Why some pain is not caused by injury – but by changes in the pain system

Many people experience persistent pain even when examinations show no damage to muscles, tendons, or joints. Despite this, the pain is real, distressing, and function-limiting. Modern pain science shows that the explanation often lies not in the tissues, but in how the nervous system interprets and amplifies signals.

Pain is more than tissue damage

Traditionally, pain has been understood as a direct result of injury or inflammation. This model explains acute injuries well but falls short when it comes to persistent pain.

Research shows that:

• Pain can persist after tissues have healed

• The severity of pain often correlates poorly with imaging findings

• The nervous system can become hypersensitive over time

This does not mean the pain is “psychological,” but that it is driven by neurophysiological changes.

Central sensitization – when the volume knob is turned up

With long-lasting pain, the central nervous system can undergo changes that cause normal signals to be interpreted as threatening.

Common characteristics include:

• Pain triggered by light touch or gentle movement

• Disproportionately strong pain with low loads

• Pain spreading beyond the original area

• Associated fatigue, sleep problems, and concentration difficulties

These changes represent a form of learning within the nervous system.

Why rest and passive treatment often fail

When pain is primarily driven by a sensitized nervous system, interventions targeting tissue alone tend to have limited effect.

Studies show that:

• Prolonged rest can increase pain sensitivity

• Passive treatments often provide short-term relief without lasting functional improvement

• Graded activity and safe exposure are more effective over time

Treatment must therefore address movement, safety, and understanding.

What helps when the pain system is altered

Effective approaches share several key features:

• Thorough patient education about pain physiology

• Graded, function-oriented loading

• Emphasis on coping rather than symptom hunting

• Normalization of movement and activity

These strategies help “calm down” the pain system and rebuild trust in the body.

Implications for patients and clinicians

Understanding that pain does not always signal injury can be transformative:

• Reduces fear and catastrophic thinking

• Improves adherence to active rehabilitation

• Creates realistic expectations for recovery

For physiotherapists, this requires clear communication and clinical confidence.

Summary

Persistent pain is not always caused by ongoing tissue damage. In many cases, a sensitized pain system is the primary driver. Treatment that combines education, graded activity, and self-efficacy has the strongest evidence for improving outcomes in these conditions.

Sources

• Woolf, C. J. (2011). Central sensitization: Implications for the diagnosis and treatment of pain. Pain, 152(3 Suppl), S2–S15. https://doi.org/10.1016/j.pain.2010.09.030

• Nijs, J., et al. (2017). Treatment of central sensitization in patients with chronic pain. Physical Therapy, 97(9), 853–864. https://doi.org/10.1093/ptj/pzx061

• Moseley, G. L., & Butler, D. S. (2015). Fifteen years of explaining pain. The Journal of Pain, 16(9), 807–813. https://doi.org/10.1016/j.jpain.2015.05.005