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Fall is here, cross-country running season has begun and the 26th Steamtown Marathon is only a few weeks away! With that in mind, running injuries, some very specific to women, are on the increase…

While driving to or from work have you noticed more local running enthusiasts in the past few years? Moreover, have your noticed that most of the runners are women? Scranton Running Company has contributed to NEPA’s participation in a national trend; more women are engaged in running than men! Female runners account for 9.7 million runners (57%) while 7 million males run on a national level.

With this surge, the female runner has been subjected to a host of related injuries, including shin splints, which often lead to stress fractures. New research has found that stress fractures may be related to the loss of weight and body mass associated with the sport.

A recent study from Ohio State University found that female runners with a Body Mass Index (BMI) below 19 may have a higher risk of developing stress fractures than women with a BMI of 19 or above. Furthermore, the study also found that these women took longer to recover from these injuries.

According to Timothy Miller, MD, “When body mass index is very low and muscle mass is depleted, there is nowhere for the shock of running to be absorbed other than directly into the bones. Until some muscle mass is developed and BMI is optimized, runners remain at increased risk of developing a stress fracture,”

The study also found that female runners with a BMI of 19 or higher with severe stress fractures required 13 weeks to recover from their injuries and return to running. Runners with a BMI lower than 19, however, took more than 17 weeks to recover.

They concluded that women should know their BMI and consult with a medical professional to maintain a healthy number. Additionally, women should cross-train and include resistance training to improve the strength and muscle mass of the lower extremities to prevent injury.

The current BMI wisdom, according to the National Institutes of Health, is 19.8 for men and 24 for women, however, strong and competitive women tend to have a BMI of 26. A BMI of 18 is considered malnourished.

What is BMI?

Body mass index (BMI) is a measure of body fat based on height and weight of adult men and women over 20 years of age, according to the National Institutes of Health.

BMI = (weight in pounds / height in inches squared) X 703)

Example 1: a person who weighs150 pounds and is 68 inches (5 feet 8 inches) tall has a BMI of 22.8

Example 2: a person who weighs 110 pounds and is 66 inches (5 feet 5 inches) tall has a BMI of 17.7

Underweight      < 18.5%

Normal weight      18.5 to 24.9%

Overweight      25 to 29.9%

Obesity            30 and over

What is a stress fracture?

A stress fracture is fatigue damage to bone with partial or complete disruption of the cortex of the bone from repetitive loading. While standard x-rays may not reveal the problem, a bone scan, and MRI will. It usually occurs in the long bones of the leg, mostly the tibia (shin bone) but also the femur (thigh) and foot. Occasionally, it occurs in the arm.

Who is at risk for stress fractures?

FEMALE RUNNERS WITH BMI LOWER THAN 19 – is a primary risk factor.

10-21% of all competitive athletes are at risk for stress fractures. Track, cross country and military recruits are at greatest risk. Females are twice as likely as males to have a stress fracture. Other athletes at risk are: sprinters, soccer and basketball players, jumpers, ballet dancers are at risk in the leg and foot. Gymnasts are also vulnerable in the spine while rowers, baseball pitchers, golfers and tennis players can experience the fracture with much less frequency in the ribs & arm.           

The problem is much more prevalent in weight bearing repetitive, loading sports in which leanness is emphasized (ballet, cheerleading) or provides an advantage (distance running, gymnastics).

Stress fractures usually begin with a manageable, poorly localized pain with or immediately after activity such as a shin splint. Over time, pain becomes more localized and tender during activity and then progresses to pain with daily activity and at rest.

Other Causes of Stress Fractures

Prevention & Treatment

Source: Ohio State University, Science Daily

Visit your doctor regularly and listen to your body.     

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This article is not intended as a substitute for medical treatment. If you have questions related to your medical condition, please contact your family physician. For further inquires related to this topic email:

Paul J. Mackarey PT, DHSc, OCS is a Doctor in Health Sciences specializing in orthopaedic and sports physical therapy. Dr. Mackarey is in private practice and is an associate professor of clinical medicine at Geisinger Commonwealth School of Medicine. For all of Dr. Paul's Articles, visit our exercise forum!