Every time your foot strikes the ground while running, your bones absorb forces up to three times your body weight. This stress is essential for strong bones—but when it becomes too much, it can break them down instead. Bone Stress Injuries (BSIs) are some of the most common, and misunderstood, running injuries we see in our clinic. Unlike other fractures, BSI’s are often atraumatic in nature and do not require any high force or traumatic incident to arise. In this blog post, we’ll explore what bone stress injuries are, how common they are, what causes them, and how we can help you manage them at Central Performance.
How Common Are Bone Stress Injuries in Runners?
Up to 21.1% of collegiate cross-country runners in the U.S. experience a BSI in a single season. Among endurance athletes, BSIs are one of the most frequent overuse injuries—especially in runners. Half of track-and-field athletes report a history of BSI on more than 1 occasion, and 10.3% to 12.6% of cross-country and track-and-field athletes with a history of BSI sustain a subsequent BSI when prospectively followed for 1 to 2 years. (Adachi et al., 2022)
Bone Turnover is Normal ; Until it’s Not
Where do they occur the most?
The most commonly affected bones include the tibia (shin bone), metatarsals (foot bones), and femur (thigh bone). Areas of bone stress can be broken down into high risk and low risk based on their location. High risk sites are at greater risk of progressing to a complete fracture or experiencing delayed healing. Common locations of bones stress in runners can be seen below; if you are a runner and feeling pain in this regions they are not to be ignored!
What Causes Bone Stress Injuries?
Understanding the root causes of BSIs is essential for both treatment and prevention. Here’s what puts runners most at risk:
- Training Errors – Too much too soon. Nothing screams red flag like a sudden increase in load. Increases in mileage, intensity, or frequency without adequate adaptation time can overload the bones places the bone at much greater risk of injury.
- Biomechanical Issues – Poor running mechanics, improper footwear or muscle imbalance and weakness can increase stress on specific areas of the skeleton. Other movement patterns may contribute to altered loading of certain structures in the body such as overstriding may place more force through the femur or hip.
- Nutritional Deficiencies
- Calcium Intake: Bone mineral is predominantly formed from calcium, therefore a lack of adequate calcium means bones do not have the necessary building blocks to build and maintain normal healthy bone. A common mistake is thinking a normal calcium blood test means calcium intake is adequate. In fact, the body protects blood calcium at all costs and will leach calcium out of the bones to maintain normal blood calcium. A normal blood calcium test doesn’t tell you much about your bone health in most cases.
- Vitamin D Levels: Vitamin D plays a crucial role in how our body processes and absorbs calcium. 90% of our Vitamin D comes directly from sunlight. Low levels of Vitamin D increase the odds of poor bone health via its influence on calcium. Most blood tests suggest a Vitamin D level less than 50 nmol/L is low, but there is an increased incidence of bone stress injuries when levels are less than 75 nmol/L.
- Hormonal Factors
- Particularly in female runners, conditions such as relative energy deficiency in sport (RED-S). Relative Energy Deficiency in Sport (RED-S) occurs when an athlete consistently consumes fewer calories than they expend, leading to widespread disruptions in bodily functions. Adequate energy is essential for normal bone remodeling and repair. When energy intake is insufficient, the bone renewal process slows, resulting in weakened, brittle bones that are more prone to injury.
- Low energy availability – impacts hormone production, particularly estrogen and testosterone, which play key roles in maintaining bone density and strength. A deficiency in these hormones can lead to reduced bone mineral density and structural weakness, increasing the risk of stress injuries and conditions like secondary osteopenia or osteoporosis.
Signs That You May Have a Bone Stress Injury
- Pain worsened with hopping that reproduces symptoms
- Gradual onset of symptoms
- Pain whilst running that does not warmup and lingers following the session (there is exceptions to this especially in the early stages)
- Focal tenderness to the touch on a bony surface
- Recent increase in load aligned with the symptoms (load does not specifically have to be increase kilometres this could also be increased intensity or speed work)
- Pain at night while inactive in the sore region
Physio For Bone Stress – Central Performance Sydney / Surry Hills
If these symptoms sound familiar, it’s worth checking in. The earlier we catch a BSI, the quicker and safer your return to running can be. Click below to ask a question or to book a physio appointment online.
Shin Splints vs. Bone Stress Injuries: What’s the Difference?
| Feature | Shin Splints (MTSS) | BSI |
| Tissue Involved | Periosteum (bone lining) and surrounding soft tissue | Actual bone structure depending on severity |
| Pain Pattern | Diffuse, along the inner edge of the shin (sometimes outer) | localised, focal pain on the bone |
| Onset | Gradual, often with increased running load | Also gradual, may escalate faster if not managed |
| Pain During Activity | Often warms up with running, worse after. Inconsistent symptoms | May worsen during activity, doesn’t warm up or ease following the session |
| Pain With Palpation | Broad area of tenderness (3-10cm) | Pinpoint tenderness (1-2cm) |
| Risk of Progression | Usually resolves with rest and load adjustment | Can progress to a full fracture if ignored and in high risk area |
| Imaging | Not always visible, MRI may show inflammation | MRI shows bone oedema or fracture line if severe |
Why it Matters:
Shin splints are typically less serious and respond well to load management, strengthening, and biomechanical corrections. A BSI, on the other hand, can worsen into a stress fracture if not identified and treated early. If pain becomes more focal, persists at rest or night, or doesn’t respond to conservative management, a bone stress injury should be ruled out.
Bottom Line:
If you’re experiencing persistent shin pain, don’t assume it’s just shin splints. Early assessment by a physiotherapist can help differentiate between the two and ensure you get on the right rehab path as early as possible.
How We Diagnose & Treat BSIs at Central Performance
At Central Performance, we have the privilege of treating avid runners on a daily basis. This gives us a significant advantage when it comes to diagnosing, treating, and preventing bone stress injuries that unfortunately we see too many of. Here’s how we can help:
- Accurate Diagnosis: Early detection is key to preventing a stress reaction from progressing to a full fracture. We utilise clinical assessments, a comprehensive history of injury training load and we can directly refer for necessary imaging such as MRI, X-Ray or CT to confirm or rule out a diagnosis of bone stress.
- Load Management and Rehabilitation: A graded and structured return-to-running plan is essential. We help modify your training load while incorporating low-impact cross-training and catered strengthening options to maintain capacity during recovery to allow for an optimal return to running.
- Gait and Biomechanical Assessment: We offer analysis of your running biomechanics to identify any abnormalities in your movement patterns that may be contributing to excessive bone stress or altered loading of certain joints and provide corrective strategies. Our running program is headed up by our Level 4 National running coach Ben Liddy who has a wealth of experience coaching multiple National level runners currently.
- Strength and Conditioning Programs: Optimal and specific bone loading is absolutely essential in building resilient bones. A targeted and comprehensive program of exercises will help improve bone strength, address muscle imbalances, and enhance overall running efficiency and reducing injury risk.
- Nutritional and Lifestyle Guidance: We work with you to ensure optimal nutrition and bone health strategies, including proper fueling and supplementation if needed. Alternatively, referral to a Sports Dietitian in cases where we feel this may appropriate.
- Preventative Strategies: We educate runners on smart training principles, appropriate footwear selection, and strategies to minimise injury risk.
Frequently Asked Questions (FAQs) About Bone Stress Injuries
1. How long does it take to recover from a bone stress injury?
Recovery varies based on severity. Mild stress reactions may heal in 4-6 weeks, while stress fractures can easily take 8 weeks to several months before being able to be re-loaded. This largely depends on the site of injury as well as the severity.
2. Can I still exercise with a BSI?
Yes! Low-impact activities like swimming, cycling, and other cross training can help maintain fitness while allowing the bone to heal. Your physio will be able to guide you through this process and cater to prepping for specific events or maintaining your current conditioning.
3. What’s the difference between a stress reaction and a stress fracture?
A stress reaction is early-stage bone weakening, while a stress fracture is a disruption in the cortical surface. Bone stress is a continuum with the Fredrickson Grading System being the most commonly used to describe injury severity.
4. How can I prevent BSIs from recurring?
Consulting with your Physio! Collaboration between your physiotherapist and coaching staff will help to map out gradual training progressions, improve bone strength through targeted strength training, and ensure proper nutrition & recovery.
5. Do BSIs always require imaging for diagnosis?
Not always. Clinical tests can often identify a BSI, but MRI is the gold standard if imaging is required.
6. What’s the most common mistake runners make after a BSI?
Returning to running too soon without a proper rehabilitation plan, leading to reinjury.
7. Are certain runners more prone to BSIs?
Yes! Female runners, athletes with low energy availability, and those with poor biomechanics have a higher risk.
8. Should I take calcium or Vitamin D supplements?
Only if your intake is inadequate. Blood tests can help determine if supplementation is necessary.
9. Do soft surfaces reduce the risk of BSI?
Running on varied terrain can help distribute stress more evenly, but training errors still pose the greatest risk.
10. When can I start running again after a BSI?
This depends on pain levels, imaging results, and clinical assessment. A graded return-to-run program is essential so please consult with your Physiotherapist or Sports Physician.
