We have all heard stories of, or experienced first-hand, the devastating toll a stress fracture or bone stress injury (BSI) can take on an athletic season and in some cases, an athletic career.
The bad news: Once an athlete sustains a BSI, they are more likely to sustain subsequent BSIs.
The good news: With the right attention to lifestyle and training practices, athletes can optimize bone health and ultimately prevent or minimize risk of BSI.
BSIs are overuse injuries to the bone that commonly occur in athletes who engage in repetitive exercise. BSI scan range from a stress reaction (bone pain without a detectable fracture), to a more advanced stress fracture (bone pain with a small fracture). Because BSI recovery typically takes 6-8 weeks and up to 6 months depending on severity and injury location, sustaining multiple BSIs is particularly devastating to an athletic career.
BSIs occur in both male and female athletes (there have been several season-stopping cases in the NBA for example), however, females and athletes who compete in “leanness” sports are especially at risk for BSI. A variety of lifestyle and training decisions can put any athlete at risk of a boney injury. Therefore, optimization of bone health and prevention of both initial and subsequent BSI should be an important consideration for athletes and their respective training and support staffs.
A well-balanced diet and a little sun exposure will typically provide adequate nutrition for optimal skeletal health. With that said, key nutrients for bone health include protein, magnesium, phosphorus, potassium, fluoride, and in particular, calcium and vitamin D.
Athletes should aim to consume approximately 1,000-1,300 mg of calcium per day through foods and supplement as needed.
Vitamin D recommendations are a bit more nuanced. About 400-800 IU per day of vitamin D are necessary for calcium absorption. This can be difficult to achieve through diet alone. If supplementation is needed, dosing should be individualized. Factors such as latitude, season, skin pigmentation and whether athletes play indoor or outdoor sports can drastically effect vitamin D status. Importantly, whereas there is no beneficial effect to supplementing to a level that would elevate Vitamin D concentrations above the cut-off for sufficiency, there are potential detrimental effects in terms of musculoskeletal health. Therefore, extreme or unnecessary supplementation is discouraged, but adequate vitamin D is essential for minimizing BSI risk. [2, 3]
Orreco’s biomarker panels can identify both deficiencies, but also excesses in a range of biomarkers related to bone health.
Energy availability is defined as energy intake minus energy expenditure through exercise. Low energy availability is difficult to identify, but should be suspected in the event of loss of body mass or restricting calories with the intent of losing body mass, lowBMI (≤17.5 kg/m2) and, in women, disrupted menstruation. Low energy availability leads to hormonal changes (in men and women), impaired bone health and increased BSI risk. If low energy availability persists, some bone loss may be irreversible.
Treatment strategies should include increasing energy intake, decreasing training, or a combination of both.Pharmacological interventions are not recommended until other strategies have been attempted for at least 1 year. [4, 5]
Athletes are most susceptible to BSI during periods of new or increased loading. A broad rule of thumb is that total loading should be no more than 10% higher than what an athlete has been exposed to over the past 3-4 weeks, factoring in both training/competition volume and training/competition intensity. Even if overall minutes trained/played remain constant, if there isa marked increase in intensity, athletes may be a heightened risk of BSI. This is especially important to consider for athletes already thought to be at risk of BSI (e.g. prior BSI, insufficient nutritional status, suspected low energy availability, etc.) If intensity increases, keep volume the same. In general, if volume increases, keep intensity the same. 
For individuals with a history of BSIs, it may be beneficial to address problematic biomechanical patterns specific to the athlete’s position or sport. For example, in the case of runners, strength training and gait retraining to modify sub-optimal movement patterns (e.g. minimizing hip drop, decreasing stride length, etc.) may modify future BSI risk. Importantly, changes to established movement patterns will introduce new loads to musculoskeletal tissue. Bone adaptation is a relatively slower process than soft tissue adaptation and thus, in the context of optimizing bone health, intentional changes in movement patterns should be attempted during a time when training volume and intensity can be reduced for a period of at least 2-3 months. 
ADXA scan may be used to determine underlying bone health. Because weight-bearing athletes tend to have higher bone density than non-athletes, a DXA Z-score (a Z-score takes into account the average for the population) of<-1 is cause for concern. 
Following BSI diagnosis, NSAID (i.e. naproxen, ibuprofen) use can inhibit bone healing and thus should generally be avoided. .
Sleep deprivation and stress (in it’s various forms) can also negatively impact bone health and should be considered in any holistic BSI prevention strategies. 
Finally, recent evidence suggests that even after a BSI is healed, due to the general disuse that the weight-bearing skeleton experiences during the recovery process, bone mineral density is compromised for several months, even in the uninjured leg. This suggests that individuals will remain at elevated risk of subsequent BSI at least temporarily, following return to sport. In the case of individuals who have had more than one BSI, this is especially important to consider in planning return to sport. 
Strategies for optimizing bone health and preventing BSI are multifactorial and highly individual. If you are an athlete or you work with an athlete with concerns about bone health, carefully assess individual risk factors that may be modified to reduce BSI risk. Understand that bone tissue responds gradually, but with time, persistence and the appropriate intervention, it will respond.
1. PalaciosC. The role of nutrients in bone health, from A to Z. Crit Rev Food Sci Nutr.2006;46(8):621-8. Epub 2006/11/10. doi: 10.1080/10408390500466174. PubMed PMID:17092827.
2. Holick MF. Vitamin D deficiency. N EnglJ Med. 2007;357(3):266-81. Epub 2007/07/20. doi: 10.1056/NEJMra070553. PubMedPMID: 17634462.
3. Owens DJ, Allison R, Close GL. VitaminD and the Athlete: Current Perspectives and New Challenges. Sports Med.2018;48(Suppl 1):3-16. Epub 2018/01/26. doi: 10.1007/s40279-017-0841-9. PubMedPMID: 29368183; PubMed Central PMCID: PMCPMC5790847.
4. Mountjoy M, Sundgot-Borgen J, Burke L,Ackerman KE, Blauwet C, Constantini N, et al. International Olympic Committee(IOC) Consensus Statement on Relative Energy Deficiency in Sport (RED-S): 2018Update. Int J Sport Nutr Exerc Metab. 2018;28(4):316-31. Epub 2018/05/18. doi:10.1123/ijsnem.2018-0136. PubMed PMID: 29771168.
5. De Souza MJ, Nattiv A, Joy E, Misra M,Williams NI, Mallinson RJ, et al. 2014 Female Athlete Triad Coalition ConsensusStatement on Treatment and Return to Play of the Female Athlete Triad: 1st International Conference held in San Francisco, California, May 2012 and 2nd International Conference held in Indianapolis, Indiana, May 2013. Br J SportsMed. 2014;48(4):289. doi: 10.1136/bjsports-2013-093218. PubMed PMID: 24463911.
6. Warden SJ, Davis IS, Fredericson M.Management and prevention of bone stress injuries in long-distance runners. JOrthop Sports Phys Ther. 2014;44(10):749-65. doi: 10.2519/jospt.2014.5334.PubMed PMID: 25103133.
7. Fedgo AA, Stahlman S. Increased riskfor stress fractures and delayed healing with NSAID receipt, U.S. Armed Forces,2014-2018. MSMR. 2020;27(2):18-25. Epub 2020/02/28. PubMed PMID: 32105494.
8. Swanson CM, Kohrt WM, Wolfe P, WrightKP, Jr., Shea SA, Cain SW, et al. Rapid suppression of bone formation marker in response to sleep restriction and circadian disruption in men. Osteoporos Int.2019;30(12):2485-93. Epub 2019/08/26. doi: 10.1007/s00198-019-05135-y. PubMedPMID: 31446439; PubMed Central PMCID: PMCPMC6879850.
9. Popp KL, Ackerman KE, Rudolph SE, Johannesdottir F, Hughes JM, Tenforde AS, et al. Changes in Volumetric BoneMineral Density Over 12 Months After a Tibial Bone Stress Injury Diagnosis:Implications for Return to Sports and Military Duty. Am J Sports Med.2021;49(1):226-35. Epub 2020/12/02. doi: 10.1177/0363546520971782. PubMed PMID:33259223.