Rectus Abdominus

This week let's look at the Rectus Abdominus and take a break from the many muscles of the front end. Don't let the picture fool you, this muscle isn't THAT small and plays a BIG part in our horses' lives.
Name: Rectus Abdominus
Location: Originates in the chest and inserts at the 4th to 9th costal cartilages, runs the length of the belly, and attaches to the femur via the accessory ligament.
Role: Flexes the spine
Affected by: ill-fitting cinches, improper carriage while under saddle
Other info: This muscle is one of the key muscles that are involved with rounding the back and achieving collection. When this muscle is too contracted, the horse will have a roach back. It is also considered the main muscle for flexing the spine.
A good exercise to activate this muscle on your horse from the ground is belly lifts. To do this, use your fingers on the belly of the muscle, starting about where the girth would sit, and apply pressure up, running down the length of the muscle. A normal response from the horse would be to contract the rectus abdominus muscle and you will see the spine flex. Contracting the rectus abdominis results in them tilting their pelvis forward and down and flexing (rounding) the whole length of the spine, but especially the lumbosacral junction. If you had to pick one muscle that was most efficient at flexing the spine, this would be it.
A reminder that some horses are more sensitive to this and may react more then others!
If your horse doesn’t have much of a belly lift to speak of, there are ways of helping to strengthen the muscle. Regular belly lifts, exercises over poles/cavelleties, and riding up and down hills are all excellent to do routinely.
Having a strong rectus abdomnius muscle will make it way easier on your horse to collect and remain in a proper frame under saddle.
For those who may like some more reading, a fantastic article by Deb Bennett can be found below. The ‘ring of muscles’ outlined in the article are the key components to attaining collection in the horse. he rectus abdominus is one of these crucial muscles. Without these muscles in balance and being used effectively under saddle, there is no possible way for the horse to carry itself correctly.
http://www.equinestudies.org/.../ring_of_muscles_2008_pdf...