Nutellafiend wrote:
Sacral stress fractures and other stress fractures are caused by none other than over use, can you pinpoint it to one workout or session? No! This is degradation over time, she has been pushing her body for years and years. We're all genetically different some people are just not built to run forever like we hope we can. Eventually time will take us all.
Stress fractures are usually associated with an increased training load, usually hard speed work. The bone breaks down because it is not able to recover from the increased stress placed on it by the increased training demands. It is not an issue of accumulating miles over years.
I had a metatarsal stress fracture after getting into the best shape of my life. I built a solid base one summer and then transitioned into speed work. The speed work was significantly faster than what I had ever been capable of doing to the point of being close to PRs on tempo runs. Five years later, I have continued to be in the same shape and have not had another stress fracture. By your theory, I should keep getting them. But I don't.
Kara went from high mileage marathon training to doing lots of hard speed work on the track to prepare for hitting PRs on the track this summer. That kind of shift to hard speed work is a big risk factor for stress fractures, whether you have been running for 20 years of 3 years.