A vision for my life - Because what we focus on expands

Thursday, October 25, 2007

10/25/07: The Surprising History of the 220-Age Formula

Let's assume for a moment that you need to know your max heart rate, even though it has very little relevance in endurance training. It's commonly accepted that 220-age = max heart rate, right? And since it's so commonly accepted, and in textbooks, and taught to most trainers, it's certainly based on proper testing and scientific evidence, right?

Ummmm...not so much....

Although common sense tells me that age based formulas wouldn't be capable of predicting hr training zones with any accuracy, since we're all so unique, I had no idea that such a widely accepted formula could possibly be based on only 11 data points.... Quoting from the study:

"Despite the acceptance of this formula, research spanning more than two decades reveals the large error inherent in the estimation of HRmax (Sxy=7-11 b/min). Ironically, inquiry into the history of this formula reveals that it was not developed from original research, but resulted from observation based on data from approximately 11 references consisting of published research or unpublished scientific compilations. Consequently, the formula HRmax=220-age has no scientific merit for use in exercise physiology and related fields. A brief review of alternate HRmax prediction formula reveals that the majority of age-based univariate prediction equations also have large prediction errors (>10 b/min)."

Emphasis added

The study concludes:

"1. Currently, there is no acceptable method to estimate HRmax.

2. If HRmax needs to be estimated, then population specific formulae should be used. However, the most accurate general equation is that of Inbar (17) (Table 3); HRmax=205.8-0.685(age). Nevertheless, the error (Sxy=6.4 b/min) is still unacceptably large.

3. An acceptable prediction error for HRmax for application to estimation of VO2max is <±3 b/min. Thus, for a person with a HRmax of 200 b/min, error equals ±1.5%. If this precision is not possible, then there is no justification for using methods of VO2max estimation that rely on HRmax prediction formulae.

4. Additional research needs to be performed that develops multivariate regression equations that improve the accuracy of HRmax prediction for specific populations, and modes of exercise.

5. The use of HRmax is most prevalent in the fitness industry, and the people who work in these facilities mainly have a terminal undergraduate degree in exercise science or related fields. These students/graduates need to be better educated in statistics to recognize and understand the concept of prediction error, and the practical consequences of relying on an equation with a large standard error of estimate (Sxy).

6. Textbooks in exercise physiology and exercise prescription should contain content that is more critical of the HRmax=220-age or similar formulae. Authors need to stress the mode-specificity of HRmax, provide alternate, research substantiated formula, and express all content of items 1-5, above. Similarly, academic coverage of HRmax needs to explain how this error detracts from using HRmax estimation in many field tests of physical fitness and in exercise prescription."

All the more reason I'm in favor of using a combination of RPE and HR, or better yet, doing a time trial and determing lactate threshold with some amount of accuracy.

Here's a link to the study: href="http://faculty.css.edu/tboone2/asep/Robergs2.pdf">

Live with purpose...Enjoy the adventure....
Live at cause....not effect....

1 comment:

Carrie said...

Or just run to you feel your heart beating in your hair. Works for me!