Soft tissue injury is a very interesting topic. If we think about it, it is really the basis of the majority of what we as massage therapist work on every single day. Because of this, I feel like it is a foundation piece which every therapist should have a good grasp on. Knowing why soft tissue injuries occur and, of course, how they heal gives us a better understanding of why soft tissue conditions occur.
Now, knowing why injuries occur is one thing, but knowing why they KEEP occurring is maybe an even more important fact to know. Many of you know the basics of how muscles get injured, but do you know why certain injuries continue to return? Or maybe you need to know what causes certain muscular conditions like tendonitis and other repetitive stress injuries. These questions can all be wrapped up together and answered with one solution. That solution is the Cumulative Injury Cycle.
Now, there are varying degrees and causes of soft tissue injury, but the process of injury, healing, and re-injury are very similar and can be broken down into a nice easy cycle which makes studying it much easier. I have put together a graphic which is similar to others you may (or may not) have seen. This is mainly for clarity sake and I will break down the steps for a more detailed look. Take a good look at it so you are familiar with the process.
Note: For simplicity sake, we will use muscle tissue as our example throughout this post.
An injury can be any sort of trauma to soft tissue. This could be anything from a minor strain to catastrophic full tear of a muscle, crush or contusion injury. The injury is the starting point for the cumulative injury cycle. It can either be the acute beginning of an injury, or it can be a continuation/ re-injury of a previous injury.
The inflammatory process is the natural way the body protects an injured area while at the same time beginning the healing process. When an injury is sustained, swelling and inflammation are the characteristics of increased blood flow allowing for clotting around the injury along with the cellular healing process to begin. Spasm and stiffness are present during this time.
As the remodeling process begins, collagen fibers are laid down, and tissue regenerates, reconstructing the damaged area. This process begins around 48 hours after the original injury and can last for months depending on the severity of an injury. This is where scar tissue and adhesions are formed which is good for healing damaged tissue but can become restrictive to blood flow and limit oxygen and nutrient distribution.
Weak and Tight
The result of an injured muscle is weakness within the muscle as well as tightness. This creates the inability for the muscle to contract and operate properly, limiting its functionality.
Friction / Tension
Because of increased amounts of scar tissue and adhesions within the muscle fibers, the ability of the muscle to contract and stretch is hindered. This forces the muscle to work harder to achieve the same level of contraction that was once easy. This overworking, once again, leads to potential injury and more adhesive tissue being laid down as part of healing. In other words, the cycle starts over again.
As the cycle continues, and injury adds to injury, the increased levels of scar tissue hinder the amount of circulation within the tissue. When this occurs, oxygen and nutrient delivery are lessened, affecting the health of the muscle even more. This step, although present with a first-time injury, is magnified with chronic muscle injuries and repeated passes around the injury cycle.
Re-Injury and Repetitive Stress Injuries.
Where the cumulative injury cycle becomes valuable is understanding how it relates to repetitive stress injuries and chronic soft tissue injury patterns. Conditions like tendinitis, tendinosis, tenosynovitis, carpal tunnel syndrome…etc. are all related to the above cycle. Even repeated muscle strains are explained through this model.
The important thing to know in relation to repetitive stress conditions is that they are simply an ongoing aggravation of an original injury. As adhesive tissue is laid down, muscle health and function diminish as described above. The increased amount of friction and tension within a muscle causes strength and elasticity to diminish. This forces the muscle to work harder to accomplish the same amount of contraction/ strength as before. As the workload rises, the potential for injury does the same.
Now apply this to someone who works at a computer all day typing. Typing may not seem like it could cause an acute injury…but it can. It is not a strain in the sense that we think, but more a “micro-trauma”. Stated another way, it is minor overtaxing of the tissue which results in a brief healing process and scar tissue being laid down. These “micro-traumas” by themselves do not cause a painful acute injury, but the cycle of injury and healing is the same.
Now, as a single occurrence, these minor tissue injuries are nothing to be afraid of. However, as the same activities are done over and over again, and our “micro-traumas” occur repeatedly, this is where true damage can take place. The affected muscle becomes more inhibited by scar tissue, and circulation becomes lessened leading to increased tension and friction. The cycle continues to repeat itself until inflammation becomes constant and painful, and the muscle is weakened enough to make the same task difficult that was once very easy for it to accomplish. This is how conditions like tendonitis and carpal tunnel occur. In the case of our desk worker, carpal tunnel is the result of inflamed and swollen tendons causing pressure on the median nerve. Not fun.
This also explains why repetitive stress conditions continue to be an ongoing problem. A common treatment for repetitive stress injuries is rest and stretching. Although this may allow for inflammation and pain to diminish because of decreased workload for the muscle, it does not affect the amount of scar tissue, which is the root problem, that is within the tissue. Once the aggravating activity is resumed without treatment of the scar tissue, inflammation will return and pain will resume; continuing on with the cumulative injury cycle.
The cumulative injury cycle demonstrates chronic injury patterns as well. As an example, take a hamstring strain suffered by an athlete. The first time it occurs, it probably heals quite quickly depending on the severity of the tear. However, now that a tear has occurred that muscle is now going to be prone to re-injury if that scar tissue is not remodeled correctly and adhesive tissue is not realigned. Circulation will be diminished, tension will be increased, and weakness will be present. Naturally, there is going to be a lower level of function in that muscle without proper rehabilitation. You hear about hamstring injuries and professional athletes having ongoing issues quite a bit. Well, this is the reason. Once a muscle is strained once, it has a much higher chance of re-straining and the injury cycle repeating itself over and over.
This theory can also be applied to chronic postural issues. As certain muscles become overstretched due to poor posture, they also suffer “micro-traumas” and become weakened due to adhesive tissue restrictions and the resulting reduced circulation. Over time, these muscles lose flexibility and responsiveness, contributing to postural issues. Once again, the cycle applies the same.
The examples I have given here are only a few but are some of the most common muscle dysfunctions we see. As therapists, we should know that we can treat these conditions quite effectively. This can be done by manipulating the adhesive tissue, thus, breaking the cumulative injury cycle. Once adhesive tissue and scar tissue function are restored, circulation and health can return to the tissue. Once treated, healing can occur and functionality will return; bringing with it strength and flexibility. The root of the problem has been treated.
The concept of the cumulative injury cycle is very simple but really explains the root cause of many chronic and acute injuries. As therapists, understanding what causes certain conditions makes us better practitioners and gives us the ability to treat those conditions with confidence. By knowing the details of the Cumulative Injury Cycle, we can understand not only why certain injuries happen, but also why they continue to occur repeatedly. This will further our ability as soft tissue specialists to help intervene in this downward cycle and treat chronic conditions which affect our clients.
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