High Intensity Exercise Increases Post-exercise Levels Of Interleukin-1 Receptor Antagonist

BACKGROUND: Prolonged acute exercise triggers an anti-inflammatory response in healthy adults, including an increase in circulating levels of IL-1 receptor antagonist [IL-1Ra]. The purpose of this study was to examine the effects of a single moderate-intensity or high-intensity exercise bout on plasma IL-1Ra levels in healthy adults. METHODS: Six participants (33% female, median age 29 [interquartile range 26.5-39.0] (years), BMI 31.1 [24.6-35.0] (kg/m2) free of cardiovascular or rheumatologic disease, underwent a standardized cycle ergometer protocol to measure lactate threshold (LT) and peak oxygen consumption (VO2peak). Participants then completed three visits in a random order: 1) control (CON); 2) high-intensity exercise (HIE - 75% ∆ between LT and VO2peak); and 3) a moderate intensity exercise visit (MIE - at LT) on a cycle ergometer. Exercise was matched for energy expenditure within subjects. Venous blood was sampled pre-exercise/control, and every 30 minutes up to 180 min. Percent change in plasma levels of IL-1Ra (∆IL-1Ra%) from pre-exercise to peak post-exercise was measured using enzyme-linked immunosorbent assay (ELISA). Data are presented as median [IQR] and compared between intensities using Wilcoxon signed-rank test. RESULTS: VO2peak was 26.0 [20.6-31.6] (ml/kg/min), representing 124 [106-137] % of predicted. Baseline IL-1Ra levels were 192 [135-278] pg/mL. Energy expenditure was well matched between intensities (HIE: 276 [216-286] kcal, 29 [26-30] min; MIE: 275 [216-275] kcal, 50 [50-50] min). There were no significant changes in IL-1Ra during CON (∆IL-1Ra +20% [+2 to +26%]; p = 0.16) and MIE (+14% [-3 to +67%]; p = 0.31), whereas HIE increased IL-1Ra (+128% [+37 to +286%] at 135 [120-173] min; p = 0.03; Figure).CONCLUSION: High-intensity exercise elicits a greater anti-inflammatory response than moderate-intensity exercise or no exercise control in healthy adults. This work was funded by NIH R01DK129510-01.