I don't know about you, but spring always inspires me to get outside and run. But, as you renew your weekly running goals, it might be time to renew something else -- your shoes.

There's no definite answer as to how often you need to replace your running shoes -- it will vary depending on how often you run, the distances you run and the shoes themselves. However, most experts agree that you should start paying attention by 300 miles, and by 500 or 600 miles, you almost definitely should replace them. You might think they're fine, but you know those new aches you're feeling in your knees, hips and back? Those are all signs that it's time for a new pair.

So what should you get? Well, "Runner's World" has come out with their Spring 2009 Shoe Guide, and it's a great place to start shopping. First, they explain how to determine the right type of shoe for you. For example, your weight has some bearing on whether your shoes should have more cushion or more stability. Arch type and pronation will also make a difference, and while there are ways to figure this out at home, I've had good luck going to runners' specialty stores for advice.

"Runner's World" did their homework in creating the guide, asking 350 wear-testers around the country to run in them for a month and report back. And, they mechanically tested each shoe in the RW Shoe Lab, so there was plenty of feedback on every shoe.

This year's Editor's Choice was the Asics Gel-Kayano 15 ($135), but they also awarded the Best Update (Saucony ProGrid Stabil C S, $115), Best Debut (Karhu Strong Fulcrum Ride, $140), Best Buy (Mizuno Wave Nexus 3, $80) and many more. Styles are shown for men and women, and every shoe has notes from multiple testers along with information about the pros and cons of each shoe.

Did you find your favorite shoe on the list? Let us know what you love to run in by leaving a comment!