App measures efficiency at a given speed

By Scott Douglas

A new app called Kangarun can help improve running form by measuring your vertical oscillation, the app's developer claims.

"Exercising without a coach, I was naturally interested in finding a way to independently and easily measure my running efficiency," says developer Enrico Sandoli. "In other words, was I using my muscle energy in the best possible way, or was I spending more than was needed to bounce up and down? If that was the case, I was increasing my risk of getting injured, or, at best, I was wasting a lot of energy that I could better employ to go faster."

To use Kangarun, you attach an iPhone to your waistband while you run. Sandoli says readings are more accurate when done on a treadmill, because your running speed is constant. The app calculates the amount of energy you spend in vertical motion compared to your total energy expenditure, and produces a percentage value of running efficiency. A lower value means less efficient running, Sandoli says, because you're expending energy to go up and down instead of forward.

The app produces a graph that can detail changes in efficiency over time. It doesn't, however, tell you how to get more efficient. Excess vertical oscillation is often caused by weakness in your rear-body musculature, especially the glutes. It's also important to keep in mind that runners' efficiency can vary greatly by pace – someone who's a model of efficiency at 5:00 per kilometre pace might become an energy profligate at 3:45 pace. In these cases, more time spent at the faster pace usually leads to greater efficiency not only at that pace, but at slower paces as well.

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