Bone Stress Injury
Small Strains, Bigger Setbacks
Bone stress injuries (BSIs; i.e., stress fractures/stress reactions) occur when bone is loaded repetitively and cannot repair itself quickly enough. Initially, BSIs are stress reactions, and with continued loading, they can progress to stress fractures. Most athletes recover over weeks to months, but a past BSI is the strongest predictor of a future one. Treating the injury alone misses the chance to address why it happened in the first place.
Common BSI contributors include: sudden training increases, low energy availability, menstrual changes in women or low testosterone in men, low vitamin D or calcium intake, sleep loss, high life stress, muscle imbalances or other biomechanical issues.
BSI management (diagnosis and treatment) works best as a team effort: a sports medicine physician to determine the severity of the injury and an initial offloading plan; a sports dietitian to optimize fueling for training and injury recovery; a sports psychologist to address underlying psychological risk factors; a physical therapist/strength coach to build capacity and address movement patterns and a coach/athletic trainer to manage load and recovery.
Bottom line: heal the bone, identify the cause and change the inputs so the next season isn’t lost to a similar injury.
Click graphic for printable PDF
What is a bone stress injury?
A bone stress injury (BSI) happens when repeated loading outpaces the bone’s ability to repair.
The spectrum runs from stress reaction (bone is irritated, no fracture line) to stress fracture (a small fracture line). Pain with impact, focal tenderness and pain that lingers or pulses even at rest are common.1-4 Imaging, often magnetic resonance imaging (MRI), helps grade the injury and determine an initial treatment plan.5-9
Load versus capacity: why the same run can become risky
Bone injury occurs when the applied load exceeds the tissue's current capacity.
Capacity isn’t fixed and can change with energy/fuel availability, sleep, illness, psychological stress, hormones and recent training.10-13 That means a six-mile easy run that was safe last month may exceed capacity this week if you’re coming off a recent injury, under-fueled, sleep-deprived or stressed. When tissue capacity changes, the effective load on bone might be different than it used to be, even if volume and pace don’t change.
Special case:
In the postpartum period (≤12–18 months after pregnancy), especially while breastfeeding, estrogen is low, sleep and fueling are often compromised and bone mineral density (BMD) declines.14,15 This transient, reversible decrease in hip/spine BMD that can occur during lactation typically recovers after stopping breastfeeding.14 But during this critical time, athletes may have reduced bone-loading tolerance, increasing risk for BSI, even if the training volume seems low; impact progression should be made cautiously.
Why a BSI is not always “one and done”
The clearest risk factor for a future BSI is a prior BSI.4 If athletes rest until pain resolves, but do not address the factors that caused the BSI, risk for future injury remains.
Each BSI should trigger a structured review of:
Training
Fueling
Sleep
Hormones
Biomechanics
Key risk factors
Most athletes have more than one.
Training load errors (with focus on the last 2 months)
Rapid jumps in mileage, intensity, hills, plyometrics or game minutes; big changes in surface or shoes; too few recovery days.4,16-19
Low energy availability/Relative Energy Deficiency in Sport (REDs)
Energy intake that does not meet the demands of training. While there may be many signs of inadequate fueling, in females, this may manifest as missed/irregular periods or delayed menarche; in males, this may include low libido or low testosterone. Voluntarily restricting any category of food is a risk factor for low energy availability.10,12,20,21
Inadequate bone nutrition
Low vitamin D status and/or low calcium intake.4,22
Biomechanical errors and strength deficits
limited calf/foot strength, hip/glute weakness, overstriding/low cadence or asymmetry after prior injury.23,24
History and health
Prior BSI, recent injury that required time off, low BMD, rapid growth, illness, high life stress and insufficient sleep.4,25-27
Significant change in training surface and/or footwear
For example, transitioning too quickly from softer surfaces and running shoes to a hard track and spikes.
Team-Based Care
Effective care aligns roles across the support team.
Sports medicine physician:
Grades the injury (reaction vs. fracture), protects high-risk sites (e.g., femoral neck, navicular) and sets initial impact limits.
Sports dietitian (RD):
Aligns energy intake with training load; addresses calcium, vitamin D, and protein timing.
Physical therapist/strength coach:
Builds capacity (foot/ankle, calf, hip/glute, core), corrects modifiable mechanics and guides progressive return to play plyometrics.
Coach/athletic trainers:
Shapes the weekly training curve, plans recovery and tracks workload.
Behavioral/sport psychology:
Supports as needed to address stress, sleep and habit change.
Recovery Roadmap4,28,29
Based on BSI severity and pain, the medical team can help guide non- to partial- to full weight-bearing as appropriate. Physical therapy, biking, swimming and/or deep-water running can be added into the recovery plan as appropriate. High-grade BSIs (stress fracture with a visible fracture line) or those in locations prone to delayed healing (e.g., femoral neck, navicular) may need crutches and/or an aircast boot for offloading. Most BSIs resolve with conservative care, but some require surgical management.
Return to run, stepwise. Walk-run intervals → short continuous runs → gradual volume → then intensity. Change one variable at a time.
Strength before speed. Restore foot/calf and hip strength; add controlled impact (hops, bounds) when pain-free walking is easy.
Zero pain tolerance. Use pain as the guide. If something hurts, stop immediately and take at least one day off before trying again. There should also be no BSI-related pain following an exercise session.
Fuel to heal. Increase energy intake, prioritize protein and meet calcium (~1,000–1,300 mg/day) and vitamin D targets per clinician guidance.
Prevent the next one. Smooth week-to-week load, rotate footwear, plan recovery weeks, fuel adequately, track your periods/libido and protect sleep. During times of high stress, low sleep and/or low fuel, consider reducing training load.
BSIs reflect a mismatch: load greater than recovery.
Treating the bone is necessary, but finding and correcting the causes changes an athlete’s future risk. With coordinated care addressing training, fueling, strength and recovery, more athletes can return to sport and minimize reinjury risk.
Research Resources
WHSP Academy: Bone Stress Injury Article & Infographic Citations
Changes in volumetric bone mineral density over 12 months after a tibial bone stress injury diagnosis: implications for return to sports and military duty
Popp KL, Ackerman KE, Rudolph SE, Johannesdottir F, Hughes JM, Tenforde AS, et al.
Am J Sports Med. 2021;49(1):226–35. doi:10.1177/0363546520971782
Restrictive eating and prior low-energy fractures are associated with history of multiple bone stress injuries
Gehman S, Ackerman KE, Caksa S, Rudolph SE, Hughes JM, Garrahan M, et al.
Int J Sport Nutr Exerc Metab. 2022;32(5):325–33. doi:10.1123/ijsnem.2021-0323
Return to sport following low-risk and high-risk bone stress injuries: a systematic review and meta-analysis
Hoenig T, Eissele J, Strahl A, Popp KL, Sturznickel J, Ackerman KE, et al.
Br J Sports Med. 2023;57(7):427–32. doi:10.1136/bjsports-2022-106328
Low energy availability is difficult to assess but outcomes have large impact on bone injury rates in elite distance athletes
Heikura IA, Uusitalo ALT, Stellingwerff T, Bergland D, Mero AA, Burke LM
Int J Sport Nutr Exerc Metab. 2018;28(4):403–11. doi:10.1123/ijsnem.2017-0313
Comparison of bone quality among winter endurance athletes with and without risk factors for Relative Energy Deficiency in Sport (REDs): a cross-sectional study
Wyatt PM, Drager K, Groves EM, Stellingwerff T, Billington EO, Boyd SK, et al.
Calcif Tissue Int. 2023;113(4):403–15. doi:10.1007/s00223-023-01120-0