DXA-Scans-webUltramarathon athletes and sports medicine experts, Drs. Tracy Hoeg, John Diana, and Marko Bodor along with Drs. Emily Krause and Michael Frederickson from Stanford, investigate bone health in ultramarathon runners. 

Climbing more than 18,000 feet and descending nearly 23,000 feet over mountain trails and dirt roads, the Western States 100-Mile Endurance Run is a highly sought-after challenge for select racers worldwide.  More than just running; this race offers an immense opportunity to investigate the effects of extremes on the human body.

With a focus on risk factors for decreased bone mineral density and stress fractures, each runner’s bone mineral density was measured within 48 hours of the race start via the mobile dual-energy X-ray absorptiometry scan (DXA) units onsite. Dr. Hoeg obtained study approval from the Institutional Review Board (IRB) through UC Davis and preliminary results were presented at the American Medical Society for Sports Medicine and the Western States Endurance Run Medical Conferences.

“It was my passion and interest in ultramarathon research that brought me and my family to California from my home in Denmark in 2013”, said Dr. Hoeg. “I have continued my involvement in research at the Western States in partnership with UC Davis ever since.  I met Dr. Bodor for the first time at Western States after I gave a talk on ultramarathon research – and that day is what led to me doing a fellowship at the Bodor Clinic. My favorite part of the study has been what we have learned about human physiology, the connections with the runners and friendships made with the Stanford research team.”

Highlights of the research conducted:

  • 61 runners from the 2018 Western States Run were enrolled.
  • Each runner completed an online questionnaire assessing dietary habits, history of bone stress injury (BSI) and if applicable, menstrual dysfunction.
  • Bone mineral density (BMD) was assessed via mobile DXA scans.
  • 21% percent of females and 33% of males had low BMD for their age.
  • Males had relatively lower BMD than females.

Bone-HealthOverview and other findings included in the study:

What is a bone stress injury (BSI)?

A BSI is an overuse injury whereby the rate of bone loading is greater than the rate of recovery, causing pain that increases with running and does not go away after warming up.

The latest research reveals that decreased BMD and prior BSIs appear to be at least as common among adult ultrarunners as in collegiate runners. 42% of females and 30% of males in our study reported one or more prior BSIs. Ultramarathon runners tend to have decreased bone mineral density despite running being a weight-bearing sport. Surprisingly, our male ultrarunners were found to have even lower bone mineral density compared to females.

What are the factors involved?

BSIs occur due to modifiable extrinsic factors (the load applied to the bone and degree of rest and recovery), or intrinsic factors (the strength of the bone) related to training and health. Adequate caloric intake, calcium intake, vitamin D levels, and a regular menstrual cycle in women, in addition to participation in weight-bearing sports, are all important for bone health. About half of the female ultramarathon runners in our study reported irregular periods. 52.8% of males and 57.9% of females showed behaviors consistent with an eating disorder or restrictive caloric intake.

Team-Bone-DensityWhy is this research important to the future of sports medicine?

Collegiate runners are known to be at high risk for stress fracture and decreased bone mineral density. Their risk factors for these problems have recently become well-defined, by, among others, Drs. Kraus and Fredericson. It is not known if older ultramarathon runners have the same risk for bone health problems and if they have the same risk factors. Decreased bone mineral density and bone stress injuries can lead to serious fractures that can cause long term disability (in the worst-case scenario). It is important to understand how runners can minimize their risk of stress fractures.

What should you do if you think you may be experiencing symptoms of a BSI?

Do not ignore BSI warning signs. A BSI can end your running career if you keep running with it and it’s in your best interest to identify it as early as possible. If you have pain that does not dissipate with running or increases, seek medical care.

Images courtesy of Tracy Hoeg, MD
Bottom image from left to right: Kira Fay Skaggs; Tracy Hoeg; MD, Emily Kraus, Md; and Megan Roche, MD.

Read more on the research results published by Dr. Tracy Hoeg in the article “Bone Health in Adult Long-Distance Runners” in iRunFar’s Running Science Column.


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