R-R Intervals / Online HR Variability Measures your heartbeat intervals and reflects autonomic nervous system activity in heartbeat regulation. The R-R interval measurement is most useful at rest and at low intensities. Relaxation rate indicates the state of your physical recovery. Running Index (optional - only with S3 or G3 sensors) Based on heart rate and speed data measurement during the run. Running Index is based on heart rate and speed data measured during the running exercise. It gives daily information about the runner’s performance level, both aerobic fitness and running economy. Improvement in running efficiency indicates improved economy of running performance. Polar Fitness Test™ with OwnIndex® Measures your fitness level in 5 minutes. A fitness test that measures your aerobic/cardiovascular fitness at rest in just five minutes. The result, Polar OwnIndex, predicts your maximal oxygen uptake (V02max). With the Polar Fitness Test you can measure your aerobic fitness by yourself, automatically and without any exertion. No other equipment other than a heart rate monitor is needed. The Polar Fitness Test is as accurate in predicting the VO2maxas any sub-maximal fitness test. The test is based on gender, age, height, body weight, level of physical activity, heart rate and heart rate variability at rest. The OwnIndex ranges usually from 20 to 95 and is comparable to VO2max, the golden standard of aerobic fitness. OwnIndex is most meaningful when following changes in your fitness over a long period of time. Find out how fit you are for your age and gender by comparing your result to the global references listed in the Polar user\\\'s manuals. Interval trainer (hr, pace distance) guided workouts Create your personal multizone workouts with heart rate/speed/distance and timing guidance. Allows you to create and name your own favorite workouts based on time, heart rate, speed/pace or distance guidance with up to three linked timers or distances and up to three target zones. Polar sport zones Helps you to train at the right intensity. Polar sport zones provides an easy way to select and monitor the intensity of your training and to follow Polar’s sport zones based training programs. The training is divided into five zones based on percentages of your maximum heart rate: very light (50-60%HRmax), light (60-70% HRmax), moderate (70-80%HRmax), hard (80-90% HRmax) and maximum (90-100% HRmax). ZonePointer Makes it easy to stay in your target zone. A visible and moving symbol on the display of your Polar product indicating that you are inside the pre-set target zone. ZoneLock Simply the easiest way to set a target zone. You can activate a target zone with a press of a button during your run. You can also deactivate the zone alarm just as easily – by pressing a button. Event Countdown Timer Set your goal and stay motivated. Keeps your motivation high by showing how many days are left before your next running event (e.g. Berlin 23 days)