IL6 and infection: In the absence of exercise, high blood levels of this cytokine can generate a supra-physiological inflammatory response, which interferes in several key processes in the regulation of glucose homeostasis and could contribute to insulin resistance41; however, after a strenuous exercise, serum IL-6 concentration increases in the muscle by 100-fold up to 24 hours due to muscle contractions42; consequently, this cytokine increases insulin sensitivity, improves glucose tolerance43, and plays a key role in rebuilding muscle cells and fighting infections through the activation of macrophages40, 44.