Why Pain Can Persist Like A False Car Alarm

Car Alarm Note

Not all injuries are the same. The diagnosis may be the same, however the course of injury and overall prognosis can be completely different from one person to the next.

Generally speaking, initial healing from an injury occurs over the course of 4-8 weeks. Hence, after a common surgery like an ACL reconstruction, individuals start to feel pretty good in terms of symptoms around 8 weeks as the swelling/inflammation dials down. After the initial healing takes place, symptoms usually are minimal even as the body continues to remodel itself over the next year.

Surgery is a great example because apart from the injury, there is tissue that gets damaged from the actual surgery. It gives an example that after there was tissue damage from the actual surgical procedure, we can expect that most people will start to feel a lot better after the initial healing process.

Yet, something common like “low back pain” or “runner’s knee” can easily persist after that 4-8 week period. Many times people report repeating episodes over years. Why does this happen? There are several reasons why individuals may be prone to the same injury over and over again.

For long-standing injuries, pain does not correlate with tissue damage.

Initially, your pain was more correlated with tissue damage. Given what you now know about the course of tissue healing, the body is actually great at healing itself! In many cases, it is not the actual injury/tissue damage that persists – it is the pain that persists. This happens because your body and its headquarters (your nerves and brain = nervous system) remember how you got into trouble in the first place. With persistent (this is a much better word than “chronic” because it does not have to stay with you for the rest of your life!) pain, your body is trying to protect you too much. In all seriousness, pain is not a bad thing! At the end of the day, it helps keep us alive. In persistent cases of injury, our nervous system can be doing too much of a good thing by keeping us too safe. The consequence is unfortunately way too much pain. The real question is, what can your health provider do for you?

Physical therapy can be very successful in treating long-standing persistent conditions. The trick is to carefully reintegrate people back into activities. The body is incredibly resilient – it can just become over sensitive. The example I often give is that your pain is like a car alarm. Ideally, it should sound when someone is breaking into the car = tissue damage. However, the ideal situation is not always the case. We have all been in a parking lot when no one is even near a car and yet the alarm continues to sound! Like the human body, it is very common that we can have pain even when there is no tissue damage happening (no one is breaking into the car!). For example, individuals without a limb can still have very excruciating phantom limb pain even when there is no tissue there to be damaged. 

Let’s take the example of a persistent case of low back pain. Our body can develop a very keen awareness to that low back especially over many years of bending forward, sitting, or every time we move a certain way. Every time we start to bend forward for example and start to feel pain, we are likely not creating any further damage. Your body just may be trying to overprotect you! Most often, low back pain can be resolved within 4-6 weeks with a unique program designed specifically for each person. Research continues to show that the more patients understand their pain, the more pain relief they will likely have. This is in addition to a great regimen of hands-on treatment (manual therapy) and tailored exercise program.

Although an over-responsive car alarm/nervous system can be a factor in persistent injuries, it is just one factor that may be impeding recovery. If you think an over-sensitive nervous system may be contributing to your injury, it is best to seek advice from a physical therapist that specializes in persistent (chronic) conditions. The key point to remember: not all pain correlates with tissue damage. 


Moseley, L. Reconceptualizing Pain According to Modern Pain Science. Physical Therapy Reviews 2007;12:169-178.

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