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8 Articles in this Series
Introduction
Bench to Bedside: Clinical Tips From APS Poster Presentations
New Pain Research Underscores the Importance of Sufficient Rest
The Benefits of Exercise for Pain Management
Exercise as Postoperative Analgesic?
How Race Affects Pain
Increased Centralized Pain in African American Patients
Managing Post-Tonsillectomy Pain in Obese Children
Research Offers Insight Into Fibromyalgia and Pain

Exercise as Postoperative Analgesic?

In a study presented at this year’s APS meeting, a group of researchers sought to determine whether adult male rats given 6 weeks of voluntary wheel running prior to chronic constriction injury (CCI) of the sciatic nerve would help attenuate the subsequent allodynia and inflammatory processes.1

The researchers from the Center for Neuroscience at the University of Colorado, Boulder, found rats that were given unrestricted access to their running wheels prior to CCI had significantly reduced allodynia later on, compared to the control rats that were housed with a locked wheel preventing them from running.

Exercise prior to surgery helped reduce allodynia after surgery.The anti-nociceptive benefit of the voluntary running appeared to have a lasting effect, too. After using the running wheel for 6 weeks, researchers took away the rats’ access to the running wheel at the conclusion of the inflicted CCI injury. For the next 14 weeks, the protective benefits of the exercise remained, and even after the conclusion of the CCI, the rats still appeared at an advantage because they had been physically active prior to the nerve injury.

“The attenuated allodynia in CCI rats was associated with decreased inflammatory marker expression at two weeks after CCI,” specifically P2XR4, phospho-p38 MAPK, phospho-p65 of NFkB, and BDNF—all attenuated in the spinal L4-L5 dorsal quadrants. Also, markers for macrophage infiltration, Iba1 and CCL2, decreased in the injured sciatic nerve, the authors reported.

According to the authors, it’s possible the protection the voluntary running provided to the CCI rats may have been more related to a suppression of inflammatory signaling, rather than some kind of alternative activation, given the fact both iNOS (M1 macrophage marker) and Arg1 (M2 macrophage marker) were decreased in the injured sciatic nerve.

Dealing with DOMS after Exercising

The data suggests regular voluntary running can offer a resilience to chronic pain caused by nerve injury. However, patients who decide to start on a rigorous exercise program may need to be aware of the prohibitive effects of delayed onset muscle soreness (DOMS).

DOMS, which is sometimes also referred to as muscle fever, is a pain and stiffness felt in the affected muscles 24 to 72 hours following exercise, particularly if the exercise is strenuous and/or the person is not accustomed to the physical activity. While there are still many questions as to what DOMS actually is, the pain likely can be attributed to microtrauma to muscle fibers after repeated eccentric, or lengthening, contractions of the muscle.2,3

Practitioners may benefit their patients by informing them of what DOMS is. Such soreness and stiffness caused by DOMS may be misunderstood to be a harmful injury. Even if patients are aware of DOMS, the pain it causes could influence them to have less range of motion and feelings of weakness in the affected site, as well.

According to another study presented at this year’s APS meeting, a person’s activity level may decrease because of DOMS. However, the researchers from the University of Florida, Gainesville, also found it was more likely patients worked out less because they feared the DOMS pain rather than harbored catastrophizing thoughts about it.4

Because of this, encouraging patients to try to maintain their range of motion through the “sore days” could be beneficial to maintaining healthy, regular physical activity, and reaping the apparent benefits physical activity may have on protecting the body from endogenous pain modulation.

References

1. Grace P, Strand K, Galer E, et al. Prior voluntary wheel running is protective for neuropathic-like pain. Poster presented at: Annual Meeting of the American Pain Society; May 11-14, 2016; Austin, Tx. Poster 464.

2.  Miles MP, Clarkson PM. Exercise-induced muscle pain, soreness, and cramps. J Sports Med Phys Fitness. 1994;34(3):203-216.

3.  Cheung K, Hume PA, Maxwell L. Delayed onset muscle soreness: Treatment strategies and performance factors. Sports Med. 2003;33(2):145-164.

4.  Solis F, Bishop M.  Changes in physical activity and its association with pain-related negative affect and pain sensitivity before and after exercise-induced low back pain. Poster presented at: Annual Meeting of the American Pain Society; May 11-14, 2016; Austin, Tx. Poster #486.

Next summary: How Race Affects Pain
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