You'll often read that your target heart rate goal should be from 60 to 80 percent of your maximum heart rate when you exercise. And, to obtain the health benefits gained from cariovascular exercise your workout plan should include a goal of three to five workouts per week - 20 to 60 minutes (excluding warm-ups).

Although athletes often exceed the 60-80 percent target to build endurance, the average person gains little additional value when their heart rate exceeds this range. Exceeding the target range puts undue stress on your body and increases your potential for injury. The heart is simply working too fast and your body has a difficult time replenishing oxygen. On the flip side, exercise below the 60 percent target has fewer benefits for those exercising on a regular basis.

So yes, heart rate monitors are useful tools for those interested in maximizing their results in the least amount of time. They are especially useful for endurance athletes and those interested in losing weight. Keeping your heart rate within the target range allows you to exercise for longer periods without exhausting your body's resources and you achieve maximum benefits during your workout.

Here's a nice little tool for estimating your target heart rate: Calculate Target Heart Rate.

Typical Heart Rate Zones

• Warm Up (50 - 60% of max. heart rate): The right zone for people just starting a fitness program and a good warm up zone for those that regularly exercise. This zone has many benefits and a low risk of injury. It also helps you lower your body fat, blood pressure and cholesterol levels - it is estimated that 85% of calories burned in this zone are from body fats.

• Mild Exercise Zone (60 - 70% of maximum heart rate): This zone basically offers the same benefits as the warm up zone, except you burn more calories due to the increased level of exercise.

• Aerobic Zone (70 - 80% of maximum heart rate): The aerobic zone will improve your cardiovascular and respiratory system and strengthen your heart. This zone is preferred by endurance athletes and those interested in significantly improving their level of fitness.

• Anaerobic Zone (80 - 90% of maximum heart rate): Endurance athletes benefit from training in this zone. This zone helps to improve your VO2 maximum - greatest amount of oxygen one can consume during exercise. Your doctor or a higher end fitness facility can test your VO2 max. It takes more than just measuring your heart rate while running on a treadmill; specialized equipment you breath into while exercising is the best way to measure it. Exercising in the anaerobic zone also improves your endurance levels by increasing your lactate tolerance (you fight fatigue better). This is a high intensity zone. Only include it in your workout if you know what you are doing and you have your physicians approval.

• Max Heart Rate (90 - 100% of maximum heart rate): Consult a physician before creating a workout plan that includes exercises to achieve max heart rate. Although this zone can be achieved and you'll burn lots of calories, most people - even those in excellent shape - will only exercise in this intense zone for very short periods of time.