Inflammatory response and the relationship to mood following high-intensity interval exercise

Introduction The mood experience following a bout of exercise has been associated to enjoyment but also anti-inflammatory effects mediated by the release of interleukin-6 (IL-6). IL-6 may therefore provide a mechanism underlying the mood enhancing response to high-intensity exercise. The aims of the present study were to compare the effect of high-intensity interval exercise (HIIE) on acute inflammatory response and the relationship to mood. Methods Eight physically active males (age 25±6 years, V ╠çO2max 49.02±5.53 ml·kg-1·min-1) undertook two 20 min HIIE trials (10 x 1 min intervals at 80% V ╠çO2max (HIIE80) and 90% V ╠çO2max (HIIE90) interspersed with 1 min active recovery) applied in a repeated measures cross-over design. Plasma IL-6 and leukocyte concentrations measured by high-sensitivity ELISA and mood, measured using the Brunel Mood Scale (BRUMS; Terry et al., 2003) were collected before (pre), immediately after (post), 30 min (post30) and 60 min (post60) post-exercise and mood also measured 24h post exercise (post24). Results Average workload and total energy expenditure was significantly greater for the HIIE90 trial (216 ± 48W and 120.58 ± 6.43 kcal, respectively) compared to the HIIE80 trial (P<0.001, 95% CI=20.98, 34.02 and P<0.05, 95% CI=-14.36, -0.77, respectively). IL-6 significantly increased in the HIIE90 with a 164.15% (2.64 fold) increase observed post30 (P<0.05, 95% CI=-0.10, -0.04). However, IL-6 and leukocyte response did not significantly differ between the two intensities (P > 0.05) and total mood disorder (TMD) did not significantly differ between trials (F (1, 7)=0.52, P=0.50, η┬▓=0.07, observed power = .10). Feelings of tension were significantly reduced post30 (P = .003, 95% CI = 1.10, 4.65), post60 (P=0.001, 95% CI =1.68, 5.07) and post24 (P=0.01, 95% CI = 0.78, 3.73) following HIIE80. Correlations between IL-6 and mood identified a large and significant negative relationship between IL-6 and fatigue at post30 after HIIE80 (r= -0.78, P =0.02). Conclusions HIIE90 elicited a significant transient increase in IL-6 which may provide an effective strategy to target inflammatory dysregulation, however, there was no significant changes in TMD between the two intensities. There was an effect on tension and fatigue with a negative relationship between IL-6 and fatigue after HIIE80 which was effective in significantly reducing feelings of tension. Given the transient pleiotropic effects of IL-6 to exercise, further research is required to establish the long-term implications of anti-inflammatory properties of HIIE on mood. References Terry, P. C., Lane, A. M., & Fogarty, G. J. (2003). Construct validity of the POMS-A for use with adults. Psychology of Sport and Exercise, 4 (2), 125-139.