Dogs have a great capacity for assisting their human counterparts in their daily lives and are very excited and willing to perform these tasks. This assistance can be in many forms, which include, but are not limited to, physical assistance dogs, guide dogs, detection dogs, military and police dogs, search and rescue dogs and hunting dogs.
In the human world, there has been a great deal of research in developing programs to prepare the human for their activity as well as occupational studies designed to create optimal work environments and safe working conditions. Related to the dog, performance related factors can be organized into three general categories, Physical, Physiological, and Psychological (The 3P’s).
Many studies have been performed in dogs looking at the behavioral and mental components of canine performance. Other studies have been performed to better understand the metabolic or physiologic factors related to the canine athlete and to a lesser extent the working dog. Some basic biomechanical studies have been done to assess the structural dynamics of canine movement in relation to canine sports but minimal have been done to assess this related to the daily activities of those dogs who work with us on a daily basis.
The body can be divided into segments which allows for a mechanistic approach to evaluating and understanding movement and locomotion. How these segments or components work together or interact to create movement can provide the information needed to optimize these functions. Optimizing the components of movement will lead to improved function and a decrease in structural breakdown. This results in a positive activity experience and a long healthy career.
The neuromusculoskeletal system of the dog acts much like the humans except their posture typically has all four legs on the ground instead of two. So, although the nerves, bones and muscles are functioning the same in both species, the forces are applied differently. In general nerves stimulate muscles to move bones around the joints. In dogs there is a great deal of knowledge related to activity and functions of the nerves, bones and joints. There is an abundance of literature on the cellular physiology of muscles, but a lesser amount is known about the physical actions of muscles in relation to locomotion and movement. Since the muscles are the movement generators, it is important to have an understanding of how this occurs.
Walking and running are two of many types of locomotion described in the dog. Locomotion is described as the movements of the body that allows it to get from one location to another. The body is made of components or segments, so it is the sum of the segmental movements that produce locomotion. The legs are the main structures creating locomotion and it is the muscles that work together to create the related movements. How they work together to create fluid movement is a learned effort that begins at birth and continues throughout the dog’s lifetime. Muscle training and muscle memory are two key components to developing a conditioning program for a dog or creating a post-injury rehabilitation program. Therefore it is important to have a good understanding of how the muscles work and which muscles are used in locomotion.
Each leg will go through a step cycle. Therefore a biped (human) will have two step cycles, a quadruped (dog) will have four step cycles and centipede would have 100 step cycles. It is typically defined as the actions the leg goes through from one point in the cycle until the leg again reaches that point of the cycle. It is generally defined as the leg actions that occur starting at the first touchdown of the paw until that paw again touches down. There is a complex interaction of muscles that allows for smooth fluid movement.
There are primary muscle actions, synergistic muscle actions and related antagonistic muscles working together in various levels that create the movement of the leg throughout the phases of the step cycle. Studies have used electromyography to identify which muscles are active and when at various points in the step cycle. Understanding the muscle activity of locomotion is important when diagnosing lameness, developing a conditioning program or creating a rehabilitation protocol. When a joint is inflamed or osteoarthritis is present, it changes how the legs move, thus affecting the related muscular actions. Neural inflammation (i.e. Lumbosacral Disease, etc) will also affect how the muscles move the leg. In these scenarios, the primary problem should be addressed but so should the secondary muscle inflammation, the related trigger points and fascial issues. Having a sound understanding of the muscular actions in locomotion should help the practitioner prepare the proper therapeutic design.
Author: Robert Gillette