A tempo run is a type of training run designed to improve a runner's speed and endurance. It typically involves running at a steady, challenging pace that is faster than a normal jog but sustainable for a longer duration. This pace is often referred to as the "comfortably hard" pace, where the runner can speak in short sentences but not hold a full conversation. Tempo runs are usually performed over a distance of 20 to 40 minutes, depending on the runner's fitness level and goals. Incorporating tempo runs into a training plan can help enhance a runner's lactate threshold, allowing them to run faster for longer periods during races.