What creates "Top-Line" Musculature?

Core stability has been shown to be vital in all horses, especially the ridden horse. This model highlights how core stability is gained and improved; through the use and engagement of the abdominal musculature and ‘top line’ musculature. When the abdominal musculature is recruited and contracts, it allows the flexion and extension of the thoracolumbar spine – this creates the flexion of the bow seen in the model above.

The improvement in top-line musculature is often mistakenly thought to come about through lowering the horse's head, but this actually comes about through the engagement of the core. This creates lift through the back and freedom of movement in the limbs. It is less about the position of the head and more about the correct musculature being used. The development of top-line muscles is vital in carrying a rider, as these muscles will help support the rider's weight, and saddle, without the horse falling on the forehand allowing it to move correctly.

There are some aspects that can predispose a horse to have poor top-line musculature and core engagement. If the animal has a lordotic or sway back spinal posture then asking them to lift through the back is even more difficult, but equally as important as it will further the likelihood of other issues later in the animal's life such as kissing spines and neck pathologies. Animals that carry an exaggerated high head position often develop ewe neck with overdeveloped ventral neck musculature. This muscle development is often seen in racehorses, due to the encouragement to gallop with a higher head position to allow them to intake as much air as possible while still moving at top speeds.

Exercises can be completed to help improve core engagement to follow the bow and string theory. This includes long reining and in-hand walking. These help improve correct gait motions, proprioception, and encourage a forward movement from the hindlimbs through the body. A second exercise that can be used is pole work, this should be used slowly and only when the animal can confidently and safely complete the exercise. This encourages the horse to lower the head and lift through the back to navigate the poles. Poles also encourage interlimb co-ordination and engagement of both pelvic stabiliser but also lumbosacral stabiliser to improve core strength.