Inflammatory response to a high-force eccentric exercise protocol in oral contraceptive users and non-users

Abstract

Researchers have demonstrated that oral contraceptive users have elevated serum C-reactive protein (CRP) levels. However, it is unclear whether or not CRP is elevated in response to inflammation. Results of preliminary studies indicate that individuals with elevated CRP exhibit diminished release of interleukin-6 (IL-6), an inflammatory mediator with anti-inflammatory properties. Low IL-6 may cause less control of inflammation and a resultant elevation of CRP. The inflammatory response was compared between female oral contraceptive (OC) users and non-OC users because of the known elevation of CRP in OC users. A high-force eccentric exercise protocol was used to induce muscle damage to the biceps brachii via 45 repetitions of the elbow flexors of the non-dominant limb. Blood was collected pre-exercise and at 4-, 8-, 12-, 24-, 48-, 96-, and 120-h post-exercise for analysis of muscle damage and inflammatory markers.

At baseline, cortisol was greater in the OC group than the non-OC group. CRP was greater in OC users than non-OC users at all time points. Soluble tumor necrosis factor-receptor 1 (sTNF-R1) and cortisol decreased, and IL-6 increased, in the post-exercise phase, indicating an inflammatory response. Because IL-6 increased post-exercise while sTNFR1 decreased, IL-6 was most likely released from skeletal muscle and acted as an antiinflammatory agent. Although total cortisol was higher in the OC group, these findings may be controversial, as free cortisol may have greater implications on inflammation. CRP did not appear to be associated with the other inflammatory markers and IL-6 secreted from skeletal muscle has an anti-inflammatory effect.