Inflammatory Response Following Moderate and Vigorous Aerobic Exercise

The purpose of this study was to establish the effect of an acute bout of moderate and vigorous aerobic exercise on production of the inflammatory cytokine interleukin-6 (IL- 6) and the acute phase protein C-reactive protein (CRP). Ten male recreationally trained cyclists (average age 30.3 ± 5.7 years) completed two 40-minute cycling bouts on two separate occasions. A moderate-intensity exercise bout was performed at 50% of VO_2max and a vigorous-intensity exercise bout was performed at 80% of VO_2max. Blood samples were taken before exercise, 30 minutes into exercise, and then 15, 30, 45, 60, 90, 120, 180, and 240 minutes post-exercise. Average percent of VO_2max for moderate and vigorous exercise was 52.7 ± 1.6 and 76.8 ± 5.0 percent, respectively. There was a significant increase in CRP during and following both moderate and vigorous exercise (p < 0.05). IL-6 was increased 15-minutes after moderate exercise, and during and for I-hour following vigorous exercise (p < 0.05). The increase in IL-6 was greater following vigorous compared to moderate exercise (p = 0.001). Change in IL-6 during vigorous exercise was correlated with the change in CRP immediately following the exercise bout (p = 0.003, r = 0.826). These results show that an acute bout of moderate or vigorous exercise can result in an acute phase response during exercise. This acute phase response is related to the inflammatory response that occurs during exercise.