Progression runs are great for building stamina, mental strength and learning to run increasingly faster at the end of a race. A progression run is a run with structured pace increases from beginning to end. The distance and pace will vary based on your specific training goals.
Practicing this is also a method that can be applied during races. A runner can learn how to make a long solid sustained push at the end, which can be particularly devastating at the high school and collegiate level.
The way a progression run is structured, it forces runners to start slowly. While learning mental patience runners have a chance to allow the body to fully warm-up. Progressions runs can be incorporated several times during the training cycle without fear of over training or injury.
The goal of a progression run is to become comfortable running your goal race pace on tired legs at the end of your workout. They should be designed to boost your stamina by introducing speed gradually over the course of your training run.
There are ton of variations but below is just a basic sample. You can mix this up by doing a paced run out and a more aggressive run back to your starting point, go by times, etc.
A sample progression run:
Mile 1: Warmup pace
Mile 2: 10k pace
Mile 3: 5k pace
> Optional 5k End <
Mile 4: 1 mile pace
Mile 5: 10k pace
Mile 6: Warmup/Cool down pace
> 10k End