Bone Stress Injuries In Runners

Bone stress injuries (BSIs) are among the most feared running injuries, often forcing athletes to take extended time off from training or competition. Defined as the bone’s “focal failure” under repeated loading, BSIs encompass stress reactions and stress fractures—conditions where the bone’s ability to withstand impact is surpassed by running’s repetitive forces.

Why Do Runners Get Bone Stress Injuries?

Runners place substantial, repetitive loads on bones, particularly in the legs, feet, and hips. Most injuries occur when training load (such as mileage, intensity, or frequency) is increased too rapidly, or when poor nutrition, inadequate recovery, or underlying health conditions (like low bone density or hormonal issues) compromise bone remodelling and repair. Runners are also at risk if muscle fatigue prevents shock absorption, transferring extra force to bone and causing microdamage.

Common causes include:

• Sudden jumps in training volume or intensity

• Poor fuelling or calorie restriction (RED-S risk)

• Insufficient rest days and recovery periods

• Low bone density, vitamin D deficiency, or osteoporosis

• Biomechanical factors (overpronation, lower limb alignment)

Symptoms and Early Warning Signs

BSIs develop gradually, often starting as localised pain that worsens with weight-bearing activity and eases with rest. Key signs include:

• Focal bone pain increasing during runs

• Tenderness over the affected area

• Swelling, redness, or inability to hop or run without pain

  
  

  Ignoring these warnings increases the likelihood of progressing to a full stress fracture, which requires stricter rest.

Grading and Diagnosis

Bone stress injuries are graded by severity (MRI findings), guiding treatment and return-to-run timelines:

• Grade 1: Periosteal oedema (“bad shin splints”)

• Grade 2–3: Bone marrow oedema (increasing severity)

• Grade 4: Fracture line visible

  
  

  Recovery ranges from 6–16 weeks depending on grade, bone involved, and risk factors.

Recovery and Rehabilitation

The cornerstone of BSI recovery is load management. This involves a period of restricted running or cross-training (such as cycling or swimming) to promote bone healing while maintaining overall fitness. Early rehab may include:

• Gradual reintroduction of weight-bearing activity

• Progressive strength training, targeting lower limb and core muscles

• Nutritional optimisation (adequate calories, calcium, and vitamin D)

• Blood flow restriction training for muscle and bone stimulation, if advised by clinicians

  
  

  Return-to-running must be systematic, with incremental increases in duration and intensity, and regular monitoring for symptoms.

How Runners Can Reduce Risk

Evidence-based tactics for prevention:

• Progress training loads gradually (no more than 10% per week)

• Prioritise rest and recovery; don’t ignore fatigue or pain

• Fuel adequately—avoid diets that restrict key nutrients or calories

• Monitor menstrual health (in females) for hormone-driven bone changes

• Strengthen muscles to support bones and absorb shock

• Consult professionals for individual gait analysis, footwear advice, and tailored strength programmes

Takeaway

Bone stress injuries are a major setback for runners, but they can be prevented and managed with careful attention to training, nutrition, and early symptom recognition. Runners who listen to their bodies—and seek help quickly—can return stronger, with the right support and a structured plan.