A graphic depicting Teton Running Company's elite team and denoting that the featured workout is a progression runFeatured Workout

Progression Run

You may have heard that the tempo run is the biggest fitness bang for your buck. The question is, how do you get the most our of your tempo. there are many variations on the tempo run. Some like shorter, faster tempos, 3-4 miles between 10K and Half-Marathon pace. Some like to go 6 miles at around Half-Marathon pace or a little slower. Some Marathon training programs prescribe as much as 15 miles at Marathon pace. The most effective way to build fitness is to take a varied approach. using multiple variations of a tempo run will not only give you more well-rounded fitness, but it will also hone your internal pace clock. 
One of the best ways to challenge yourself, improve your fitness, and teach your body to run different paces is the progression run. This is generally a longer tempo run (1.5X-2X your standard tempo distance.) The idea with a progression run is to start at a pace that is slightly challenging, but still fairly comfortable, maybe 10-15% faster than your easy day pace. Run this pace for 12.5% of the total distance, then increase the pace by 2-3% and run the new pace for 12.5% of the total distance, increase by 2-3% again and run the new pace for another 12.5% of the total distance, continue to do this for the full duration of the workout. The workout won't feel all that challenging until about halfway.
Progression running is certainly challenging, but it provides a few benefits. First of all, the workout doesn't start out very hard, you will get the luxury of easing into the pain. It is also easy to hit your pace early on which provides encouragement for the latter parts of the workout. Progression also teaches your body to speed up and expend more effort as it gets tired, instead of slowing down. Aside from being a workout that does a great job of stimulating your aerobic threshold, it also teaches your body to continue buffering lactic at increased paces and later in the workout. This will help you in the mid to late stage of a race.
The example in this video is with our Teton Running Elite team. They headed out to Rexburg to run an 8 mile progression run on the course for the Teton Dam Half-Marathon. John (purple shorts, yellow shirt) was hoping to start around 5:40 pace and finish around 5:10 pace. Micah (red shorts) was hoping to start at 5:40 pace and stick with that pace for the whole distance, progressing only to 5:25 at the fastest, and Richard (white shirt, black shorts) ran every other half mile with John. The workout was going according to plan until they hit a long uphill stretch that also featured a 10-15 mph headwind. This forced the decision to turn around at 6.5 miles and run the last 1.5 miles downhill.