1. Low-Intensity Exercise Reverses Chronic Muscle Pain in the Rat in a Naloxone- Dependent Manner 
Marie K. Hoeger Bement, PT, PhD, Kathleen A. Sluka, PT, PhD 
Archives of Physical Medicine and Rehabilitation 
Volume 86, Issue 9, Pages (September 2005)
DOI: /j.apmr
Copyright © 2005 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

2. Fig 1
Timeline of the first exercise experiment. In the second experiment, all the rats exercised, and naloxone or saline was administered systemically 20 minutes prior to exercise. Before both experiments, the rats trained on the treadmill for 4 days.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr )
Copyright © 2005 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

3. Fig 2
Low-intensity exercise reverses mechanical hyperalgesia in a chronic muscle pain model. Mechanical withdrawal threshold decreased bilaterally 4 hours after the second intramuscular acid injection. Fifteen to 30 minutes of exercise reversed this decrease in mechanical threshold compared with nonexercising controls. Data are median with the 25th and 75th percentiles. Abbreviations: INJ1, before intramuscular injection 1 of pH 4.0 saline; INJ2, before intramuscular injection 2 of pH 4.0 saline. *Significantly increased from nonexercising control (P<.05).
Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr )
Copyright © 2005 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

4. Fig 3
Analysis of the AUC shows a reversal in mechanical withdrawal threshold in the rats that exercised versus those that did not. The difference between the mechanical withdrawal threshold 24 hours after each exercise session and the withdrawal threshold 4 hours after the second intramuscular acid injection (ie, hyperalgesia) was analyzed for the AUC. We used the same procedure for the nonexercising controls. Exercise significantly decreased mechanical hyperalgesia compared with the nonexercising controls. Data are mean ± standard error of the mean (SEM). *Significantly increased from nonexercising control (P<.05).
Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr )
Copyright © 2005 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

5. Fig 4
Analysis of the AUC shows that daily naloxone administration (10mg/kg intraperitoneal) before exercise significantly attenuated the antihyperalgesic effects of exercise when compared with animals that received daily saline before exercise. Data are mean ± SEM. *Significantly decreased from control (P<.05).
Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr )
Copyright © 2005 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions