What Are Stress Bone Injuries?
Stress bone injuries occur when microdamage accumulated during exercise exceeds the repair capacity of bone tissue. This process generates porosity in the bone, decreasing its resistance to fatigue. Factors such as the magnitude of loads, repetition, and biomechanics play a crucial role.
Although microfractures are normal and necessary to stimulate bone regeneration, an imbalance in load can delay repair and cause more serious injuries. In sports like running, injuries commonly appear between 3 and 4 weeks after a sudden increase in training intensity or volume.
Risk Factors in Runners
1. Training Load Errors
The rapid increase in load, both in intensity and volume, is the main trigger for stress injuries. Inadequate training management can overload the bones before they adapt to new stress levels.
2. Poor Biomechanics
Running technique significantly affects the forces transmitted to the bones. Low cadence, an overly long stride, or excessive impact during foot strike increase the risk of microdamage.
3. Energy Deficiencies
The deficit of available energy, common in athletes who do not balance their caloric intake with energy expenditure, negatively affects bone density. This condition, known as Relative Energy Deficiency in Sport (RED-S), is especially prevalent in female runners.
4. Early Sports Specialization
Athletes who specialize in unidirectional sports, such as running, from an early age are less likely to develop structurally robust bones. This increases susceptibility to injuries during adulthood.
Prevention of Stress Bone Injuries
1. Training Load Control
A progressive approach to training is essential. Tools such as the Acute:Chronic Workload Ratio (ACWR) allow monitoring of the load and avoiding sudden peaks.
Additionally, it is advisable to prioritize increasing volume over intensity. The non-linear relationship between load magnitude and bone fatigue suggests that running at moderate speeds for longer periods may be safer than training with frequent sprints.
2. Muscle Strengthening
An appropriate muscle strengthening program improves the muscles’ ability to absorb loads and distribute them efficiently. Strength exercises not only reduce the risk of injuries but also contribute to maintaining bone density.
3. Incorporation of Rest Periods
Rest is crucial to allow bone tissue repair. It is recommended to include at least one rest day per week and low-intensity periods every three months. Additionally, alternative exercises such as swimming or cycling can help maintain physical fitness without subjecting the skeleton to excessive loads.
4. Variation in Load Types
Incorporating multidirectional activities fosters a more robust skeleton. Varying disciplines exposes bones to forces in different directions, which improves their ability to withstand repetitive loads.
5. Correction of Running Technique
Increasing cadence and shortening stride length can reduce impact on bones. Studies have shown that a higher cadence decreases ground reaction forces and the risk of tibial fractures.
6. Adequate Nutrition
Maintaining a positive energy balance and ensuring sufficient intake of calcium and vitamin D is vital for bone health. Runners should be aware of their nutritional needs and avoid prolonged deficits.
Myths and Realities about Running and Bone Health
It is a myth that running long distances alone builds strong bones. Evidence shows that activities such as jumping or changing direction have a more significant impact on bone adaptation. In fact, bones become “desensitized” to repetitive loads during running, so adding impact exercises in different planes can be more beneficial.
Risk and Recovery Monitoring
The use of wearable technologies, such as sports watches and acceleration sensors, facilitates tracking of training load. Although there are still no perfect clinical metrics for predicting injuries, these tools help identify risk patterns.
In case of injury symptoms, such as persistent or localized pain, it is crucial to reduce activity and seek medical attention. Early detection and appropriate treatment can prevent serious complications.
Conclusion
Stress bone injuries are preventable with proper training management, optimal biomechanics, and a balanced approach to recovery and nutrition. Adopting these strategies not only reduces the risk of injuries but also improves sports longevity and performance of runners. Based on current science, athletes can optimize their workload to achieve their goals without compromising their bone health
References
Warden, S. J., Edwards, W. B., & Willy, R. W. (2021). Preventing bone stress injuries in runners with optimal workload. Current Osteoporosis Reports, 19(4), 298–307. Preventing Bone Stress Injuries in Runners with Optimal Workload
