FEED YOUR KNEES
Your joints, like the rest of your body, need plenty of fruits and vegetables. Even recreational athletes require a minimum of five servings of each per day. It's the only way to get the micronutrients—vitamins and minerals—you won't get from other food. "Your body needs calcium, magnesium, zinc, and vitamin C to heal injuries," says Dr. William Sterett, of Vail, Colorado's Steadman Hawkins Clinic, a top orthopedic center. "Multivitamins can help, but nothing delivers nutrients as well as fresh foods." Joints also benefit from essential oils: Add oily fish (or omega-3 supplements), olive oil, avocados, and almonds to your meals a few times a week.

GET AN ALIGNMENT
Check your musculoskeletal symmetry with this simple test. Stand on a step, facing down. Put one foot forward, so you're supported on one leg. Dip down until your supporting knee is

Q&A: When should I retire my running shoes?

When they're worn out, of course, but brace yourself: That could be sooner than you think. "If you're running a few times a week or more, you should probably be replacing them every six months," advises McClure. While the shoes may show limited exterior signs of wear, the interior midsole may have lost essential cushioning.

bent about 30 degrees, then stand back up. Watch your weight-bearing knee: If it deviates from a straight path (don't panic, most do), you could have alignment issues. Correction may require expert help—from an orthopedist or experienced trainer—but the following easy fixes often solve minor problems.

1.> Shoe Inserts Creating a stable, neutral platform under your foot is step one, and an over-the-counter insole is an inexpensive, effective way for most people to get the necessary support. Many ski boots have "cantable" cuffs to accommodate off-center alignment. Have a shop help you; it's quick and simple.

2.> Bike Fit Saddle height and forward reach are the two macro-adjustments you need to consider. There should be a slight bend in the knee at the bottom of the pedal stroke, and the reach will be determined by how aggressively you ride. "Recreational riders will have a torso tilting at 45 degrees or greater," says Andy Pruitt, a cycling-biomechanics expert and the clinical director at Colorado's Boulder Center for Sports Medicine. "Racers will be 45 degrees or less."

3.> Good Form "Whether your sport is static or dynamic, in order to maintain good alignment you need to have proper form," says Dr. Raffy Mirzayan, an orthopedic surgeon who has worked with the Los Angeles Lakers and Dodgers. Quick tips: Runners, reduce side-to-side movement in your arms, shoulders, and torso. Cyclists, develop a rounder pedal stroke by staying seated and spinning in a lower gear on climbs. Skiers, keep your shoulders square to the fall line by actively reaching your uphill hand downhill.

FLEX TIME
Tight muscles are like weak muscles: bad for your joints. Yoga, Pilates, and sport-specific warm-up routines are great ways to keep limber, particularly if you're a desk jockey all week, as hours in a chair promote tighter limbs and impaired circulation. Do a ten-minute light aerobic warm-up, followed by ten minutes of activity-specific stretching, before every workout. Start here:

1.> Runner's Lunge Step one foot forward and drop until your rear knee almost touches the ground. Let your back heel rise, then sink into a stretch.

2.> Quad Stretch Brace on a wall, rail, or friend. Grab one foot and pull it back against your butt. Better yet, do the same stretch lying facedown.