Massage is usually thought of as something that works on muscles, joints and other tissues. But pain is not produced only where an injury occurs. Chronic pain also involves changes in the spinal cord and brain. A recent animal study explored whether massage might influence these central pain-processing systems.

The study focused on neuropathic pain, which occurs when nerves themselves are damaged or diseased. People with neuropathic pain may experience burning, electric-shock sensations, numbness or exaggerated sensitivity to normally harmless stimulation. Over time, continuing nerve signals can make the nervous system increasingly sensitive—a process often called central sensitisation.

The study

Researchers used 45 male rats divided into three groups: healthy controls, rats with experimentally induced sciatic nerve injury, and injured rats receiving Tuina massage. The nerve injury was produced using the established chronic constriction injury model.

Massage began four days after the nerve injury. Rather than allowing therapists to apply an uncontrolled amount of pressure, the researchers used a sensor-equipped glove to standardise the treatment. Pressure was applied at approximately 5 N, 120 times per minute for 10 minutes once daily.

The researchers then measured two things: how sensitive the animals were to mechanical and heat stimuli, and what was happening in their brains using resting-state functional MRI.

Massage reduced pain-related behaviour

Following nerve injury, the rats became much more sensitive to pressure and heat. By days 7, 10 and 17, however, the massage-treated rats tolerated significantly greater mechanical pressure and heat exposure than untreated injured rats.

In simple terms, the massage-treated animals behaved as though their pain sensitivity was decreasing.

This is important because the treatment was not simply associated with a temporary response immediately after massage. Improvements continued across the treatment period.

Chronic pain affected much more than the sensory areas of the brain

The MRI results provide an interesting reminder for therapists: chronic pain is not simply a message travelling from an injured nerve to one “pain centre”.

Nerve injury changed spontaneous activity across many brain regions. These included areas involved in:

• sensory processing,
• movement,
• memory,
• emotion,
• attention,
• and integration of sensory information.

The researchers grouped these changes into networks related to emotional processing, pain and sensory integration, and pain-related motor control.

This supports the broader view that persistent pain becomes a whole nervous-system experience, involving considerably more than the damaged tissue itself.

The hippocampus may be particularly important

One of the most interesting findings involved the hippocampus, a brain region normally associated with learning and memory but which also participates in the emotional and contextual processing of pain.

Seven days after nerve injury, untreated rats showed abnormal activity in the left hippocampus. Rats receiving massage showed significantly lower activity in this region.

By day 17, the difference between massage-treated and untreated animals was no longer statistically significant, partly because the untreated animals were also gradually recovering. Importantly, however, the massage group’s improvement in pain behaviour followed a similar time course to the changes seen in hippocampal activity.

The authors therefore suggest that massage may influence the way chronic pain is processed centrally, rather than working only on tissues around the injured nerve.

How could touch affect the brain?

Massage produces continuous sensory information that travels through peripheral nerves into the spinal cord and brain.

The study proposes that rhythmic, non-threatening mechanical stimulation may help regulate nervous-system activity and influence brain plasticity—the nervous system’s ability to reorganise itself.

Previous work cited by the authors suggests that massage may influence inflammatory signalling, spinal glial cells and neurotransmitter activity. The present study adds evidence that massage may also alter functional brain activity associated with chronic neuropathic pain.

This provides a different way of thinking about massage.

Rather than imagining that therapists are simply “loosening muscles” or mechanically correcting tissues, massage may also act as a sensory input into the nervous system.

What does this mean for therapists?

The study supports an increasingly important concept in pain science:

Where someone feels pain is not necessarily the only place where the pain problem is being maintained.

With persistent pain, the nervous system can change how strongly it responds to sensory information. Brain regions involved with memory, emotion, threat and movement may all become part of the pain experience.

Massage may therefore help some people not only through its local mechanical effects but also by providing safe sensory input that modifies pain processing.

Massage may be influencing how the nervous system interprets the information coming from those tissues.

An important limitation

The most important caution is that this was an animal experiment, not a clinical trial in people.The study therefore shows a possible biological mechanism.