Background Major depressive disorder (MDD) is associated with chronic inflammation. Exercise training can treat depression in adults with MDD, potentially through reducing inflammatory activity. This improvement may occur through adaptations to repeated acute inflammatory responses. Cytokine responses to acute steady-state exercise of varying intensities were determined in women with different levels of depression.

Methods This analysis included 19 women with MDD who each participated in four sessions consisting of 30 min of quiet rest, light, moderate, or hard intensity exercise. Blood samples were collected pre- and within 10 min post-session. Changes in the levels of IL-6, IL-8, IL-10, and TNF were evaluated in each session.

Results Serum concentrations of IL-6, IL-8 and TNF were all significantly elevated following vigorous exercise (i.e., hard) compared to the quiet rest session. No changes in cytokine levels occurred after light and moderate exercise. Depression severity did not appear to influence the acute inflammatory response to exercise.

Limitations The sample size was small, all female, and from a secondary data analysis, which limits the generalizability of the findings.

Conclusions Repeat, acute increases in inflammatory activity following hard exercise sessions may prompt adaptations and lead to reductions in chronic inflammation over time. This dose-response study identified an exercise intensity threshold to induce acute inflammatory responses in women with MDD.