The Effects of Acute Aerobic Exercise on Inflammatory Markers and Mood in Individuals with Multiple Sclerosis and Spinal Cord Injury
1Donia S, 2Allison D, 1Gammage K, 1Ditor D
1Brock University, St. Catharines, Ontario, Canada; 2McMaster University, Hamilton, Ontario, Canada
One bout of exercise has been shown to improve mood in individuals with spinal cord injury (SCI) and multiple sclerosis (MS), however the underlying mechanisms are not fully understood. It is possible that exercise-induced changes in inflammation account, in part, for the exercise-induced changes in mood in these populations. This hypothesis is reasonable as individuals with SCI and MS exhibit chronically elevated levels of pro-inflammatory cytokines, and work from our lab has shown that long-term reductions in pro-inflammatory cytokines result in improved mood. The purpose of this study was to determine if exercise-induced reductions in pro-inflammatory cytokines contribute to exercise-induced improvements in mood in individuals with SCI and MS.
Thirteen individuals (6 SCI, 7 MS; 3 male, 10 female; age 57.2±7.6years) were recruited for participation. Participants with SCI ranged in level (C2-L2), severity (AIS A-D) and years post-injury (1-24 years; avg 8.2±8.8 years). Participants with MS had relapsing-remitting or secondary progressive, and ranged in disease progression (EDSS 3.5-6.0) and years post-diagnosis (4-42; avg 13.0). Participants completed a single 30-minute bout of moderate-intensity exercise at 60% of the pre-determined VO2peak. Mood was assessed before, immediately after, and one-hour post-exercise, via the Profile of Mood States Questionnaire (POMS). Blood samples were taken before, immediately after, and one-hour post exercise, and subsequently analyzed for serum pro-inflammatory cytokines (IL-6, IFN-g, and TNF-a), as well as tryptophan (TRP) and kynurenine (KYN) as previous work from our lab has shown that reductions in pro-inflammatory cytokines improve mood via the kynurenine pathway, which is integral in serotonin production. Following the bout of exercise, there was a significant improvement in mood as shown by a reduction in the total POMS questionnaire score from pre to post-exercise (32.5±25.8 to 22.4±21.9; p=0.025), as well as pre to one hour post-exercise (32.5±25.8 to 21.6±25.0; p=0.01). Subscale analysis showed significant reductions in the Tension, Depression and Anger components of the POMS from pre to post-exercise and from pre to one-hour post-exercise as well. Regarding pro-inflammatory cytokines, there were no exercise-induced changes in IL-6, but there was a significant main effect for time for TNF-a (with post-hoc analyses showing significant reductions from pre to one-hour post-exercise) and a trend for a main effect for time for IFN-g (p=0.06). There were no changes in TRP, KYN or KYN/TRP. There were no correlations between changes in mood and changes in cytokines when all participants were analyzed. However, when considering only the participants that responded to exercise with an improved mood, there were significant correlations between exercise-induced changes in depression and exercise-induced changes in IL-6 (r=0.853; p=0.03) and trends for changes in TNF-a (r=0.722; p=0.07) and IFN-g (r=0.647; p=0.16). These results suggest that exercise-induced changes in mood may be accounted for, in part, by exercise-induced changes in pro-inflammatory cytokines in individuals with SCI and MS, but the reduction in pro-inflammatory cytokines may not be changing mood via acting on the kynurenine pathway
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