stride duration, stance duration and protraction duration are key variables when describing the gaits of terrestrial animals. Together, they determine the duty factor (the fraction of the stride for which the limb maintains contact with the ground surface), from which the peak vertical force can be estimated. When an animal changes speed, these variables change at different proportions. Limited measurements of these variables and predictions of peak limb force have been undertaken for large mammals performing high-speed over-ground exercise. This study set out to make such measurements, employing a previously validated system consisting of limb-mounted accelerometers and a Global Positioning System data logger. Measurements were made on nine elite Thoroughbred racehorses during gallop locomotion over a range of speeds from 9 to 17 m s(-1). No statistically significant differences were seen in any variables between the lead and non-lead limbs for either the fore or hind pairs of limbs. Mean stance durations of 131 and 77 ms in the forelimbs and 143 and 94 ms in the hindlimbs were recorded at speeds of 9 and 17 ms(-1), respectively. Equivalent values for protraction duration were 364 and 342 (fore) and 355 and 326 ms (hind). Peak limb forces (from duty factor) at 17 ms(-1) were 24.7 N kg(-1) body weight (range 22.6 to 26.0 N kg(-1) body weight) for the forelimbs and 15.3 N kg(-1) (range 13.7-16.2 N kg(-1) body weight) for the hindlimbs. The duration of the aerial phase of the stride (when no limbs are in contact with the ground) was independent of speed. Overlap time (when more than one leg is on the ground) dropped with speed and approached zero at maximum speed.
The gallop differs from most other quadrupedal gaits in that each limb plays a unique role. This study compares the ground forces applied by the four limbs and uses force differences between limbs to address the question of why the gallop is the fastest quadrupedal gait. Individual ground forces were recorded from each of the four limbs as six dogs galloped down a runway at constant speed. Trials were videotaped at high speed using a camera positioned perpendicular to the runway, and velocity was measured using photosensors. The trailing forelimb applied greater peak vertical forces than the lead forelimb, however the vertical impulses from the two forelimbs were similar because the lead forelimb had a longer contact interval. The trailing forelimb and lead hindlimb applied greater peak accelerating forces and accelerating force impulses than their contralateral limbs despite their tendency to have shorter contact intervals. The accelerating impulse of both forelimbs combined did not differ significantly from that of both hindlimbs. The forelimbs applied a greater decelerating impulse than the hindlimbs, such that their net fore-aft impulse was decelerating whereas that of the hindlimbs was accelerating. The greater accelerating impulse applied by the trailing forelimb and greater decelerating impulse applied by the lead forelimb are consistent with the forelimbs acting as elastic struts rather than being actively retracted. In contrast, greater accelerating forces were produced by the lead hindlimb while the center of mass was lifted, suggesting that the hindlimbs are more actively extended or retracted during stance. The differences in ground forces measured between paired limbs suggest that the lead forelimb and trailing hindlimb are limited in their ability to apply forces by their positions in the stride cycle rather than by their muscular capacity. Although a bound or half-bound would allow more limbs to produce their maximal forces, a gallop may generate higher speeds because it is more efficient. Galloping could be more efficient than other gaits involving sagittal bending if the increased number of ground contact intervals decreased either the decelerating forces applied at the onset of ground contact or the vertical motion of the center of mass.
Using a force plate, ground reaction force ( grf ) patterns at take-off and landing between the hooves and the ground were recorded for all limbs of 5 Dutch Warmbloods jumping a 0.8-m vertical fence from the right-leading canter. Distribution of the grf and force impulses over the 4 limbs at take-off and landing were considerably different from those recorded at the normal canter. At take-off, the propulsory grf of the hind limbs were 3 to 5 times higher than at the normal canter, depending on the jumping technique of the horse. At landing, the propulsory grf were mainly increased in the trailing forelimb and in both hind limbs. The vertical grf amplitudes and force impulses were of similar magnitude to those at the canter, although increases up to 160% were found in the hind limbs of the horse with the worst jumping technique. The trailing forelimb carried the highest loads, up to twice the animal's body weight; grf amplitudes tended to increase when higher fences were used. However, the jumping technique of the horse may have more influence, because an easily jumping horse could clear a 1.3-m-high fence with similar loads on the limbs.
The purpose of this study was: to quantitate the peak vertical ground reaction force acting on the forelimbs of dogs as they landed after jumping an obstacle; to compare that force at three heights; and to evaluate factors that may affect vertical ground reaction force. Thirteen military working dogs were studied. A strain gauge force plate was used to measure force. Three measurements were recorded for each dog at each height. The means of the medians of the three forces for each dog at each height were compared using a repeated measures analysis of variance. Mean force at 63 cm was 986.9 ± 221.5 N, mean force at 79 cm was 1175.0 ±227.4 N, and mean force at 94 cm was 1366.1± 268.5 N. There was a significant difference in mean force at the three jump heights (p = 0.0002). The significance was unchanged when force was normalized for body weight. Statistical models were used to evaluate the effect of other independent variables. Factors that were found to effect force were body weight, breed, and sex of the dog. Further studies are needed to determine the clinical significance of these findings.
Vertical ground reaction force was measured in thirteen dogs landing on a force plate after jumping an obstacle. Three readings were taken for each dog at each of three heights, and the mean vertical ground reaction force was compared. Force readings were significantly different at each height, increasing as height increased. Factors that were found to effect vertical ground reaction force were body weight, breed, and sex.
0030, Alexander et al., 1979 features profiles of Syncerus and Loxodonta and the force vector acting on the fore and hindlimb at foot-down. They also list the cross-sectional properties of the tibia, humerus, and metatarsal. Their stress data suggest that the stress that vertebrate limb bones experience do not increase with increasing body mass.
A standard terminology for the description of equine jumping technique is proposed. To facilitate comparisons between strides, it is recommended that the stride be maintained throughout the approach, the take off, the jump, the landing and the move off. The stride in which the horse jumps the fence, called the jump stride, is subdivided into the take off, the jump suspension, and the landing. Take off is the period from impact of the first hind limb until lift off of the last hind limb in the jump stride. The jump suspension is the period from lift off of the last hind limb at take off until impact of the first forelimb at landing. Landing is defined as the period from impact of the first forelimb after the jump suspension until the next impact of the trailing hind limb. The stride before the jump stride is called approach stride 1. It is preceded by approach stride 2, approach stride 3, and so on. The strides following the jump stride are called move off strides 1, 2, 3 and so on in chronological order. An advantage of this nomenclature is its flexible nature, allowing for the inclusion of a variable number of strides on either side of the fence. When a horse takes 3 strides or less between 2 successive fences, the strides are known as intermediate strides 1, 2 and 3, counting from the first fence to the succeeding one. The application of the proposed terms is illustrated using data from a horse jumping a vertical fence 1.55 m high.
Films of buffalo and elephant running, and detailed measurements on dissected legs, have been used to estimate the maximum stresses which occur in locomotion, in certain muscles, tendons and bones. These stresses are similar to stresses previously determined for some other, smaller mammals.
A force platform has been used to obtain records of the forces exerted on the ground by an Alsatian dog, during take-off for running long jumps and standing scale jumps. The records have been analysed in conjunction with cinematograph film, taken simultaneously, and anatomical data. Stresses in the principal muscles of the hind limb, and in the triceps, have been calculated and the values obtained are compared with the stresses found by other investigators in isometric experiments with excised mammal muscles. Stresses in certain tendons and bones have been calculated, and the values obtained are compared with published values for the strength of tendon and bone. Evidence is presented that the gastrocnemius and plantaris muscles behave, in take-off for a jump, essentially as passive elastic bodies. Most of the elastic energy is probably stored in their tendons. A tendency for distal limb muscles to be pinnate, with much shorter fibres than proximal limb muscles, is noted and discussed.
Typescript (photocopy). Thesis (M.S.)--Texas A & M University, 1991. Vita. Includes bibliographical references. "Major subject: Veterinary Medicine and Surgery."
Little is known about the risks of injury to dogs participating in the relatively new sport of canine agility. The purpose of this study was to identify the factors that put the participating dog at risk as well as determine the anatomical sites that were most commonly injured.
A retrospective survey using a paper and web-based data collection instrument was used to evaluate dogs participating in the sport of canine agility.
Of the 1627 dogs included in the study, 33% were injured, and of those 58% were injured in competition. Most injuries occurred on dry outdoor surfaces. Border Collies were the most commonly injured, and injuries were in excess of what would be expected from their exposure. For all dogs, soft tissue injuries were most common. The shoulders and backs of dogs were most commonly injured. Dogs were most commonly injured by contact with an obstacle. The A-frame, dogwalk and bar jump obstacles were responsible for nearly two-thirds of injuries that resulted from contact with the obstacle.
Border Collies are at higher risk for injury than would be expected from their exposure. The A-frame, dogwalk and bar jump obstacles put the shoulders and backs of dogs at risk.
For the first time, this study gives us insight into injuries occurring in dogs participating in canine agility. This will help direct prospective studies that evaluate the safety of individual obstacles, direct rule changes and enable practitioners to understand the risks of the sport.
Ground reaction forces, impulses, and their relationships to morphometric measurements were evaluated for walking gait in 17 healthy dogs. A force plate was used to record forces at 1-ms intervals. Vertical, craniocaudal, and mediolateral forces were measured and normalized by body weight. Impulses, defined as the total force applied over time, were calculated in vertical and craniocaudal directions. Craniocaudal impulses were further divided into braking and propulsion phases. Braking impulses were significantly greater in the forelimbs (P less than or equal to 0.001), whereas propulsion impulses were generally greater in the hind limbs. Impulses and peak forces were then compared with morphometric measurements (body weight, humeral and femoral lengths, and paw length). All relationships were linear, with correlation coefficients significant (P less than or equal to 0.001). As the size of the dog increased, braking, propulsion and vertical impulses increased. Conversely, as morphometric measurements increased, peak vertical forces decreased. Thus, larger dogs had a lower peak force on each limb, but had a higher total impulse applied during stance phase. As stance phase time increased, peak vertical forces decreased. The results indicated that healthy dogs had significant correlations between ground reaction forces, impulses, and morphometric measurements.
The percentage of limb contact time spent in braking and propulsion was determined for the forelimbs and hind limbs of Greyhounds at 2 walk speeds and 3 trot speeds. Limb contact times decreased significantly (P < 0.05) as velocity increased between each velocity range. At a slow walk (0.92 to 1.03 m/s), braking and propulsion were 56.1 and 43.6% of contact time in the forelimbs and 41.6 and 58.1% of contact time in the hind limbs, respectively. At a fast walk (1.06 to 1.17 m/s), braking and propulsion were 56.7 and 43.5% of contact time in the forelimbs and 41.5 and 58.4% of contact time in the hind limbs, respectively. There was no significant difference in the percentage of contact time that the forelimbs and hind limbs spent in braking and propulsion between the 2 walk velocities. At the slow trot (1.5 to 1.8 m/s), braking and propulsion were 56.8 and 43% of contact time in the forelimbs and 30.1 and 67.6% of contact time in the hind limbs, respectively. At the medium trot (2.1 to 2.4 m/s), braking and propulsion were 55.9 and 43.5% of contact time in the forelimbs and 33.8 and 63.2% of contact time in the hind limbs, respectively. At the fast trot (2.7 to 3.0 m/s), braking and propulsion were 57.2 and 43% of contact time in the forelimbs and 37.5 and 61.1% of contact time in the hind limbs, respectively. Braking percentage increased and propulsive percentage decreased significantly (P < 0.05) in the hind limbs between the slow and fast trot speeds.(ABSTRACT TRUNCATED AT 250 WORDS)
Limb symmetry was evaluated by measuring ground reaction forces in 2 groups of normal-gaited dogs at a trot. Data were collected from 2 groups of 21 dogs trotted at dog/handler velocities of 1.25 to 1.55 m/s and 1.85 to 2.05 m/s, respectively. Of these dogs, 9 participated in both groups to allow comparison of data at both velocities. Additionally, 16 of the dogs in group 1 were measured in 2 directions of movement to determine whether directional dependence was present. Collected data were then applied to 3 described symmetry indices.
Each index was easy to calculate, but all had limitations. A major limitation was variation in magnitude of ground reaction forces measured between the different axes and the effect of this variation on precision of the derived indices. Vertical ground forces provided the most consistent symmetry indices, in part because of their large magnitude. The indices indicated that no dog had perfect right-to-left symmetry during a trotting gait. Statistical differences were not found in any of the measurements of directional dependence. Likewise, comparing symmetry data in dogs trotted at both velocities indicated no significant differences in any axis.
However, further analysis of the data revealed the actual amount that a variance attributable to right-left limb variation was negligible. Most of the variance was attributable to trial variation. Thus, the aforementioned indices, which use nonconsecutive footfall methods to evaluate limb symmetry, actually measure principally trial variation and not limb-to-limb variation.
Trotting and hopping animals use muscles, tendons and ligaments to store and return elastic energy as they bounce along the ground. We examine how the musculoskeletal spring system operates at different speeds and in animals of different sizes. We model trotting and hopping as a simple spring-mass system which consists of a leg spring and a mass. We find that the stiffness of the leg spring (kleg) is nearly independent of speed in dogs, goats, horses and red kangaroos. As these animals trot or hop faster, the leg spring sweeps a greater angle during the stance phase, and the vertical excursion of the center of mass during the ground contact phase decreases. The combination of these changes to the spring system causes animals to bounce off the ground more quickly at higher speeds.
Analysis of a wide size range of animals (0.1–140kg) at equivalent speeds reveals that larger animals have stiffer leg springs (kleg∝M0.67, where M is body mass), but that the angle swept by the leg spring is nearly independent of body mass. As a result, the resonant period of vertical vibration of the spring-mass system is longer in larger animals. The length of time that the feet are in contact with the ground increases with body mass in nearly the same way as the resonant period of vertical vibration.
The current state of canine kinetic and kinematic gait analysis, as developed for the objective description of movement for the study of musculoskeletal disease and lameness, is reviewed. Basic terminology of gait is discussed. Ground reaction forces, dynamic flexion, and extension angles and angular velocities are described for the canine walk and trot and for lameness in cranial cruciate ligament rupture and canine hip dysplasia.
To compare the trotting gaits of Labrador Retrievers and Greyhounds to determine whether differences in locomotion are attributable to differences in their manner of moving or to body size and shape differences between these 2 breeds.
8 healthy 5-month-old Greyhounds and 5 healthy Labrador Retrievers between 6 and 18 months old.
A series of 4 force platforms was used to record independent ground reaction forces on the forelimbs and hind limbs during trotting. Values of stride parameters were compared between breeds before and after normalization for size differences. Standard values of absolute and normalized stride period and stride length were determined from linear regressions of these parameters on relative (normalized) velocity. Forces were normalized to body weight and compared at the same relative velocity.
Greyhounds used fewer, longer strides than the Labrador Retrievers to travel at the same absolute speed. After normalization for body size differences, most measurable differences between breeds were eliminated. Subtle differences that did persist related to proportion of the stride that the forefoot was in contact with the ground, timing of initial hind foot contact relative to initial forefoot contact, and distribution of vertical force between the forelimbs and hind limbs.
Results suggest that apparent differences in the trotting gait between Labrador Retrievers and Greyhounds are mainly attributable to differences in size, and that dogs of these 2 breeds move in a dynamically similar manner at the trot.
Tendon injuries are an important problem in athletic horses and are probably caused by excessive loading of the tendons during demanding activities. As a first step towards understanding these injuries, the tendon loading was quantified during jump landings. Kinematics and ground reaction forces were collected from the leading and trailing forelimbs of 6 experienced jumping horses. Joint moments were calculated using inverse dynamic analysis. It was found that the variation of movement and loading patterns was small, both within and between horses. The peak flexor joint moments in the coffin and fetlock joints were larger in the trailing limb (-0.62 and -2.44 Nm/kg bwt, respectively) than in the leading limb (-0.44 and -1.93 Nm/kg bwt, respectively) and exceeded literature values for trot by 82 and 45%. Additionally, there was an extensor coffin joint moment in the first half of the stance phase of the leading limb (peak value 0.26+/-0.18 Nm/kg bwt). From these results, it was concluded that the loading of the flexor tendons during landing was higher in the trailing than in the leading limb and that there was an unexpected loading of the extensor tendon in the leading limb.
An increase in gear ratio of the limb extensor muscles during joint extension has been suggested to be a mechanism that facilitates optimal power production by skeletal muscles. The objectives of this study were to: (1) measure gear ratios at the wrist, elbow, shoulder, ankle, knee, and hip joints of jumping dogs, (2) compute the work performed by each of these joints, and (3) measure muscle shortening velocity for a joint exhibiting an increasing gear ratio during joint extension. The gear ratio out-lever was computed by dividing the ground reaction force (GRF) moment by the GRF, whereas the in-lever was directly measured as the perpendicular distance from the joint center to the line of action of the extensor muscle. In addition, changes in fascicle length were measured from the vastus lateralis muscle using sonomicrometry. Of the joints examined, only the gear ratios at the shoulder and knee joints increased during jumping in a manner that could facilitate peak power production of actively shortening muscles. The vastus lateralis was found to shorten at an average velocity of 3.20 muscle lengths per second. This is similar to estimates of shortening velocity that produce peak muscular power in mammals the size of dogs. Additionally, the knee extensors were found to produce a large proportion (26.6%) of the positive external work of the limbs. These observations suggest that dynamic gearing in jumping dogs may allow the extensor muscles of the knee joint to shorten in a way that maximizes their power production.
Maximum running speed is constrained by the speed at which the limbs can be swung forwards and backwards, and by the force they can withstand while in contact with the ground. Humans sprinting around banked bends change the duration of foot contact to spread the time over which the load is applied, thereby keeping the force on their legs constant. We show here that, on entering a tight bend, greyhounds do not change their foot-contact timings, and so have to withstand a 65% increase in limb forces. This supports the idea that greyhounds power locomotion by torque about the hips, so--just as in cycling humans--the muscles that provide the power are mechanically divorced from the structures that support weight.
the-kennel-club.org.uk/asp/shop/fullDisplay.asp?item=Kennel+ Club+Year+Book+2009%2F2010&dept=publications
- See
2 See: http://www.the-kennel-club.org.uk/asp/shop/fullDisplay.asp?item=Kennel+ Club+Year+Book+2009%2F2010&dept=publications. 282 T. Pfau et al. / The Veterinary Journal 190 (2011) 278–283
Joint moments in the distal forelimbs of jumping horses during landing
- T Pfau
T. Pfau et al. / The Veterinary Journal xxx (2010) xxx–xxx Meershoek, L.S., Roepstorff, L., Schamhardt, H.C., Johnston, C., Bobbert, M.F., 2001.
Joint moments in the distal forelimbs of jumping horses during landing. Equine
Veterinary Journal 33, 410–415.
- T Pfau
T. Pfau et al. / The Veterinary Journal xxx (2010) xxx-xxx
The mechanics of jumping by a dog
- Alexander