Specialty Program - Youth

Can risk factors for stress fractures be identified in female runners?

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stretch affect
October 15, 2020

Female runners are at least twice as likely as men to develop stress fractures. Researchers from Thomas Jefferson University sought to find the reason and suggest possible measures for preventing stress fractures.  

The study consisted of 40 female recreational runners both with a history of stress fractures and without to assess what contributed to the likelihood of getting a stress fracture.

The study provided two key findings that should not be overlooked when preventing stress fractures in female runners:

  • Physiological reasons – bone structure and density and hormonal status
  • Training routine – training intensity, nutrition, insufficient strengthening, and ignoring pain

What is a Stress Fracture?

According to the Mayo Clinic, stress fractures are tiny cracks in the bone that are caused by repetitive force often brought on by increasing the amount or intensity of an activity too quickly.

In our normal daily activities, our bones go through a process known as bone remodeling.

Bone remodeling is constant; up to 10% of all bone mass may be undergoing remodeling at any time. Bone is resorbed (the breaking down of the bone) by osteoclast cells (derived from bone marrow) and new bone is deposited by osteoblast cells.

When there is greater bone resorption than bone formation, this can lead to a greater risk of a stress fracture.

Risk Factors for a Stress Fracture: Physiological Factors

The study revealed that physiological factors, which are often overlooked, should play a much more important role when evaluating injury and preventing stress fractures.

The physiological factors evaluated include:

Bone Structure and Density

“Women with a history of stress fractures had lower hip bone mineral density compared to women with no history of stress fractures, indicating that decreased bone strength could increase the risk of injury.”

Bone mineral density is a measurement of the amount of minerals in your bones. It is measured by a test called a dual-energy X-ray absorptiometry (DXA).

The results, referred to as a T-score, are based on the bone mineral density of a healthy 30-year-old compared to your own value. A score of 0 is considered ideal.

The National Institutes of Health offers the following guidelines for bone density scores:

Normal: between 1 and -1

Low bone mass: -1 to -2.5

Osteoporosis: -2.5 or lower

Severe osteoporosis: -2.5 or lower with bone fractures

Also as a part of bone density, bone remodeling can be evaluated by a blood test that looks for these markers. This can be an important step as study results showed “increased bone turnover in the group of women with stress fractures.”

Hormonal Status

The researchers found that while there was no difference in estradiol hormone levels between the two groups, women who had a stress fracture history reported menstrual changes or irregular periods as a result of their training, or during peak training times.

While hormone levels do not appear to be a driving force behind stress fractures, irregular menstrual cycles can be an indicator of too much training or increasing training load too quickly.

“Our findings also indicate that asking female runners about any menstrual irregularities during heavier training times is important during routine screening.”

Risk Factors for a Stress Fracture: Training Routine

The reference below pulled from the study is all too common among athletes who are pushing themselves to be the best.

“Women with histories of stress fractures had increased their training load more quickly. Also, while they knew of the importance of nutrition and strengthening exercises, women with a history of stress fracture more often reported not having or making the time for a balanced diet and proper cross-training to complement their running regimen.”

Let’s evaluate each of these items and what you can do to prevent them.

Increasing Training Load Too Quickly

Have a plan well in advance of any races. You should not be increasing any week’s training load by more than 10%. If you are beginning to feel overuse issues, you need to reduce your mileage or incorporate low-impact cross-training activities. You should also incorporate warm-up stretches and exercises to protect yourself from injuries.

The Importance of Cross-Training for Runners

Sometimes you are forced into cross-training like swimming or biking to replace the high impact activity of running, but cross-training is actually very beneficial to greater running fitness.

According to Runners World there are three main ways cross-training can increase your speed:

  1. Enhance a runner’s efficiency
  2. Increase a runner’s power
  3. Increase the amount of time a runner is able to spend training without accumulating fatigue or getting injured

Cross-training also provides a form of active recovery—a type of rest—that is so critical when it comes to recovering from a stress fracture. A light workout can accelerate recovery beyond outright rest by just slightly increasing the body’s need for recovery.

Strength Training Exercises

Strength training helps prevent early muscle fatigue, injury, and the loss of bone density that comes with aging.

Runners should focus on exercises that will specifically benefit them in the sport. Runners typically don’t need to isolate individual body parts. In other words, you don’t need a “leg day” or an “arm day”.

Choose exercises that develop runner-specific power like core, glutes, hamstring, and hips. These important muscle groups will help with your performance.

Nutrition and Diet

We are not going to focus on the types of food you should eat, but rather eating habits that can help in preventing stress fractures.

  1. Eat to accommodate increased energy expenditure — the more you work out or the greater the intensity of your workout, the more energy you will need from food.
  2. Eat a post-workout snack — Getting nutrients after exercise can help you rebuild your muscle proteins and glycogen stores. It also helps stimulate the growth of new muscles.
  3. Eat healthy fats to decrease inflammation
  4. Focus on calcium and Vitamin D intake
  5. Consider dietary supplements to boost bone density — Calcium, Magnesium, Collagen, Strontium Citrate, Drynaria, and Vitamin D3 are all supplements that help boost bone density. NOTE: (with the exception of Vitamin D) you should not take these if you are taking bisphosphonates. There needs to be a break, or “washout period”, between the bisphosphonate and these items because they will not work effectively. Alternatively, if you take Calcium, Magnesium, Strontium, and Drynaria at the same time, they should be taken 2 hours apart to get maximum absorption.

Ignoring Pain

“Women in [the stress fracture] group reported pushing through the pain and running despite an injury more often than those without stress fractures. In the interviews, it sounded like these women had trouble knowing which pain was normal, and which pain was abnormal.”

If you have difficulty deciding when to push through pain and when to back off, seek advice from a physical therapist, orthopedic doctor, or chiropractor that can help you interpret pain cues from the body and help you differentiate between normal aches and pains and indicators of a serious injury. Of course, we at Stretch Affect are here to help as well.

Key Takeaways for Preventing Stress Fractures

  1. Pay attention to your training load. Do not increase more than 10% a week.
  2. Pay attention to your menstrual cycle. If it becomes irregular, this could be a sign of increasing training load too quickly.
  3. Do weight-bearing exercises. Weight-bearing exercises helps increase bone density and improve muscle fatigue.
  4. Don’t ignore pain. If pain is preventing you from performing get it checked out by a qualified professional.
  5. Use cross-training when needed to decrease the high-intensity act of running. Also, use cross-training to recover.
  6. Focus on your diet, being mindful of consuming Calcium and Vitamin D
  7. For those with poor bone density, consider dietary supplements such as Collagen, Strontium Citrate and Drynaria

If you are in the San Diego area or need virtual assistance, schedule a visit with Stretch Affect to evaluate your running training plan and ways to prevent stress fractures. Assisted stretching will help keep you safe and performing well.


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