Nutrition Management of Bone Stress Injuries
Updated: Apr 29
By the summer of 2017, I had been a dietitian for five years, had attended university (nutrition studies) for nine years, had accumulated two degrees, and was halfway through a diploma in sports nutrition. At the time, I had transitioned into working as a dietitian in sports. I was then presented with an athlete with a bone stress fracture—something I had neither heard of nor been exposed to managing as a dietitian. Thus, this blog is for:
Those experiencing a stress fracture and wanting to learn the role of nutrition in its cause, management, and/or prevention.
Dietitians who were never formally taught about what a stress fracture is and/or how to manage one nutritionally.
If you haven’t read my article on bones, check it out here. For the rest of this blog, I’ll focus on:
What are bone stress reactions and fractures, collectively known as bone stress injuries?
Who is at risk and why?
What are low- and high-risk bone stress injury sites?
What is nutrition’s role in prevention and treatment of bone stress injuries?
Given my website is focused on nutrition, for those desiring more information on bone structure and the influence of biometrics, shoe inserts, and other non-nutrition factors in bone stress injuries, check out the Hoening et al. (2022) paper. (1)
What are Bone Stress Reactions and Fractures?
Bones are active tissues that are constantly remodeling: They’re being broken down due to damage from everyday life, exercise, and simply old tissue that needs replacing, while being rebuilt to replace those damaged cells. This is the same mindset of muscles needing to recover with protein and other nutrients after training. Damaged cells need adequate recovery to continue to tolerate the demands of a training schedule.
This microdamage in bones is normal, so long as bone formation outpaces removal. (1) Otherwise, the microdamage can accumulate resulting in a bone that cannot keep up with demands. Demands could be:
An intense increase in familiar or new exercise: For instance, a sharp increase in weekly mileage for a cross-country runner, during an athlete’s preseason training calendar with an uptick in exercise after weeks of rest or less-intense/frequent activity, or an inactive adult beginning CrossFit out of the blue.
A chronically underfueled athlete who continues to train normally: Their bones are slowly being weakened due to the calorie deficit and hormonal shifts seen with low energy availability (read more about that here).
Bone stress reactions and fractures are two types of bone stress injuries (BSI), which are “an overuse injury that develops in response to repetitive loads applied to generally normal bone. (1) They are diagnosed by either an MRI (primary choice) or CT scan. (1,2)
What is a Stress Reaction?
A reaction is considered a precursor to a stress fracture and may be asymptomatic. (3) It presents as swelling of the bone (edema) on MRI and would not show a fracture line. (1)
What is a Stress Fracture?
Fractures can present as a fracture line, non-union of bone, and/or a displaced or non-displaced fracture. Moderate to severe edema is present. (1,3)
Who is at Risk and Why?
Sport Type
High-impact sports with repetitive loads are more commonly related to BSI. For instance, gymnastics, cross-country running, track, basketball, lacrosse, soccer, and field hockey. Regarding the site of injury, this relates to the bones being loaded: (1)
Gymnasts and wrestlers often experience vertebral BSI.
Cross-country athletes in the tibia (40% of BSI in this population).
Throwers in the humerus (the upper arm bone).
Basketball players in the metatarsals (51%).
Rowers in the rib bones, as they load the rib cage during the catch phase of a stroke (i.e., when the oar first enters the water).
Adaptive athletes in the upper body, due to the increased demands and reliance on the upper body.
Often there is a delay between a change in activity and the development of a BSI of roughly 4-6 weeks. Changes can be duration, frequency, intensity, or type. (1) In my experience working with cross-country runners, an increase in training intensity and/or an uptick in weekly mileage are common culprits. This is why a once annual nutrition meeting with athletes is not enough.
Prior Stress Fracture
This has been found to be the most significant risk factor. (4) Bennell et al. (1996) found that 60% of track athletes presenting with a stress fracture had a history of them, and 12.6% of that population had a reoccurring stress fracture within the next 12 months. (5)
REDs, Underfueling, and Low Energy Availability
Those experiencing Relative Energy Deficiency in Sport (REDs) are at a higher risk of BSI due to the chronic mismatch of caloric intake and exercise energy expenditure, as the hormonal changes seen in REDs “negatively affects bone density, remodeling capacity and fracture resistance.” (1)
Barrack et al. (2014) evaluated the relationship between the Female Athlete Triad risk factors and likelihood of a BSI. The study found that the presence of a single risk factor increased BSI risk by 15-20%, further increasing to 30-50% in the presence of multiple risk factors. (6) These included greater than 12 hours of exercise per week, a low bone mineral density measurement, a body mass index below 21 kg/m^2, menstrual dysfunction, dietary restraint, participation in a sport with an emphasis on lean bodies, and a low calcium intake. (3,7)
Sex and Ethnicity
In comparison to male counterparts, BSI risk is higher in female athletes (1.8-2.3-fold increase) and female military recruits (3.1-3.6-fold increase), which may in part be related to REDs. (1)
Research in the Military adds another layer related to race and ethnicity: BSI rates are lowest in Black individuals with non-Hispanic white women having the highest risk (92% higher). (1)
Corticosteroid, NSAID, and Acetaminophen Use
From a medication perspective, both corticosteroids and prolonged NSAID use have been linked to BSI. (1) Common NSAIDs include Aspirin, Aleve, and ibuprofen (Motrin, Advil). (8)
Given the estimated annual cost of stress fractures for the US Department of Defense is roughly $100 million, Hughes et al. (2019) evaluated US Army soldier NSAID and acetaminophen (e.g., Tylenol) users and if they had been prescribed one within the 30 to 180 days leading up to a confirmed stress fracture diagnosis. The researchers found that “NSAID prescription overall was associated with a 2.9-fold (95% CI 2.8-2.9) increase in stress fracture risk within the full Army population.” Compared further to those fractures occurring during basic training—an intense 11-week period “at the beginning of military service that is characterized by increased levels of physical activity and high incidence of stress fracture”—the increased risk of fracture was even higher (5.3-fold). (9)
Why is this? Hughes et al. (2019) included in their discussion the connection between NSAID use and a reduction in mechanical loading-induced bone anabolism (a.k.a., a reduction in bone building in response to exercise in the presence of an NSAID consumed before exercise). Both NSAIDs and acetaminophen reduce prostaglandins, which also have a role in bone formation. (9)
What is the Timeline for Bones to Heal?
It depends. Often, BSI are categorized into low-risk and high-risk sites, yet Hoening et al. (2023) described this black-and-white classification as lacking “detailed scientific evidence.” (10) In the presence of a BSI, dietitians working closely with a medical doctor and physical and/or athletic trainer must understand the timelines of any injury.
Low-risk BSI
These injury sites often heal without major complications and, given they're lower risk, a progression back into training often occurs earlier. (10) Sites tend to be on the compressive side of bones and have greater blood flow, meaning more oxygen and nutrient delivery to enhance the rate of healing. Recovery from a low-risk BSI could be as soon as eight weeks. (2)
Examples of low-risk sites include: (1,10)
Humerus (upper arm bone)
Forearm
Hand
Rib
Sacrum (lower spine)
Pelvic girdle
Femoral shaft (upper leg bone)
Fibula (lower leg bone)
Posteromedial tibial shaft (lower leg bone)
First to fourth metatarsal shaft
Calcaneus (heel)
High-risk BSI
Sites prone to complications, non-union, and longer healing times—upwards of 22 weeks—include: (1,3,10)
Olecranon (elbow)
Lumbar spine (including pars interarticularis [spondylolysis])
Femoral neck (superior/tension side)
Femoral head
Patella (knee cap)
Tibial plateau (the larger of two lower leg bones and so weight bears more) (11)
Anterior tibial shaft (lower leg bone; tension side)
Talus (large bone in the ankle)
Medial malleolus (bony bump on the inside of the ankle)
Tarsal navicular (weight-bearing middle column of the foot) (3)
Second and fifth metatarsal base
Great toe sesamoids
High-risk injuries tend to be on the tensile side of bones. (2)
What is Nutrition’s Role in Prevention and Treatment of BSI?
I always tell athletes and coaches that when it comes to BSI, the dietitian can be part of prevention (e.g., team education, frequent athlete nutrition check ins, supplement overview) or a referral from a team physician once a BSI occurs. It’s in the athlete’s and coach’s best interest to involve the dietitian early on, as we’re going to be present regardless.
In my experience, athletes think they need supplements to prevent or fix a BSI, but the main driver of nutritional prevention and treatment is calories. Improve the calories, but also consider micronutrients as a food-first approach (food carries calories = the main driver), using supplements as needed.
After reviewing the bone architecture portion of my blog, you’ll learn that vitamin D improves the absorption of calcium at the gut and kidneys and that calcium is deposited into bone along with phosphate, which forms hydroxyapatite crystals that further strengthens the bone’s triple-helix collagen protein structure. (1) Nieves et al. (2010) found that female distance runners had upwards of a 6-fold increase in BSI when consuming under 800 milligrams of calcium per day when compared to those consuming 1,500 milligrams. (12) Other research has found that those with higher vitamin D and calcium levels often have the lowest risk of BSI. (1) Lappe et al. (2008) conducted research in 3,700 military recruits and found that BSI risk was reduced by 20% in those consuming 800 IU vitamin D and 2,000 mg calcium per day. (13)
Now, 800 IU of vitamin D can be harder to hit from diet alone, so often partial supplementation is warranted. Ensure vitamin D blood work has been done, as 25(OH)D, aiming for a minimum of 20 ng/mL (50 nmol/L). (1)
However, the majority of daily calcium requirements can be gained through diet. Plenty of calcium-containing foods also contain calories, protein, and phosphorus (85% of the body’s phosphorus is found in bones and teeth), which is helpful in the bone-strengthening, energy availability equation. (14) For instance:
1 cup Fage plain Greek yogurt (2% milk fat): 160 calories, 265 mg calcium, zero vitamin D.
1 cup Tropicana calcium-fortified orange juice: 110 calories, 350 mg calcium, 100 IU vitamin D.
1 cup Darigold cow’s milk (2% milk fat): 130 calories, 309 mg calcium, 120 IU vitamin D.
1 cup Silk soymilk (original): 110 calories, 450 mg calcium, 120 IU vitamin D.
1/3 container of House Foods premium firm tofu (ingredient: calcium sulfate): 105 calories, 195 mg calcium, zero vitamin D.
For more dietary sources of calcium, check out the National Institutes of Health calcium fact sheet.
Take-home Messages
BSI keeps an athlete from training for weeks and depending on the injury site and severity, can force athletes to miss an entire season of competition. Early and frequent nutrition interventions can help bolster an athlete’s awareness and education around BSI prevention.
References
(1) Hoening, T., Ackerman, K.E., Beck, B.R., Bouxsein, M.L., Burr, D.B., … & Warden, S.J. (2022). Bone stress injuries. Nat Rev Dis Primers,8(1):26. https://pubmed.ncbi.nlm.nih.gov/35484131/
(2) Carlson, N. [Nathan Carlson]. (2023, January 5). Everything you need to know about stress fractures [Video]. YouTube. https://www.youtube.com/watch?v=929Y2lVAats
(3) deWeber, K. (2023). Overview of stress fractures. UpToDate. Retrieved April 29, 2024, from https://www.uptodate.com/contents/overview-of-stress-fractures
(4) Wright, A.A., Taylor J.B., Ford, K.R., Siska, L., & Smoliga, J.M. (2015). Risk factors associated with lower extremity stress fractures in runners: a systematic review with meta-analysis. Br J Sports Med,49(23):1517-23. https://pubmed.ncbi.nlm.nih.gov/26582192/
(5) Bennell, K.L., Malcolm, S.A., Thomas, S.A., Wark, J.D., & Brukner, P.D. (1996). The incidence and distribution of stress fractures in competitive track and field athletes. A twelve-month prospective study. Am J Sports Med,24(2):211-7. https://pubmed.ncbi.nlm.nih.gov/8775123/
(6) Barrack, M.T., Gibbs, J.C., De Souza, M.J., Williams, N.I., Nichols, J.F., … & Nattiv, A. (2014). Higher incidence of bone stress injuries with increasing female athlete triad-related risk factors: a prospective multisite study of exercising girls and women. Am J Sports Med,42(4):949-58. https://pubmed.ncbi.nlm.nih.gov/24567250/
(7) De Souza, M.J., Nattiv, A., Joy, E., Misra, M., Williams, N.I., … & Matheson, G. (2014). 2014 Female Athlete Triad Coalition consensus statement on treatment and return to play of the female athlete triad. Br J Sports Med,48(4):289. https://pubmed.ncbi.nlm.nih.gov/24463911/
(8) NSAIDs (Nonsteroidal Anti-Inflammatory Drugs). (2023, July 24). Cleveland Clinic. Retrieved April 27, 2024, from https://my.clevelandclinic.org/health/treatments/11086-non-steroidal-anti-inflammatory-medicines-nsaids
(9) Hughes, J.M., McKinnon, C.J., Taylor, K.M., Kardouni, J.R., Bulathsinhala, L., … & Matheny, Jr., R.W. (2019). Nonsteroidal anti-inflammatory drug prescriptions are associated with increased stress fracture diagnosis in US Army population. J Bone Miner Res,34(3):429-36. https://pubmed.ncbi.nlm.nih.gov/30352135/
(10) Hoening, T., Eissele, J., Strahl, A., Popp, K.L., Sturznickel, J., … & Rolvien, T. (2023). Return to sport following low-risk and high-risk bone stress injuries: a systematic review and meta-analysis. Br J Sports Med,57(7):427-32. https://pubmed.ncbi.nlm.nih.gov/36720584/
(11) Bourne, M., Sinkler, M.A., & Murphy, P.B. Anatomy, Bony Pelvis and Lower Limb: Tibia. [Updated 2023 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526053/
(12) Nieves, J.W., Melsop, K., Curtis, M., Kelsey, J.L., Bachrach, L.K., … & Sainani, K.L. (2010). Nutritional factors that influence change in bone density and stress fracture risk among young female cross-country runners. PM R,2(8):740-50. https://pubmed.ncbi.nlm.nih.gov/20709302/
(13) Lappe, J., Cullen, D., Haynatzki, G., Recker, R., Ahlf, R., & Thompson, K. (2008). Calcium and vitamin D supplementation decreases incidence of stress fractures in female navy recruits. J Bone Miner Res,23(5):741-9. https://pubmed.ncbi.nlm.nih.gov/18433305/
(14) Phosphorus. (n.d.). Icahn School of Medicine at Mount Sinai. Retrieved April 29, 2024, from https://www.mountsinai.org/health-library/supplement/phosphorus
