The optimum conditioning level should exercise the heart at 70 to 85 percent of your maximum heart rate. How do you determine your maximum heart rate? Your doctor can tell you what that number is by conducting a stress test, or you can approximate it for yourself. To approximate your maximum heart rate from the number 220 subtract your age in years. So, if you are 35, your maximum heart rate would be 185. Your target zone then for working out would be 70 to 80 percent of 185 or 129 to 157 beats per minute.

Why is it important to know your target zone for exercising? Because if you are below the target zone you would get little heart conditioning and if you are above the target zone, the burden on your heart could be very dangerous. Many aerobic machines at gyms have heart rate monitors, so it is a good idea to continually monitor your heart rate, especially if you are new to working out.

Be careful with this information though... you cannot expect to get to your maximum heart rate if you are just starting out. You must listen to your body and make sure you are not overloading it to quickly. If you try to push it too hard, your body will start to shutdown. Work your way up to your 80%... start with a lower percent maybe 40% and see how your body responds... then go up from there. Slow and steady wins the race!