How Does BMI Affect the Heart Rate Response to Exercise?

BMI can affect your recovery heart rate.

BMI can affect your recovery heart rate.

Exercise helps to improve your heart health by strengthening your heart muscles. This allows your heart to pump more blood with each beat decreasing strain and lowering your risk of heart disease. If you are overweight or obese, exercise may leave you feeling as though your heart is going to pump right out of your chest. This is because your heart needs to work much harder to keep enough blood flowing throughout your body.

Body Mass Index

Body mass index -- or BMI -- is a measurement of your body weight in relation to your height. It is a useful marker for obesity because it is easy and inexpensive to measure. BMI should be seen as a screening, not diagnostic, tool to alert you to possible health risks caused by being overweight or obese. To calculate your BMI, weigh yourself and measure your height. Convert your height to inches and square it. For example, if a women is 5 feet 8 inches tall, her height is 68 inches. Multiple 68 by 68 to get 4,624. Divide her weight by her height squared and then multiply that number by 703. For a woman with a height of 68 inches and a weight of 150 pounds, multiply 703 by 150 divided by 4,624. This yields a BMI of 22.8 putting her within the healthy range. The range for being overweight is 25 to 29.9 and a BMI of 30 or above is obese.

Heart Rate

Your heart rate is a measure of how fast and often your heart must pump to circulate blood. At rest without physical or emotional stress or strain, your heart rate is called a resting heart rate. Higher resting heart rates are often seen in obese people, as the heart must work harder to pump blood through the excess tissue. Conversely, the resting heart rate of a physically fit woman will be lower because her heart is stronger and can work more efficiently with each beat.

Heart Rates in Exercise

Exercise requires that more oxygen be circulated throughout your body and that more blood be pumped. Your maximum heart rate is the upper limit of what your cardiovascular system can handle. To estimate your maximum heart rate, subtract your age from 220. Certain medications, including beta blockers and some medications for acid reflux, can lower your maximum heart rate. During exercise, target heart rates should be monitored, especially in overweight or obese people. During vigorous exercise, aim for a heart rate of 70 to 85 percent of your maximum. For a woman who is overweight or obese, her heart rate is already elevated and additional strain from high-intensity workouts can be dangerous. If your BMI is above 25, approach exercise slowly and under the direction of your physician.

Recovery Heart Rates

Your recovery heart rate is another useful marker in determining the risk of heart attack or cardiovascular disease. The recovery heart rate is the measure of how long it takes your heart to return to normal following exercise. To measure this, take your heart rate at the end of your workout and then again two minutes post workout. A normal recovery rate shows a decrease of 15 to 25 beats per minute. An exceptionally fit person may show a decrease of more than 25 beats, while someone whose BMI places her in the overweight or obese category will have a decrease of 12 beats per minute or less.

 

About the Author

An American writer living in the United Kingdom, Christy Mitchinson began writing professionally in 2000, during her career in laboratory science, pathology and research. She has authored training materials, standard operating procedures and patient/clinician information leaflets. Mitchinson is pursuing a Bachelor of Arts in English literature and creative writing with The Open University.

Photo Credits

  • Siri Stafford/Digital Vision/Getty Images