Also, while we are on the topic, do not get too caught up in the Heart Rate Formula.
The common formula's used to estimate "exercise zones" are another great example of something that has become accepted as truth, and used in professional and public circles, and even in scientific circles but has no scientific basis to it.
The actual doctor who invented the formula shared his concerns in an article in The New York Times Health Page (April 24, 2001): "Maximum Heart Rate Theory Is Challenged."
http://tinyurl.com/595dtuSome excerpts...
The common formula was devised in 1970 by Dr. William Haskell, then a young physician in the federal Public Health Service and his mentor, Dr. Samuel Fox, who led the service's program on heart disease. They were trying to determine how strenuously heart disease patients could exercise.
In preparation for a medical meeting , Dr. Haskell culled data from about 10 published studies in which people of different ages had been tested to find their maximum heart rates.
The subjects were never meant to be a representative sample of the population, said Dr. Haskell, who is now a professor of medicine at Stanford. Most were under 55 and some were smokers or had heart disease.
On an airplane traveling to the meeting, Dr. Haskell pulled out his data and showed them to Dr. Fox. ''We drew a line through the points and I said, 'Gee, if you extrapolate that out it looks like at age 20, the heart rate maximum is 200 and at age 40 it's 180 and at age 60 it's 160,'' Dr. Haskell said.
At that point, Dr. Fox suggested a formula: maximum heart rate equals 220 minus age.
In three recent studies, Dr. Lauer and his colleagues found that people whose rates fell less than 12 beats within a minute after they stopped exercising vigorously had a fourfold increased risk of dying in the next six years compared with those whose heart rates dropped by 13 or more beats.
Heart rate is an indicator of heart disease, said Dr. Michael Lauer, a cardiologist and the director of clinical research in cardiology at the Cleveland Clinic Foundation. But, he added, it is not the maximum that matters: it is how quickly the heart rate falls when exercise is stopped.
An average healthy person's heart rate drops about 20 beats in a minute and the rates of athletes ''nose dive by 50 beats in a minute,'' Dr. Lauer said.
''I've kind of laughed about it over the years,'' Dr. Haskell said. The formula, he said, ''was never supposed to be an absolute guide to rule people's training.'' But, he said, ''It's so typical of Americans to take an idea and extend it beyond what it was originally intended for.''This is also great review article on the whole issue.
THE SURPRISING HISTORY OF THE "HRmax=220-age" EQUATION
ROBERT A. ROBERGS AND ROBERTO LANDWEHR
JEPonline
Journal of Exercise Physiologyonline
Official Journal of The American Society of Exercise Physiologists (ASEP)
ISSN 1097-9751
An International Electronic Journal
Volume 5 Number 2 May 2002
CONCLUSIONS AND RECOMMENDATIONS
Based on this review of research and application of HRmax prediction, the following recommendations can be made;
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. Prediction of Maximal Heart Rate
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.For the record, at 50, according to the formula, my Maximum Heart Rate is supposed to be 170 and I should exercise between 110 (65%) and 153 (90%). The Heart Rate Reserve Formula is slightly better and gives me the same Maximum Heart Rate and a range of 130 to 160. However, when I run my Heart Rate can be in the 150-170s and even in the 180s when I sprint, and these numbers have changed little over the last 25 years even though the formula is based on these numbers declining with advancing age.
SO, WHAT DO YOU DO?The only true way to know what your maximum heart rate is and your "zones" are is to have a "maximal" exercise tolerance test or stress test done. When I studied exercise physiology, I was able to undergo several, and so, have some knowledge of my "numbers."
For those of you who can not have a test done, or have limitations due to health/medical issues, the next best measure of exercise intensity is what is called "Rate of Perceived Exertion" or RPE,
The following article, from the CDC, provides an explanation of the Rating of Perceived Exertion (RPE).
Perceived exertion is how hard you feel your body is working. It is based on the physical sensations a person experiences during physical activity, including increased heart rate, increased respiration or breathing rate, increased sweating, and muscle fatigue. Although this is a subjective measure, a person's exertion rating may provide a fairly good estimate of the actual heart rate during physical activity* (Borg, 1998).
Practitioners generally agree that perceived exertion ratings between 12 to 14 on the Borg Scale suggests that physical activity is being performed at a moderate level of intensity. During activity, use the Borg Scale to assign numbers to how you feel (see instructions below). Self-monitoring how hard your body is working can help you adjust the intensity of the activity by speeding up or slowing down your movements.
Through experience of monitoring how your body feels, it will become easier to know when to adjust your intensity. For example, a walker who wants to engage in moderate-intensity activity would aim for a Borg Scale level of "somewhat hard" (12-14). If he describes his muscle fatigue and breathing as "very light" (9 on the Borg Scale) he would want to increase his intensity. On the other hand, if he felt his exertion was "extremely hard" (19 on the Borg Scale) he would need to slow down his movements to achieve the moderate-intensity range.
*A high correlation exists between a person's perceived exertion rating times 10 and the actual heart rate during physical activity; so a person's exertion rating may provide a fairly good estimate of the actual heart rate during activity (Borg, 1998). For example, if a person's rating of perceived exertion (RPE) is 12, then 12 x 10 = 120; so the heart rate should be approximately 120 beats per minute. Note that this calculation is only an approximation of heart rate, and the actual heart rate can vary quite a bit depending on age and physical condition. The Borg Rating of Perceived Exertion is also the preferred method to assess intensity among those individuals who take medications that affect heart rate or pulse.
How to Use the Perceived Exertion Scale
While doing physical activity, we want you to rate your perception of exertion. This feeling should reflect how heavy and strenuous the exercise feels to you, combining all sensations and feelings of physical stress, effort, and fatigue. Do not concern yourself with any one factor such as leg pain or shortness of breath, but try to focus on your total feeling of exertion.
Look at the rating scale below while you are engaging in an activity; it ranges from 6 to 20, where 6 means "no exertion at all" and 20 means "maximal exertion." Choose the number from below that best describes your level of exertion. This will give you a good idea of the intensity level of your activity, and you can use this information to speed up or slow down your movements to reach your desired range.
Try to appraise your feeling of exertion as honestly as possible, without thinking about what the actual physical load is. Your own feeling of effort and exertion is important, not how it compares to other people's. Look at the scales and the expressions and then give a number. RPE Scale
6 No exertion at all
7 Extremely light
8
9 Very light - (easy walking slowly at a comfortable pace)
10
11 Light
12
13 Somewhat hard (It is quite an effort; you feel tired but can continue)
14
15 Hard (heavy)
16
17 Very hard (very strenuous, and you are very fatigued)
18
19 Extremely hard (You can not continue for long at this pace)
20 Maximal exertion
Of course, there is always the simplest method which is known as the "Talk Test. Basically, if you can carry on a light conversation while exercising, then you are in a good intensity range. Once your speech starts to break, slow, or cause discomfort, you’re working too hard.
And, research, published in the September 2004 issue of Medicine & Science in Sports & Exercise, the official scientific journal of the American College of Sports Medicine (ACSM), proved that the Talk Test is a simple method to determine appropriate levels of exercise intensity. The results indicated the exercise intensity at the Talk Test was approximately the same as at the ventilatory threshold during exercise ( a marker of exercise intensity). When speech was no longer comfortable, exercise intensity was consistently above the ventilatory threshold.
Having said all that....
Once again, keep is simple!
In Health,
Jeff
by Golden Ghost » Mon Nov 24, 2008 5:00 pm 
