When you run, you reduce stress and enhance your overall well-being. Be aware that you also get an elevated heart rate. With the increased exertion, your heart must react with an increase in beats per minute to supply your muscles and lungs with the higher demand for oxygen and blood. The harder and faster you run, the higher your heart rate. Understand this principle and gauge your effort so as to not over do it.
Maximum Heart Rate
Before you go for a run and elevate your heart rate, find your maximum heart when exercising. The long-used standard formula is subtracting your age from 220, but now, according to the American Heart Association, a new gender-specific formula is being used. The original study was done on men and the same formula applied to women. The AHA found that because of the physiological differences between the genders, a formula for women was needed. If you are a woman, 206 minus 88 percent of your age determines your max heart rate. If you are a man, use the standard formula.
Time of Day Variations
You may be surprised that your maximum heart rate while running can be anywhere from five to 10 beats per minute slower in the morning than in the evening. According to the Pfitzinger Lab Reports article, "Factors That Affect Heart Rate During Running," this time of day discrepancy can cause you to misjudge your effort by using your morning heart rate as a guide for your evening run and visa versa. One reason for the lower morning heart rate is that your body's metabolism has not had time to increase with the activities and stresses of the day.
Weather Effects
The Pfitzinger Lab report also notes that an increase in temperature and humidity can have dramatic effects on your running heart rate. When the temperature increases from 60 to 75 degrees, your heart rate can increase two to four beats per minute. With an increase from 75 to 90, you may see an increase of up to 10 bpm, with high humidity possibly causing an even greater increase. The report notes that you should run at another, cooler time if the conditions are too hot and humid to run safely.
Dehydration Effects
One of the biggest problems for many runners is staying hydrated enough to run well. The Pfitzinger report cites a 1992 study showing that losing as little as 1 percent of your body weight by sweating results in an increase of 7 bpm. The report says that many runners typically lose up to two pounds of body fluid per hour on a very hot day, resulting in an even more dramatic heart rate increase. Thus, staying properly hydrated while running not only allows you to run better, but stabilizes your heart rate too.
Heart Rate As a Guide
If you understand your body's physiological reaction to running with an elevated heart rate and the variables that can affect it, you should be able to use heart rate as an accurate gauge of your effort. If you are a beginning runner and are not yet ready to increase to a higher level of effort, use the American Heart Association's target heart rate zones as a general guide. This AHA target zone is broad based according to your age, and suggests staying anywhere from 50 to 85 percent of your max heart rate.
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