46 Forerunner ® 301 Owner’s ManualAPPENDIX > TRAINING WITH HEART RATE ZONESA PPENDIXTraining with Heart Rate ZonesMany runners, bikers, and other athletes are using heartrate “zones” to measure and increase their cardiovascularstrength and improve their level of fitness.What are heart rate zones?A heart rate zone is simply a range of heartbeats perminute (bpm). The five commonly accepted heart ratezones are numbered from 1–5 according to increasingintensity. Generally, heart rate zones are calculated basedon percentages of your maximum heart rate. See Table 1to learn some of the effects of exercise as your heart ratereaches each of these zones during a workout.How do heart rate zones help you achievefitness goals?Knowing your heart rate zones can help you measureand improve your fitness by knowing and applying theseprinciples:• Your heart rate is a good measure of workoutintensity.• Training in certain heart rate zones can help youimprove cardiovascular capacity and strength.• Knowing your heart rate zone can prevent you fromovertraining and decrease your risk of injury.See Table 1 to learn the benefits of training in each heartrate zone.How does the Forerunner determine my heartrate zones?If you know your maximum heart rate, you can enter itand allow the Forerunner to calculate your heart rate zonesbased on the percentages shown in Table 1 (see “Setting HRZones Manually” in the Customizing section). However,the Forerunner 301 has a built-in feature called AutoLearn,which determines your heart rate zones automatically andcontinues to adjust them as your fitness level improves. Todetermine your heart rate zones, the Forerunner pinpointsyour lactate threshold—the point where your body switchesfrom aerobic energy consumption to anaerobic energy