Polar RCX5 endurance training watch. GPS enabled training computer. Tracks speed, stride and pace. Improves performance with endurance training programmes. Polar Fitness Test measures aerobic fitness. Running Index scores your performance. Race Pace to control your speed. The Polar RCX5 is designed to improve the performance of endurance athletes through coaching, monitoring and pacing. If you're looking to improve your fitness and want to keep up to date with how well you're doing, the smart Fitness Test will tell you exactly what you need to know in just five minutes. By regularly comparing your test results, you can see what progress you are making and how your fitness is improving. If you're looking to keep on top of your running performance you'll find the Running Index feature a big help. Regular use over time allows you to see how efficient your running is. Your Running Index score is calculated automatically after every run, based on your heart rate and from the speed data collected from your GPS or stride sensor. A higher reading indicates that you can run faster with less effort. Endurance programmes from Polar include recommended warm-up, exercise and cool-down phases for every training session. The programmes are customised to your specific needs and fitness level and optimise endurance training by adapting and updating your training routines every four weeks. You can create these programmes in polarpersonaltrainer.com and upload them to a compatible training computer.