Stress fractures are a common injury among runners, resulting from repetitive loading and overuse of the bones. These fractures can significantly impact training and performance, often requiring a period of rest and rehabilitation. In this blog, we will explore the development of stress fractures in runners, including the causes, risk factors, and preventive measures that can help athletes mitigate the risk of this debilitating injury.
Common stress fracture sites in runners
Stress fractures of the tibia, metatarsals, and fibula are the most frequently reported sites. Medial tibial stress syndrome, also known as shin splints, is the most common form of early stress injury. This diagnosis reflects a spectrum of medial tibial pain in early manifestations before developing into a stress fracture.
The location of stress injuries varies by sport. Among track athletes, fractures to the navicular, tibia, and metatarsals are most common, and among distance runners, the tibia and fibula are most common.
Causes of stress fractures in runners
Stress fractures in runners occur when the repetitive forces applied to the bones exceed their ability to repair and remodel. Several factors contribute to the development of stress fractures:
- Overtraining: Engaging in excessive mileage, intensity, or frequency of running without adequate rest and recovery can increase the risk of stress fractures. The bones need time to adapt and strengthen in response to the demands placed upon them.
- Biomechanical Factors: Abnormal running mechanics, such as overpronation (excessive inward rolling of the foot), high arches, or imbalances in muscle strength and flexibility, can lead to increased stress on specific bones, making them more susceptible to fractures.
- Inadequate Footwear: Worn-out or inappropriate running shoes that lack proper support and cushioning can contribute to excessive impact forces on the bones, increasing the risk of stress fractures.
What happens in the bone with a stress fracture?
A stress fracture is a very small, microscopic fracture that occurs in the outside portion of a bone called the cortex.
In healthy bone there is a balancing act when the bone is placed under load or stress, such as running. The body keeps up with these increases in load or stresses by generating osteoblasts, cells that make bones. At the same time there are osteoclasts—cells that take away older weaker bone. This is how we “build bone” and is hugely important in combating osteoporosis.
However if have a balance between osteoblastic activity and osteoclastic activity is disrupted in favour of the osteoclasts then the bone weakens and this is when stress fractures occur.
Risk Factors for Stress Fractures in Runners :
Certain factors can increase an individual’s susceptibility to stress fractures:
- Previous History: Runners who have previously experienced stress fractures are at a higher risk of developing them again. It is essential for these individuals to address the underlying causes and take preventive measures to minimize the risk of recurrence.
- Female Athletes: Female runners, particularly those with menstrual irregularities or low bone density, are more prone to stress fractures. These factors can disrupt the normal bone remodeling process and weaken the bones’ structural integrity.
- Nutritional Deficiencies: Inadequate intake of essential nutrients, especially calcium and vitamin D, can compromise bone health and increase the likelihood of stress fractures.
Prevention and Management of stress fractures
Preventing stress fractures in runners involves adopting a multi-faceted approach:
- Gradual Training Progression: Gradually increasing training volume, intensity, and frequency allows the bones to adapt and strengthen over time. Avoid abrupt changes that can overload the bones and increase the risk of stress fractures.
- Proper Footwear: Invest in well-fitting, supportive running shoes that suit your foot type and gait mechanics. Replace worn-out shoes regularly to maintain optimal cushioning and shock absorption.
- Cross-Training and Strength Training: Incorporate cross-training activities, such as swimming or cycling, to reduce repetitive impact forces on the bones while maintaining cardiovascular fitness. Incorporating strength training exercises that target the lower body and core muscles can improve muscular strength and stability, reducing the strain on bones.
- Jumping and landing exercises.The addition of exercises to improve bone strength such as jumping type exercises help the bone adapt to absorbing forces associated with running. Check out this blog on bone strength exercises for shin splints
- Balanced Nutrition: Maintain a well-balanced diet rich in calcium, vitamin D, and other essential nutrients that support bone health. Consult with a registered dietitian to ensure you meet your nutritional needs as a runner.
- Rest and Recovery: Allow for adequate rest and recovery periods between training sessions. Listen to your body and take appropriate rest days to prevent overuse injuries.
Stress fractures pose a significant risk to runners, but with a proactive approach to prevention, athletes can reduce their susceptibility to this injury. By understanding the causes, risk factors, and preventive measures outlined in this blog, you can make informed decisions about training volume, footwear, cross-training, and nutrition.