Cardio Respiratory FitnessCardio respiratory fitness, sometimes called cardio, cardio endurance, aerobic fitness, or aerobic capacity, is one of the basic components of physical fitness. Cardio respiratory fitness is a condition in which the body's cardiovascular (circulatory) and respiratory systems function together, especially during exercise or work, to ensure that adequate oxygen is supplied to the working muscles to produce energy. Cardio respiratory fitness is needed for prolonged, rhythmic use of the body's large muscle groups. A high level of cardio respiratory fitness permits continuous physical activity without a decline in performance and allows for rapid recovery following fatiguing physical activity. Activities such as running, bicycling, swimming, cross-country skiing, rowing, stair climbing, and jumping rope place an extra demand on the cardiovascular and respiratory systems. During exercise, these systems attempt to supply oxygen to the working muscles. Most of this oxygen is used to produce energy for muscular contraction. Any activity that continuously uses large muscle groups for 20 minutes or longer taxes these systems. Because of this, a wide variety of training methods are used to improve cardio respiratory endurance. Physiology of Aerobic TrainingAerobic exercise uses oxygen to produce most of the body's energy needs. It also brings into play a fairly complex set of physiological events.
Correctly performed aerobic exercise, overtime, causes positive changes in the body's cardio respiratory system. These changes allow the heart and vascular systems to deliver more oxygen-rich blood to the working muscles during exercise. Also, those muscles regularly used during aerobic exercise undergo positive changes. By using more oxygen, these changes let the muscles make and use more energy during exercise and, as a result, the muscles can work longer and harder. During maximum aerobic exercise, the trained individual has an increased maximum oxygen consumption, and is better able to process oxygen and fuel and can therefore provide more energy to the working muscles.
In the presence of oxygen, muscle cells produce energy by breaking down carbohydrates and fats. In fact, fats are only used as an energy source when oxygen is present. Hence, aerobic exercise is the best type of activity for attaining and maintaining a low percentage of body fat. A person's maximum aerobic capacity can be modified through physical training. To reach very high levels of aerobic fitness, one must train hard. The best way to improve cardio respiratory fitness is to participate regularly in a demanding aerobic exercise program. Many factors can negatively affect one's ability to perform well aerobically. These include the following:
Any condition that reduces the body's ability to bring in, transport, or use oxygen reduces a person's ability to perform aerobically. Inactivity causes much of the decrease in physical fitness that occurs with increasing age. Taking part in a regular exercise program can slow some of this decrease in aerobic fitness. Certain medical conditions also impair the transport of oxygen. They include diseases of the lungs, which interfere with breathing, and disabling heart conditions. Another is severe blocking of the arteries, which inhibits blood flow to the heart and skeletal muscles. Smoking can lead to any or all of the above problems and can, in the long and short term, adversely affect one's ability to do aerobic exercise. FITT factorsA person must integrate several factors into any successful fitness-training program to improve his fitness level. These factors are summarized by the following words, which form the acronym FITT. Frequency, intensity, time, and type. They are described below as they pertain to cardio respiratory fitness. A warm-up and cool-down should also be part of each workout. FrequencyFrequency refers to how often one exercises. It is related to the intensity and duration of the exercise session. Conditioning the cardio respiratory system can best be accomplished by three adequately intense workouts per week. You should do these on alternate days. By building up gradually, you can get even greater benefits from working out five times a week. However, recognize the need for recovery between hard exercise periods and you should adjust the training intensity accordingly. You must also be aware of the danger of over training and recognize that the risk of injury increases as the intensity and duration of training increases. IntensityIntensity is related to how hard one exercises. It represents the degree of effort with which one trains and is probably the single most important factor for improving performance. Unfortunately, it is the one factor many ignore. Changes in cardio respiratory fitness are directly related to how hard an aerobic exercise is performed. The more energy expended per unit of time, the greater the intensity of the exercise. Significant changes in cardio respiratory fitness are brought about by sustaining training heart rates in the range of 60 to 90 percent of the heart rate reserve (HRR). Intensities of less than 60 percent HRR are generally inadequate to produce a training effect, and those that exceed 90 percent HRR can be dangerous. You should gauge the intensity of your workouts for cardio respiratory fitness by determining and exercising at your training heart rate (THR). Using the THR method lets you find and prescribe the correct level of intensity during cardio respiratory exercise. By determining one's maximum heart rate, resting heart rate, and relative conditioning level, an appropriate THR or intensity can be prescribed. One's ability to monitor the heart rate is the key to success in cardio respiratory training. The heart rate during work or exercise is an excellent indicator of how much effort a person is exerting. Keeping track of the heart rate lets one gauge the intensity of the cardio respiratory exercise being done. With this information, one can be sure that the intensity is enough to improve his/her cardio respiratory fitness level.
Percent MHR methodWith this method, the THR is figured using the estimated maximal heart rate. You can determine your estimated maximum heart rate by subtracting your age from 220. Thus, a 20-year-old would have an estimated maximum heart rate (MHR) of 200 beats per minute (220 - 20 = 200). To figure a THR that is 80 percent of the estimated MHR for a 20-year-old in good physical condition, multiply 0.80 times the MHR of 200 beats per minute (BPM). This example is shown below.
Formula
When using the MHR method, one must compensate for its built-in weakness. A person using this method may exercise at an intensity, which is not high enough to cause a training effect. To compensate for this, a person who is in poor shape should exercise at 70 percent of his MHR; if he is in relatively good shape, at 80 percent MHR; and, if he is in excellent shape, at 90 percent MHR. Percent HRR method A more accurate way to calculate THR is the percent HRR method. The range from 60 to 90 percent HRR is the THR range in which people should exercise to improve their cardio respiratory fitness levels. If you know your general level of cardio respiratory fitness, you can determine which percentage of HRR is a good starting point. For example, if you’re in excellent physical condition, you could start at 85 percent of you HRR; if you’re in reasonably good shape, at 70 percent HRR; and, if you’re in poor shape, at 60 percent HRR. Most cardio respiratory workouts should be conducted with the heart rate between 70 to 75 percent HRR to attain, or maintain, an adequate level of fitness. If you have reached a high level of fitness you may derive more benefit from working at a higher percentage of HRR, particularly if you cannot find time for more than 20 minutes for cardio respiratory exercise. Exercising at any lower percentage of HRR does not give the heart, muscles, and lungs an adequate training stimulus. The example below shows how to figure your THR by using the resting heart rate reserve (HRR). A 20-year-old male in reasonably good physical shape is the example. Step 1: determine the MHR by subtracting your age from 220.
Formula
Calculation
Step 2: determine the RHR in beats per minute (BPM) by counting the resting pulse for 30 seconds, and multiply the count by two. A shorter period can be used, but a 30-second count is more accurate. This count should be taken while you’re completely relaxed and rested. How to determine heart rate reserve (HRR) by subtracting the RHR from the estimated MHR. If your RHR is 69 BPM, the HRR is calculated as shown here.
Formula
Calculation
Step 3: calculate the THR based on 70 percent of HRR (a percentage based on a good level of cardio respiratory fitness).
Formula
Calculation
As shown, the percentage (70 percent in this example) is converted to the decimal form (0.70) before it is multiplied by the HRR. The result is then added to the resting heart rate (RHR) to get the THR. Thus, the product obtained by multiplying 0.70 and 131 is 91.7. When 91.7 is added to the RHR of 69, a THR of 160.7 results. When the calculations produce a fraction of a heartbeat, as in the example, the value is rounded off to the nearest whole number. In this case, 160.7 BPM is rounded off to give a THR of 161 BPM. In summary, a reasonably fit 20-year-old with a resting heart rate of 69 BPM has a training heart rate goal of 161 BPM. To determine the RHR, or to see if one is within the THR during and right after exercise, place the tip of the third finger lightly over one of the carotid arteries in the neck. These arteries are located to the left and right of the Adam’s apple. Another convenient spot from which to monitor the pulse is on the radial artery on the wrist just above the base of the thumb. Yet another way is to place the hand over the heart and count the number of heartbeats. During aerobic exercise, the body will usually have reached a "steady state" after five minutes of exercise, and the heart rate will have leveled off. At this time, and immediately after exercising, you should monitor your heart rate. You should count your pulse for 10 seconds, and then multiply this by six to get your heart rate for one minute. This will let you determine if your training intensity is high enough to improve your cardio respiratory fitness level. For example, use the THR of 161 BPM figured above. During the 10-second period, you should get a count of 27 beats (161/6= 26.83 or 27) if you’re exercising at the right intensity. If your pulse rate is below the THR, you must exercise harder to increase your pulse to the THR. If your pulse is above the THR, you should normally exercise at a lower intensity to reduce the pulse rate to the prescribed THR. You should count as accurately as possible, since one missed beat during the 10-second count, multiplied by six, gives an error of six BPM. A person who maintains his/her THR throughout a 20- to 30-minute exercise period is doing well and can expect improvement in his/her cardio respiratory fitness level. You should check your exercise and post-exercise pulse rate at least once each workout. If you take only one pulse check, do it five minutes into the workout. Another way to gauge exercise intensity is "perceived exertion." this method relies on how difficult the exercise seems to be. Remember, you should be able to converse normally. If you’re gasping for breath and cutting your words short, then slow down. TimeTime, or duration, refers to how long one exercises. It is inversely related to intensity. The more intense the activity, the shorter the time needed to produce or maintain a training effect; the less intense the activity, the longer the required duration. To improve cardio respiratory fitness, you must train for at least 20 to 30 minutes at your THR. TypeOnly aerobic exercises that require breathing in large volumes of air improve cardio respiratory fitness. Worthwhile aerobic activities must involve the use of large muscle groups and must be rhythmic. They must also be of sufficient duration and intensity (60 to 90 percent HRR). Examples of primary and secondary exercises for improving cardio respiratory fitness are as follows:
Secondary (done with partners or opponents of equal or greater ability.)
The primary exercises are more effective than the secondary exercises in producing positive changes in cardio respiratory fitness. The secondary activities may briefly elevate the heart rate but may not keep it elevated to the THR throughout the entire workout. SummaryCardio respiratory fitness is an essential component in your body’s overall fitness level, and will help shed pounds of excess, unwanted fat. Use the VFC’s online calculators to help estimate your training heart rate, and stick with it. Most importantly have fun! Don’t get stuck doing the same cardio workout over and over. Variety is the spice of life, and the same should go for you exercise program as well, mix it up and try something new. Get some friends or a significant other involved, and have a good time. |