Being Thin Could Boost Stress Fracture Risk in Female Runners

Being Thin Could Boost Stress Fracture Risk in Female Runners

Female runners with a low body weight are more likely to have stress fractures and take longer to recover from them, according to a new study.

Researchers from the Ohio State University Wexner Medical Center reviewed data on dozens of injuries suffered by female college runners. They found that runners with a body mass index (BMI) below 19 were more likely to suffer stress fractures than others. BMI is an estimate of body fat based on weight and height.

Women with a low body weight were also sidelined longer after an injury. Among those with the most severe stress fractures, recovery time was 13 weeks for women with a BMI of 19 or higher. That compared to more than 17 weeks for those with a BMI below 19, the study found.

“We found that over time, we were able to identify the factors that put female runners at an increased risk of developing a stress fracture,” said study co-author Dr. Timothy Miller, assistant professor of clinical orthopedic surgery and sports medicine.

“One of the most important factors we identified was low body weight, or low body mass index,” he said in a hospital news release.

Having too little lean muscle mass to dissipate the impact of repetitive pounding on hard surfaces makes the bones of runners’ legs vulnerable to injury, according to Miller.

“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,” he explained.

Female athletes should maintain a BMI of 20 to 24, Miller suggested.

A woman who is 5 feet, 5 inches tall and weighs 120 pounds has a BMI of 20, according to the U.S. Centers for Disease Control and Prevention.

The BMI for an average American woman is 26, the CDC says.

To prevent injury, Miller said women should stay at a healthy BMI and include resistance training in their workout regimen to strengthen their lower legs, “even if that means adding weight from additional muscle mass.”

The study was published recently in the journal Current Orthopaedic Practice.

Stress Fractures in Young Athletes

Teen girl holding ice pack on shinCompetitive sports can give some young athletes an edge over their peers. When fun, teamwork, and good sportsmanship are the top goals, sports can improve young kids’ physical and emotional health, self-esteem, and even their relationship skills. Unfortunately, young athletes must also compensate for still-growing bones, tendons, and muscles. Sometimes sports injuries happen.

The most common type of sports injury is an overuse injury such as a stress fracture. Overuse injuries are becoming more common in young athletes Playing sports year-round without time off doesn’t give young bodies enough time to rest and recover.

How stress fractures happen

Stress fractures happen when muscles are too tired to take on the impact of exercise, and the bones absorb the added stress. When those bones become too strained, they develop a tiny break known as a stress fracture.

 

Most stress fractures affect the bones in the lower leg. Stress fractures are also common in the feet.

These are the most common causes of stress fractures:

  • Increasing the frequency or intensity of exercise too quickly
  • Suddenly changing the workout surface
  • Getting sudden and significantly more playing time
  • Using or wearing gear that doesn’t offer enough support, such as shoes that are worn out
  • Insufficient periods of rest between practice or events

Stress fractures can happen during any number of sports, but they tend to be most frequent in young athletes who participate in sports that involve running and jumping, such as basketball, gymnastics, and track and field. These sports involve repetitive movements that strain the muscles and bones. This increases the risk for a stress fracture.

Preventing stress fractures

Parents and coaches can do many things to help reduce the risk for stress fractures in growing bones. Make sure that your young athletes follow these guidelines:

  • Eat a balanced, nutritious diet rich in calcium and vitamin D for strong, healthy bones.
  • Participate in conditioning practice for sports.
  • Do cross-training (alternating types of physical activities).
  • Stick to sports that are age-appropriate.
  • Always warm up before practice or games and cool down afterward.
  • Get a complete physical exam before participating in sports.
  • Wear athletic shoes (and any other needed gear) that are appropriate for the sport and that offer plenty of protection and cushioning.
  • See a healthcare provider for any persistent pain or limp.
  • Drink plenty of fluids and stay hydrated for practices and games.
  • Don’t resume sports or exercise too quickly after a stress fracture or other injury.

Also, make sure that your child’s coach is aware of the signs of stress fracture. This may be milder in nature than a more severe sports injury. Pain, particularly pain that gets better when the child is allowed to rest, is the most common symptom of a stress fracture.

Stress fractures typically heal with rest alone, but injured athletes may need to take off from their sport for as long as 6 to 8 weeks to properly recover. If your child complains of any pain that persists during sports, schedule a visit with your child’s healthcare provider.