Heart rate and age are necessary components in estimating your heart’s response to exercise.  Heart rate is the number of times your heart beats per minute. The age-adjusted equation for estimating your maximum heart rate is 220 minus your age. The product of this equation is used to determine your heart rate at a given intensity level, expressed as a percentage of your maximum heart rate.

Maximum Heart Rate and Age
Maximum heart rate is determined by factors within your heart’s electrical system that cause your heart to contract and relax for so many beats per minute. This maximum limit is genetically determined and decreases with age. For example, if you are 35 years old, your estimated max heart rate should be 185 beats per minutes (bpm). At 50 years, your max heart rate is 170 bpm.

Exercise Recommendations
Aerobic exercise typically is recommended as a percentage of your max heart rate. The American College of Sports Medicine (ACSM) advises three to five days of moderately to vigorously intense aerobic exercise per week to reduce your risks of chronic disease. ACSM defines moderately vigorous as 64 percent to 76 percent of your max heart rate. At 35 years old, your heart rate for moderately vigorous exercise should be between 118 bpm (220 – 35 = 185 bpm; 185 x 0.64 = 118 bpm) and 141bpm (185 x 0.76 = 141 bpm). Vigorously intense exercise is exercising at 77 percent to 93 percent of your max heart rate. Use a heart-rate monitor to quickly check your status.

Although your maximal heart rate is genetically determined, proper training can improve your heart’s response to exercise as you get older. Progressive aerobic exercise improves your cardiovascular system. One such improvement is in the amount of blood your heart pumps in a single beat, referred to as stroke volume. Exercise increases your stroke volume, decreasing the need for your heart to beat faster, so your heart rate decreases (improves) at any age as your fitness level increases.

Misconceptions You might be confused with the recommendation to exercise in your fat-burning zone, which usually is 60 percent to 75 percent of your max heart rate to burn a lot of fat. As you get older, you will be more tempted to exercise only in this zone because fat deposits are increasing and are more visible on your body. Use a range of intensities from 60 percent to 95 percent of your max heart rate to increase the amount of calories you burn, working toward 3,500 calories, which equals a pound of fat.

Warning Certain medications will increase or decrease your resting or exercise heart rates.  If you are taking medications, always get medical clearance from your doctor before beginning an exercise program. You will have to monitor your heart rate at a given workload.  For instance, if you usually walk on a treadmill at 3 mph on a 2 percent incline, track your heart rate. In this manner, even while on medication that alters heart rate, you will know how your heart rate varies from what it should be, based on the max heart rate equation. Also, use your perceived exertion to help you monitor your response to exercise while on medication. If your heart rate response is normal but you feel out of breath and dizzy, stop exercising immediately, and seek medical attention.

Read more: http://www.livestrong.com/article/114179-heart-rate-exercise-age/#ixzz1Fmti6SiP