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Tuesday, September 20, 2011

Get Started with these Heart Rate Equations

Heart rate training might seem like rocket science, but it's actually easy to learn.  The hardest part is getting accurate estimates of heart rate max and the percentages that will produce the desired training effect.

Heart Rate Maximum Equations
The most well known equation that estimates maximum heart rate is:

220 - age = HRmax

This equation assumes that no matter the fitness level, everyone loses one beat per minute from their maximum heart rate for every year they get older.  The rate of loss does not happen to everyone and is the reason for this equation's large standard deviation (+/- 12-15 bpm)- a measure of variability.  For both sexes younger than 40 years, this equation underestimates HRmax; for both sexes older than 40 years old, this equation overestimates HRmax (5).  This equation was created mainly for convenience purposes.  If the number calculated from this number happens to be your actual maximal heart rate, you're very lucky!

The most accurate equation (2) is not as easy to remember, but will give a better estimate than the equation above:

206.9 - (0.67 x age) = HRmax

Since the accuracy of target heart rate depends heavily on the accuracy of the heart rate maximum, spend a little more time and memorize this equation instead.

Target Heart Rate Equations:
The first equation involves simple multiplication:

THR = HRmax * desired percentage

Unlike the equation above, the method below factors resting heart rate into the equation.  For this reason, the equation below is more accurate ONLY if the resting heart rate is measured accurately.  As mentioned in the post about the limitations with heart rate training, several variables may cause heart rate to vary as much as 1 - 6 bpm from day to day (1,3,4) .  For this reason, this method requires constant updating to account for this variability.  Otherwise, training intensity might be too high or low; possibly enough to work the entirely wrong metabolic system and produce the wrong training effect- a very bad problem for athletes and non athletes.

THR = ((HRmax - HRrest) x desired percentage) + HRrest

Resources:
  1. Astrand, P.-O. and Saltin, B. (1961). Oxygen uptake during the first minutes of heavy muscular exercise. Journal of Applied Physiology, 16, 971-976.
  2. Gellish, RL, Goslin B.R., Olson R.E., McDonald A., Russi G.D., Moudgil V.K. Med Sci Sport Exercise. 2007;39(5):822-9.
  3. Lambert, M.I., Z.H. Mbambo, and A. St Clair Gibson. "Heart rate during training and competition for long-distance running." Journal of Sports Sciences 16 (1998): S85-S90. Print.
  4. Selley, E.A., Kolbe, T., Van Zyl, C.G., Noakes, T.D. and Lambert, M.I. (1995). Running intensity as determined by heart rate is the same in fast and slow runners in both the 10- and 21-k, races. Journal of Sports Sciences, 13, 405-410.
  5. Thompson, Walter R., Neil F. Gordon, and Linda S. Pescatello. ACSM's guidelines for exercise testing and prescription. 8th ed. Philadelphia: Lippincott Williams & Wilkins, 2010. Print.