By AntiFragile Physical Therapy, Asheville, NC Smartwatches have changed the way people approach training. From tracking recovery and heart rate to estimating VO₂ max and training zones, wearable technology gives athletes more access to performance data than ever before. And while these tools can be incredibly useful, there’s one important distinction many people don’t realize: Most smartwatches are estimating your training zones, not directly measuring them. That difference