The Thoracic Sling

The thoracic sling is something of a hot topic in riding right now. But what is it? Why is it even important?

The thoracic sling is one element of “good posture” in a horse, much like having our chest open is an element of good posture in humans. The front limb of the horse is not held to the rest of the body by a bony connection; it is completely connected with soft tissue (muscles and ligaments). This soft tissue that connects the front (thoracic) limb to the ribcage is called the thoracic sling. Because of this soft connection, there’s quite a bit of movement that can happen, which is good. The horse’s shoulder blade (scapula) can move quite a bit along the ribcage, and the ribcage can move up and down within the two front limbs. However, when the ribcage moves down, the scapulas don’t have as much room to move. The scapula can also get limited by an ill-fitting saddle, which also can impinge on the muscles that also help the thoracic sling lift the ribcage.

In dressage, we talk a lot about the horse moving “uphill.” This feeling comes from the thoracic sling engaging and from the pelvis tucking, bringing the hind limbs more “under” the horse and allowing the shoulders to move more freely. This frees the horse to have a bigger gait for extended gaits, and it allows the horse to move in collection more easily, as the front legs are out of the way. The back can then arch up and into the rider’s seat. The demands for this work starts at 2nd level, which is pretty early in dressage training.

However, in other disciplines, it’s not always considered as big of a deal. In hunter/jumper, it’s talked about some with flatwork, but it’s not emphasized. In western work, we don’t hear much about it at all outside biomechanics-focused circles.

So why should it matter if the horse engages its thoracic sling and lets the hind quarters under and arches the back? If we compare western reining and dressage, what’s the difference, and why should it matter?

Well, this is why we need to look at history. Dressage came out of necessity for battle. Good warhorses were expensive to buy, train, and maintain, and they didn’t have joint injections and all the medicines we have now. Knights and horsemasters learned pretty quickly through necessity what helped their horse work better and stay working longer. They may not have been able to explain it like we can, but let’s face it: they had better knowledge of horse anatomy than they did of human (because, well, they ate horses that didn’t work out… necessity meant they couldn’t afford to keep a “pasture puff”). So, they learned that getting their horses to build up their hindquarters, backs, and thoracic sling meant they were more agile and could work more comfortably longer, even into their 20s.

Why is this? Basically, it’s because horses aren’t meant to carry a weight on their backs. Structurally, their backs are not the strongest for what we ask. Gravity pulls down on them, and they only have 1-2 degrees of available movement per joint in the thoracic spine (the part that we sit on). The lumbar spine (the part behind the saddle) has no available movement until we get to the lumbo-sacral joint, which has a lot, but then the sacral spine (between the two big “hip bones”) is also fused. So, if we start pulling down on the thoracic spine, it starts having problems, and we get problems in the lumbosacral joint as well (ever seen a “hunter’s bump”? It usually comes from poor movement/compensation patterns). There’s a lot of other connective tissue involved that means the legs get into an unhealthy movement pattern, and they break down too (stifle problems, chronic suspensory injuries, etc.). Ask different disciplines at what age do they retire their horses, and you’ll hear a lot of young ages (15, 8, even younger in some circles). Some may just reduce the work load, such as semi-retiring the horse to become a beginner’s or child’s mount, but basically, the horse is broken down. We can start them earlier to get more time, or perhaps we look at helping them use their bodies in such a way that reduces the amount of stress on the joints.

Why don’t all disciplines do this then? Well, it’s complicated. Western work doesn’t in most cases because there’s an advantage to dropping the thoracic sling when working cattle: it brings the horse closer to cattle. Vaquero horses and bullfighters, the ancestors of modern western riding, strategically drop their thoracic sling when working cattle and then pick it back up again. However, the history of American ranch work has another influence. Ranch workers in the American West had to work cattle in rough conditions (and still do), and horses were a little easier to come by. So, they started horses younger and faster and didn’t take the time to develop that posture in their horses because they didn’t have the time, unlike their Iberian ancestors. As a result, most western horses stay down in their ribcage. That’s why western collection looks a lot different from dressage collection; it’s biomechanically different (slower, smaller steps instead of bouncier, higher steps). Now, in some sorting/penning circles and in Vaquero circles, they’re emphasizing the thoracic sling more because using it and then strategically dropping it is healthier for the horse and provides more agility and more effective work.

In hunter/jumpers, it’s not as emphasized because of the history coming from foxhunting. More of the horses were thoroughbreds, often former/failed racehorses, and the emphasis was more or less on fun and socializing. The horses didn’t need a lot of training to go from racing, especially from steeplechase, to go to foxhunting. The modern sport descendent didn’t add that thoracic sling training back in enormously. So, it’s not as emphasized most of the time. However, there are quite a few more successful hunter/jumper trainers who emphasize it for better agility between fences and for a stronger, more elegant topline for hunters. Eventers are on some spectrum between dressage and h/j, depending on level of competition (Olympic eventers sometimes have more biomechanically sound dressage than most dressage riders…), thanks to their dressage ancestry through military riding (the ancestor of eventing)

However, no matter the discipline, it’s never a mistake to develop the thoracic sling and other postural muscles for a healthy back. I’ve ridden a few hunters that are “stuck” in their withers, and they ride a bit like a box truck. They’re stiff, tricky to steer, and while they go over fences like a dream, they’re not easy to just “ride.” A horse that is developed, even at a fairly low extent, it so much easier to turn and can be more comfortable to jump, as they have more of a shock-absorbing apparatus built into their front end for landing from a jump. That’s why the best jumpers have been schooled mostly in “flatwork” (dressage, really). For western disciplines, it’s also great for helping the horse work cattle, as mentioned earlier, and it can keep those amazing powerhouse quarter horses healthier longer in their work (those sweet, often quite straightforward to ride horses get dissed so much in dressage, but they often have such a great “can-do” personality, which makes them amazing workhorses).

I can’t forget about the gaited horses (an often-forgotten segment in the horse world, but something of a passion of mine). The history of gaited horses comes from the Dark and Middle Ages, where they were used for long distance riding getting from one place to another comfortably (it’s been more recently realized, there was a lot of travel during those ages). In the US, gaited horses were used for the same thing, but now have been relegated more to “pleasure” riding, such as trail riding and saddle-seat. The bare bones necessity element in gaited horses meant a lot of people didn’t historically train much for back strength, and that’s come through in today’s riding. However, it’s great for those horses as well; their gaits sometimes clean up if they struggle to get a clean gait, and those who have good gaits develop more expressive gaits and are more agile (which can come in handy if things get a bit out of hand in the show ring).

Endurance isn’t even an exception, though things are a bit different. For humans, it’s not reasonable to keep the core engaged on a marathon run. The same goes for the horse, but it is healthy to “check in” and engage the horse’s thoracic sling and other back/hindquarter muscles periodically on an endurance ride, and it’s important to train it in the arena between endurance rides. I’ve known endurance riders who schooled dressage regularly for their horse’s health. Interestingly, however, there’s a lot of historical evidence of training dressage horses for distances, and I remember a conversation with Karl Mikolka (former SRS Chief Rider) who said he remembered schooling a young stallion over 6 miles routinely in one training session in the arena (which translates to 60 rotations around the arena! Or, if he were still living, he’d ask how many strides that is, which would be 3960 strides for the average 66-strides-in-a-mile horse…). So, classically, there’s a fair amount of endurance work in regular dressage training, so it’s fair to mix the two up! In fact, as a teen, one of my fellow group lesson students rode endurance on her 27-year old Arabian, yet she rode twice a week religiously in a group lesson with our classical dressage trainer, and that horse was super muscled (he did not look his age at all…). So, I can’t think of a better example than that for developing a horse’s thoracic sling and other muscles for endurance.

So, no matter the discipline, it’s great to engage the thoracic sling and other muscles that work with it to help the horse’s back resist gravity and stay healthier longer. It’s an amazing feeling when the horse does, as it suddenly feels like it’s floating on air and can do anything with its body (even the horse loves the feeling, even if they can’t always hold it for long in the beginning). Luckily, there are a lot of exercises, both on the ground and under saddle that can help it find how to use these muscles and keep their body healthy. The exercises on the ground entail getting the back to lift, such as by pushing up on the sternum (under the girth area) to lift the whole ribcage. Under saddle, there are dozens if not hundreds of exercises that help the horse find it. These exercises are “dressage.” Remember: “dressage” just is a foreign word for “training.” That’s it. I’d like to take it further that this “training” is just good basic postural training with a lot of movements that help it as well as show it off, sort of like Pilates for horses. Every horse can benefit from it. So give it a try and see how it can help your horse! You won’t regret it, no matter your discipline.

-Emily Wright