Now you can have it all: Running at a quicker pace can actually lessen the impact of your workout, reducing your risk for knee injuries

Corbis Images

Slow and steady may seem like the best way to minimize impact and avoid injury on a run, but speeding up may save your knees. A new study in the Journal of Orthopedic and Sports Physical Therapy found that running at a faster speed reduces the overall stress to your knee by 30 percent-a massive difference for any runner with knee woes (about 13 percent of you, according to a Runner's World poll). (Check out these tips on Knee Pain and Running from Marisa D'Adamo.)

Researchers looked at runners logging 1,000 meters at 5, 7.3, and 9.8 miles per hour. For each individual stride, they found that the faster people ran, the more stress was put on the knee. However, the faster you run, the fewer strides you make to cover the same distance. That means speeding up actually allows your knees to absorb less impact over your whole run.

But don't start the stopwatch just yet. Previous Danish research shows that increasing your speed can actually add load to your lower leg and foot, putting your Achilles and plantar fascia at risk. "You're going faster, but it's actually causing you to land with more force with each stride. Those intense forces in a short amount of time can be damaging to your body if you don't train properly," says Scott Weiss, a New York-based exercise physiologist and athletic trainer.

Training properly is key. The main issue people have when increasing speed: They tend to start running on their toes. But running on your toes can't be maintained without your lower legs taking a beating, Weiss explains. (Find out how to Run Faster, Longer, Stronger, and Injury-Free.) "Since we became bipedal (using two legs to walk), natural human gait has been to land on the heel of the foot-and that's the best way to absorb shock from the body," Weiss says.

And despite the idea that running on your toes or mid-foot will help you speed up, a study from the University of Spain found that when people ran a half-marathon, those who landed on their heels were significantly more economical when pacing at 8:46 per mile or 7:25 per mile. In fact, mid-foot strikers only clocked in 38 seconds faster, on average, for 13.1 miles than rear-foot strikers.

The safest way to learn to speed up while heel-striking is with the help of a running coach. But if you're going it alone, focus on either increasing your stride length or frequency while maintaining your heel landing, Weiss suggests. "That will help you become faster and avoid loading both your knee and your lower leg muscles." (Also try these 6 Rules for Running Faster.)