5 Forerunner ® 205/305 Owner’s ManualappendIxSee the next page to learn aboutthe benefits of training in eachheart rate zone.How can I determine myheart rate zones?If you know your maximum heartrate, you can enter it and allowthe Forerunner to calculate yourZone % of Max.Heart Rate Perceived Exertion Benefits1 50%–60% Relaxed, easy pace;rhythmic breathingBeginning-level aerobictraining; reduces stress2 60%–70%Pace comfortable;slightly deeper breathing,conversation possibleBasic cardiovasculartraining; good recoverypace3 70%–80%Pace moderate;more difficult to holdconversationImproved aerobiccapacity; optimalcardiovascular training4 80%–90%Pace fast and a bituncomfortable;breathing forcefulImproved anaerobiccapacity and threshold;improved speed5 90%–100%Pace a sprinting effort,unsustainable for long periodof time; labored breathingAnaerobic andmuscular endurance;increased power