Forerunner 405 Owner’s Manual Using Accessoriesshirt if suitable for your activity.Synthetic fabrics that rub or flapagainst the heart rate monitorcan create static electricity thatinterferes with heart rate signals.Move away from sources ofstrong electromagnetic fields andsome 2.4 GHz wireless sensors,which can interfere with yourheart rate monitor. Sources ofinterference may include veryhigh voltage power lines, electricmotors, microwave ovens,2.4 GHz cordless phones, andwireless LAN access points.Heart Rate ZonesCaution: Consult yourphysician to specify heartrate zones/targets that areappropriate for your fitnesslevel and health condition.•Many athletes are using heart ratezones to measure and increase theircardiovascular strength and improvetheir level of fitness. A heart ratezone is a set range of heartbeats perminute. The five commonly acceptedheart rate zones are numbered from1–5 according to increasing intensity.The Forerunner sets the heart ratezone ranges based on your maximumheart rate set in your user profile,according to the table on page 43.You can also customize your heartrate zones in your user profile ofGarmin Connect or Garmin TrainingCenter. After customizing your heartrate zones, transfer data to yourForerunner.How Do Heart Rate ZonesAffect Your Fitness Goals?Knowing your heart rate zones