When most runners tackle hills, they focus on the difficulty of the climb. But downhill running poses its own set of challenges—and rewards.
Descending feels easy aerobically, but each step triggers muscle-damaging eccentric contractions in the quadriceps and lower legs, says Greg Wells, Ph.D., an exercise physiologist at the University of Toronto and the author of Superbodies: Peak Performance Secrets from the World's Best Athletes.
On level ground, these muscles shorten as they fire; on declines, they elongate while under tension as they work to control your speed. This creates more micro-tears in each fiber, which stimulates muscle growth but leaves you fatigued and sore. That's one reason the Boston Marathon, with its four-mile downhill opening stretch, is such a hard course. (See just how tough Boston's Heartbreak Hill is.)
Practicing running down hills prepares your body to handle these eccentric contractions, decreasing the negative effects and improving your performance on net-descent courses like Boston's. But even if you're not training for a hilly race, you can benefit from incorporating regular downhill running into your routine: The muscle you build working on the decline translates into faster paces on any terrain.
You will be able to run faster with less effort, giving you the ability to perfect your technique at near-top speeds. And then there's something any kid could tell you: "Downhill training can be a tremendous amount of fun," Wells says. Here's how to safely enjoy the way down.
Select Your Slope
You can practice downhill running through either focused repeats or an extended run on a hilly route. Either way, you'll want to choose your hills wisely, says Sean Coster, an exercise physiologist and running coach at Complete Running in Portland, Oregon. Extreme grades—say, 20-percent drops—increase the impact too much (and the risk of ankle, hip, and knee injuries).
Instead, look for a gradual slope of no more than eight percent. (To determine the grade, use a GPS watch that tracks elevation: Run up the hill and then scope your data for the elevation change. Divide this by the distance you ran in feet to get the slope—.08 equals eight percent.)
Choose softer, more forgiving surfaces, such as grass or gravel, if you're new to downhill work. But if you're training for a hilly road race, progress to some paved declines in the months beforehand to practice, says Rebekah Mayer, national training manager at Minneapolis-based Life Time Run.