Runners often track their heart rates as a way to measure workload and track progress. Your maximum heart rate is the highest workload your body can handle during maximal exercise. Max heart rate varies from person to person, and depends on factors such as age, sex, body mass, hydration levels and physical condition. Most runners do not run at their max heart rate, instead opting to run in the recommended training range of 50 to 85 percent of their max.
Calculating Maximum Heart Rate
There are multiple ways to measure maximum heart rate. The least invasive method is to use the age-predicted formula, where you subtract your age from 220. If you are 20 years old, your max heart rate would be 200 using this method. You can also measure your maximum heart rate through exercise testing. A maximal exercise test is performed to exhaustion in an exercise physiology laboratory with a qualified technician; your heart rate is measured throughout the test and the highest heart rate reached is your maximum. Sub-max exercise tests are similar, but you only work for a predetermined amount of time and your maximum heart rate is extrapolated from data based on your reactions to the test.
Training Intensity
The American Heart Association recommends that exercisers stay within 50 to 85 percent of the max heart rate. Anything below 50 percent is not enough to challenge the cardiovascular system, and anything above 85 percent poses a danger to the vascular tissue. Beginning runners should stay on the low end of the intensity range and slowly build to training at higher intensities.
Monitoring Heart Rate
Your heart rate can be easily monitored during a run. You can self monitor by finding your pulse in your radial artery, on the thumb side of your wrist, with your first two fingers. Count the number of beats for 20 seconds, then multiply by three to get the total beats per minute. You can also monitor your heart rate electronically. Most modern exercise equipment will monitor your heart rate with hand sensors, or you can buy a chest strap monitor to wear during a run.
Factors Affecting Heart Rate
Many factors can affect your heart rate from run to run. According to the American College of Sports Medicine, medications for heart problems, blood pressure or thyroid problems keep heart rates low. You may also see a sudden heart rate decrease if you are dehydrated. Dehydration causes cardiac drift, where heart rate slows during exercise because blood becomes too dense to pump normally. If you notice a sudden decrease in your heart rate during a run, be sure to rehydrate quickly.
References
- American Heart Association: Target Heart Rates
- "ACSM's Guidelines for Exercise Testing and Prescription, 7th Edition"; American College of Sports Medicine; 2006
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