In the Zone
Zone 1: 60% to 70%
This is a very comfortable effort, used for warm-up and cool-down.
Zone 2: 70% to 80%
Used for the bulk of training, this relaxed effort allows you to hold a conversation.
Zone 3: 81% to 93% This is a comfortably hard effort, during which you can only say short, broken sentences.
Zone 4: 94% to 100% Often a 5K pace, this is a very hard effort that’s sustainable, but only lets you speak a few words at a time.