| The most important factor for improving | | | | For example, a person in excellent physical condition |
| cardiorespiratory fitness (cardio or CR) is the intensity | | | | could start at 85 percent of his HRR; if he is in |
| of the workout. Changes in CR fitness are directly | | | | reasonably good shape, at 70 percent HRR; and, if he |
| related to how "hard" an aerobic exercise is | | | | is in poor shape, at 60 percent HRR. |
| performed. The more energy expended per unit of | | | | Most CR workouts should be conducted with the |
| time, the greater the intensity of the exercise, the | | | | heart rate between 70 to 75 percent HRR to attain, or |
| greater the effect on cardiorespiratory fitness. | | | | maintain, an adequate level of fitness. A person who |
| You have to know how hard is "hard" to determine if | | | | has reached a high level of fitness mayderive more |
| an aerobic exercise like running is producing a CR | | | | benefit from working at a higher percentage of HRR, |
| training effect or if it's just burning a few calories. The | | | | particularly if he cannot find more than 20 minutes for |
| heart-rate during work or exercise is an excellent | | | | CR exercise. |
| indicator of how much effort you are exerting. Only by | | | | Exercising at any lower percentage of HRR than 60 |
| keeping track of your heart during a workout can you | | | | does not give the heart, muscles, and lungs an |
| be sure that the intensity is enough to improve your | | | | adequate training stimulus. Before anyone begins |
| CR fitness level. In other words, your ability to monitor | | | | aerobic training, he should know his THR (the heart |
| your heart rate is the single most important key to | | | | rate at which he needs to exercise to get a training |
| success in CR training. | | | | effect). |
| Training Heart Rate (THR) = Desired Intensity of the | | | | The example below shows how to figure the THR by |
| Workout | | | | using the resting heart rate (RHR) and age to estimate |
| THR is the heart rate at which you need to exercise | | | | heart rate reserve (HRR). A 20 year old in reasonably |
| to get a training effect. The U.S. Army fitness gurus | | | | good physical shape is theexample. |
| have given us two methods to determine THR. The | | | | STEP 1: Determine the MHR by subtracting your age |
| first method, percent maximum heart rate (%MHR) is | | | | from 220. i.e. MHR = 220 - 20 = 200. |
| simpler to use, while the second method, percent | | | | STEP 2: Determine the resting heart rate (RHR) in |
| heart-rate-reserve (%HRR) is more accurate. | | | | beats per minute (BPM) by counting the restingpulse |
| %MHR Method | | | | for 30 seconds, and multiply the count by two. A |
| With this method the THR is figured using the | | | | shorter period can be used, but a 30 second count is |
| estimated maximal heart rate. You can estimate your | | | | more accurate. This count should be taken while you |
| maximum heart rate (MHR) by subtracting your age | | | | are completely relaxed andrested. For this example |
| from 220. Thus, a 20 year old would have an | | | | we use a RHR of 69 BPM. |
| estimated maximum heart rate (MHR) of 200 beats | | | | STEP 3: Determine the heart rate reserve (HRR) by |
| per minute (220 - 20 = 200). | | | | subtracting the RHR from the estimate MHR. i.e. HRR |
| A person who is in poor shape should exercise at 70 | | | | = 200 - 69 = 131 BPM |
| percent of his MHR; if he is in relatively good shape, at | | | | STEP 4: Calculate THR by (1) multiplying HRR by the |
| 80 percent MHR; and, if he is in excellent shape, at 90 | | | | relative fitness level as a percentage and (2) adding |
| percent MHR. | | | | the result to the HRR. For example, our 20 year old in |
| Examples: | | | | good physical condition will exercise at 70% HRR. |
| A 20 year old in good physical condition would have a | | | | (1) .70 * 131 = 91.7 |
| THR of 160 beats per minute (BPM). 220 - 20 = 200 * | | | | (2) 91.7 + 69 = 160.7 |
| .80 = 160 BPM. | | | | In summary, a reasonably fit 20-year-old with a resting |
| A 30 year old in good physical condition would have a | | | | heart rate (RHR) of 69 BPM has a training-heart-rate |
| THR of 152 beats per minute (BPM). 220 - 30 = 190 * | | | | (THR) goal of 161 BPM. |
| .80 = 152 BPM. | | | | During aerobic exercise, the body will usually have |
| A 40 year old in poor physical condition would have a | | | | reached a "Steady State" after five minutes of |
| THR of 126 beats per minute (BPM). 220 - 40 = 180 * | | | | exercise, and the heart rate will have leveled off. At |
| .70 = 126 BPM. | | | | this time and, immediately after exercising, is when you |
| %HRR Method | | | | should monitor your heart-rate to see if you are within |
| A more accurate way to calculate THR is the %HRR | | | | your desired THR range. |
| method. The range from 60 to 90 %HRR is the THR | | | | If your pulse rate is below the THR, you must exercise |
| range in which people should exercise to improve their | | | | harder to increase your pulse to the THR. If your pulse |
| CR fitness levels. If you know yourgeneral level of CR | | | | is above the THR, you should reduce the intensity to |
| fitness, you can determine which percentage of HRR | | | | reduce the pulse rate to the THR goal. |
| is a good starting point for you. | | | | |