Are you getting fitter—or getting closer to an injury? Two triathletes each train nine hours this week. One finishes the block stronger, faster, and ready for the next progression. The other develops shin pain that becomes a stress fracture six weeks later. On paper, their training logs look identical. In reality, they couldn't be more different. The difference isn't how long they trained—it's how much stress those nine hours placed on their body compared to what they were pr