'No pain, no gain." You probably hear this all the time, but does pushing through physical pain really improve your performance?

Not likely. More often, it can derail your training. By not listening to your body, you might be ignoring a serious injury like a pelvic stress fracture, an overuse injury seen particularly in female runners. This tiny crack in the pelvic bone can, if left untreated, lead to a complete fracture.

Heather Moore, owner of Total Performance Physical Therapy, believes pelvic stress fractures often go undiagnosed because they present as low back pain, hip pain, or generalized weakness.

Know your risk factors: A recent study found that among runners with stress fractures, up to 10 percent were injuries to the pelvic bone. According to Ellen Casey, a physician with Drexel Sports Medicine, athletes in endurance and running sports are more prone to these injuries, especially women.

Poor flexibility, muscle imbalance or weakness, running style, and ramping up training too quickly can cause pelvic stress fractures. Changing two facets of training - like speed and distance - at the same time can overload the body.

Treatment: Rest from training and manage the pain. Be patient. Full healing can take three or four months. See a physician if pain is severe or not improving.

Before returning to your normal exercise routine, identify and fix what caused the injury in the first place. Experts recommend all female athletes with stress fractures be screened for the Female Athlete Triad.

Train smart: Rosemarie Boehm, attending physician at Einstein Medical Center, offers these tips to avoid this common injury:

1.    Cross-train to build strength and flexibility in all muscles.

2.    Give your body a day of rest.

3.    Eat right. Are you getting enough calcium and Vitamin D?

4.    Make changes to your training gradually.

5.    Wear appropriate footwear.

6.    Have your gait analyzed.

Are you at risk for the Female Athlete Triad?

Poor nutrition + lack of menstruation + low bone density = the Female Athlete Triad.

Essentially, disordered eating and overtraining can lead to an absence of menstruation and a thinness of bones. According to Ellen Casey, a physician with Drexel Sports Medicine, although some women with the Female Athlete Triad have eating disorders, many are just not aware how many calories they need to maintain their high level of activity.

Bottom line: It is not normal to miss menstrual periods. If you have, see a physician for an evaluation.