TRAINING HEART RATE AND AEROBIC EXERCISE Completing the ideal aerobic workout session requires the proper type (mode) of exercise along with the appropriate frequency, intensity, and duration. Frequency is the number of times the exercise is to be preformed per week. Duration is the total time expended exercising, and may vary with the intensity. Intensity is the degree of stress placed on the body during the exercise. Determining the intensity of your aerobic workout is very important. Exercise too hard and your body quickly becomes fatigued, reducing the total exercise time (duration). Conversely, if little stress is applied to the body during a workout, you will fail to achieve the results you want. How can intensity be determined, and how can it be estimated during a workout? The best way to determine your personal intensity levels for aerobic exercise is to undergo a cardiovascular fitness test. This test is usually preformed three ways -- employing a treadmill, a bicycle ergometer (special work cycle), or step bench. (Note: It is strongly advised to complete this test under the guidance of certified professionals. Such tests can be performed at your physician's office, local university, community recreation center, YMCA, or Jewish community center). The treadmill and ergometer are preferable and usually found in laboratories, clinical settings, and up-scale fitness clubs. The step bench is mainly used for field testing. However, each testing method can provide adequate data to estimate exercise intensity. Other field studies include the 1.5 mile and 12 minute runs. These tests require an accurate timing device (stop watch or a watch with a second hand). The times are then compared to tables of known values to determine a fitness classification. Dr. Ken Cooper, the father of aerobics, has these classification tables in several of his books. What the fitness test will yield is an assessment of your cardiovascular tolerance. It measures how well your heart and vascular system respond to the body's increasing demand for oxygen as stress is applied in increments until exhaustion (at either a sub-maximal or maximal level). This test is used to calculate a fitness capacity (at sub-maximal levels) or VO2 MAX -- the maximum amount of oxygen utilized by the body at peak exhaustion. From this data, a MET level can be assigned based on the consumption of oxygen during exercise. One MET equals the amount of oxygen the body consumes at rest, defined as 3.5 milliliters of oxygen per kilogram of body weight per minute (3.5 ML/KG * MIN). During exercise, oxygen consumption may increase by many multiples, boosting the number of METS as high as 22 or more (that's 22 times the body's oxygen consumption at rest or 77 ML/KG * MIN. Consider an average person, at 160 lbs/72.7 kg, at rest consuming 255 milliliters per minute, while at 22 METS consuming 5.6 liters per minute. That's quite an impressive achievement! Other measurements taken during the fitness test are heart rate and possibly blood pressure. Both increase until sub-maximal or maximal levels are reached. Heart rate is especially important due to its linear relationship with oxygen consumption. Thus, the importance of the cardiovascular test -- to be able to calculate this linear relationship. Once a relationship has been established between oxygen consumption and heart rate, estimating the intensity of a workout session simply becomes a matter of monitoring your heart rate as you exercise. By setting up suitable training parameters, you can get optimal results each time you exercise. By monitoring your pulse occasionally (every five minutes or so) you can be assured the proper intensity is being maintained. Karvonen et al., has generated a formula for determining the training or TARGET HEART RATE. This formula was first studied in 1957. It requires several measurements: your maximum exercising heart rate, target percentage max heart rate for training (this can be a single percentage or be restricted to high and low values), resting heart rate, and a calculator (or paper and pencil). The following calculations are presented as examples. Example: You have found out after completing your fitness evaluation that your maximum heart rate is 187 bpm (beats per minute). Additionally, you determined your resting heart rate to be 70 bpm (This is best accomplished by sitting quietly in a chair after rising out of bed in the early morning and taking your pulse for 30 seconds or one minute. Remember if you take your pulse for 30 seconds, multiply by two to get beats per minute). You have also been instructed (by trained, certified professionals) to exercise at a training level between 65% and 75% of max heart rate (NOTE: most aerobic programs are conducted at intensity levels between 60% and 85% of maximum heart rate. This corresponds to oxygen consumption levels of between 43% and 78% VO2 MAX). Karvonen's formula: Training Heart Rate = % training level (max HR - resting HR) (THR) + resting HR. Remember to convert percentage training level to fraction form, e.g., 65% converted to fraction is 0.65; 75% is 0.75. Substituting the above data: max HR = 187 bpm resting HR = 70 bpm low % max HR = 65% (0.65) high % max HR = 75% (0.75) LOW THR = 0.65 (187 - 70) + 70 = 0.65 (117) + 70 = 76.05 + 70 = 146.05 or 146 bpm or 24 beats per 10 seconds HIGH THR = 0.75 (117) + 70 = 87.75 + 70 = 157.75 or 158 bpm or 26 beats per 10 seconds The difference between 24 and 26 may not seem like much but remember, the total spread can be between 12 and 18 beats per minute (10 second pulse count x 6 = one minute pulse). Remember to take your pulse promptly as the heart begins to recover quickly. Also, the best place to monitor your pulse is the radial artery found at the right side of the right wrist between the major tendon of the brachioradialis and the radius (bone). Gently place the index, middle, and ring fingertips in between the bone and tendon, press slightly, and release pressure until you feel the pulse. This process takes some getting used to, so practice until you become proficient enough to use this method very fast. If you feel more comfortable monitoring your left wrist, just reverse the above process. The TRAINING HEART RATE RANGE in the above example was between 24 and 26 beats per 10 seconds. Exercising at this level will provide the intensity necessary to maintain an adequate MET level. Recollect that the MET level is directly related to oxygen consumption. This will help you to visualize just how vigorous the heart works to deliver oxygen to the exercising muscles. The energy required to run this system demands certain fuels. These fuels can be obtained from many sources within the body. The Training Heart Rate (THR) relates directly to the efficiency of fuel utilization. Fuels that provide energy to sustain exercise are carbohydrates, fats, and proteins. When exercising at the appropriate intensity and duration, with adequate frequency, fats and carbohydrates are selectively chosen by the body as fuels of choice. Over time, and adhering to a proper training schedule, the storage of fat decreases causing the body to lose an equivalent amount of weight. This loss of weight and volume enhances body image. BOTTOM LINE? You can lose weight using this formula, or maintain your present weight. It's really up to you! Exercise is an important ingredient to safe and effective weight loss. There are many other benefits of aerobic exercise, but if the INTENSITY of the activity is not up to par, the results will not be up to par either. Good luck and GOODHEALTH! Allan G. Stevens 76702,562 Reference: Karvonen, M., et al., The effects of training heart rate: a longitudinal study. Ann Med Exptl Biol Fenn, 35:307-315, 1957.