Why Cardio?

Posted on June 12, 2008

Cardio training can have many beneficial effects on our bodies. By “cardio” I mean regular aerobic exercise that can be maintained for at least 20 minutes. Some examples include walking, jogging, biking, swimming, etc. To get the benefits of aerobic exercise, the intensity of the activity you choose should be somewhere between 60-90% of your maximum heart rate.¹ Maximum heart rate can easily be estimated by subtracting your age from 220. The duration of your workout is dependent on your intensity; a lower intensity can be maintained longer than a higher intensity.

Here are some of my favorite benefits of regular aerobic exercise training:

1. Regular aerobic exercise can help contribute to weight control, specifically fat loss without the loss of lean body mass. To lose weight, energy (calories) burned through physical activity and metabolism must be greater than energy consumed (through eating and drinking). This can be achieved by a combination of regular exercise and healthy eating. Some people think that calorie restriction alone will help them lose weight, and it will, but they will also lose valuable muscle tissue. Aerobic exercise will help with weight loss while maintaining or even increasing lean body mass.

2. Regular aerobic exercise can help prevent some types of cancers. Through regular aerobic exercise we can fight obesity and physical inactivity, both of which increase the risk of cancers of the colon, breast and kidney. Research has also found evidence suggesting the risk of developing prostate cancer can be decreased with physical activity.² While the exact physiological reasons why exercise and physical activity reduce the risk of these cancers is not entirely known, experts are certain that exercise and physical activity do contribute to the reduction of the risk of these cancers.³

3. Regular aerobic exercise can help increase our heart’s efficiency. A good measure of this is your resting heart rate. A lower resting heart rate after a period (usually a few weeks) of regular aerobic exercise training shows this increased efficiency. Because the heart muscle has been trained and strengthened, it can pump more blood per beat and therefore does not have to beat as many times. This can save a lot of heart beats over a lifetime.

4. Mitochondria are the “powerhouse” of cells. Regular aerobic exercise will increase the size and number of mitochondria in trained muscle cells. This increase in mitochondrial density is important for the use of fat as fuel during sub-maximal aerobic exercise. When a fat molecule is to be broken down to be used as fuel, it is broken down into a fatty acid and a glycerol molecule. The fatty acid is transported by the blood to the mitochondria where it is processed to be used as fuel. With an increase in the number of mitochondria in the muscle cells, the body can process and use more fatty acids as fuel. This conserves the potential energy stored as carbohydrate for other uses.⁴

5. When a person is aerobically trained, more capillaries develop to improve the oxygen and carbon dioxide exchange between blood and cells. Regular aerobic exercise can reduce the development of heart disease by increasing the number of capillaries in the body. If an artery is damaged or if blood flow is blocked, the blood can easily be rerouted via these new capillaries to where it needs to get to and deliver the necessary oxygen. This increased number of capillaries occurs not only in the heart, but also in the brain and all other parts of the body, thus also reducing the risk of stroke and other cardiovascular problems.⁵

6. Symptoms of depression and anxiety can be reduced through regular aerobic exercise. One study found that drugs with harmful side-effects are often prescribed to alleviate depression, even though some studies have found them to be less effective than regular exercise programs. Another study found that “exercise of more than 20 [minutes in] duration appears necessary for reduction in anxiety levels, irrespective of how anxiety is measured.”⁶

These are just a few of the many benefits of regular aerobic exercise. With all this evidence, is there any question that “cardio” is a good thing? Find the time to get some exercise. Get the heart rate up and try to keep it up for at least 30 minutes most days of the week.

Philip E. Allsen, Joyce M. Harrison and Barbara Vance, Fitness for Life: An Individualized Approach, 6th ed (Boston: WCB/McGraw Hill, 1997) 52. [↩]
Franca Bianchini, Rudolf Kaaks and Harri Vainio, “Weight Control and Physical Activity in Cancer Prevention,” Obesity Reviews: An Official Journal of the International Association for the Study of Obesity 3 (2002): 5-6. [↩]
Steven G. Aldana, The Culprit and the Cure: How Lifestyle is the Culprit Behind America’s Poor Health and How Transforming That Lifestyle Can be the Cure (Mapleton, UT: Maple Mountain Press, 2005), 146. [↩]
William D. McArdle, Frank I. Katch and Victor L. Katch, Exercise Physiology: Energy, Nutrition, and Human Performance, 6th ed (Baltimore: Lippincott Williams and Wilkins, 2007): 478-80. [↩]
Aldana, 142. [↩]
P. Callaghan, “Exercise: A Neglected Intervention in Mental Health Care?” Journal of Psychiatric and Mental Health Nursing 11 (2004):478-79. [↩]