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| GAITS AND MOVEMENTS OF DRESSAGE HORSES The gaits performed in dressage competition are the walk, trot, canter, rein back, passage and piaffe. The walk, trot and canter each have several variations that differ in speed of progression. From slowest to fastest these are the collected, working, medium and extended gaits. Horses are supposed to maintain the same stride frequency (tempo) during the transitions between these gait types. In other words, they should change stride length independent of stride frequency. The Walk The walk is a four beat gait with a lateral footfall sequence: RH, RF, LH, LF. The footfalls should be evenly spaced in time, giving a regular, four-beat rhythm. The limb support sequences alternate between bipedal and tripedal supports (figure 6). The bipedal supports always consist of a forelimb and a hind limb, which may be a diagonal or a lateral pair. The tripedal supports may be two hind limb and one forelimb or two forelimbs and one hind limb. The Fédération Equestre Internationale (FEI) recognizes four types of walk: collected, medium, extended and free. (There is no working walk.) The free walk, in which the horse is allowed freedom to stretch the neck, is only performed in lower levels of competition. Speed of the medium and extended walks is significantly faster than that of the collected walk (table 1) as a result of a large increase in stride length and a small increase in stride rate. The differences between medium and extended walks are quite small. Table 1: Velocity, stride length and stride rate for the different types of walk.
Stride length in the walk can be considered as the sum of the lateral distance (distance between the hind hoof and the next placement of the ipsilateral fore hoof) plus the tracking distance (distance between the fore hoof and the next placement of the ipsilateral hind hoof). Changes in stride length at the walk are almost entirely due to adjustments in tracking distance. Lengthening of the stride is accompanied by a wider arc of limb rotation during the stance phase, which results in the angle between the cannon bone and the ground being more acute at ground contact and more obtuse at lift off in the extended walk than in the collected walk (Clayton, 1995). Although dressage horses are required to maintain a regular, four-beat rhythm in the walk, only a minority of horses achieve this. When the rhythm becomes irregular, the horses show either lateral couplets (lateral or pacing rhythm) in which there is a shorter time between the lateral footfalls or they show diagonal couplets (diagonal rhythm) in which there is a shorter time between the diagonal footfalls. Clayton (1995) found that a majority of national level dressage horses showed lateral couplets, with the same footfall pattern being present in all types of walk.
The half pirouette in collected walk is a half circle in which the forelimbs move around the hind quarters. The inside hind limb acts as a pivot point for the movement, but it continues to step in the rhythm of the walk strides. In a study at the Atlanta Olympics (Hodson et al. 1999), the majority (8/11) horses completed the half pirouette in three strides, the remaining horses used four strides. This is consistent with the FEI rules, which stipulate three to four strides in a half pirouette. None of the horses maintained a regular four-beat rhythm in the walk pirouette. Instead, the footfall of the inside hind limb occurred relatively early in the stride. Consequently, the time between footfalls of the outside fore and inside hind hooves was short, while the time between footfalls of the inside hind and inside fore hooves was long. This indicates that, to compensate for the lack of forward movement, the horses become more reliant on the inside hind limb to maintain their balance. The Trot The trot is a two beat gait in which the diagonal pairs of limbs move more or less synchronously, and the footfalls of the diagonal limb pairs are evenly spaced in time. The diagonal support phases are usually separated by periods of suspension, except in a very slow (jog) trot. Therefore, each stride has two diagonal support phases and two suspensions. Slow motion analysis has shown a slight dissociation between ground contact and lift off of the diagonal fore and hind limbs. The interval between the fore and hind contacts is known as the diagonal advanced placement. The value is positive if the hind limb contacts the ground before the forelimb, zero if the diagonal pair contact the ground simultaneously, and negative if the hind limb contacts the ground after the forelimb. Positive diagonal advanced placement is considered a desirable characteristic that is indicative of good balance (Holmström et al. 1995). It occurs in horses that travel with an elevated forehand, which is a characteristic of collection. However, a negative diagonal advanced placement does not preclude a horse from being successful in dressage. In the Seoul Olympics, 15% of the extended trot strides that were analyzed had a negative diagonal advanced placement (Deuel and Park, 1990). Four types of trot are performed in competition: collected, working, medium and extended (Table 2). Speed and stride length differ significantly between each type of trot, and stride frequency is significantly slower in collected than extended trot (Clayton 1994a). Deuel and Park (1990) have shown a positive relationship between speed and stride length and a negative relationship between speed and stride duration in a group of top level competitors. Interestingly, dressage horses that qualified for the individual medal finals in the Seoul Olympics tended to have higher speeds, longer stride lengths and higher stride frequencies in the extended trot than horses that failed to qualify (Deuel and Park, 1990). Table 2: Velocity, stride length and stride rate for the different types of trot.
The ground reaction forces in passage resemble those of the collected trot (Clayton, unpublished data). The forelimbs have a higher peak vertical force than the hind limbs. The longitudinal GRF is almost entirely retardingin the forelimbs, and almost entirely propulsive in the hind limbs. The forelimbs elevate the forehand, while the hind limbs provide forward and upward propulsion (figure 9).
Piaffe (or piaffer) has the same stride rate as passage but the movement is performed almost in place, so the stride length is very short. Horses maintain their balance in the absence of forward movement by increasing the durations of the stance phases and the overlaps. There is always at least one hoof in contact with the ground, so piaffe has no suspension (airborne) phase. Therefore, piaffe is a stepping gait, rather than a leaping gait, with a gradual transfer of body weight from one diagonal to the other. However, the amount of overlap between successive diagonal stance phases is shorter in the better quality piaffe (Clayton 1997). As in passage, the limbs pause momentarily at their most elevated position in the swing phase. Each horse performs somewhat differently with its own individual coordination pattern and, although the mean value of the diagonal advanced placement for piaffe in a group of horses was negative (Argue 1994; Holmström et al. 1994), the best competitive horses have a positive diagonal advanced placement (Clayton, 1997).
The canter is the only asymmetrical gait of dressage horses. It has a transverse sequence of limb placements, so the leading fore and hind limbs are on the same side of the body. Four types of canter are performed in dressage competitions: collected, working, medium and extended, which have significantly different speeds (Clayton 1994b). The stride frequency is the same for the different types of canter, so changes in speed are accomplished by alterations in stride length (table 3). Stride length increases as a result of a small increase in the distance between the two hind limbs, a small increase in the distance between the two forelimbs, and a large increase in the distance covered during the suspension. The ability to generate a high vertical velocity at the start of the suspension allows the horse to stay airborne longer and to cover a greater distance during the suspension. Table 3: Velocity, stride length and stride rate for the different types of canter.
During the lead changes, all four limbs have long stance durations and short swing durations, and there is a diagonal dissociation with contact of the leading hind hoof preceding that of the trailing fore hoof. In the two tempi changes (Deuel and Park, 1990), the stride immediately preceding the change (pre-change stride) has a slower speed, shorter stride length and higher stride frequency than the stride following the change (post-change stride). The shorter stride length of the pre-change stride is a result of taking a shorter step between the two forelimbs and covering less distance during the suspension. In pre-change strides ground contact of the trailing forelimb precedes that of the leading hind limb, whereas in the post-change strides the sequence is reversed. In the one tempi lead changes, the strides share characteristics of both the pre- and post-change strides in the two tempi changes. The support sequence varies between horses, reflecting individual differences in technique, but the diagonal dissociation almost always involves placing the leading hind limb before the trailing forelimb. There is a pronounced reliance on overlap between the two hind limbs in the early part of the stride, which is similar to the post-change stride for the two tempi changes. Later in the stride there is a reliance on forelimb overlap (Deuel and Park, 1990).
In the canter pirouette, horses are supposed to maintain the tempo and rhythm of the collected canter strides. However, a study of horses competing in the individual medal finals at the Barcelona Olympics showed that the tempo is significantly slower in the pirouette strides (68 strides/min) than in the collected canter strides (95 strides/min). The footfalls of the diagonal limb pair are dissociated in the pirouette strides giving a distinct four-beat rhythm, in contrast to the three beat rhythm of the canter strides. Also, there is no suspension between successive pirouette strides (Burns and Clayton, 1997). The lack of forward movement in the pirouette makes it difficult for the horse to maintain its balance. The horse compensates by increasing the limb stance durations and the overlaps between limbs. This is particularly obvious for the inside hind limb in which the stance duration is greatly prolonged as a means of maintaining the horse’s balance in the absence of forward movement (Burns and Clayton, 1997).
Argue CK (1994) The Kinematics of Piaffe, Passage and Collected
Trot of Dressage Horses. PhD Thesis, University of Saskatchewan,
Saskatoon.
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