The effect of endurance training and downhill running on the expression of IL-1β, IL-6, and TNF-α and HSP72 in rat skeletal muscle

•Myokines are cytokines, e.g. IL-6, produced by skeletal muscle fibers.•Endurance training increased muscle levels of IL-6 and IL-1β.•Endurance training reduced muscle levels of TNF-ɑ.•Endurance training attenuated increases of HSP72 in response to downhill running.•Endurance training did not reduced increases of IL-6 in response to downhill running. This study investigated changes in the myokines IL-1β, IL-6, and TNF-α, as well as HSP72, after endurance training and after a session of downhill running. Twenty-eight rats were allocated to four different groups: 1. Eight weeks of endurance training at 65–70% VO2max (Trained); 2. Endurance training and a single session of downhill running on a 16° slope (Trained plus downhill); 3. A single session of downhill running (Sedentary plus downhill); and 4. Sedentary (Control, no exercise). Soleus and extensor digitorum longus (EDL) muscles were harvested 48h after training and/or a single session of downhill running and protein levels of IL-1β, IL-6, TNF-α, and HSP72 were measured and compared to the levels in the control animals. Creatine kinase (CK) was measured in plasma. Endurance training augmented intramuscular levels of HSP72 and IL-6 in both soleus and EDL muscles (p