Tracking the duration or frequency of your physical activity is easy, but it's difficult to measure the intensity of your exercise. Intensity refers to the percentage of maximal oxygen consumption, also called VO2 max, that your body uses while you exercise. For example, moderately intense exercise typically uses 40 to 59 percent of your VO2 max, according to Indiana University. You can't measure your oxygen consumption without special equipment, but you can estimate the intensity of your exertion during a walk by measuring your heart rate and doing a talk test.
Step 1
Subtract your age from 220 to find your maximum heart rate if you are male. For example, a 30-year-old male has a maximum heart rate about 190. If you are female, multiply your age by 0.88 and subtract that number from 206. For example, a 30-year-old female has a maximum heart rate of about 180.
Step 2
Take your pulse at your neck or wrist when walking, using your index and middle fingers to feel your heartbeat. Count how many times your heart beats in 30 seconds and then multiply by 2. For example, if your heart beats 53 times in 30 seconds, your heart rate is 106 beats per minute.
Step 3
Divide your heart rate while exercising by your maximum heart rate. For example, 106 divided by 190 is about 56 percent, while 106 divided by 180 is about 59 percent. Moderate-intensity exercise should be between 50 to 70 percent of your maximum heart rate, while vigorous-intensity exercise should be between 70 to 85 percent of your maximum heart rate, according to the Centers for Disease Control and Prevention.
Step 4
Determine whether you can sing or talk while walking. If you can sing, your workout is low in intensity. If you can talk but not sing, your workout is moderate in intensity. If you can't say more than a few words, your exercise is vigorous.
Tips and Warnings
- Talk to your doctor if you aren't sure how intensely you should exercise.
References
- Centers for Disease Control and Prevention; Measuring Physical Activity Intensity; March 2011
- Centers for Disease Control and Prevention; Target Heart Rate and Estimated Maximum Heart Rate; March 2011
- Indiana University: Principles of Exercise Prescription
- "New York Times"; Recalibrated Formula Eases Women’s Workouts; Tara Parker-Pope; July 2010
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