Concept
Heart-rate zones
Working ranges that translate heart rate into training decisions. Their value comes from matching a suitable model to the purpose of the run, not from treating boundaries as biological walls.
Choose one model before reading the zones
Percent of maximum heart rate is simple, heart-rate reserve includes resting heart rate, and threshold-based models describe harder sustainable work. The same run can receive different zone labels under different systems.
Match the range to the training goal
Easy and recovery running should remain repeatable. Long runs usually protect controlled aerobic effort. Threshold, interval, and race-specific sessions use higher intensity deliberately and require more recovery.
Cross-check heart rate with pace and effort
Pace describes external output while heart rate reflects part of its internal cost. Heat, hills, fatigue, stress, and sensor error can separate the two, so conversation, breathing, perceived effort, and recovery remain necessary checks.
Review patterns instead of single beats
Zones are most useful for seeing whether easy days repeatedly become moderate, whether hard work has a purpose, and whether the weekly mix still supports recovery.
Select one primary zone model, define the purpose of the session, and use a broad working range alongside pace and perceived effort.
A zone number is not a universal prescription: Zone 2 differs between models, and crossing a boundary briefly does not instantly change the workout.