Shoulder-in is a useful ‘straightening’ exercise for the horse’s quarters and back – it is classed as a lateral movement because the inside foreleg crosses over the outside foreleg. This exercise is a three track movement – the outside hind leg has its own track, the outside fore and the inside hind have their own ‘dual’ track, and the inside fore has its own track.
If you are riding a shoulder-in on the right rein, your right side is the inside. The horse’s forehand will be at an angle of around 30 degrees from the side of the arena and the horse will be looking to the inside.
In shoulder-in, the horse must be attentive and bending around the rider’s inside leg. Circles are excellent exercises to develop bend and ensure the horse is moving off the leg – ride circles of different sizes and on both reins, before performing a shoulder-in. Coming directly off a circle into the movement helps an inexperienced horse maintain the bend. The pace should be active yet steady. Make sure you have ‘throughness’ in the back; ie the horse should be balanced and rhythmical with his quarters engaged. He should be in a relaxed, soft outline.
Setting up the movement
In the early stages of learning, the movement is often ridden down the long side of the school using a wall or fence as a guideline. Use the preceding turn to help you prepare for the movement and maintain an inside bend, putting slightly more weight on your inside seat bone to free up the horse’s outside shoulder. The outside fore leg leads the movement and extends forward, while the inside fore crosses it.
As you are asking for the movement it also helps to very slightly turn your hips and shoulders to the inside – by mimicking the movement of the horse’s body in a shoulder-in, he will find it easier to carry the rider. Carry the hands and ask for inside flexion – maintain an inside bend!
The diagram below may be crude! But hopefully it helps us understand what is meant by ‘3 tracks’ – the outside hind leg has its own track, the outside fore and the inside hind have their own ‘dual’ track, and the inside fore has its own track. The arrows below show the direction of movement.
Riding a shoulder-in
Gently ‘sponge’ the inside rein and apply your inside leg at the girth. This leg asks the horse to step forward and cross his inside fore over the outside fore – the hindlegs do not cross. Make sure your outside hand is supportive, maintaining a firm and even contact to stop the horse falling in at the inside shoulder or simply turning his body, as if he were on a circle. The rider’s outside leg is slightly behind the girth to prevent the quarters swinging out. Look up and try not to drop your hip or shoulder to the inside – this may unbalance the horse and cause him to lean on the inside rein or come off the ‘line’.
Remember that the forehand leads – the quarters don’t swing out to the outside. If the horse is initially confused, opening and slightly lifting the inside hand will guide the horse’s forehand to the inside. Practice the movement on both reins.