Healthy muscles play a key role in reducing the wear and tear on joints, tendons, ligaments and other important structures in the horse’s body. Tight, sore or underdeveloped muscles can limit a horse’s ability to move as they were designed, predisposing them to injury over time.
Here’s a closer look at some of the ways your horse’s muscle work to fulfill their important role.
1. JOINT STABILIZATION
All movement is initiated by muscular contraction, but it is the larger muscles that are primarily responsible for this task. Below these muscles are smaller more specialized muscles that take care of fine-tuned adjustment. Unlike some of the larger muscles which may cross multiple joints, these finer muscles typically span only one joint and have more specific actions – a key one being stabilization of the joint in question.
Not only do these stabilizing muscles lie in closer proximity to the joints, they are also almost always more richly innervated. Where as the bigger muscle groups like the gluteals, quadriceps and hamstrings might have one motor neuron responsible for activating a group of 1000 muscle fibres, the smaller specialized muscles will have about one motor neuron per 20-30 muscle fibres (and sometimes less).
The proximity of these muscles to the joints and the range of ways they can respond to achieve fine-tuned coordination are features that make them especially important in protecting and stabilizing the joints during locomotion and athletic activity.
Research has indicated that inflammation and injury can adversely affect the function of these muscles, even after the original injury has healed. Fortunately targeted exercises can be used to help activate and strengthen them during the rehabilitation process, helping to ensure a complete recovery.
Proprioception is the sense of knowing where the body and limbs are in space. Throughout the body there are specialized nerve receptors that relay information back to the central nervous system giving us this kinesthetic sense. These receptors are found in many of the connective tissues including the ligaments, joint capsules and muscles.
Muscles have two specialized types of sensory receptors – golgi tendon organs and muscle spindles. The golgi tendon organs provide information about changes in muscle tension and are located where the muscle fibres extend into the tendons that attach muscle to bone. When the muscle contracts there is an increased pulling force on the tendon which activates the golgi tendon organs.
Muscle spindles monitor the degree of stretch in a muscle. These receptors are found throughout the muscle belly and are arranged in parallel with the muscle fibres. When the muscle is stretched or lengthened the spindles are activated.
This information is an important part of the ongoing conversation between the muscles and the brain during movement and athletic effort. It helps ensure safe movement and appropriate muscular responses to say, for example, stepping in a deep spot of footing. Fatigue and acute or chronic inflammation can hinder the accurate functioning of these key sensory receptors, underling the importance of appropriate athletic conditioning and proactive care with respect to muscular health.