Aerobic exercise, but not flexibility/resistance exercise, reduces serum IL-18, CRP, and IL-6 independent of β-blockers, BMI, and psychosocial factors in older adults

Increased serum levels of inflammatory mediators have been associated with numerous disease states including atherosclerosis, Type II diabetes, hypertension, depression, and overall mortality. We hypothesized that a long-term exercise intervention among older adults would reduce serum inflammatory cytokines, and this reduction would be mediated, in part, by improvements in psychosocial factors and/or by β-adrenergic receptor mechanisms. Adults ⩾age 64 were randomly assigned to either an aerobic exercise treatment (CARDIO) or a flexibility/strength exercise treatment (FLEX) 3 days/week, 45 min/day for 10 months. A subgroup of subjects treated with non-selective β1β2 adrenergic antagonists were included to evaluate the potential role of β-adrenergic receptor adaptations as mediators of an exercise-induced change in inflammation. The inflammatory mediators [C-reactive protein (CRP), IL-6, tumor necrosis factor (TNF)-α, and IL-18] and the psychosocial factors (depression, perceived stress, optimism, sense of coherence, and social support) were measured pre- and post-intervention. The CARDIO treatment resulted in significant reductions in serum CRP, IL-6, and IL-18 compared to the FLEX treatment (significant treatment × time interaction, p < .05), whereas TNFα declined in both groups (main effect of time, p = .001). However, several psychosocial factors (depression, optimism, and sense of coherence) improved in both groups suggesting that the reduction of CRP, IL-6, and IL-18 in the CARDIO group was not mediated by improvements in psychosocial scores. With respect to the potential role of β-adrenergic receptors, both CARDIO subjects treated with β-adrenergic antagonists and those who were not treated with those medications demonstrated similar reductions in serum CRP, IL-6, IL-18, and TNFα. In summary, we have observed that an aerobic exercise intervention can significantly reduce serum inflammatory mediators, but β-adrenergic receptors and psychosocial factors do not appear to be involved.