Recombinant human interleukin-6 infusion during low-intensity exercise does not enhance whole body lipolysis or fat oxidation in humans

nterleukin-6 (IL-6) is released from adipose tissue under noninflammatory conditions, which contributes to about 30% of the circulating IL-6 levels at rest. Recently, IL-6 was shown to be produced in skeletal myocytes during contraction. In addition, IL-6 is released into the circulation during contraction in significant quantities. However, the precise biological roles of the skeletal muscle-derived increase in circulating IL-6 levels have not been fully elucidated. At the start of moderate-intensity exercise, the rate of appearance and disappearance of fatty acids increases, which changes progressively as exercise progresses. It is possible that IL-6 acts in an endocrine-like manner to increase circulating lipids. The role of the cytokine IL-6 in regulating fatty acid metabolism in human beings during exercise was examined.