By Carol Kutik

When reading the guidelines for aerobic fitness, several seemingly contradictory numbers appear: 30 minutes a day, 150 minutes per week, 75 minutes per week, 300 minutes per week, etc.  You may ask yourself, “Why are these numbers so different? Can they all be right? Which one is for me? Why are any of them important? Where do they come from?”

They are important because cardiorespiratory or “aerobic” fitness is a foundation of health. Being able to take in oxygen and put it to use to make energy (cardiovascular fitness) allows you to engage in activities of daily living with ease and more fully participate in recreational and athletic activities. Regular and consistent aerobic activity that stresses your heart, lungs and blood vessels to work harder improves your cardiovascular fitness and health.

The numbers come from the 2008 Physical Activity Guidelines for Americans released by the United States Department of Health and Human Services, which tell us:

• 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. Typically, one minute of vigorous-intensity aerobic physical activity is considered equal to two minutes of moderate-intensity aerobic physical activity.
• 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 throughout the week.