A trigger point is often described as a painful nodule found in a taut band of muscle. Trigger points can often refer pain elsewhere, limit range of motion, cause painful movement, and make a muscle weaker.
It all starts with electrical impulses and chemicals reactions. A muscle contracts when it receives a message from a nerve, via electrical impulses. This neurological transmission starts in the brain, and makes it way down a nerve until it reaches a receptor called the motor end plate. when stimulated, by the neurological impulse, the motor end plate releases a chemical called acetylcholine. This chemical travels to the muscle cell, and causes the cell to release calcium. Calcium causes the muscle fibers to contract. In a normally functioning neuromuscular unit, when the muscle contraction is no longer needed, the motor end plate stops releasing acetylcholine, and the muscle cell reabsorbs the calcium, which causes the muscle to relax it’s contraction.
If trauma occurs, like overloading of the muscle, or there is an significant increase in acetylcholine released by the motor end plate there will be an excessive amount of calcium released by the muscles cell. This will cause a very strong contraction in the muscle fibers that are affected. This strong contraction causes a decrease in circulation getting to the affected tissues. If there is a lack of circulation getting to the contracted muscle fibers, the muscle cells do not get enough oxygen and nutrients that are necessary for them to reabsorb the calcium. The result is muscle fibers that are chronically stuck in contraction, with a decrease in healthy circulation. This is what causes the taut band in the affected muscle, and the hyper irritable spot, aka trigger point, is the location of the dysfunction. Because this dysfunction causes a cycle of muscle contraction, leading to decrease circulation, leading to more muscle contraction, the trigger point, and pain will not go away on its own. Intervention, such as massage therapy and stretching is needed to break the cycle by increasing circulation and releasing adherences between muscle fibers.
Understanding The Different Types of Muscular Overload that cause trigger points
Muscular overload comes in several different flavors, some are obvious, while others are a bit more elusive. Let’s take a closer look at each type of muscular overload:
- Exertion Overload: This is the most obvious form of muscular overload and simply means that a muscle was not strong enough to perform a task required of it. For example, bending at the waist to lift a heavy object is likely to create an exertion overload in the low back muscles. Trigger point activity resulting from this type of overload is more prominent in unconditioned muscles. People who partake in resistance training (lifting weights) are likely to develop exertion related trigger points when the just begin training, or return to it after a long hiatus. Most of the time, this type of overload occurs in a sudden fall, when a person tries to brace against an impact.
- Overuse or Repetitive Stress Overload: An overload of this type is probably the most common cause of trigger point activity, though this is just my personal estimate. In these cases, the muscle’s functional endurance is exceeded by a given task. Examples include performing repetitive movements at a job day after day, sporting activities, and gardening. Often the pain associated with overuse injuries is attributed to tendonitis, but I find it remarkable how many cases of tendonitis can be indirectly resolved with trigger point therapy, by a qualified RMT.
- Biomechanical Overload: Muscles work together in functional groupings called myotatic units to create bodily movement. For any given movement, the muscles within a myotatic unit can be classified into two groups: synergists and antagonists. Synergistic muscles work together to produce a specific bodily movement, while antagonistic muscles act to produce the opposing bodily movement. Biomechanical overload occurs when one of the muscles in a myotatic unit is weakened by trigger point activity. In this situation, a synergistic muscle becomes overloaded by the additional work load that it must take on because of its dysfunctional partner, and an antagonistic muscle becomes overloaded by a distortion in the nerve supply controlling it. Trigger point formation in a muscle due to biomechanical overload occurs frequently in established myofascial pain disorders, and must be recognized to treat these disorders effectively.
- Postural Overload: One of the more subtle ways of overloading a muscle is to place it in an over-shortened or overstretched state for a prolonged period of time.This type of overload, termed postural overload, can be either of a mechanical or neurological nature, and is closely related to biomechanical overload. There are two very common types of postural overload that cause trigger points to form within a muscle; antalgic and degenerative.
Antalgic postural overloads occur when a person holds their body in a certain manner to avoid the pain from an injury. For example, a person may hold their head to one side to diminish the pain from a neck cramp, or lean their trunk forward to avoid aggravating a backache.
Degenerative postural overloads occur secondarily to the long-term changes in posture associated with aging or disease. Examples include an exaggerated sway in the lower back, or the forward head and sunken chest posture so frequently seen in older adults.
In either type of postural overload, some muscles are kept in abnormally shortened position, while others are kept in an abnormally elongated position, predisposing both groups of muscles to the development of trigger points.
- Referred Pain Overload: Pain that is referred to a muscle from trigger points in other muscles, or from joints and internal organs, can overload a muscle’s control mechanism and cause trigger points to form within it. In trigger point therapy, trigger points that develop secondarily to the referred pain from other trigger points are called satellite trigger points. Any myofascial disorder that is more than 2 days old, is likely to involve satellite trigger point activity. If the referred pain is severe enough, muscle tension associated with an unconscious guarding reflex may also produce trigger point activity in the local muscles.
- Muscle Trauma Overload: Physical trauma to a muscle, like that which might occur during a fall or automobile accident, can directly activate trigger points in that muscle. This may occur from a reflex response to the pain associated with the tissue damage, or because of an impairment in the muscle’s functional capacity.