Supporters Vs Movers

Everyone knows how we (and our furry friends) move, right? Muscles pull on joints causing them to move and allowing our pets to walk, run, jump, kick, pounce, play and roll on their back for tummy scratches. But that is only the story that we can see playing out. The muscles that cause movement are big and bulky and all that running, jumping, kicking and pouncing builds up these muscles further. This makes them easy to see and feel. When your pet runs or plays with you you can see and feel those big muscles doing their job. These big, bulky muscles are the 'movers' and they are super important when getting from A to B.

However, there is a whole other story being played out in the background that we don't see.

We (humans, dogs, goats, horses, cats and bats) all have a second group of muscles which are the unsung hero's. These muscles are the the 'supporters'. Often they are not big and bulky so we don't notice if they decrease in size and many are hidden away underneath the the movers. While the mover muscles help you get from A to B, the supporters help you stay standing up when you get there.

This means that your precious pet could be running (or flying) around with no support. And like any structure that loses its support it runs the risk that a big shake can result in everything falling in a broken heap. While we do want to build the strength of these 'movers' for dog sports, we also want to do this safely, which means we first need to ensure the 'supporters' are doing their job to prevent injury and protect joints. So when you are exercising your pet, you need to make sure that you do exercises to build 'supporters' as well as 'movers'.

While we do want to build the strength of these 'movers' for dog sports, we want to do this safely, which means we first need to ensure the 'supporters' are doing their job to prevent injury and protect joints. 

We bias these supporting muscles by using unstable surfaces such as wobble discs and foam blocks and work at the limit of the dogs ability to use these muscles. We know we are at this limit when they maintain a correct topline and have very fine muscle contractions to maintain their balance. If you see large movements and the dog wobbling around and moving lots then you are actually working the 'movers' rather than 'supporters' defeating the point of the exercise.

Lets look at the canine shoulder and identify some of the different muscles involved in keeping the humerus (upper arm) firmly against the scapular (shoulder blade).

The supporters in this equation are the muscles that spread across the scapular and attach close to the joint on the humerus. You may have heard of rotator cuff muscles in people- dogs have exactly the same muscles that do a very similar function. 

Here is a model of the canine shoulder bones. The ‘supporters’ aka rotator cuff muscles in purple cover the entire flat surface of the scapula and join to the top of the humerus at the head.  They contract in patterns depending on the angle of the joint and how much force is moving through the shoulder to keep the humerus pressed firmly up against the scapular.

The ‘mover’ in this diagram is the triceps which originates on the scapular and inserts on the ulnar (the funny bone).  I have just drawn in the supporters on the outside of the scapular and Triceps to keep the picture easy to understand.

The two Red lines show what happens with the ligaments and joint capsule that join the scapular and humerus together. When standing the ligament at the back is stretched, and the front ligament is loose. If it were also tight it wouldn't be possible for the joint to flex because the ligament would be too short.

This is what it looks like when the supporters are working correctly when the triceps shortens during shoulder flexion. The humerus stays in firmly in contact with the scapular and the forces are safely transmitted between the limb and the body. The front joint capsule (red) is now stretched and the back is relaxed.

This diagram shows what would happen if we only have the joint capsule and ligaments holding the scapular in place. The humerus loses contact with the scapular and slide around which can lead to arthritis and joint pain. Both sides of the joint capsule are taut and there is a great deal of stretch placed on both ligaments as they attempt to keep the joint together.

Now if we look at what happens when we have no support around the shoulder joint at all. When the the humerus has nothing keeping it attached to the scapular and it moves forward and completely disconnects from the scapular. As you can imagine the forces are not going to be able to move at all between the limb and the body. You are going to have a completely lame and unhappy dog. 

So these examples show how important it is to have these supporting muscles working at full capacity. Supporting muscles surround every joint in the body- every vertebra, in the wrist and feet. If the 'supporters' are injured or weak the ‘movers’ will try and take over the task of supporting joint - but  the only way they can do this is by trying to not move the joint! Of course this just means they also stop moving the limb correctly and will cause further problems with forces moving through the body. 

Dr Jaime Jackson