Introduction: Physical activity is known to have salutary effects in the elderly. However, it is also well documented that exercise, especially unaccustomed and strenuous exercise, elevates levels of pro-inflammatory cytokines. The overproduction of these cytokines may lead to inflammation subsequently, causing muscle damage and weakness. Our purpose was to investigate the effects of acute eccentric exercise and its adaptation to eccentric training on inflammatory responses in aged untrained men. Methods: Thirteen healthy men (66-75 years) volunteered to train 2 days a week during 8-wk, using an inclined leg-press device. One week before, and one week later of the training program, all subjects performed an eccentric bout using as eccentric movement the negative phase of the inclined leg-press. NF-kB activation and IL-6, iNOS and COX-2 gene expression were measured in peripheral blood mononuclear cells at rest, immediately after each bout and at 3h.

Results: A single bout of eccentric exercise caused a significant increase in NF-kB activation. Translocation of NF-kB to the nucleus resulted in increased gene expression of enzymes with an inflammatory function, such as iNOS and COX-2. The mRNA level and protein content of IL-6 were also increased after the first eccentric-damaging bout. Following the training program, acute exercise only increased COX-2 mRNA level, to a lower extent than following the first eccentric bout. Conclusion: A twice-weekly, 8-wk, eccentric training program significantly attenuates changes in NF-kappaB-related pro-inflammatory genes.