Whether you're training for a marathon or enjoying a daily jog, running may be a good way to maintain good health. But it’s hard on the joints, especially the knees.

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As many as 70 percent of runners may experience knee injuries at some point in their lives, according to Dr. Kevin Plancher, an orthopedic surgeon and sports medicine specialist.

And spring is one of the most common times of the year for running injuries to take hold.

“We see a lot of runners with injuries in the springtime and it’s not because they did anything wrong,” said Plancher, who owns Plancher Orthopedics and Sports Medicine with offices in New York City and Greenwich, Conn. “Runners get so excited once the warm weather hits that they go out and start running without stretching and without replacing their shoes from last year. And injuries can occur in runners whether they’re 20 or 40 or 60 years old.”

The most common knee injuries are patello-femoral pain, also known as runner’s knee, and iliotibial band (ITB) syndrome.

Runner's knee occurs when the kneecap (patella) rubs against the bottom of the thighbone, and can result in irritation and erosion of cartilage, Plancher said. ITB syndrome involves irritation to the band of tissue that runs along the outside of the thigh, which can become irritated from repetitive rubbing over the outside of the knee.

There are ways to prevent knee injuries, however.

“Just because you're a runner doesn't mean you'll have runner's knee — or any other knee injury," Plancher said. "These problems are typically caused by overuse or by a misalignment of the joint that's exacerbated by improper running habits — all things that can be avoided."

Here are some tips on how to prevent knee injuries:

1. Wear the right shoes. Forget cushioning for a second. First, runners need to find a shoe that fits their feet correctly. For example, some people have wide widths, others have more narrow widths. A doctor can help you find the right the fit for your foot.

Also, Plancher warns that even the most expensive pair of sneakers probably won’t provide runners with adequate support.

“A lot of running shoes nowadays have little support,” Plancher said, suggesting that users remove the inserts or insoles that come with their sneakers and buy new ones that offer better support.

“There are good inserts and bad inserts, it doesn’t really matter the brand,” he said. “The most important thing is to buy one that has a little rigidity to it. If you can bend it in half, it’s not going to offer you enough support.”

2. Always stretch. Stretching your muscles is necessary before any run whether long or short, fast or leisurely, Plancher said.

“Don’t underestimate the importance of stretching,” he said. “It’s the best way to get the blood flowing, especially in cool weather.”

In addition to knee injuries, stretching can also help runners prevent hip injuries, shin splints, and foot-cramping, Plancher said.

3. Cross train. Not surprisingly, runners tend to focus on one and only one method of exercise: running. Doing so tends to bring the body out of balance. In the case of runners, they tend to end up with hamstrings (the muscles the run along the back of the thigh) that are stronger than their quadriceps (which run along the front of the thighs.)

Plancher recommends runners add core-strengthening workouts to their routine that strengthen both the front and the backs of thighs, as well as the muscles of the hips and buttocks.

4. Don’t over do it. Once the warm weather hits, runners tend to immediately begin running long distances. Often, it’s a matter of taking on too much too soon. Plancher recommends starting out slowly and building your way back up to the longer runs you were doing last spring and summer.

For those who run year-round, overtraining can occur from running long distances too often without any breaks in between.

“Be sure to incorporate one or two days of rest each week, and mix a few easy or short runs in with the hard or long ones,” Plancher said. “Don't increase your mileage by more than 10 percent a week. Start at a slow pace and be sure to stretch before and afterwards, to keep your muscles limber and your joints flexible.”

5. Eat right, supplement wisely. Runners need to the right types of nutrients in order to maintain healthy joints. Experts recommend adults get 1,000-1,200 milligrams of calcium each day, Plancher said. Dark green vegetables and dairy products are the best sources of calcium.

Additionally, many runners take glucosamine and chondroitin sulfate supplements. Glucosamine is an amino sugar that seems to play a role in cartilage formation and repair, and chondroitin is a complex carbohydrate that helps cartilage retain water and maintain its elasticity. Plancher said some doctors even offer glucosamine shots to their patients.

Although the supplements don’t help everyone, some research has shown that taking the two together can provide relief for people with moderate-to-severe osteoarthritis pain. Plancher recommends a dosage of 1,500 mg per day of glucosamine and 1,200 mg a day of chondroitin sulfate.