Exercise may help relieve neuropathic pain or pain related to nerve damage, according to a new study.

Researchers from the latest experimental say that exercise eases pain by reducing levels of certain inflammation-promoting substances called cytokines.

Neuropathic pain is a common type of chronic pain state usually caused by damaged, dysfunctional, or injured nerve fibers, and is frequently seen in patients with trauma, diabetes, HIV, alcoholism and other conditions.

Patients report symptoms of burning pain and numbness that cannot be controlled by conventional pain medications. Some antidepressants and antiepileptic medications have been shown to be helpful, but these drugs also carry significant side effects.

Lead researcher Yu-Wen Chen of China Medical University in Taichung, Taiwan and his colleagues conducted a study on male rats with sciatic nerve injury.

Researchers found swimming or treadmill running reduced abnormal pain responses to temperature and pressure by 30 percent to 50 percent in rats, as well as reduced expression of inflammation-promoting cytokines in sciatic nerve tissue.

The latest findings, published in the June issue of Anesthesia & Analgesia, confirm previous research suggesting that inflammation and pro-inflammatory cytokines play a role in the development of neuropathic pain in response to nerve injury.

Researchers noted that exercise was also found to increase expression of a heat shock protein-27, which may have contributed to the decreases in cytokine expression.

While health professionals have generally recommended exercise for patients with various types of chronic pain, there are conflicting data as to whether working out is helpful in relieving neuropathic pain.

Study results also support past findings that inflammation adds to the development of neuropathic pain, including the possible roles of pro-inflammatory cytokines.

While physical activity may not completely eliminate neuropathic pain, Chen said that the latest findings support the benefits of exercise in reducing chronic pain associated with nerve damage, and suggested that exercise be used as a nondrug therapy for treating neuropathic pain.