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Copyright of Xinjiang Agricultural Sciences is the property of Xinjiang Agricultural Sciences Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

OBJECTIVE To measure the trunk vertical displacement (VD) in horses trotting on a water treadmill (WT) at different water depths (WDs) and speeds. ANIMALS 6 sound Standardbred horses (median age 12 years [IQR:10.5-12]). METHODS The horses were trotted on a WT at 2 speeds (3.5 m/s and 5 m/s) and during 4 conditions: dry treadmill (DT), WD at mid-cannon (WD-CAN), mid-radius (WD-RAD), and shoulder (WD-SHOUL). The dorsoventral movement was obtained with accelerometers placed over the withers, thoracolumbar junction (T18), tuber sacrale (TS), and sacrum (S5). The VD was defined with the median value of the upward (Up) and downward (Down) amplitudes of the vertical excursion during each stride. The difference of VD at each sensor location was compared between the DT and the 3 WDs, and between the 2 trotting speeds for the same condition. RESULTS The VD amplitudes were significantly increased at any sensor location when trotting in water at WD-CAN and WD-RAD compared to DT (P < .05 for all), with the highest increase at WD-RAD and T18. When the speed increased from 3.5 to 5 m/s, the VD amplitudes were significantly decreased at T18 at each water level (P = .03), and at WD-RAD only for the withers and TS (P = .03). CLINICAL RELEVANCE Both water depth and speed affect the trunk VD in horses at trot on a WT with an opposite effect. The VD increases when increasing the WD up to mid-radius, while the VD decreases when increasing the trotting speed, with the main effects observed at the thoracolumbar junction. [ABSTRACT FROM AUTHOR]

The article examines the portrayal of single mothers in the South Korean drama "When the Camellia Blooms" and argues that it challenges traditional narratives by presenting a more empowered and independent single mother character. The drama addresses contemporary issues such as the #MeToo movement and misogynist murders, while also emphasizing solidarity and alternative parenting communities. The article discusses the use of flower analogies, particularly the camellia, to represent femininity and lack of agency for women in South Korean society, but also highlights how the drama challenges these stereotypes by portraying the protagonist as an independent and empowered single mother. It explores the shift from patriarchal motherhood to feminist mothering and the importance of context in interpreting flower symbolism. [Extracted from the article]

Simple Summary: Finding the cause of lameness in a horse often involves desensitizing different areas of the limbs, known as diagnostic anaesthesia. When combined with measuring changes in movement, for example, with inertial measurement units, different patterns may emerge in relation to how expert veterinarians perceive these changes. This study has analyzed interactions between perceived changes and measured gait parameters when horses were trotted in-hand in straight lines before and after different types of diagnostic anaesthesia were administered. Our study shows that movement of both the head and pelvis—the most commonly used indicators of lameness—change differently in relation to expert opinion and in association with what part of the limb has undergone elimination of pain. Generally, eliminating pain in a forelimb reduces the asymmetry of head movement (reduced head nodding), but also improves the ability of the horse to utilize the hind limb on the opposite side of the lame forelimb for pushing off from the ground. Eliminating pain in a hind limb appears to improve weight-bearing (supporting the body against gravity) as well as pushing off. This is observed for both the hind and front end of the horse, reducing both hip hike and head nod. Limited evidence is available relating gait changes to diagnostic anaesthesia. We investigated associations between specific movement patterns and diagnostic anaesthesia of different anatomical structures in a retrospective analysis. Referral-level lameness cases were included with the following criteria: presence of diagnostic anaesthesia of a forelimb and/or hind limb; subjective efficacy classified as "negative", "partially positive", or "positive"; quantitative gait data available from inertial measurement units. Gait changes were calculated for three forelimb (palmar digital, abaxial sesamoid, low 4-point nerve block) and five hind limb diagnostic blocks (tarso-metatarsal, metatarsophalangeal joint block, deep branch of lateral plantar, low 6-point, abaxial sesamoid nerve block). Mixed models (random factor "case", fixed factors "diagnostic anaesthesia type" and "efficacy", two-way interaction) assessed the head and pelvic movement (p < 0.05, Bonferroni correction). Four parameters were significantly affected by forelimb anaesthesia (N = 265) (all p ≤ 0.031) and six by hind limb anaesthesia (N = 342) efficacy (all p ≤ 0.001). All head movement parameters and pelvic push-off asymmetry were significantly affected by the two-way interaction after forelimb anaesthesia (all p ≤ 0.023) and two pelvic movement symmetry parameters by the two-way interaction after hind limb anaesthesia (all p ≤ 0.020). There are interactions between block efficacy and type resulting in changes in weight-bearing and push-off-associated head and pelvic movement symmetry after diagnostic anaesthesia. [ABSTRACT FROM AUTHOR]

Copyright of Equine Veterinary Journal is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Simple Summary: Racehorses routinely trot over tarmac, artificial and turf surfaces to access gallop tracks and during warm-up exercises. While undertaking these activities, jockeys may assume either a rising or two-point seat position. Understanding how hoof movements vary depending on jockey seating style may have a bearing on safety and stability, and this may vary across surfaces with contrasting fundamental properties, such as hardness and regularity. This study fitted inertial measurement units (IMUs) to the forelimb hooves of six retired Thoroughbred racehorses as they trotted in a randomized order over tarmac, artificial and turf surfaces, with their jockey in rising and two-point seat positions. The IMUs enabled hoof landing, mid-stance, breakover, and swing durations to be calculated, in addition to stride length, for each trial condition. Landing duration was significantly shorter on the tarmac than on the turf and artificial surfaces. Mid-stance duration was significantly longer on the tarmac than on the artificial surface and increased for the two-point seat position. Neither surface nor jockey position affected breakover, but the presence of a jockey increased breakover compared to in-hand exercise. Swing duration was significantly longer on turf compared to the artificial surface. Stride length was significantly shorter on tarmac than on turf, and stride length had a strong positive correlation with speed. Injuries to racehorses and their jockeys are not limited to the racetrack and high-speed work. To optimise racehorse-jockey dyads' health, well-being, and safety, it is important to understand their kinematics under the various exercise conditions they are exposed to. This includes trot work on roads, turf and artificial surfaces when accessing gallop tracks and warming up. This study quantified the forelimb hoof kinematics of racehorses trotting over tarmac, turf and artificial surfaces as their jockey adopted rising and two-point seat positions. A convenience sample of six horses was recruited from the British Racing School, Newmarket, and the horses were all ridden by the same jockey. Inertial measurement units (HoofBeat) were secured to the forelimb hooves of the horses and enabled landing, mid-stance, breakover, swing and stride durations, plus stride length, to be quantified via an in-built algorithm. Data were collected at a frequency of 1140 Hz. Linear Mixed Models were used to test for significant differences in the timing of these stride phases and stride length amongst the different surface and jockey positions. Speed was included as a covariate. Significance was set at p < 0.05. Hoof landing and mid-stance durations were negatively correlated, with approximately a 0.5 ms decrease in mid-stance duration for every 1 ms increase in landing duration (r2 = 0.5, p < 0.001). Hoof landing duration was significantly affected by surface (p < 0.001) and an interaction between jockey position and surface (p = 0.035). Landing duration was approximately 4.4 times shorter on tarmac compared to grass and artificial surfaces. Mid-stance duration was significantly affected by jockey position (p < 0.001) and surface (p = 0.001), speed (p < 0.001) and jockey position*speed (p < 0.001). Mean values for mid-stance increased by 13 ms with the jockey in the two-point seat position, and mid-stance was 19 ms longer on the tarmac than on the artificial surface. There was no significant difference in the breakover duration amongst surfaces or jockey positions (p ≥ 0.076) for the ridden dataset. However, the mean breakover duration on tarmac in the presence of a rider decreased by 21 ms compared to the in-hand dataset. Swing was significantly affected by surface (p = 0.039) and speed (p = 0.001), with a mean swing phase 20 ms longer on turf than on the artificial surface. Total stride duration was affected by surface only (p = 0.011). Tarmac was associated with a mean stride time that was significantly reduced, by 49 ms, compared to the turf, and this effect may be related to the shorter landing times on turf. Mean stride length was 14 cm shorter on tarmac than on grass, and stride length showed a strong positive correlation with speed, with a 71 cm increase in stride length for every 1 m s−1 increase in speed (r2 = 0.8, p < 0.001). In summary, this study demonstrated that the durations of the different stride cycle phases and stride length can be sensitive to surface type and jockey riding position. Further work is required to establish links between altered stride time variables and the risk of musculoskeletal injury. [ABSTRACT FROM AUTHOR]

Simple Summary: Riders are often frustrated because when they recognise a decline in their horse's performance, they seek professional advice and are informed that their horse is not lame based on an examination in hand ± on the lunge. The Ridden Horse Pain Ethogram (RHpE) was developed to facilitate the recognition of musculoskeletal pain in horses. An RHpE score of ≥8/24 reflects the likely presence of musculoskeletal pain. The aim of this study was to document observations made during ridden exercise of 150 horses with a history of poor performance, comparing RHpE scores before and after nerve blocks ± change of saddle. The most frequent lameness grade when ridden was 2/8 (range: 0–4); 35% of the horses had no overt lameness but lacked hindlimb impulsion. The most frequent RHpE score was 9/24 (range: 2–15/24), which declined to 2/24 (range: 0–12) after the interventions and was associated with improved gait quality and rideability. Despite recent professional saddle fit, an ill-fitting saddle contributed to poor performance in 37% of the horses. This study highlights the importance of ridden exercise in the investigation of poor performance/ low-grade lameness and the value of the RHpE to verify the presence of musculoskeletal pain. Nerve blocks are vital to determine the source(s) of pain that compromise performance. The Ridden Horse Pain Ethogram (RHpE) was developed to facilitate the recognition of musculoskeletal pain. The aim of this study was to document changes in RHpE scores before and after diagnostic anaesthesia was performed to alleviate pain ± when the saddle was changed. One hundred and fifty horses underwent ridden exercise as part of an investigation of poor performance. The RHpE was applied before and after the interventions. Fifty-two (34.7%) horses exhibited a bilaterally symmetrical short step length and/or restricted hindlimb impulsion and engagement. Fifty-three (35.3%) horses had episodic lameness; only forty-five (30.0%) horses were continuously lame. The median maximum lameness grade when ridden was 2/8 (interquartile range [IQR]: 0–3; range: 0–4). Fifty-six (37.3%) horses had an ill-fitting saddle, which was considered likely to influence performance. The median RHpE scores after the interventions (2/24 [IQR: 1–3, range: 0–12]) were significantly lower than before the interventions (9/24 [IQR: 8–11, range: 2–15]) (Wilcoxon signed-rank z = 10.6, p < 0.001). There was no correlation between the RHpE score and maximum lameness grade before diagnostic anaesthesia (Spearman's rho = 0.09, p = 0.262). It was concluded that the absence of overt lameness does not preclude primary musculoskeletal pain. Gait quality and performance can be improved by diagnostic anaesthesia, with substantial reductions in RHpE scores. [ABSTRACT FROM AUTHOR]

Limited evidence is available relating gait changes to diagnostic anaesthesia. We investigated associations between specific movement patterns and diagnostic anaesthesia of different anatomical structures in a retrospective analysis. Referral-level lameness cases were included with the following criteria: presence of diagnostic anaesthesia of a forelimb and/or hind limb; subjective efficacy classified as “negative”, “partially positive”, or “positive”; quantitative gait data available from inertial measurement units. Gait changes were calculated for three forelimb (palmar digital, abaxial sesamoid, low 4-point nerve block) and five hind limb diagnostic blocks (tarso-metatarsal, metatarsophalangeal joint block, deep branch of lateral plantar, low 6-point, abaxial sesamoid nerve block). Mixed models (random factor “case”, fixed factors “diagnostic anaesthesia type” and “efficacy”, two-way interaction) assessed the head and pelvic movement (p < 0.05, Bonferroni correction). Four parameters were significantly affected by forelimb anaesthesia (N = 265) (all p ≤ 0.031) and six by hind limb anaesthesia (N = 342) efficacy (all p ≤ 0.001). All head movement parameters and pelvic push-off asymmetry were significantly affected by the two-way interaction after forelimb anaesthesia (all p ≤ 0.023) and two pelvic movement symmetry parameters by the two-way interaction after hind limb anaesthesia (all p ≤ 0.020). There are interactions between block efficacy and type resulting in changes in weight-bearing and push-off-associated head and pelvic movement symmetry after diagnostic anaesthesia.

Copyright of Angle Health Law Review is the property of Angle Publishing Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Injuries to racehorses and their jockeys are not limited to the racetrack and high-speed work. To optimise racehorse-jockey dyads’ health, well-being, and safety, it is important to understand their kinematics under the various exercise conditions they are exposed to. This includes trot work on roads, turf and artificial surfaces when accessing gallop tracks and warming up. This study quantified the forelimb hoof kinematics of racehorses trotting over tarmac, turf and artificial surfaces as their jockey adopted rising and two-point seat positions. A convenience sample of six horses was recruited from the British Racing School, Newmarket, and the horses were all ridden by the same jockey. Inertial measurement units (HoofBeat) were secured to the forelimb hooves of the horses and enabled landing, mid-stance, breakover, swing and stride durations, plus stride length, to be quantified via an in-built algorithm. Data were collected at a frequency of 1140 Hz. Linear Mixed Models were used to test for significant differences in the timing of these stride phases and stride length amongst the different surface and jockey positions. Speed was included as a covariate. Significance was set at p < 0.05. Hoof landing and mid-stance durations were negatively correlated, with approximately a 0.5 ms decrease in mid-stance duration for every 1 ms increase in landing duration (r2 = 0.5, p < 0.001). Hoof landing duration was significantly affected by surface (p < 0.001) and an interaction between jockey position and surface (p = 0.035). Landing duration was approximately 4.4 times shorter on tarmac compared to grass and artificial surfaces. Mid-stance duration was significantly affected by jockey position (p < 0.001) and surface (p = 0.001), speed (p < 0.001) and jockey position*speed (p < 0.001). Mean values for mid-stance increased by 13 ms with the jockey in the two-point seat position, and mid-stance was 19 ms longer on the tarmac than on the artificial surface. There was no significant difference in the breakover duration amongst surfaces or jockey positions (p ≥ 0.076) for the ridden dataset. However, the mean breakover duration on tarmac in the presence of a rider decreased by 21 ms compared to the in-hand dataset. Swing was significantly affected by surface (p = 0.039) and speed (p = 0.001), with a mean swing phase 20 ms longer on turf than on the artificial surface. Total stride duration was affected by surface only (p = 0.011). Tarmac was associated with a mean stride time that was significantly reduced, by 49 ms, compared to the turf, and this effect may be related to the shorter landing times on turf. Mean stride length was 14 cm shorter on tarmac than on grass, and stride length showed a strong positive correlation with speed, with a 71 cm increase in stride length for every 1 m s−1 increase in speed (r2 = 0.8, p < 0.001). In summary, this study demonstrated that the durations of the different stride cycle phases and stride length can be sensitive to surface type and jockey riding position. Further work is required to establish links between altered stride time variables and the risk of musculoskeletal injury.

Summary: Background: The Ridden Horse Pain Ethogram (RHpE) was developed to facilitate identification of musculoskeletal pain. Objectives: To determine the influence of rider skill on ridden horse performance and behaviour, the latter using the RHpE. It was hypothesised that gait quality at trot and canter would improve with a more skilled rider compared with a less skilled rider, but the RHpE scores would be similar. Study design: Repeated measures investigation. Methods: Forty horses, in regular work and presumed by their riders to be nonlame, were ridden by their normal rider (N) and a skilled professional rider (P), performing a dressage‐type test over 8.5 min. Twenty horses were ridden first by rider P, and 20 were ridden first by rider N. The presence of lameness or gait abnormalities in canter was recorded. Standardised video recordings were acquired. All videos were anonymised and presented in random order to the assessors. Rider skill and horse gait quality were graded (Fédération Equestre Internationale scale, 1–10), and the RHpE was applied to each horse using the video recordings. Results: Rider P had a higher median skill score (6/10) compared with the N riders (4.5/10) (P<0.001). There was a correlation between rider skill scores and gait quality scores (P<0.001). The presence of lameness or gait abnormalities in canter, when ridden by riders N and P, varied among horses. The median RHpE score for all horses was 9/24 (range 3–14). There was no difference in mean or median RHpE scores between the N riders and rider P. There was some variance in the frequency of occurrence of specific behaviours between the N riders and rider P. Main limitations: The identity of rider P could not be concealed. Conclusions: There was no direct relationship between rider skill level and the RHpE score, but riders did alter the manifestations of some behaviours. [ABSTRACT FROM AUTHOR]

Background: There is a paucity of research describing the gait pattern of lame horses at the walk. Objectives: To describe the changes in motion pattern and vertical ground reaction forces (GRFz) in horses with induced forelimb lameness at the walk and compare those changes with the changes observed at the trot. Study design: Experimental study. Methods: In 10 clinically sound Warmblood horses, moderate forelimb lameness was induced using a sole pressure model followed by trot and walk on a treadmill. Kinematic data were collected using 3D optical motion capture (OMC), and GRFz by an instrumented treadmill. Mixed models were used to compare sound baseline versus forelimb lameness (significance was set at P <.05). Results: Lameness induction significantly reduced peak GRFz on the second force peak, and vertical impulse in the lame limb. Stride and stance duration in all limbs were reduced. Lameness significantly affected the vertical movement symmetry of the head and withers. Maximum limb retraction angle, fetlock extension and protraction speed were reduced in the lame limb. Body centre of mass (COM) translation was reduced in the side‐to‐side direction and increased in the vertical and fore‐aft directions. Several compensatory kinetic and kinematic changes were observed in the nonlame limbs. The observed changes in both kinetics and kinematics were generally smaller at walk with fewer variables being affected, compared to the trot. Main limitations: Only one degree and type of orthopaedic pain (sole pressure) was studied. Conclusions: Compensatory strategies of forelimb lameness at the walk include alteration of several kinetic and kinematic parameters and have some specific patterns and inter‐individual differences that are not seen at the trot. However, much like at the trot, head movement and forelimb vertical force symmetry seem to be the most useful parameters to detect forelimb lameness at walk. [ABSTRACT FROM AUTHOR]

Abstract Background The equine m. gluteus medius (GM) is the largest muscle of the horse, its main movement function is the extension of the hip joint. The objective of the present study was to measure equine GM activity in three adjacent locations on GM during walk and trot on a treadmill, in order to document potential differences. Fourteen Haflinger mares were measured using surface electromyography and kinematic markers to identify the motion cycles on three occasions over 16 weeks. The electrodes were placed on left and right gluteus medius muscle over the middle of its widest part and 5 cm lateral and medial of it. For data processing, electrical activity was normalised to its maximum value and timing was normalised to the motion cycle. A Gaussian distribution approach was used to determine up to 10 modes of focussed activity, and results were analysed separately for stance and swing phase of the ipsilateral hindlimb. Results Fair reliability was found for mean mode values (Cronbach’s alpha = 0.66) and good reliability was found for mean mode locations (Cronbach’s alpha = 0.71) over the three data collection days. The magnitude of muscle activity identified as mean mode value was much larger at trot than at walk, and mean mode value was significantly different between stance phases of walk and trot for all electrode positions (p

Summary: Regular monitoring of movement asymmetry with inertial measurement units (IMUs) to aid in the diagnosis of the underlying cause of a lameness is feasible. Normal ranges for specific groups of horses may be required, with consideration of expert veterinary opinions for both asymmetry screening and lameness assessment. The aim of this study was to determine movement asymmetry values compared with expert lameness scores to enable screening for lameness in Thoroughbreds in race training. IMU gait assessment during in‐hand trot‐up was performed in 25 racehorses undergoing routine gait analysis or lameness examination at the Singapore Turf Club. Video recordings were graded numerically (0–5) for lameness by six experienced racehorse veterinarians. Inter‐observer agreement and consistency were determined. Median lameness scores were used to calculate sensitivity and specificity for head, withers and pelvic movement asymmetry. Guideline values for aligning movement asymmetry values with expert opinions about forelimb and hindlimb lameness were determined from receiver operating characteristics (ROC). Inter‐observer agreement was poor to fair, inter‐observer consistency was good (intraclass correlation coefficient: 0.667 for forelimbs and 0.617 for hindlimbs). ROCs indicated higher discriminative power for hindlimb lameness using pelvic asymmetry (90% sensitivity, 93% specificity) compared with forelimb lameness using head asymmetry (69% sensitivity, 89% specificity) or withers asymmetry (44% sensitivity, 89% specificity). When compared to expert lameness scores from videos of a limited number of Thoroughbred racehorses, preliminary guideline values for movement asymmetry screening for forelimb lameness (>|14.5 mm|) and hindlimb lameness (>|7.5 mm|) are higher than previously reported clinical thresholds of >|7 mm| for head movement and >|4 mm| for pelvic movement asymmetry. [ABSTRACT FROM AUTHOR]

Changing gait is crucial for adaptive and smooth animal locomotion. Although it remains unclear what makes animals decide on a specific gait, energy efficiency is an important factor. It has been reported that the relationship of oxygen consumption with speed is U-shaped for each horse gait and that different gaits have different speeds at which oxygen consumption is minimized. This allows the horse to produce energy-efficient locomotion in a wide speed range by changing gait. However, the underlying mechanisms causing oxygen consumption to be U-shaped and the speeds for the minimum consumption to be different between different gaits are unclear. In the present study, we used a neuromusculoskeletal model of the rat to examine the mechanism from a dynamic viewpoint. Specifically, we constructed the musculoskeletal part of the model based on empirical anatomical data on rats and the motor control model based on the physiological concepts of the spinal central pattern generator and muscle synergy. We also incorporated the posture and speed regulation models at the levels of the brainstem and cerebellum. Our model achieved walking through forward dynamic simulation, and the simulated joint kinematics and muscle activities were compared with animal data. Our model also achieved trotting by changing only the phase difference of the muscle-synergy-based motor commands between the forelimb and hindlimb. Furthermore, the speed of each gait varied by changing only the extension phase duration and amplitude of the muscle synergy-based motor commands and the reference values for the regulation models. The relationship between cost of transport (CoT) and speed was U-shaped for both the generated walking and trotting, and the speeds for the minimum CoT were different for the two gaits, as observed in the oxygen consumption of horses. We found that the resonance property and the posture and speed regulations contributed to the CoT shape and difference in speeds for the minimum CoT. We further discussed the energy efficiency of gait based on the simulation results.

Changing gait is crucial for adaptive and smooth animal locomotion. Although it remains unclear what makes animals decide on a specific gait, energy efficiency is an important factor. It has been reported that the relationship of oxygen consumption with speed is U-shaped for each horse gait and that different gaits have different speeds at which oxygen consumption is minimized. This allows the horse to produce energy-efficient locomotion in a wide speed range by changing gait. However, the underlying mechanisms causing oxygen consumption to be U-shaped and the speeds for the minimum consumption to be different between different gaits are unclear. In the present study, we used a neuromusculoskeletal model of the rat to examine the mechanism from a dynamic viewpoint. Specifically, we constructed the musculoskeletal part of the model based on empirical anatomical data on rats and the motor control model based on the physiological concepts of the spinal central pattern generator and muscle synergy. We also incorporated the posture and speed regulation models at the levels of the brainstem and cerebellum. Our model achieved walking through forward dynamic simulation, and the simulated joint kinematics and muscle activities were compared with animal data. Our model also achieved trotting by changing only the phase difference of the muscle-synergy-based motor commands between the forelimb and hindlimb. Furthermore, the speed of each gait varied by changing only the extension phase duration and amplitude of the muscle synergy-based motor commands and the reference values for the regulation models. The relationship between cost of transport (CoT) and speed was U-shaped for both the generated walking and trotting, and the speeds for the minimum CoT were different for the two gaits, as observed in the oxygen consumption of horses. We found that the resonance property and the posture and speed regulations contributed to the CoT shape and difference in speeds for the minimum CoT. We further discussed the energy efficiency of gait based on the simulation results. [ABSTRACT FROM AUTHOR]

The majority of terrestrial mammals adopt distinct, discrete gaits across their speed range. Though there is evidence that walk, trot and gallop may be selected at speeds consistent with minimizing metabolic cost (Hoyt and Taylor, 1981, Nature, 291, 239–240), the mechanical causes underlying these costs and their changes with speed are not well understood. In particular, the paired, near‐simultaneous contacts of the trot is puzzling as it appears to demand a high mechanical work that could easily be avoided with distributed contacts, as with a "running walk" gait or "tolt." Here, a simple condition is derived—a ratio including the pitch moment of inertia and back length—for which trotting is energetically advantageous because it avoids the energetic consequences of pitching. Pitching could also be avoided if the impulses from the legs were orientated through the center of mass. A range of idealized gaits is considered that achieve this zero‐pitch condition, and work minimization predicts a transition from trot to canter at intermediate speeds. This can be understood from the geometric principles of achieving a "pseudoelastic" collision with each impulse (Ruina et al., 2005, J Theoretical Biol, 14, 170‐192). However, at high speeds, a transition back to trot is predicted that is not observed in nature. Research highlights: Trotting and cantering gaits can avoid pitching and associated mechanical work demands. A transition from trot to canter with increasing speed is correctly predicted; however, the account fails at higher speeds, predicting a return to trotting. [ABSTRACT FROM AUTHOR]

Copyright of Xinjiang Agricultural Sciences is the property of Xinjiang Agricultural Sciences Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, a dynamic based control algorithm for six-link quadruped locomotion is proposed. Up to now, a lot of researches have been conducted in the field of quadruped locomotion but most of the researches are based on the detailed modeling of a robot and its surrounding. Such methods are not able to generate a stable locomotion when the surrounding changes. However, the main characteristic of vertebral motion is the adaptability of their motions. So this is important to propose a control algorithm based on the robot dynamics. The algorithms that can guarantee the stability are classified to two categories of dynamic based and trajectory based methods. The trajectory based algorithms need detailed information about gait which is not necessarily available. But the dynamic based algorithms use some geometric constraints to reach a stabilizer controller. These geometric constraints generate the proper gaits. So in this study by employing the dynamic based control algorithm, we proposed a controller for generating the Trot and Pace gait on a straight and flat path for quadruped robot locomotion. Given that the quadruped robot has four degrees of freedom, three geometric constraints are needed to provide rhythmic locomotion. In this study, the stability of quadruped locomotion has been proved using the Poincaré return map. [ABSTRACT FROM AUTHOR]

One of the goals of the neuromotor control system is to minimize the cost of locomotion by reducing mechanical energy losses. Collisional mechanics, which studies the redirection of the downwards motion of the center of mass (COM) by ground reaction forces (GRF) generated by the limbs, represents an important source of energy loss. The primary objective of this study was to compare collisional mechanics and the associated mechanical energy losses in horses performing diagonally-synchronized gaits over a range of speeds. It is to be expected that collisional energy losses will be high when the COM velocity vector is closely aligned with the GRF vector. This condition is achieved in piaffe, an artificial gait performed in dressage competitions that has a diagonal limb coordination pattern similar to trot but performed with little or no forward velocity. Therefore, we hypothesized that collisional energy losses would be higher in piaffe than in trot. Synchronized kinematic and GRF data were collected from three highly-trained horses performing piaffe, passage and trot at a range of speeds. Derived variables were vertical excursion and velocity of the trunk COM, fore and hind limb compression expressed as percentage reduction of standing limb lengths, range of limb pro-retraction, GRF vector magnitude and vector angle, collision angle (8), and mechanical cost of motion (CoMotmech). Linear regression was used to investigate the relationship between CoMotmech and speed for each gait. Partial correlation was used to seek relationships between COM excursion and limb mechanics for each gait. Piaffe, passage and trot were clearly separated on the basis of speed. In all gaits the trunk was high at contact and lift off and descended to its lowest point in midstance following the pattern typical of spring mass mechanics. Mechanical cost was significantly (p < :05) and inversely related to speed in trot and piaffe with the value increasing steeply as speed approached zero due to a near vertical orientation of both the COM velocity vector and the GRF vector. Limb compression during stance was significantly (p < :05) linked to trunk COM vertical excursion in all gaits, with a stronger relationship in the forelimb. Hindlimb compression was, however, large in piaffe where the force magnitudes are notably smaller. The study illustrates the potential value of studying artificial gaits to provide data encompassing the entire range of locomotor capabilities. The results supported the experimental hypothesis by showing a threefold increase in collisional energy losses in piaffe compared with trot. In all gaits, dissociation between diagonal limb contacts and lift offs was thought to be an important strategy in reducing in collisional losses. Piaffe, the most costly gait, has similar characteristics to hopping on the spot. It appears that greater hindlimb compliance and a lower step frequency are important energy conservation strategies for piaffe. [ABSTRACT FROM AUTHOR]

While the size of the Weimaraner may assist in the breed performing the tasks of a sporting dog, the large size coupled with these tasks may also make the breed more susceptible to orthopedic issues. The understanding of the normal gait mechanics of the Weimaraner can be a useful tool in examining for gait abnormalities associated with these orthopedic issues, and yet, research concerning breed-specific gaits in the canine is limited. Therefore, study objectives were to define the normal Weimaraner trotting kinematics and determine the influence of speed on these parameters. Markers were attached to palpation points on the limbs and head of American Kennel Club registered Weimaraners. Dogs were tracked while performing a slow (1.2-1.7 m/s) and fast (1.9-2.3 m/s) trotting speed. Frame-by-frame analysis was performed. Paw ground contact and lift-off was documented and marker displacement was tracked. At both speeds, the trot had a diagonal footfall sequence with diagonal limb pairing alternating between diagonal bipedal support and suspension. The faster speed was achieved with significant increases in stride length and displacements of the head, withers, and fore and hind paws (P <.05). Range of motion of the elbow and hip significantly increased as the dog transitioned from a slow to fast speed (P <.05). Through gait analysis, the Weimaraner trot was defined as a 2-beat diagonal rhythm gait with suspension. Speed did not change these characteristics, but did influence stride length and linear and angular displacements, and thus, should be a consideration in clinical examination. [ABSTRACT FROM AUTHOR]

There is considerable debate about the social license to compete with horses and controversy about training methods for dressage horses. The objectives were to: 1. apply the Ridden Horse Pain Ethogram (RHpE) to dressage horses competing at elite Grand Prix level; 2. compare RHpE and judges’ scores; and 3. document deviations in gaits from Fédération Equestre Internationale (FEI) guidelines. Video recordings of 147 competitors from nine World Cup competitions were assessed. Spearman’s rank correlation coefficient tested the correlation between RHpE and judges’ scores. The median RHpE score was 3 (IQR 1, 4; range 0, 7). There was a moderate negative correlation (Spearman rho −0.40, p < 0.001) between the RHpE scores and the judges’ scores. Mouth open with separation of the teeth for ≥10 s (68%), head behind vertical ≥10° ≥10 s (67%), an intense stare for ≥5 s (30%) and repeated tail swishing (29%) were the most frequent RHpE behaviours. Deviations from FEI guidelines were most frequent in passage, piaffe, canter flying-changes, canter pirouettes and “halt-immobility-rein back five steps-collected trot”. In conclusion, most horses appeared to work comfortably for the majority of the test. Further investigation of the influence of a double bridle compared with a snaffle bridle on head position and mouth opening is merited.

Kinematic measurements of fourteen Haflinger horses without lameness, walking and trotting on a treadmill were taken to document the location of the centre of the body (CB), defined as the centre between markers on the head, on the withers, on the sacral bone and on the lateral wall of all four hooves in relation to the sacral bone marker. During walk and trot, there are three dimensional CB position (x: forward-backward, y: side-to-side, and z: up and down). For each horse minimum of eight motion cycles were considered in walk as well as in trot. For all three axes, mean CB location, its standard deviation and its 95% confidence interval (CI) were calculated. For statistical analysis, Shapiro-Wilk test and Spearman’s correlation test were carried out. Mean body mass was 463±42 kg, CI (439, 487); mean height at the withers was 131±5 cm, CI (128, 134); mean height at the sacrum was 128 ± 2 cm, CI (127, 130). Mean CBx was in front of the sacrum (walk 74±2 cm, CI (72, 75); trot 73±2 cm, CI (72, 74); walk vs trot p=0.008). Mean CBz was below the sacrum (-71±2 cm, CI (-73, -70) in walk; -69 ± 2 cm, CI (-70, -68) in trot; walk vs trot p=0.001). Positive correlations were found between MeanCBx and trunk length in walk and trot, which could highlight the biomechanical importance of the trunk as it plays a crucial role in deceleration and acceleration. The analysis of the body location centre may be used to identify differences between horses of the same breed, and thus support evaluation of the quality of the horse during locomotion.

Objective: To measure the trunk vertical displacement (VD) in horses trotting on a water treadmill (WT) at different water depths (WDs) and speeds., Animals: 6 sound Standardbred horses (median age 12 years [IQR:10.5-12])., Methods: The horses were trotted on a WT at 2 speeds (3.5 m/s and 5 m/s) and during 4 conditions: dry treadmill (DT), WD at mid-cannon (WD-CAN), mid-radius (WD-RAD), and shoulder (WD-SHOUL). The dorsoventral movement was obtained with accelerometers placed over the withers, thoracolumbar junction (T18), tuber sacrale (TS), and sacrum (S5). The VD was defined with the median value of the upward (Up) and downward (Down) amplitudes of the vertical excursion during each stride. The difference of VD at each sensor location was compared between the DT and the 3 WDs, and between the 2 trotting speeds for the same condition., Results: The VD amplitudes were significantly increased at any sensor location when trotting in water at WD-CAN and WD-RAD compared to DT (P < .05 for all), with the highest increase at WD-RAD and T18. When the speed increased from 3.5 to 5 m/s, the VD amplitudes were significantly decreased at T18 at each water level (P = .03), and at WD-RAD only for the withers and TS (P = .03)., Clinical Relevance: Both water depth and speed affect the trunk VD in horses at trot on a WT with an opposite effect. The VD increases when increasing the WD up to mid-radius, while the VD decreases when increasing the trotting speed, with the main effects observed at the thoracolumbar junction.

Summary: Background: With the view of implementing gait symmetry measurements in Thoroughbreds in training for early detection of injuries, repeatability of inertial measurement unit (IMU) gait parameters needs to be established. Objectives: To assess the variation of head and pelvis movement symmetry in Thoroughbreds in training. Study design: Repeated observations in horses in race training. Methods: Daily and weekly repeat gait assessments were conducted in 14 Thoroughbreds equipped with IMUs on poll, sacrum and right (RTC) and left (LTC) tuber coxae. Gait was assessed in trot, in‐hand, on a level concrete surface. Difference between vertical displacement minima and maxima and range of motion (ROM) were obtained. Ranges containing 50% (median), 75, 90 and 95% of absolute daily and weekly differences were calculated and intraclass correlation coefficients (ICC) calculated for daily and weekly repeats. Results: Median absolute daily differences ranged from 4 to 7 mm and median weekly differences from 4 to 8 mm. 90% of daily differences were between 9 and 16 mm and 90% of weekly differences between 11 and 19 mm. ICC values were found on average across sensors and gait parameters as 0.73 (ranging from 0.40 to 0.92 across parameters) for daily repeats and as 0.65 (0.27 to 0.91) for weekly repeats. Main limitations: Horses were of varying training and movement asymmetry levels, and no veterinary lameness examination was conducted. Conclusions: Daily and weekly repeat gait assessments in this group of Thoroughbreds in training show lower ICC values than previously reported from within‐day repeats in horses during lameness examinations. We recommend conducting repeatability studies for specific groups of horses when planning long‐term studies aiming at identifying horses at risk of injury. [ABSTRACT FROM AUTHOR]

Genetic analyses in donkeys are likely to face compromises in terms of sample size and population structure. This study aims at implementing a suitable model to estimate breeding values and genetic parameters for gaits in Andalusian donkeys. Empirical observation revealed that ambling donkeys (showing a slightly uneven, non-isochronous 1-2, 3-4 lateral sequence gait) did not walk (i.e. presented an isochronous, even 1-2-3-4 sequence gait) and vice versa. However, the two donkey groups could trot, equally. In this study, 2700 gait records were registered from 300 donkeys. The sample included 1350 gait records from 169 ambling/trotting donkeys and 1350 gait records from 131 walking/trotting donkeys. Fixed effects included year, season, sex, farm/owner, husbandry system, weather, ground type and appraisers. Weight and age were included as covariates. MTDFREML software was used to estimate (co)variance components, genetic parameters and predict breeding values and their accuracies in both sets, separately. Gaits’ heritability ± SE estimates were 0.56 ± 0.155, 0.53 ± 0.317 and 0.67 ± 0.166 for amble, walk and trot, respectively. Genetic correlations were 0.31 ± 0.216, 0.42 ± 0.115 and 0.28 ± 0.178, for amble and walk, amble and trot and walk and trot, respectively. Not all gaits are suitable to treat every human sensomotor condition. We developed a locomotion selection index, assessing the relative loss/gain in index accuracy when each gait modality was excluded to develop different gait specific therapeutic lines to genetically select the best performing donkeys from each gait modality. Our results suggest that gait genetic lines could be developed and may be potential selection criteria to consider in assisted-therapy donkey breeding programs. [ABSTRACT FROM AUTHOR]

Background Horses show compensatory head movement in hindlimb lameness and compensatory pelvis movement in forelimb lameness but little is known about the relationship of withers movement symmetry with head and pelvic asymmetry in horses with naturally occurring gait asymmetries. Objectives To document head, withers and pelvic movement asymmetry and timing differences in horses with naturally occurring gait asymmetries. Study design Retrospective analysis of gait data. Methods Head, withers and pelvic movement asymmetry and timing of displacement minima and maxima were quantified from inertial sensors in 163 Thoroughbreds during trot-ups on hard ground. Horses were divided into 4 subgroups using the direction of head and withers movement asymmetry. Scatter plots of head vs. pelvic movement asymmetry illustrated how the head-withers relationship distinguishes between contralateral and ipsilateral head-pelvic movement asymmetry. Independent t test or Mann -Whitney U test (P<0.05) compared pelvic movement asymmetry and timing differences between groups. Results The relationship between head and withers asymmetry (i.e. same sided or opposite sided asymmetry) predicts the relationship between head and pelvic asymmetry in 69-77% of horses. Pelvic movement symmetry was significantly different between horses with same sign vs. opposite sign of head-withers asymmetry (P<0.0001). Timing of the maximum head height reached after contralateral ('sound') stance was delayed compared to withers (P = 0.02) and pelvis (P = 0.04) in horses with contralateral head-withers asymmetry. Main limitations The clinical lameness status of the horses was not investigated. Conclusion In the Thoroughbreds with natural gait asymmetries investigated here, the direction of head vs. withers movement asymmetry identifies the majority of horses with ipsilateral and contralateral head and pelvic movement asymmetries. Withers movement should be further investigated for differentiating between forelimb and hindlimb lame horses. Horses with opposite sided head and withers asymmetry significantly delay the upward movement of the head after 'sound' forelimb stance. [ABSTRACT FROM AUTHOR]

Present study was carried out to determine changes in oxidative stress biomarkers, haematological and biochemical profiles in six clinically healthy Marwari mares subjected to twenty km moderate intensity exercise on every 10th day and three Km daily, in desert sandy track in hot subtropical environment for a period of 40 days. Venous blood samples were collected for determination of selected blood parameters pre exercise and immediately post-exercise in the exercising mares and of the resting control mares. Average of last three trials of 20 Km was taken for comparison and statistical analysis. Post-exercise plasma malondialdehyde (MDA) values were significantly higher while whole blood MDA values were not significantly different from the pre exercise. In exercising mares, whole blood MDA levels were observed significantly lower than the resting control mares. Plasma MDA levels, which was observed significantly high immediately after exercise subsided after ten days and pre exercise values of plasma malondialdehyde were found not statistically different from those of the resting control mares. Thus, the findings reflected decrease in oxidative stress levels in trained Marwari horses undergoing moderate intensity exercise. Significant changes were observed in many of the biochemical and haematological parameters immediately after exercise reflected the normal physiological response of Marwari mare to moderate intensity exercise in hot environment with mild muscular damage. [ABSTRACT FROM AUTHOR]

Many factors associated with the saddle and the rider could produce pain in horses thus reducing performance. However, studies of horse–saddle–rider interactions are limited and determining their effects remains challenging. The aim of this study was to test a novel method for assessing equine thoracic and lumbar spinal movement under the saddle and collect data during trotting. Back movement was measured using inertial measurement units ( n  = 5) fixed at the levels of thoracic vertebrae T6, T12 and T16, and lumbar vertebrae L2 and L5. To compare unridden and ridden conditions, three horses were trotted in hand then at the rising trot (seated phase: left diagonal, rider seated; standing phase: right diagonal, rider standing). The protraction–retraction angles of the forelimbs and the hind limbs were also calculated in two dimensions (2D) using reflective markers. To compare conditions, linear mixed-effects regression models were used and estimated means (standard error) were calculated. The range of motion (ROM) of the caudal thoracic and thoracolumbar regions decreased respectively by −1.3 (0.4)° and −0.6 (0.2)° during the seated phase compared to the unridden condition. Concomitantly, the ROM of protraction and retraction angles increased in the ridden condition. This study demonstrated the ability of inertial measurement units to assess equine vertebral movements under the saddle. The rider, at the rising trot, affected the horse's global locomotion with measurable changes in the vertebral kinematics under the saddle. [ABSTRACT FROM AUTHOR]

Background: Most Friesian horses reach their anaerobic threshold during a standardized exercise test (SET) which requires lower intensity exercise than daily routine training. Aim: to study strengths and weaknesses of an alternative SET-protocol. Two different SETs (SETA and SETB) were applied during a 2 month training period of 9 young Friesian dressage horses. SETB alternated short episodes of canter with trot and walk, lacking long episodes of cantering, as applied in SETA. Following parameters were monitored: blood lactic acid (BLA) after cantering, average heart rate (HR) in trot and maximum HR in canter. HR and BLA of SETA and SETB were analyzed using a paired two-sided T-test and Spearman Correlation-coefficient (p* < 0.05). Results: BLA after cantering was significantly higher in SETA compared to SETB and maximum HR in canter was significantly higher in SETA compared to SETB. The majority of horses showed a significant training response based upon longitudinal follow-up of BLA. Horses with the lowest fitness at start, displayed the largest training response. BLA was significantly lower in week 8 compared to week 0, in both SETA and SETB. A significantly decreased BLA level after cantering was noticeable in week 6 in SETA, whereas in SETB only as of week 8. In SETA a very strong correlation for BLA and average HR at trot was found throughout the entire training period, not for canter. Conclusions: Young Friesian horses do reach their anaerobic threshold during a SET which requires lower intensity than daily routine training. Therefore close monitoring throughout training is warranted. Longitudinal follow up of BLA and not of HR is suitable to assess training response. In the current study, horses that started with the lowest fitness level, showed the largest training response. During training monitoring HR in trot rather than in canter is advised. SETB is best suited as a template for daily training in the aerobic window. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine whether autonomic nervous activity of a rider with no disability was altered by one practical and applicable horse trekking (HT) exercise. Changes in autonomic nervous activity were analyzed by heart rate variability (HRV). Twenty-three participants with no disability rode horses along a predetermined HT course at trotting and walking for 60 min. HRV was sampled at 60 min before and immediately, following 60 min, and 120 min after HT. As a control, the same measurements were performed for 22 age-matched participants during their rest. Only in the HT group, the value of normalized unit in high frequency component (HF nu), an index of parasympathetic nervous activity, was higher at 120 min after treatment than before HT ( P < 0.05). The low / high frequency ratio (LF / HF), believed to reflect sympathetic nervous activity, was lower in the HT group than those in the control group at 60 min ( P < 0.05) and 120 min after treatment ( P < 0.01). These findings suggest that a single HT shifted the autonomic nervous balance of a rider toward parasympathetic dominance. The results obtained by the present study could accelerate the use of horses for human health. [ABSTRACT FROM AUTHOR]

Knowledge about the horse–saddle–rider interaction remains limited. The aim of this study was to compare the effect of the rider׳s position at rising trot on the pressure distribution, spine movements, stirrups forces and locomotion of the horse. The horse׳s back movements were measured using IMUs fixed at the levels of thoracic (T6, T12, T16) and lumbar (L2, L5) vertebrae, the pressure distribution using a pressure mat and stirrups forces using force sensors. The horse׳s and rider׳s approximated centres of mass (COM) were calculated using 2D reflective markers. To compare both trot phases (rider seated/rider standing), three horses were trotted at the rising trot by the same rider. Means±SD of each parameter for sitting and standing were compared using a Student׳s t test ( p =0.05). Stirrups forces showed two peaks of equal magnitude in every stride cycle for left and right stirrups but increased during the standing phase. Simultaneously, the pressure for the whole mat significantly increased by +3.1 kPa during the sitting phase with respect to standing phase. The T12-T16 and T16-L2 angular ranges of motion (ROM) were significantly reduced (−3.2° −1.2°) and the T6-T12 and L2-L5 ROM were significantly increased (+1.7° +0.7°) during sitting phase compared to standing phase. During rising trot, the sitting phase does not only increase the pressure on the horse׳s back but also reduces the back motion under the saddle compared to the standing phase. These results give new insights into the understanding of horse–rider interactions and equine back pain management. [ABSTRACT FROM AUTHOR]

Background: The use of tack (equipment such as saddles and reins) and especially of bits because of rein tension resulting in pressure in the mouth is questioned because of welfare concerns. We hypothesised that rein tension patterns in walk and trot reflect general gait kinematics, but are also determined by individual horse and rider effects. Six professional riders rode three familiar horses in walk and trot. Horses were equipped with rein tension meters logged by inertial measurement unit technique. Left and right rein tension data were synchronized with the gait. Results: Stride split data (0-100 %) were analysed using mixed models technique to elucidate the left/right rein and stride percentage interaction, in relation to the exercises performed. In walk, rein tension was highest at hindlimb stance. Rein tension was highest in the suspension phase at trot, and lowest during the stance phase. In rising trot there was a significant difference between the two midstance phases, but not in sitting trot. When turning in trot there was a significant statistical association with the gait pattern with the tension being highest in the inside rein when the horse was on the outer fore-inner hindlimb diagonal. Conclusions: Substantial between-rider variation was demonstrated in walk and trot and between-horse variation in walk. Biphasic rein tensions patterns during the stride were found mainly in trot. [ABSTRACT FROM AUTHOR]

This study compared the effect of ridden tölt and trot at 3 speeds on physiological responses in trained adult (15.3 ± 1.6 yr) Icelandic horses. The experiment had a crossover design with 8 horses, 2 treatments (incremental exercise test in tölt and trot), and 2 riders. Each horse performed 2 tests per day (1 gait with 2 riders, minimum 4.5 h between) on 2 separate days, with 1 d of rest in between. The exercise test consisted of three 642-m phases at 3.0 m/s (Speed3), 4.0 m/s (Speed4), and 5.0 m/s (Speed5) and was performed outdoors on a 300- m oval gravel riding track in northern Iceland in May 2012. Heart rate (HR) was measured during warm-up, the exercise test, and after 5, 15, and 30 min of recovery. Blood samples were taken at rest, after warm-up, after each phase of the exercise test, and after 5, 15, and 30 min of recovery. Respiratory rate was counted for at least 15 s at rest, at the end of the exercise test, and at the end of the 30-min recovery, and rectal temperature was measured on these occasions. There were no differences in HR between tölt and trot at any time point (P > 0.05). At Speed3, hematocrit and plasma lactate concentration were greater (P < 0.05) in tölt (40% ± 1%, 1.1 ± 0.06 mmol/L) than in trot (39% ± 1%; 0.9 ± 0.06 mmol/L). There was a prolonged recovery of hematocrit and respiratory rate, a slower decrease in rectal temperature, and a tendency of a prolonged recovery of plasma lactate concentration (P = 0.0675) after tölt. In conclusion, there were only minor differences in physiological responses to tölt and trot in this selected group of experienced adult Icelandic horses and the biological and practical significance of the slightly elevated physiological responses to tölt and the slower recovery remains to be determined. [ABSTRACT FROM AUTHOR]

This paper employs the simplified quadrupedal passive dynamic model to analyze the underlying property of the transverse gallop. First, the simplified sagittal quadrupedal planar model of the transverse gallop, the trot, and searching methods for achieving the periodic motion are introduced. Next, we explore the dynamic performance of the transverse galloping pattern on the simplified quadrupedal passive dynamic model at different forward speeds and different stiffnesses of legs in a range of initial angular velocities at which the periodic motion is achieved, and there exists a particular property that is defined as the pitch angular velocity dynamics (PAVD) property. If the forward speed and the stiffness of legs are adequate in the transverse galloping pattern, the PAVD emerges and the forces (e.g. peak ground reaction force and average vertical force) that the model undergoes during locomotion are sharply reduced. The Froude numbers of the minimum forward speed where PAVD holds at a fixed stiffness of legs for different samples are virtually the same. Moreover, a comparison between the trot and the transverse gallop illustrates that a trot is more favorable in the range of forward speeds where the PAVD property is not achieved, while a transverse gallop is better after the property emerges. [ABSTRACT FROM AUTHOR]

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