If you are one of the 60% of Americans who is overweight and have decided to lose weight and get in better shape this information will be important to you. Why? Because appropriate exercise intensity is important for burning calories and for achieving long-term weight loss. Many cardiovascular machines now have built-in heart rate monitors which is one way to monitor your exercise intensity. They are there to help you see if you are exercising in your “target heart rate zone”.  If you are in "your zone" you will be working hard enough to burn sufficient calories and train your heart. It is equally important for you to know that being in “your zone” also assures you aren’t working too hard, nor too lightly. 

Exercise Intensity

For years, exercise leaders have used the Karvonen formula to determine a client’s estimated maximal heart rate, which is used to figure one’s exercise target heart rate. The Karvonen formula is as follows: 220-age=MHR (maximum heart rate). Recently, researchers Tanaka et al., found that the Karvonen age predicted equation significantly underestimated maximum heart rates in adults above the age of 40. Tanaka et al. found this equation to be a more accurate predictor: 208-(.07 x age)=MHR. In addition, Miller et al. felt that health care professionals should use a different formula for overweight and obese patients. That formula is: 200-(0.48 x age)=MHR. So who is right?

Franckowiak, et al.¹ set out to settle the above quandary and determine which equation is the most accurate so we can get the desired results for the effort exerted. One sure way to determine a person’s MHR is to give them a graded exercise test that safely and gradually elevates their heart rate until maximum is achieved. In Franckowiak’s study, 173 overweight or obese men and women were recruited for a 16-week weight loss intervention. The men and women were between 20 and 60 years old. Comparisons were made between men and women, across age categories, and across Body Mass Index (BMI).

Results

Tanaka’s MHR formula: 208-(.07 x age)=MHR was the most accurate for men and women aged 20-60 years who were also overweight or obese. This is good news because participants entering into an exercise program will likely drop out if the exercise intensity is too hard or they may drop out if they don’t get results because of underestimation of exercise intensity. An accurate prediction MHR is, thus, an important key to good exercise prescription and helping clients stick with an exercise program. 

Applications

Get help from an exercise leader or trainer to determine your exercise target heart rate. If you like doing your cardio by walking or on a machine without a built in hear rate monitor consider purchasing a heart rate monitor and watch that you wear that will accurately keep you in your “target heart rate zone”. The purchase will keep you motivated to stay on track with your efforts while helping you build aerobic stamina and lose weight.  

¹Franckowiak, SC, Dobrosielski, DA, Reilley, SM, Walston, JD, and Andersen RE. Maximal Heart rate Prediction In Adults That Are Overweight OR Obese. J of Strength and Conditioning Res.,25 (5) 1407-1412, 2011.