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Why Pain Persists After the Injury Heals

Raquel Mejía 6 min read Clinical Education

Pain that lasts months or years after an injury has healed is not a sign that something is still broken. It is a sign that your nervous system has changed how it processes signals. Those changes are real, measurable, and — with the right approach — reversible.

What Chronic Pain Actually Is

When pain first starts, it usually serves as a warning: tissue is damaged, and your body needs to protect it. But when pain persists well beyond normal healing time, the problem shifts from the injured tissue to the nervous system itself.

Think of it like a smoke alarm. After a fire, the alarm should reset. In chronic pain, the alarm stays on — and gets more sensitive. Sounds that never would have triggered it before now set it off. Pain scientists call this central sensitization: your nervous system has turned up its volume, amplifying signals so that things that shouldn’t hurt now do, and things that should hurt a little now hurt a lot.

This is not something you are imagining. Brain imaging studies show measurable changes in the structure and activity of the brain in people with chronic pain — particularly in areas that process emotion, attention, and threat detection. A landmark study published in The Journal of Neuroscience (2009) found that these brain changes are “a reversible consequence of chronic pain” — not permanent damage. When pain is effectively treated, the brain’s structure normalizes.

How It Affects Your Daily Life

Chronic pain does not just hurt. It drains energy, disrupts sleep, makes it hard to concentrate, and can shrink your world as you avoid activities you used to do. When your nervous system is stuck in a protective state, even routine movements can feel threatening.

Veterans carry this burden at rates far higher than the general population. National health data show that veterans experience chronic pain at 1.5 to 3 times the rate of civilians, with the gap most dramatic among younger veterans. A study of nearly six million veterans published in Military Medicine (2024) found that 53% of those with PTSD also had chronic pain. This is not a coincidence — PTSD and chronic pain share overlapping brain circuits involving the areas that process threat, emotion, and memory. When you have both conditions, each one tends to amplify the other.

It is natural to avoid activities that hurt. But over time, avoidance leads to deconditioning, which makes the nervous system even more protective, which increases pain. Gradually returning to meaningful activity is one of the most effective ways to interrupt this cycle — not because you need to push through pain, but because your nervous system needs updated information that movement is safe.

What Physical Therapy Does

Physical therapy for chronic pain is not about finding a broken structure and fixing it. It is about helping your nervous system recalibrate.

Both the VA/DoD Clinical Practice Guideline (2022) and the CDC Clinical Practice Guideline (2022) recommend non-pharmacological approaches like physical therapy as first-line treatment for chronic pain. A landmark VA trial published in JAMA (2018) — the SPACE trial, with 240 VA patients followed for 12 months — found that opioid therapy was not superior to non-opioid approaches for improving function, while non-opioid treatment produced better pain intensity outcomes.

Here is what evidence-based PT for chronic pain typically includes:

  • Pain neuroscience education. Understanding why you hurt changes how your brain processes pain. A meta-analysis of 17 clinical trials published in Physiotherapy Theory and Practice (2024) found that when pain education is combined with exercise, patients experienced meaningful reductions in pain. Knowing that your nervous system can change is itself part of the treatment.

  • Graded movement and exercise. Exercise activates your body’s own pain-suppression system. Research published in The Journal of Pain (2020) documents this effect clearly in healthy populations, and emerging evidence shows that regular exercise can reactivate this system even when it has been impaired by chronic pain. The key is starting where you are and building gradually — not forcing through a workout that spikes your symptoms.

  • Graded exposure. When specific movements feel threatening, we work through them systematically at a pace you control. This is not about ignoring pain. It is about giving your nervous system evidence that the movement is safe, which helps reduce the brain’s threat response over time.

  • Hands-on treatment. Manual therapy helps by changing how your nervous system processes signals — activating the body’s built-in pain-dimming pathways. It works best as part of a broader program, not as a standalone fix.

What You Can Expect

Chronic pain did not develop overnight, and it does not resolve overnight. Nervous system changes take time to reverse. Most people begin noticing shifts within several weeks of consistent work — sometimes in how pain feels, sometimes in what they are able to do, sometimes in how much pain dominates their thinking.

Progress is rarely a straight line. Flare-ups happen and do not mean you have lost ground. They are a normal part of how the nervous system recalibrates. What matters is the overall trend over weeks and months.

Factors that affect your timeline include how long you have had chronic pain, whether you also deal with PTSD or TBI, your sleep quality, excessive alcohol or substance use, and how consistently you can practice what you learn in sessions. If you are managing multiple conditions — as many veterans do — progress may be slower, but the science supports that it is still achievable.

When to Seek Help

Chronic pain rarely signals a medical emergency, but certain symptoms warrant prompt attention:

  • Sudden, severe pain that is different from your usual pattern
  • New numbness, weakness, or loss of bladder or bowel control
  • Pain accompanied by fever, unexplained weight loss, or night sweats
  • Significant worsening that does not respond to your usual strategies

If any of these occur, contact your healthcare provider or seek emergency care.

Sources

  • Brain gray matter changes in chronic pain are reversible. The Journal of Neuroscience, 2009
  • Comorbid chronic pain and PTSD rates among nearly six million veterans. Military Medicine, 2024
  • SPACE trial: opioid vs. non-opioid therapy for chronic pain in 240 VA patients. JAMA, 2018
  • Pain neuroscience education combined with exercise: meta-analysis of 17 RCTs. Physiotherapy Theory and Practice, 2024
  • Exercise-induced hypoalgesia: meta-analysis. The Journal of Pain, 2020
  • Fear-avoidance model and pain-related disability: meta-analysis. European Journal of Pain, 2022
  • VA/DoD Clinical Practice Guideline for Opioid Therapy in Chronic Pain, 2022
  • CDC Clinical Practice Guideline for Prescribing Opioids for Pain, 2022
  • Chronic pain prevalence among veterans vs. civilians. MMWR, 2020
  • Gray matter changes reversed after pain neuroscience education and exercise in chronic whiplash. The Journal of Pain, 2024