Abstract: Normal speed videography was used to determine the angular parameters of 28 Spanish Thoroughbreds at trot. Horses were divided into 3 groups: Group UT, comprising 9 animals (provided by the VII National Stud, Cordoba, Spain) which had undergone no specific training programme and which were hand led at the trot; Group T, formed by 19 horses considered to be highly bred and trained, and which were also hand led; and Group RT, comprising the same horses as the latter group but this time trotted by a rider. Each animal was filmed 6 times from the right-hand side, using a Hi8 (25 Hz) video camera. Angular parameters for fore- and hindlimb joints were measured in each stride from computer-grabbed frames and entered into a spreadsheet for calculation; parameters included maximum and minimum angles, range of motion, and angles at landing, lift off and maximum hoof height; the times at which maximum angle, minimum angle, lift off and maximum hoof height occurred were calculated as percentages of total stride duration. Stride velocity (mean [s.d.]) was 4.01 (0.62), 3.60 (0.34) and 3.07 (0.36) m/s for Groups UT, T and RT, respectively. Data were then compared between Groups UT-T and Groups T-RT. Compared with Group UT, horses from Group T featured a shorter stance percentage (P<0.001) in both fore- and hindlimbs. The range of motion in forelimbs was smaller (P<0.05), due to lower retraction (P<0.001); moreover, maximum retraction appeared earlier (P<0.05). Greater scapular inclination was in evidence (P<0.05) and the shoulder joint extended further (P<0.05). Fore- and hind fetlock joints revealed a relatively shorter hyperextension period during the stance phase (P<0.01). Compared with Group T, horses from Group RT had a longer stance percentage, with belated maximum retraction of the fore- and hindlimbs. The range of movement in scapular inclination was greater (P<0.05), due to a smaller minimum angle (P<0.01), and the shoulder joint flexed more (P<0.05). The elbow joint extended more and for longer during the stance phase. Initial extension of the hip joint (P<0.05) and tarsus (P<0.001) lasted longer. The carpal and fore and hind fetlock joints recorded relatively longer hyperextension times, in addition to greater hyperextension during the stance phase. The results from the present study suggest that rider-effect must be taken in consideration when well gaited horses are selected for dressage purposes.

Abstract: REASONS FOR PERFORMING STUDY: Body composition is an essential factor in athletic performance of human sprinters and long distance runners. However, in horses, many questions remain concerning relationships between body composition and performance in the different equine activities. OBJECTIVES: To determine relationships between body composition, body score, physiological and locomotor variables in a population of young Standardbreds in training. METHODS: Twenty-four 2-year-old Standardbreds were studied, body condition on a scale 0-5 and bodyweight recorded, and height at withers measured. Percentage of fat (%F), fat mass (FM) and fat free mass (FFM) were estimated echographically. During a standardised exercise test on the track, velocity, heart rate, respiratory frequency and blood lactate concentrations were measured. V4 and V200 (velocity for a blood lactate concentration of 4 mmol/l and velocity of 200 beats/min) calculated. Basic gait variables were measured at 3 different speeds with an accelerometric device. RESULTS: Body composition variables: %F and FM were significantly related to body condition score and physiological variables. Body score was highly correlated to %F (r = 0.64) and FM (r = 0.71). V4 was negatively correlated to %F (r = -0.59) and FM (r = -0.60), P<0.05. V200 was also negatively related to %F and FM, (r = -0.39 and r = -0.37, respectively, P<0.1). No relationships were found between body composition and gait characteristics. CONCLUSIONS: Body composition was closely related to indirect measurements of aerobic capacity, which is a major factor of athletic performance in middle distance running horses. POTENTIAL RELEVANCE: As in human athletes, trainers should take special note to evaluate optimal bodyweight and body composition of race horses to optimise performance.

Abstract: Six horses, highly trained for dressage competition, were used to study the stride kinematics of the walk, and to compare the kinematics of the collected, medium, and extended walks. Horses were filmed in a sagittal plane at a rate of 150 frames/s; temporal, linear, and angular data were extracted from the films. Results of ANOVA and Duncan's multiple range test indicated that the speed of the collected walk (1.37 m/s) was significantly (P < 0.01) slower than that of the medium (1.73 m/s) and extended (1.82 m/s) walks, values for which were not significantly different from each other. The increase in speed was associated with a significant increase in stride length, from 157 cm in the collected walk to 193 cm in the extended walk. This was a result of an increase in the over-tracking distance, whereas there was no significant difference in the distance between lateral placements of the limbs. Stride duration decreased (P < 0.01) from the collected walk (1,159 ms) to the extended walk (1,064 ms). Angles of the metacarpal and metatarsal segments, measured on the palmar/ plantar aspect, were higher at impact and lower at lift off in the collected than in the extended walk (P < 0.01). This indicated greater range of angular motion of this segment during the stance phase in the extended walk. Only 1 of the 6 horses had a regular 4-beat rhythm of the footfalls, with equal time elapsing between the lateral and diagonal footfalls.

Abstract: The objectives were to compare the temporal characteristics of canter pirouette strides with collected canter strides in elite dressage horses, and to determine whether the stride kinematics of the canter pirouettes fulfilled the requirements specified in the Federation Equestre Internationale Rules for Dressage Events. Eleven horses were videotaped (60 fields/s) during the individual medal competition at the 1992 Olympic Games. Temporal variables were extracted from the videotapes using standard methods. Two strides were analysed on each of the left and right leads and these were pooled to give mean values for the collected canter and the pirouettes. The pirouettes were completed in 4-9 strides, (mean of 6.4). In the collected canter strides, mean duration of the suspension was 0.013 s. There was no suspension in any of the pirouette strides, instead the stance phases of the leading forelimb and trailing hindlimb overlapped by a mean of 0.163 s. In 9 horses the trailing forelimb contacted the ground before the diagonal leading hindlimb in the collected canter, whereas in the pirouettes the leading hindlimb always made contact before the trailing forelimb (mean dissociation 0.164 s), giving the strides a distinct 4 beat rhythm. Due to increases in advanced placement between the diagonal limb pair and between the 2 forelimbs, the stride duration was longer in the pirouette (0.879 s) than the collected canter (0.629 s). It is concluded that the canter pirouette strides did not maintain the rhythm and timing of the the collected canter strides in any of the 11 horses.

Abstract: REASONS FOR PERFORMING STUDY: As critical locomotion events (e.g. high-speed and impacts during racing, jump landing) may contribute to tendinopathies, in vivo recording of gaits kinematic and dynamic parameters is essential for 3D reconstruction and analysis. OBJECTIVE: To propose a 3D model of the forelimb and a ground reaction force recording shoe (GRF-S) for noninvasively quantifying tendon and ligament loads and strains. METHODS: Bony segments trajectories of forelimbs placed under a power press were recorded using triads of ultrasonic kinematic markers linked to the bones. Compression cycles (from 500-6000 N) were applied for different hoof orientations. Locations of tendon and ligament insertions were recorded with regard to the triads. The GRF-S recorded GRF over the hoof wall and used four 3-axis force sensors sandwiched between a support shoe and the shoe to be tested. RESULTS: Validation of the model by comparing calculated and measured superficial digital flexor tendon strains, and evaluation of the role of proximal interphalangeal joint in straight sesamoidean ligament and oblique sesamoidean ligament strains, were successfully achieved. Objective comparisons of the 3 components of GRF over the hoof for soft and hard grounds could be recorded, where the s.d. of GRF norm was more important on hard ground at walk and trot. CONCLUSIONS: Soft grounds (sand and rubber) dissipate energy by lowering GRF amplitude and diminish bounces and vibrations at impact. At comparable speed, stance phase was longer on soft sand ground. POTENTIAL RELEVANCE: The conjugate use of the GRF-S and the numerical model would help to quantify and analyse ground/shoe combination on comfort, propulsion efficiency or lameness recovery.