Bone Stress Injuries: What Every Endurance Athlete Needs to Know
As an endurance athlete, you know that consistency is key to progress. But what happens when your training is derailed by persistent pain? Bone stress injuries are among the most common—and frustrating—injuries for runners, triathletes, and endurance athletes.
Bone stress injuries can start subtly but, if ignored, may progress to stress fractures, requiring weeks or even months of rest. The good news? Most bone stress injuries are preventable with proper nutrition, training load management, and recovery strategies.
In this blog post, we’ll break down:
What a bone stress injury is and how it develops
Who is at risk for bone stress injuries
Common sites for stress injuries in endurance athletes
How to reduce your risk and keep training strong
Let’s dive in!
What Is a Bone Stress Injury?
A bone stress injury occurs when bone breakdown outpaces bone repair. Bones are living tissues that constantly undergo remodeling—breaking down and rebuilding in response to the stress placed on them. When impact, load, or inadequate nutrition interfere with this natural cycle, bones weaken, leading to stress reactions and eventually, stress fractures.
Stages of a Bone Stress Injury:
1️⃣ Stress Reaction – The early stage of a bone stress injury, characterized by bone irritation and inflammation. In this stage pain may come and go.
2️⃣ Stress Fracture – If the stress reaction continues without intervention, a small crack develops in the bone, significantly increasing pain and requiring extended rest.
What Causes Bone Stress Injuries?
Bone stress injuries typically result from a combination of mechanical and metabolic factors, including:
✔️ Repetitive impact and high training volume – Runners, triathletes, and endurance athletes put constant stress on their bones. Without adequate recovery, bones don’t have enough time to repair.
✔️ Low energy availability – When athletes don’t eat enough to match their training demands, their bodies prioritize essential functions over bone repair, weakening bone structure over time.
✔️ Sudden changes in training load – Increasing mileage, intensity, or terrain difficulty too quickly can overload bones and lead to injury.
✔️ Inadequate nutrition and micronutrient deficiencies – Calcium, phosphorus, magnesium, and vitamin D are essential for bone remodeling. Insufficient intake of these nutrients and overall energy increases the risk for a bone stress injury.
✔️ Hormonal disruptions – Women with irregular or missing menstrual cycles (often due to under-fueling) are at higher risk for bone stress injuries due to reduced estrogen levels, which affect bone density.
Who’s at Risk for Bone Stress Injuries?
While any athlete can develop a bone stress injury, certain risk factors increase the likelihood:
Endurance athletes – High-impact sports like running, triathlon, and long-distance cycling put repetitive stress on bones.
Athletes with low energy availability – Not consuming enough calories or nutrients- both macro and micro- to support training increases injury risk.
Those with too high of training load – if you’re training an amount that your body is not ready or able to sustain, you are putting yourself at higher risk for a bone stress injury.
Female athletes with irregular periods – Hormonal imbalances (low estrogen) impact bone density, making stress fractures more likely.
Athletes with nutrient deficiencies – Calcium, phosphorus, magnesium, and vitamin D are crucial for bone strength. Low intake of these nutrients can contribute to bone stress injuries.
Common Sites for Bone Stress Injuries
Certain bones take more impact and repetitive load than others. The most common sites for bone stress injuries in endurance athletes include:
✅ Shin (Tibia) – The most common site, especially in runners. Bone stress injuries in the shin are often mistaken for shin splints in early stages.
✅ Foot (Metatarsals) – The small bones in the foot absorb repeated stress from impact. Having a bone stress injury in the foot can make walking very painful.
✅ Thigh (Femur) – A femur bone stress injury is less common but more serious, as femur fractures require longer recovery. This injury site is also strongly linked to low energy availability.
✅ Pelvis – These injuries are often misdiagnosed as hip flexor or groin pain. A bone stress injury in the pelvis is more common in high-mileage runners and female athletes. Much like the femur, this injury site is also strongly linked to low energy availability.
How to Reduce Your Risk of Bone Stress Injuries
Preventing a bone stress injury requires a smart balance of training, nutrition, and recovery. Here’s how to protect your bones and stay injury-free:
1️⃣ Fuel Properly—Every Meal Matters
Undereating is a major contributor to bone stress injuries. Your bones need adequate calories, macronutrients, and micronutrients to stay strong.
Key nutrients for bone health:
Calcium – Found in dairy, fortified plant milks, and leafy greens. Aim for 1,000–1,300 mg/day.
Vitamin D – Helps with calcium absorption. Get sun exposure and include fatty fish, fortified foods, or supplements.
Protein – Supports bone remodeling and repair. Include lean meats, fish, eggs, legumes, and dairy in every meal.
Carbohydrates – Fuel bone and muscle recovery. Prioritize getting enough to support your training load. Outside of workouts focus on whole grains, fruits, and starchy vegetables.
2️⃣ Increase Training Volume Gradually
Sudden jumps in mileage or intensity increase stress on bones. Instead:
Gradually increase your training – Increase weekly training volume at a gradual pace to allow your body time to adapt. Avoid inconsistent and sudden jumps in training. Pay close attention to how your body responds to increased training volume.
Rotate running surfaces – Mix trails, grass, and softer tracks with harder roads.
Incorporate cross-training – Activities like swimming and cycling reduce impact while maintaining fitness.
3️⃣ Prioritize Recovery & Strength Training
Listen to your body – If pain worsens with activity or persists, don’t ignore it!
Rest and recover – Your bones need time to repair after intense sessions.
Strength train – Weight-bearing exercises improve bone density and resilience.
4️⃣ Monitor Bone Health & Hormones
Women with irregular menstrual cycles or athletes with chronic fatigue, stress fractures, or under-fueling symptoms should get screened for low energy availability and bone density.
Talk to a sports dietitian or doctor if you experience:
🚩 Frequent stress fractures or prolonged recovery
🚩 Low energy levels, fatigue, or hormone imbalances
🚩 Persistent bone or joint pain
Take Control of Your Bone Health & Performance
Bone stress injuries don’t have to sideline your training. With proper fueling, smart training progression, and recovery strategies, you can keep your bones strong and stay injury-free.
Need help fine-tuning your nutrition and training to prevent bone stress injuries?
Book a 1:1 Fueling & Strategy Session to:
✔️ Identify gaps in your nutrition & training
✔️ Create a personalized fueling plan for stronger bones & better recovery
✔️ Get expert guidance on performance nutrition for endurance athletes
Final Thoughts: Train Smart, Fuel Well, Stay Strong
Bone stress injuries are preventable—but only if you take action before they happen. By prioritizing nutrition, gradual training progression, and listening to your body, you can stay healthy, strong, and consistent in your sport.
Your performance starts with your health. Keep fueling, keep training smart, and keep crushing your goals!