Leg Yielding & Shoulder-in
Leg yielding is controversial because its biomechanics are often not understood. It is a straightening exercise that is extraordinarily difficult to ride because:
a) it involves accurate, precise positioning of a horse, so
b) a rider must know exactly what degree of performance of the movement is appropriate to ask for in terms of a horse's stage of development,
c) its objectives are to straighten a horse while enhancing obedience to inside leg-outside rein connection,
d) most of the time it is ridden as shoulder-fore on a diagonal line, and
e) its object is confused by tests which ask it to be ridden such that there is marked crossing of fore and hind legs.
Just so a reader knows where I stand on this movement (author opinion!):
Leg yielding is a schooling movement and might not appropriate for tests for practical reasons. Its technical demands usually overface some riders who are just learning to ride USA First Level. It appears to be deceptively simple, but producing the slight horizontal movement of the skull (translation) at and ONLY at the junction of the skull and first cervical vertebra, demands expert tact from a rider. Riders just learning the movement or other later work lock the inside hip to push the horse away from the inside leg. This has the regrettable effect of producing stiffness in the horse. Solution: aids for later work are given in relaxation and follow the coordination of a specific gait.
There are important connections between leg yielding and range of motion exercises. Riding with leg aids reversed, as some people advocate, disconnects the exercise from other exercises in a horse's gymnastic schooling. Furthermore, leg yield cannot be ridden with reversed aids in walk, trot and canter (it would produce a premature flying change). Reversed aids also make it impossible to assist a horse achieve a canter transition by leg yielding from the quarterline to the long side in walk or trot, then entering canter upon reaching the long side. In this case it helps a green horse connect securely to an inside leg in a canter strike-off.
Riding a leg yield with aids reversed from shoulder-in disconnects it from all sorts of useful suppling exercises. Either way will produce a leg yield, but inside leg at the girth is the standard or default position in the rest of the dressage "school" so I choose this method. Horses are not confused by exact rein and leg aids which adjust alignment: riders might be mixed up, if they do not get clear explanations of the biomechanics and objectives of an exercise.
|Leg Yield Right (A)
Poll (1) and pelvis (5) are shifted left slightly horizontally (translated). The small amount of position has a large effect on the whole horse. Movement in the pelvis also moves the lumbar spine and sacrum (fused vertebrae, 6). Unless there is a bend in the ribcage (thoracic spine) area (3), the lumbar vertebrae (4) move as a unit with the sacrum (6) and pelvis (5). Bend in the ribcage means that the right side (outside) is stretched and the left side is compressed.
|Slight translation of the poll for either leg yield or shoulder-in enables the roll of the ribcage between the shoulder blades (2), which frees the forelegs to cross as the horse moves sideways and forward. For shoulder-in, that slight horizontal motion of the skull at the first cervical vertebra results in relaxation of the top and bottom line of connections through the whole horse.
Ovals indicate seat bone positions: the slightly weighted one is indicated by R (right). Large gray arrow indicates direction of movement.
|Shoulder-in on three tracks (C, C') and on four tracks (D, D') involve both bending and axial rotation of rib cage and pelvis in medium walk.
Dupaty de Clam disagreed with La Guérinière on the effects of this exercise on suppling the shoulders, instead advocating an exercise on a circular track with a head to the outside leg yield position.
The bend in the rib cage involves relaxation of the outside musculature and a holding of the inside musculature. The moments in the photos C' and D' are different times in a walk stride. As a result, the degree of bend that shows in the rib cage is reduced in C' and maximized in D'.
Shoulder-in in hand, 3 tracks (C') and 4 tracks (D') on a very cold winter day. The view from the front shows bend in the rib cage and straight ahead tracking of hindquarters, indicated by the front view of hind hoofs. Relaxation in the exercise is indicated by the soft outside rein and translated position of horse's head. (Raynyday Maximillian and the author; Dr. Ruth M. Vale, photographer)
Lateral work may be performed in walk and trot. Leg yield in canter is a severe exercise: its obedience effects can probably be met by exercises in counter canter. In shoulder-in, the position in canter (usually shoulder-fore) is demanding and is a preparation for cadencing the gait.