|Dr Yuri Verkhoshansky (L), the "Father of plyometrics"|
Usually, training techniques in distance running are ahead of the science. A lot of things most runners and coaches would consider core elements of a training program, like high mileage, short repeats for speed, or long runs aren't supported by a solid body of science. And that's okay! Some things, like proper long-term development, just aren't well-suited for a laboratory study. What's really perplexing, though, is when training lags behind the science. One area where this is true is explosive strength training, and plyometrics exercises in particular.
"Plyometrics" is a term that was applied to explosive jumping exercises developed originally by the Soviets. The actual root of the word means, in Greek (plio / plythein + metric), "to increase the measurement." Today, "plyometrics," or "plyos" for short, is often taken to refer to pretty much any body weight jumping exercise, but historically it referred to a very specific kind of jump training.
True plyometric training takes advantage of a muscle process called the stretch-shortening cycle, which (without getting too bogged down in details) allows your muscles and tendons to temporarily store energy from impact for a fraction of a second, then release it to help rebound off the ground. This is what allows you to jump higher after doing a "windup" instead of jumping from a dead stop. The stretch-shortening cycle plays a major role in running economy in distance runners, as the greater the percentage of impact energy you can return, the less "new" energy you need to expend each step. The critical thing to remember about the stretch-shortening cycle is that it is time-dependent: unlike a spring, it can't store energy indefinitely. The stretch-shortening cycle works best when your contact time with the ground is limited to a few tenths of a second, so slow or medium-speed jumps (or jumps which don't involve an impact immediately prior to takeoff) aren't truly plyometric.
Additionally, plyometric training is designed to get maximum force and energy return out of your muscles. As such, each plyometric exercises in a plyo training regimen needs to be done fresh. This means plyometrics are not a conditioning tool; doing many plyometric jumps in succession without taking adequate rest undermines your ability to return the maximal amount of energy possible, and thus hampers the training effect. There is no such thing as "plyometric circuit training" (though certainly similar exercises can be used in circuit training).
The lack of plyometrics programs for distance runners
Getting back to our initial point, plyometric training is a well-documented way to improve running economy and performance in distance runners. This has been documented in recreational runners (~10 miles per week, no performance data)1, moderately trained competitive runners (35-50 miles per week, 3km PRs of 9:22-10:17)2 and highly trained elite runners (60-90 miles per week, 3km PRs near 8:30).3 The fact that plyometric training has been demonstrated as an effective training method even in high level runners would make you think that it'd be quite popular. Unfortunately, that's not the case.
I don't doubt that many top runners and coaches employ plyometric training, but this practice hasn't percolated down to the distance running rank-and-file. This might be intentional, or it might just be that high level coaches are too busy to bother with publishing their entire strength and conditioning programs. There's certainly no shortage of brief articles or blog posts extolling the virtues of plyometrics, but these conclude with bland recommendations like adding a few squat jumps to your weekly routine. Full plyometrics training programs designed for distance runners are sorely lacking. After having researched plyometrics in-depth and not finding anything in the way of quality plyometrics programs for distance runners, I decided to construct my own.