Muscle Activity
Muscles are the forgotten tissue of the neuromusculoskletal system. Most all canine performance is reliant upon muscle activity. Even canine detection needs the dog to move for it to perform its detective activities. It is estimated that 99% of the dog’s muscles are used during locomotion. Since locomotion is a key component of canine performance, muscles play a very important role. Although muscle activity is a major factor in locomotion and related performance, there is minimal information available to owners, handlers and trainers on canine muscle metabolism, function and management. Most available information is on bones, joints, neurological diseases and nutrition.Types of Muscle
There are three basic types of muscles in the body: cardiac, smooth and skeletal. Skeletal muscles move bones and other structures. Dog skeletal muscle varies from other species which results in different metabolic processes. It has 70% more mitochondria than man and it is conveniently placed around the muscle cells. This allows for the dog to have a greater capacity for endurance events, especially with proper conditioning.Normal vs Abnormal Functioning
The state of the muscular system can be wide-ranging. To begin with there is a normally functioning system versus an abnormal system. In this case, an abnormal system is one that does not function properly under normal scenarios. A healthy normal functioning system can be physiologically conditioned or unconditioned. This is when a normal dog is in shape versus out of shape.Muscular State
Muscular state can also be defined within the system. Select muscles can be painful or inflamed. This can be a chronic situation or acute in relation to daily activity. An example is pain of the back muscles (something we humans can relate). There are situations where they are sore throughout the day. Other times they are sore after a certain type of workout. Muscles can be tight or have spasm-like scenarios called trigger points. Many of these situations are not expressed or articulated by the dog but may exhibit themselves by some varied movement during performance.
Muscle Injuries
Muscles can also be injured. Muscle injuries are called strains and are usually graded from 1 – 3. A Grade I is mild damage to individual muscle fibers, Grade II is a moderate strain where multiple fibers are torn and a Grade III muscle strain involves tears of the muscle tissue itself. Some grading systems are from 1-4 with the lowest grade being muscle cell disruption. Usually dogs will exhibit some form of altered locomotion and there may be some associated swelling. Severe muscle strains will always present with swelling. All of these altered states are commonly seen on dogs but some of them are not recognized.
3 Muscle Groups that can impede performance
Below are thermographic images showing heat emitted by muscles. Muscle issues can be overlooked when related to canine performance. Common muscle groups that can impede performance are 1. the epaxial paravertebral muscles of the lower back, 2. the digital muscle groups of the front leg and 3. the digital muscle groups of the rear leg. They will each present with different performance signs and are not always significant but they should not be overlooked. 
