Heart Rate Monitor Training
What is a heart rate monitor and how can it improve my performance? Is it just a fad or is there a scientific basis for training with such devices?
Like any combustion engine, your body uses oxygen and fuel to generate energy. The cardiovascular system delivers oxygen to the skeletal muscles, which then use this oxygen to “burn” various fuels (carbohydrate and fat) to yield mechanical energy. A unique feature of your body is its ability to change in response to the demands placed on it. By working out hard, you overload your aerobic systems. During rest, your body adapts to make you stronger. This is accomplished by improvements in cardiovascular and muscular function. The heart becomes stronger and more efficient and the skeletal muscles become better at extracting oxygen from the bloodstream. Within muscle cells, the mitochondria boost their enzyme systems to oxidize fuels.
All of these changes occur slowly over time. For continued improvement, you must continue to overload these systems. As you adapt, however, you require harder workouts to do this. How do you know if you are training at the right level? Physiologists have discovered that the rate of oxygen “burned” in the muscles is the best measure of aerobic work.To determine this requires expensive equipment and specialized testing facilities. Basically, an individual runs on a treadmill while heart rate and volume of inhaled and exhaled air are measured. Samples of exhaled air are periodically taken and the oxygen concentration determined. The difference between the amount of oxygen breathed in and out during the test is what the muscles have consumed to burn fuel. The rate of oxygen consumption, in liters per minute, is called VO2. The test is done at progressively harder levels until the individual “maxes” out. The maximum rate of oxygen consumption is called the VO2(max).
Research on VO2 has shown that there is a threshold below which no additional gains are achieved in aerobic exercise. For most people, this is a pace that allows for casual conversation during the workout, and is approximately 55% of VO2(max). Above this level you are sufficiently overloading your cardiovascular and muscular systems to bring about improvement. The lab equipment is much too bulky to take with you on the road. So, how do you know if you are above this level in your workouts?
The heart rate is much easier to measure and is a very good approximation of VO2. The relationship between percentage of maximum heart rate and percentage of VO2(max) is very predictable and is independent of age, gender, or level of fitness. 55% VO2(max) corresponds to about 70% max heart rate. Thus once you have determined your maximum heart rate, you have a very convenient method of monitoring your workouts.
Now that you understand the science, how do you use it to get faster? First, you must determine what your maximum heart rate is. Most people have seen the equation:
Max Heart Rate (bpm) = 220 minus age in years
This is only a rough approximation, and there is considerable variation between individuals of the same age. You can directly determine your maximum heart rate by an exercise stress test. It is vitally important that you undergo a physical examination prior to any stress test, especially if you are over 35.
Effective aerobic conditioning requires that you maintain your heart rate at the proper intensity level for at least 20 minutes per workout. If your heart rate is too high, your activity can become counter effective. For most people, as your heart rate exceeds 85% (the upper limit), your workout causes the body to become anaerobic and produce lactic acids. This also burns less fat, which can cause a burning sensation and strain within the muscles. It’s important to reach a level of intensity that is productive. A heart monitor will tune you into your body’s internal activity level and help prevent injury.
Using a heart rate monitor can help you make sure your exercise intensity is at a level that burns fat optimally and keeps the body working aerobically (not anaerobic). A regular exercise program performed at the proper heart rate levels can help increase your metabolism. It’s important that beginners do not push themselves too hard. Exercise is meant to be fun and enjoyable! The most important exercise factor for losing weight is the duration of the exercise.
For optimum results, it’s best to work out at a level that can be comfortably maintained for a longer period of time. As long as you are maintaining a comfortable intensity within your zone, you will be burning fat. Those who are just starting an exercise routine or are out of shape, should always start at a slower pace and concentrate on being able to exercise for gradually longer periods of time.
For fat burning and weight reduction the optimal zone is 55-85% of maximum heart rate. This level consists of lower intensity, longer duration exercises. For best results, increase the length of time gradually. This range is particularly recommended for those who haven’t worked out for a while or if you are starting a new exercise routine. This lower intensity helps you maintain your exercise for longer periods of time safely.
Once you have determined your maximum heart rate, you can construct a target zone for your workouts. The aerobic training zone is usually between 70% and 90% max heart rate. Most training schedules incorporate different types of workouts (eg. long slow distance, high intensity intervals). You can construct different target zones depending upon the type of workout you are performing. The heart rate monitor helps you stay in that zone so that you can achieve your goal for that workout.
The biggest advantage of using this approach in your training schedule is the ability to account for improvement. Suppose a 30 year old female averages 9 minutes per mile for a 10km workout with an average heart rate of 145 beats per minute. As she improves, her average heart rate will decrease for the same 9 minutes per mile. If she focuses only on keeping a constant time of 9 minutes per mile, she will reach a point where his workout no longer challenges her aerobic system. At this point, her workout can only maintain aerobic fitness and no further improvement can occur. If, however, she focuses on keeping an average of 145 beats per minute for each workout, she will apply a constant overload to her aerobic system. Over months, her average time per mile should steadily decrease. Another advantage is the ability to account for variable terrain and wind. Take our 30 year old and make her run into a 20mph head wind. Clearly, she must perform extra work per mile. The heart rate monitor helps her keep the applied load constant even though her time will necessarily be slower.
About Your Heart:
Although the average heart is not much larger than a clenched fist, it can pump blood at a pressure greater than a wide-open kitchen faucet. It beats 40 million times a year – year after year. When the blood is being pumped, the heart muscle contracts. The right chamber of the heart sends incoming blood filled with carbon dioxide to the lungs, which take out that gas and enrich the blood with life-sustaining oxygen. The left side of the heart receives the refreshed blood from the lungs and pumps it to the rest of the body. Each contraction is called a heartbeat. The number of heartbeats per minute is called the heart rate. This single number provides a steady status report on your body and its environment. It tells you how hard you are exercising and how fast you are using energy. It consolidates how much sleep you have had, how much you weigh, how hot it is outside, your emotional state, and a myriad of other factors.