The Impact of Exercise in Rodent Models of Chronic Pain

Mark Henry Pitcher

doi:10.1007/s11914-018-0461-9

Abstract

Purpose of ReviewPhysical activity is increasingly recommended for chronic pain. In this review, we briefly survey recent, high-quality meta-analyses on the effects of exercise in human chronic pain populations, followed by a critical discussion of the rodent literature.Recent FindingsMost meta-analytical studies on the effects of exercise in human chronic pain populations describe moderate improvements in various types of chronic pain, despite substantial variability in the outcomes reported in the primary literature. The most consistent findings suggest that while greater adherence to exercise programs produces better outcomes, there is minimal support for the superiority of one type of exercise over another. The rodent literature similarly suggests that while regular exercise reduces hypersensitivity in rodent models of chronic pain, exercise benefits do not appear to relate to either the type of injury or any particular facet of the exercise paradigm. Potential factors underlying these results are discussed, including the putative involvement of stress-induced analgesic effects associated with certain types of exercise paradigms.SummaryExercise research using rodent models of chronic pain would benefit from increased attention to the role of stress in exercise-induced analgesia, as well as the incorporation of more clinically relevant exercise paradigms.

Highlights

Chronic pain represents an urgent global health problem [1] that incurs massive social and economic costs [2, 3]
Non-pharmacological approaches are increasingly recommended as first-line treatments for certain types of chronic pain, even prior to pharmacological interventions [28]
Sabharwal et al demonstrated that as little as 5 days and up to 8 weeks of unrestricted access to running wheels prior to injury prevented injury-induced reductions in heart rate variability (HRV), a measure of autonomic health known to be negatively impacted by stress [131–134], reviewed in [135] and chronic pain [136]

Summary

Introduction

Chronic pain represents an urgent global health problem [1] that incurs massive social and economic costs [2, 3]. Geneen et al assessed 21 previous Cochrane reviews, incorporating 264 primary reports and 19,642 participants, to determine the effectiveness of different physical exercise interventions in reducing pain stemming from various chronic pain syndromes. In a 2014 Cochrane review assessing therapeutic exercise for hip OA in 9 trials (549 participants), Fransen et al [54] reported high-quality evidence in support of exercise-induced improvements in pain and physical function in individuals with hip OA. Sabharwal et al demonstrated that as little as 5 days and up to 8 weeks of unrestricted access to running wheels prior to injury prevented injury-induced reductions in heart rate variability (HRV), a measure of autonomic health known to be negatively impacted by stress [131–134], reviewed in [135] and chronic pain [136]. Relatively low levels of self-regulated exercise appear to be protective against persistent pain and persistent pain-induced stress

Conclusions

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Methods

Findings