High-Intensity Interval Training Does Not Induce Anti-Inflammatory Changes in Healthy Men

Abstract

Low-grade inflammation is associated with the risk of various chronic diseases, and the protective effects of a physically active lifestyle may be partially ascribed to the anti-inflammatory effects of exercise. The impact of moderate intensity exercise training on circulating pro-inflammatory molecules has received much attention in recent years. However, there are very few well designed and adequately powered studies on the influence of high-intensity interval training (HIIT) on circulating markers of inflammation. PURPOSE: The purpose of this study was to examine potential changes in plasma concentrations of C-reactive protein (CRP), interleukin-6 (IL6), and soluble interleukin-6 receptor (sIL6r) following four (4w) and eight weeks (8w) of HIIT in healthy men. METHODS: Healthy, sedentary men participated in a HIIT program three days/week for eight weeks. Training bouts were modeled after the traditional Wingate test, consisting of repeated, 30-second bouts of maximal intensity cycling separated by 4.5 minute rest intervals. Training began with three bouts per day and an additional bout/day was added to the regimen every two weeks, progressing up to six bouts per day in the final two weeks. Plasma concentrations of CRP, IL6, and sIL6r were assessed by ELISA at baseline, 4w, and 8w. Statistical comparisons across the three time points were done using repeated measures ANOVA. Variables that deviated from normality were log transformed prior to analysis. Significance was set to p<0.05. RESULTS: 21 men (age: 25± 5 yrs, BMI: 26.7± 6.2 kg/m2) completed the study. No significant changes were observed for CRP during training (baseline: 1.5 ± 2.3, 4w: 1.0 ± 1.4, 8w: 2.2 ± 3.0 mg/L, p>0.05). Likewise, IL6 (baseline: 1.4 ± 1.6, 4w: 1.6 ± 1.7, 8w: 1.2 ± 2.2 pg/ml) and sIL6r (baseline: 36.2 ± 23.9, 4w: 27.8 ± 22.0, 8w: 32.6 ± 22.2 ng/ml) did not change with training (all p>0.05). CONCLUSION: Though it has been suggested that HIIT may reduce inflammation, results of the present study do not indicate HIIT influences specific inflammatory mediators in healthy young men. Future research should explore the potential anti-inflammatory benefits of HIIT in different populations and disease states.