You're huffing and puffing through another aerobic workout, wondering if you're really doing yourself any good. Are you working too hard? Are you not? You look around. The person next to you has barely broken a sweat while the one in front is drenched from head to toe. You feel that "no sweat" - no benefit. However,sweating is not the best indicator of exercise intensity. You cant measure how beneficial your work out is based on the amount of sweat you produce.

Healthcare professionals recognise "heart rate" or "HR" as the best measure of exercise intensity. When you exercise, your heart beats faster to meet the body's demand for more oxygen. The more intense the activity, the faster your heart will beat. So - monitoring your heart rate (HR) during your exercise is a great way to monitor your exercise activity.

It is important to pace yourself when you exercise. The goal is not to tire too quickly, but still receive the benefits of being physically active. Even more important if you have been physically inactive.

Before you begin any exercise program, it is important to discuss your plan with your doctor. Especially if you are over the age of 35 or have a current medical condition.

There is a range of exercise intensities that are described as safe and effective for providing cardiovascular benefits. To determine what range is best for you, you need to acquaint yourself with a few terms.

1. Maximal Heart Rate

This number is related to your age. The older we get the slower our hearts beat. To estimate your maximal heart rate, subtract your age from the number 220.

2. Target Heart-rate Zone

This is the number of beats-per-minute (BPM) at which your heart should beat during aerobic exercise. For most health individuals, this zone is 50 to 80 percent of your maximal heart rate. So - if for your age your maximal heart rate is 180 (about age 40) the low end of the range (50% of maximal) would be 90 bpm, and the high end of the range (80% of maximal) would be 144 bpm.

What the recommended range means.

These numbers serve as an indication of how heard you should be exercising. Beginning aerobic exercisers should probably aim for the low range of the zone and pick up the intensity as they become more comfortable with their workouts. Those who are more fit, or are training for competitive events, may want to aim for the higher end of the zone. Note that the "target" heart rate zone is recommended for individuals without any health problems. Also, those individuals taking medication that alters the heart rate should consult their doctor for recommended exercise intensity.