Effects of heavy endurance physical exercise on inflammatory markers in non-athletes

Objectives: Physical activity has beneficial effects on cardiovascular disease but the mechanisms are still somewhat unclear. One possible pathway may be through the anti-inflammatory effects attributed to regular physical activity. Our primary aim was to study the effects of endurance physical exercise on C-reactive protein (CRP), Interleukin-6 (IL-6), Tumor Necrosis Factor-alpha (TNF alpha) during the acute and recovery phases. Secondarily, we studied the impact of diet on these inflammatory markers. Methods: Twenty men, aged 18-55 years, participated in a 14 days cross-country skiing tour. They traveled 12-30 km per day corresponding to about 10 h of heavy physical activity. The participants were randomized to a diet with either 30 or 40% of energy derived from fat. Inflammatory variables were analysed at week 0, after 1 and 2 weeks and during the recovery phase at week 6 and 8. Results: CRP and TNF alpha increased significantly during the two weeks of exercise (1.4-5.0 mg/l, p = 0.00 and 6.8-8.4 pg/ml, p = 0.00). CRP levels were significantly lower during recovery (median 0.7 mg/l) compared to baseline (median 1.4 mg/l) and did not correlate to metabolic variables. There were no significant changes in IL-6 levels during the study period. For dietary groups significant CRP changes were observed only in the high fat group during recovery. Conclusions: CRP and TNF alpha increased significantly but reacted differently during heavy physical activity while there seemed to be no significant changes in IL-6. No significant differences regarding inflammatory variables were found between the dietary groups. (C) 2009 Elsevier Ireland Ltd. All rights reserved.