Tumor necrosis factor (TNF)-α is a main deleterious pro-inflammatory cytokine found throughout the systemic circulation and up regulated following stroke and traumatic brain injury. Despite its inflammatory and injurious effects, evidence also points to TNF-α as a beneficial factor in tissue repair and neuroprotection. Furthermore, this cytokine may serve to induce endogenous neuroprotection following chronic exercise preconditioning. It is believed that exercise training produces a chronic low rating increase in TNF-α concentration, ultimately generating neuronal tolerance and protection in the setting of ischemia/reperfusion injury. Mechanisms underlying this complex picture of TNF-α have not been completely discovered, but are thought to
