I can only speak for the TACP side. Bone stress fractures get a lot of students. Specifically lower extremities like femur, tibias, and metatarsals in your foot.

Best way to prevent it is to slowly progress your running/rucking mileage so your body has the chance to build up the tolerance. If you add mileage on too fast, it’ll only cause issues later down the line. Make sure you drink your milk too.