All entries for May 2012
Just about anyone who has been on a treadmill, elliptical, or used a heart rate monitor has seen the chart that tells you to take 220 and subtract your age to get your maximum heart rate. This gives you a percentage of that maximum which puts you in a “weight loss zone”, an “aerobic zone”, or an “anaerobic zone”. Many people take this to heart and use these numbers religiously to plan training programs— but have you ever stopped to wonder where that 220-age formula came from? Would you believe me if I told you that it was an almost arbitrary number? Brace yourselves, because it is almost that “arbitrary”.
The answer of where heart rate max = 220-age is derived from is actually not even completely known. It appears to have come from a very small study in which the author concluded that 220-age “was not far off.” Years later when the data from this study was actually crunched, they determined an inherent error of 21 beats per minute (BPM). This means that if your projected maximum heart rate was 180, it could actually be anywhere between 159-201!
So why is this important? Imagine that you are 40 years old and want to create a training program using the 220-age formula to exercise at 80% of your maximum. To do this you would have to take 220-40=180, and then account for the formula’s error. Meaning the actual heart rate maximum could most likely be somewhere between 169-191. When you do the calculations for 80% of 169 and 191, you get a heart rate that equals either 153 beats per minute or 135 beats per minute, two numbers that are vastly different. So which one would you use? The answer is that you can take your pick, because either one is just as likely to be wrong.
This is why sub-maximal cardiopulmonary exercise testing can be so beneficial. This test tells you precise heart rates that correspond specifically to the physiology of your body. Unlike heart rate monitors, which use nomograms and algorithms based on mass populations to determine your caloric expenditure, these tests determine your actual caloric expenditure at a specific heart rate. Therefore, knowing your caloric expenditure along with having an organized nutrition plan is the key to weight loss. Even if your exercise and nutrition calculations were 200 calories off, one can of soda would offset all of that progress, rendering all of your hard work worthless as far as weight loss is concerned!
Cardiopulmonary exercise tests use gas exchange, which determines exactly what your body is choosing as fuel. Therefore, instead of just guessing, you can determine if you are burning fat or carbohydrates, which are the actual determinants of the so called “aerobic” “anaerobic” and “weight loss” zones. Knowing fuel utilization can also help you determine the point at which lactic acid builds up in the muscle, which correlates to muscular fatigue. Knowing where this occurs helps you to determine exercise ranges that provide cardiovascular benefit and burn large amounts calories, but do not cause the muscles to rapidly fatigue or get too sore. Lastly, these tests can determine and track your VO2max over time. For athletes, a higher VO2max often correlates with better performance, however, more importantly, the VO2max has recently been determined to be on of the best markers of cardiovascular health as well. In fact, this number is so important, that a low VO2max is considered the best indicator of mortality, which means that improving your number may be the most beneficial thing that you can do for your health.
In closing, it’s clear that the 220-age formula really has no use in an exercise or clinical setting. In fact, there is a large push to get these numbers taken out of the textbooks. For healthy people with a physician’s consent, performing a symptom limited cardiopulmonary exercise test is the best way to determine heart rate zones and plan safe, effective exercise programs.
In Good Health,
Robergs, Robert, and Roberto Landwehr . "The Surprising History of “HRmax=220-age” Equation." Official Journal of the American Society of Exercise Physiologists. 5.2 (2002): 1-10. Print. (Robergs, and Landwehr 1-10)