Bone Stress Injuries: What They Are and How to Prevent Them by Nóirín Ní Chasaide APA Physiotherapist
Bone stress injuries (BSIs) are a common and often misunderstood cause of pain—especially in runners, dancers, and active individuals who's sports and activities put impact through the bones. Although impact in general is good for your bones, when done incorrectly it can lead to a BSI.
Whether you're training for a marathon, city to surf, a couch to 5k or simply ramping up your walking routine, it’s important to understand the warning signs of a BSI and how to manage them early.
What Are Bone Stress Injuries?
A bone stress injury (BSI) occurs when a bone is repeatedly loaded (such as during running, jumping, or long-distance walking) faster than it can adapt and repair. This overloading leads to a spectrum of injury, ranging from mild swelling to an actual fracture. BSIs develop gradually over time—they’re not caused by a single trauma, but rather accumulated strain.
BSIs are commonly classified into grades based on MRI findings, which helps guide diagnosis and treatment:
• Grade 1 (Periosteal Edema):
Mild inflammation of the outer layer of the bone. Often pain-free at rest and may only appear with higher loads.
• Grade 2 (Bone Marrow Edema):
Inflammation spreads into the bone marrow. Pain may occur with moderate activity, and symptoms are usually more persistent.
• Grade 3 (More Extensive Marrow Edema):
Significant internal stress response. Pain occurs with basic activities and often lingers afterward.
• Grade 4 (Stress Fracture):
Visible crack or fracture line in the bone. Pain is typically sharp and present with most activities, and healing requires strict offloading and rest.
The higher the grade, the more serious the injury, and the longer the recovery. Early detection is key to preventing progression from a mild stress response to a full-blown fracture.
Risk Factors for Bone Stress Injuries
BSIs result from a mix of training load, biomechanics, and biological factors. Common risk factors include:
Fuelling Errors
Under-fuelling or Relative Energy Deficiency (RED-S) is often a component to a BSI. It occurs when there’s a mismatch between energy intake and expenditure, affecting not just performance but also health. It can affect anyone, regardless of gender.
Consequences of RED-S include:
• Decreased bone density and delayed bone healing
• Impaired muscle recovery and fatigue
• Increased injury risk, especially BSIs
• Menstrual dysfunction in females or reduced testosterone in males
• Weakened immune function and reduced concentration
Athletes with RED-S are more likely to sustain recurrent bone stress injuries and experience delayed return to sport. (5) Being aware of RED-S and treating it early—with input from a multidisciplinary team including a physiotherapist, dietitian, and GP or sports doctor—is essential for safe training and recovery.
Missed Periods and Bone Health
In women, menstrual irregularities are a major red flag for bone health. Missing periods—known as amenorrhea—can seriously impact bone strength and increase BSI risk.
• Women with functional hypothalamic amenorrhea (often caused by low energy availability) have 2 to 4 times higher risk of bone stress injuries. (6)
• Missing just three or more cycles in a year is associated with reduced bone mineral density (BMD) and a higher risk of stress fractures. (7)
• Menstrual function is a vital sign in female athletes. Regular periods generally indicate healthy energy balance and hormonal function, which are essential for bone remodeling.
Training Errors
1. Sudden increase in volume or intensity
• Bone Microdamage is a Normal Part of Training
Every time you run or jump, you apply stress to your bones, which causes microscopic damage. That’s not a bad thing—this is what stimulates your bones to remodel and grow stronger during rest and recovery.
• Rest is Essential for Remodeling
After mechanical loading, bones go through a cycle of resorption (breaking down old tissue) and formation (laying down new, stronger tissue). This process takes days to weeks depending on the intensity of the stress.
• However if you do too much, too suddenly the breakdown will be more than the remodelling
2. Inadequate rest, recovery and sleep
• Recovery days and deload weeks should be sheduled into your training plan
• One should also adjust their plan as needed if feeling fatigued
• Aiming for 7-9 hours sleep is essential for adequate recovery
3. Not including strength training in your training programme
• Strength plays a critical role in absorbing impact, stabilising joints, and supporting efficient movement. When strength is lacking—especially in key areas like the calves, glutes, and trunk—the mechanical load placed on bones increases, making them more susceptible to stress injuries.
• Strength training and the mechanical load it places on the bones stimulates osteogenesis (bone formation), Improves bone mineral density (BMD) and makes bones more resilient to microdamage over time
️ How to Prevent Bone Stress Injuries
BSIs are largely preventable with the right approach. Prevention strategies include:
1. Smart Training Progression
You should avoid any big changes in training load- a good rule of thumb to follow is the 10% rule—don’t increase training load by more than 10% per week. You shoudl also include de-load weeks in your training. Prioritise variety and avoid high-impact activities on consecutive days.
2. Strength & Conditioning
Incorporate strength training 2–3 times per week, focusing on the hips, calves, and trunk to improve shock absorption and alignment during movement.
3. Nutrition & Bone Health
Ensure you’re getting adequate energy intake, calcium, and vitamin D. For women, regular menstrual cycles are a key sign of healthy energy availability.
If you are experiencing symptoms of RED-S or amenorrhea, seek early advice from your physio, GP and a nutritionist to address these issues as soon as possible.
How Are Bone Stress Injuries Managed?
If diagnosed early, BSIs respond well to conservative management. Management typically involves:
• Relative rest: A period of rest will be required to let the bone heal. Wheather this means completely offloading the bone or relative rest is dependant on the grade of the BSI and which bone is effected.
• Load management: Gradual return to activity based on symptoms and healing
• Rehabilitation: Focused exercises to build strength and bone density.
• Medical input: Bone health assessments, blood tests, or DXA scans may be required aswel in some cases.
A physiotherapist will guide you through each phase and adjust your plan based on healing progress and pain response.
What To Do If You're Worried About a Bone Stress Injury
If you’re experiencing any of the below:
• Pain that worsens with activity and eases with rest
• Localised bone tenderness
• A dull ache that progresses over time
• Pain that starts to limit training or daily activities
…it’s time to seek assessment early. Left untreated, BSIs can progress into more serious fractures and result in long-term time off from sport or activity.
A physiotherapist can assess you, refer for imaging if needed, and help guide safe recovery while addressing the root cause.
References
Nattiv A, et al. (2013). Management of Bone Stress Injuries in Active Individuals and Athletes. J Orthop Sports Phys Ther, 43(3):153-171.
Tenforde AS, et al. (2016). Bone stress injuries in runners: higher risk with female sex, low energy availability, and previous injury. Br J Sports Med, 50(17):1092-1097.
Fredericson M, Jennings F, et al. (2006). Stress fractures in athletes. Top Magn Reson Imaging, 17(5): 309–325.
Warden SJ, et al. (2014). Bone stress injuries: Epidemiology, pathophysiology, and risk factors. Curr Osteoporos Rep, 12(3):190-198.
Mountjoy M, et al. (2018). IOC consensus statement on Relative Energy Deficiency in Sport (RED-S): 2018 update. Br J Sports Med, 52(11): 687–697.
Nattiv A, et al. (2013). Management of Bone Stress Injuries in Active Individuals and Athletes. J Orthop Sports Phys Ther, 43(3):153-171.
Tenforde AS, et al. (2013). Association of menstrual dysfunction with bone stress injuries in collegiate female athletes. Am J Sports Med, 41(2): 302-310.
Warden SJ, Davis IS, Fredericson M. (2014). Management and prevention of bone stress injuries in long-distance runners. J Orthop Sports Phys Ther, 44(10):749–765.