This article is from the Aerobics Fitness FAQ, by oaktree@shell.urjet.net (Robles) with numerous contributions by others.

The general formula for the average person is 220-age X 60%

and X 90% of HRmax. For example, a 30-year old would calculate

his target zone using the above formula: 220-30=190.

190x.60=114 and 190x.90=171. This individual would try to

keep his heartrate between 114 (low end) and 171 (high end)

beats per minute.

(from Evelyn Mitchell <efm@tummy.com>)

The Karvonen Formula calculates your heartrate reserve

range. To calculate it, take your pulse for one minute on

three successive mornings upon waking up. (We will be using

the case of a 30-year old male whose resting pulse was 69,70

and 71 for an average of 70 over the 3 days.)

Calculate target heartrate by subtracting your age from 220

(220-30=190).

Subtract your average resting heart rate from target heartrate

(190-70=120).

The lower boundary of the percentage range is 50% of this

plus your resting heart rate [(120 x .5) + 70 = 130]. The

higher boundary is 85% plus your RHR [(120 x .85) + 70

=172]. Using the Karvonen Formula for percentage of heartrate

reserve, this 30-year old man should be working between 130

and 172 BPM.

Like the maximum heartrate formula, the Karvonen formula

can vary from individual to individual. Not every

individual is "average", and there can be large differences

among people. Therefore heartrate alone may not be the best

indicator of how hard or how well you are working.

It is important to note that the deviation in both the

age-specific formula and the Karvonen formula is due to the

estimation of HRmax. If you have an actual HRmax from a

graded exercise test, it will be more accurate. ACSM lists

two formulas for estimating HRmax, each one with

a standard deviation of +/- 10-12 BPM:

HRmax = 220 - age (low estimate)

HRmax = 210 - (0.5 * age) (high estimate)

HR = exercise intensity * HRmax * 1.15

Source, ACSM's Guidelines for Exercise Testing and

Prescription, 5th Edition, p. 274, Williams and Wilkins

(publishers)

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