Each week, I ask a question about a common running science myth. Answer correctly and you'll be entered into the weekly raffle.
During a 60-minute easy run at steady pace, your heart rate drifts up by 8-10 bpm by the end. What does that usually mean?
A. You’re getting fitter — HR rises as VO₂max improves 📈❤️ (7.6%)
B. You’re overtraining — autonomic stress is stacking up 🔴⚠️ (7.6%)
C. Cardiovascular drift from rising core temp + sweat loss — normal and expected 🌡️💧 (59%)
D. Your “easy” pace is actually too fast — target a 2-3 bpm drift instead 🐢💥 (25.9%)
Why this is right
Cardiovascular drift is well-documented physiology — as core temperature rises and plasma volume drops from sweat, stroke volume falls slightly and heart rate rises to keep output steady. An 8-10 bpm drift over an hour at a steady pace is completely normal, especially in warmer weather. It’s only a pace-zone problem when the drift gets excessive (15+ bpm).
251 responses so far