Background Rheumatoid arthritis (RA) patients suffer from joint pain and decreased physical capacity, like muscle wasting and fatigue. Fatigue is a clinical manifestation reported by 40-80% of patients with RA and is regarded as an important feature of the disease. Aerobic exercise may be beneficial for treating this feature in RA patients, however the mechanisms involved are still unclear.
Objectives To evaluate the effect of aerobic exercise training on the endurance exercise performance in collagen-induced arthritis (CIA) mice.
Methods Male DBA1/J mice with CIA  were randomly divided into 3 groups: wildtype with exercise (WT-EXE, n=4), CIA exercised (CIA-EXE, n=5) and CIA non-exercised (CIA, n=4). Endurance exercise performance test (fatigue) was analyzed in all groups prior to booster injection and each 15 days after protocol started. Eighteen days after the disease induction (booster), WT and CIA-EXE were submitted to training on an inclined treadmill (θ=5°), 45 minutes a day, 5 days per week for 6 weeks at 60% of their own endurance exercise performance. Variables analyzed were disease score, hindpaw nociception, body weight (g), fatigue (by endurance exercise performance in min) and relative muscle weight (muscle weight in mg divided by total animal weight in g). Data was analyzed with ANOVA Two-Way followed by Bonferroni and independent sample t-test and p<0.05 was considered significant. All data are represented as Mean ± SEM.
Results Body weight was significantly higher in WT-EXE compared with CIA after 4 and 6 weeks of exercise. At week 6 of exercise, CIA-EXE had higher body weight than CIA. Fatigue test at 4 and 6 weeks of experiment was significantly different among all experimental groups; WT-EXE and CIA had, respectively, the highest and the lowest fatigue velocity. Gastrocnemius muscle weight was significantly heavier in control group than in CIA-EXE and CIA. Nociception and clinical score of arthritis did not differ between CIA-EXE and CIA.
Conclusions Inclined aerobic exercise appears as an interesting intervention in RA to treat decreased physical capacity. Collagen-induced arthritis animals demonstrated decreased endurance, and consequently increased fatigue, characteristics of a good animal model to study fatigue. The exercise protocol used in this study was able to improve this feature, demonstrating that interventions used to treat physical disabilities in RA are also valid in this model. Further studies are necessary to clarify the mechanisms behind fatigue, especially when combining exercise training and common treatments of RA.
Rosloniec EF, et al. Curr Protoc Immunol 2010; Chapter 15: Unit 15.5.1-25.
Acknowledgements Financial support: CAPES, CNPq, FAPERGS, FIPE-HCPA.
Disclosure of Interest None declared