If you run 50 to 70 miles per week, you are an advanced runner.

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Out of fear, need for food and fun, humans have been loping long distances since time immemorial. Indeed, as many as 2 million years of running, jogging, dashing and scampering probably raced by before formalized professional competitions began gaining popularity at the turn of the 19th century. The sport of running tapped into something primal and innate; over the century that followed, it gained enough ground in Great Britain, and later, the United States, to render coaching a marketable skill. In the early 20th century, stopwatch racing and the expansion of foot races were introduced around the globe [source: Sears].

Structurally, the human body has always been ill suited for sprinting. Even the best human sprinters can only achieve speeds of about 22.8 miles per hour (36.6 kilometers per hour) and can only maintain that rate for less than 15 seconds. Compare that to cursorial specialists -- animals specifically adapted to fast running, such as horses, greyhounds and pronghorn antelopes. They can gallop at around 33.6 to 44.7 miles per hour (54 to 71.9 kilometers per hour) for several minutes. Fast running also takes a greater toll on humans, burning double the metabolic energy per distance traveled than would be typical for another mammal of equal body mass.

Endurance running, which uses aerobic metabolism to power movement over long distances, is quite another story. Of all the primates, only humans lope, and we're surprisingly good at it. Indeed, distance running is rare, even among quadruped mammals. Only social carnivores (like dogs and hyenas) and migratory ungulates (such as wildebeest and horses) engage in this kind of running [source: Bramble].

Today, running bestrides the world as a sport, an industry and even as a demographic. Statistically, core runners (people who run and train year-round) are highly educated, moderately affluent, and favor a 5 kilometer (3.1 mile) run, second only to a half-marathon. With proper training and practice, most healthy individuals can achieve a 5K (3.1 miles), and the numbers reflect this: The average age among core runners clocks in at around 38.6 years old [source: Running USA].

As the popularity of running the 5k has grown, so too has interest in maximizing performance via advanced training techniques. This raises a question: What constitutes "advanced"? Well, the term certainly falls into the realm of the subjective, but if you run about 50 to 70 miles (80.4 to 112.6 kilometers) per week and can crank out a 5K in less than 17 minutes (men) or 20 minutes (women), then you probably qualify.

If you're ready to kick your 5K into high gear, read on.