Cardiorespiratory Exercise - How Much is Enough?
By: Carol Kutik
Cardiorespiratory (aerobic) exercise challenges and enhances the efficiency of your heart and lungs, increasing their ability to deliver blood and oxygen throughout the body. The health benefits of engaging in such activity are numerous and applicable to individuals of all ages, including older adults. A reduction in coronary risk factors, including hypertension, cholesterol levels and triglyceride levels are well documented. Also included in the list of benefits are a reduction in the risk of stroke with moderate to high amounts of activity, a strong protective role in the prevention of diabetes and increased control of insulin and glucose in the management of diabetes. Add to the list decreased risk of some cancers, averting age-related bone loss and osteoporosis, weight management, decreased stress and depression and a “better mood,” and the reasons to engage in cardiorespiratory exercise become even more compelling.
How much is enough and how hard should it be? The 2008 Physical Activity Guidelines for Americans released by the United States Department of Health and Human Services include the following:
- Perform 150 minutes per week of moderate-intensity aerobic physical activity, or 75 minutes per week of vigorous-intensity aerobic physical activity, or a combination of both.
- Additional health benefits are obtained from performing greater amounts of activity than those quantities.
- Perform aerobic bouts that last at least 10 minutes, preferably spread out through the week.
Exercise intensity is arguably the most important element to monitor, and at the same time often the most difficult to quantify. There are numerous methods that can be used to monitor intensity. Using heart rate has been widely employed; however, accuracy requires knowledge of an individual’s true maximal heart rate, which requires a maximal effort exercise test. Since this type of test is not available or may not be appropriate for most individuals, the true max is difficult to define. The standard 220 – age formula can be used but has a significant margin of error. Heart rate can also be altered by certain disabilities and by certain medications. By all means, use heart rate if applicable to you!
An easier-to-use-but-reliable method is called Rating of Perceived Exertion (RPE). Using the following chart, an individual can rate his/her perceived level of exertion. While it may not feel as clear at first, it becomes easier to judge intensity over time. Moderate-intensity activity is in the 4-6 range, and vigorous-intensity activity is in the 7-8 range.
Very Light Activity
Breathing not changed
Easy to breathe and carry on a conversation
Breathing more heavily - can carry on a conversation but it requires more effort
On the verge of becoming uncomfortable - conversation requires maximum effort
Very Hard Activity
Difficult to maintain exercise or speark
Maximum Effort Activity
Full out effort - no conversation possible
Most important for older adults is safe and appropriate progression. Begin slowly and gradually increase your time and intensity. This may take weeks or months. Check with your doctor before beginning an exercise program so that he/she can alert you to any modifications that may apply to your individual health history. Also, be certain to include a 5 to 10 minute warm up and cool down.
What activities promote improvement or maintenance of cardiorespiratory fitness? Virtually any type of activity that involves a large amount of muscle, can be performed in a rhythmic fashion, and be sustained for more than a few minutes can be classified as cardiorespiratory exercise. Choices can range from walking, pushing, cycling, and swimming, playing tennis or basketball, using elliptical trainers and dancing. When possible and appropriate, including a variety of aerobic exercises can enhance performance, eliminate boredom, and decrease the risk of overuse injury. Talk with a fitness professional about ways to vary your routine.