Why Your Watch Pace Is Lying to You
You ran 9:00/mile today. Last Tuesday, also 9:00/mile. Same fitness. Same effort. Right? Maybe not. Tuesday was flat, 60°F, fresh legs after a rest day. Today was rolling hills, 82°F, and you slept five hours. Your watch displayed the same number both times. But Tuesday’s 9:00 was a cruise. Today’s 9:00 nearly broke you. Your watch pace is measuring the wrong thing. It’s measuring speed over ground. What you actually need to know is how hard your body is working to produce that speed — and those are two very different questions. ...