Cardiorespiratory fitness is a measure of the heart and lung's functionality. A healthy heart efficiently pumps blood at a steady rate. Generally speaking, lower blood pressure and a lower resting pulse rate indicate healthy cardiovascular function, while high lung capacity in conjunction with good blood oxygenation indicate good respiratory fitness. Doctors can use several tests to estimate cardiorespiratory fitness, and patients can improve their performance on these tests by increasing their exercise rate and eliminating unhealthy lifestyle choices such as smoking.
Treadmill Stress Test
A treadmill stress test is the most common test of cardiovascular fitness. For the test, you get on a treadmill and a doctor monitors your vital signs as you walk and then run at progressively faster rates. Depending upon your health history, your doctor may monitor your oxygen intake during this test or may simply take your vital signs at various stages throughout the test. When you finish on the treadmill, your doctor will also check to see how long it takes your heart rate to return to normal. A slower return generally indicates lower cardiorespiratory health.
Spirometry is a lung capacity test that also measures how quickly you can exhale. Doctors use it to test for a variety of conditions, including asthma, chronic obstructive pulmonary disease and emphysema. However, it also offers a general measure of cardiorespiratory fitness. During the test, a doctor or nurse clips your nose shut and then uses a machine to measure your breathing as you inhale and exhale. You will have to inhale deeply and slowly and then exhale as forcefully as you can several times.
Doctors sometimes use exercise tests instead of stress tests to assess cardiorespiratory fitness as well as overall physical fitness. Your doctor, for example, might ask you to walk as far as you can in six minutes, then measure your vital signs after this walk. He will give you an assessment of your overall fitness based upon the distance covered, your vital signs and the period of time it takes your vital signs to return to normal after the test.
Lung Diffusion Testing
A lung diffusion test estimates how well the lungs diffuse gases. High blood oxygenation and efficient gas diffusion strongly correlate with good cardiorespiratory health. A doctor or nurse places a clip on your nose, then asks you to inhale a tracer gas through your mouth. You must hold your breath for a few seconds, then exhale into a machine. Your doctor will then test your exhalation to determine how much of the tracer gas you absorbed. Higher absorption generally correlates with better cardiorespiratory function.