A tempo run is a type of training run designed to improve a runner's speed and endurance. It involves running at a steady, challenging pace that is faster than a typical easy run but sustainable for a longer duration. This pace is often referred to as the lactate threshold, where the body starts to accumulate lactic acid, helping runners learn to maintain speed without fatigue. Tempo runs are usually performed over a distance of 20 to 40 minutes, depending on the runner's fitness level. They can be incorporated into a training plan for various events, including marathons and half-marathons, to enhance overall performance.