Just like letting your body recover, good nutrition is another key to avoiding serious injury when running. "You're expending a lot more calories and you want to make sure you're replenishing with good, solid nutrition and not a lot of junk food. Try to replenish with good fuel," she says. "I think our bodies are really like the best car you can imagine. If you're going to try to perform at the highest level and you're a NASCAR driver, you're not going to put economy fuel into your car—you're going to use really good fuel."

One increasingly common running injury, especially among women, is stress fractures. Dr. Weber says many of these injuries actually stem from premature osteopenia, or lower than normal bone density. The condition is considered a precursor to osteoporosis and is most often found in 50- and 60-year-olds—not 30-something athletes.

If in her diagnosis Dr. Weber discovers that a runner has osteopenia, she says the next discussion she has with a patient is about nutrition. "We have to educate them on proper eating," she says. "Are they having any deficiencies of vitamin D or things like that?"