To work out efficiently and maximize the results of your fitness program, you want to monitor your heart to ensure that you are working out at an appropriate percentage of your of maximum heart rate.     

Your heart has a theoretical maximal value at which during extreme exertion, you approach physical exhaustion.  Coming too close to this value is dangerous for those at risk for heart attacks.  The percent of maximum heart rate tells you how close you are to your maximal value.  For most people, exercising within a range between 55% and 75% of maximum heart rate will yield the greatest benefit.  Always  consult with your doctor before beginning a new exercise program.  MIO calculates your percent of maximum heart rate based on the personal data you enter into the watch and displays your  percent of maximum heart rate every time you take your heart rate reading.  For more information click here.