Watch Your Form
Running is a natural movement, so good running form should feel natural, says Bakoulis. "Some of the best runners in the world have terrible form!" she says. "But that's not to say that you shouldn't strive to start out with good posture habits."
Here's what to aim for:
Keep it up—your eyes should be looking ahead. Keep your chin up and back, not dropped toward your chest or jutting out in front of you.
One word: relaxed. Many runners tense their shoulders so they creep toward their ears. This causes fatigue and slows you down. Shake out your arms and keep your shoulders low and loose.
"Your legs do what your arms tell them to do, so you want your arm swing to drive your legs forward in a nice straight line," says Kastor. That means swinging your arms forward and back, not across your body. Keep your elbows bent about 90 degrees and cup your hands into loose fists with fingers lightly touching your palms.
Run "tall," so your back is comfortably straight. Avoid leaning forward from the waist.
Pointed straight ahead and upright, not tilted forward or back.
Legs and Feet
Your feet should feel quick and light, says Kastor. "You want to feel springy, like you're popping off the ground." Shorten your stride so your feet land directly underneath your body. Land on your heel to midfoot and push off through the ball of your foot.
Take It Easy
It's easy to overdo it on the days you feel good, or when you're running with a faster friend. But doing too much too soon is a classic rookie mistake that can lead to injury and burnout. "When you're first starting out, your goal should just be to have fun and run every other day," says Glover. Once you're running consistently, you can add days until you're running five days a week or more. Increase your time/distance by no more than 10 percent from week to week.
The 10% Rule
Add just enough time (or distance) to improve your fitness, and stay injury-free
THIS WEEK if you ran: 90 minutes
NEXT WEEK run: 99 minutes
THIS WEEK if you ran: 120 minutes
NEXT WEEK run: 132 minutes
THIS WEEK if you ran: 150 minutes
NEXT WEEK run: 165 minutes