Stress fractures are most likely caused by which factor combination?

• A. Injury from sharp impact
• B. Decreasing exercise intensity and wearing supportive shoes
• C. Increasing exercise intensity and running on hard surfaces
• D. Resting completely

Answer: (C)

Stress fractures happen when a bone is subjected to repetitive loading that outpaces its ability to repair and strengthen between sessions. When you increase exercise intensity, each stride or hop puts more force through the bone. Running on hard surfaces amplifies these forces and the rate at which load is applied, so microdamage accumulates faster than it can be repaired. Over time, this progressive damage leads to a stress fracture. The other scenarios don’t fit this pattern: a sharp, single event causes an acute fracture, not a fatigue fracture; reducing training load or wearing supportive shoes lowers risk; and complete rest stops repetitive loading and healing work rather than initiating a fracture.