What causes stress fractures in runners?

Stress injuries are often seen in running and jumping athletes and are associated with increased volume or intensity of training workload. In healthy bone, osteoblasts repair areas of trauma or injury and produce new bone in the remodeling response. However, if time is not sufficient for osteoblasts to generate new bone, the rate of resorption by osteoclasts exceeds new bone formation, and thus, the bone weakens. Accumulated repetitively over time, this leads to stress reactions, and if training is not modified, these become completed stress fractures. Risk factors include an energy deficiency diet and low levels of Vitamin D. The female athlete triad also increases the risk Rapid changes in training programs including increased distance, pace, volume, or cross training without adequate time for adaptation can contribute. Failure to follow intense training days with easy ones for recovery can also contribute to injury.