Tuesday, February 3, 2009

Maximum Heart Rate and Fitness

I get this question all the time.."how do I know how hard I should be working?". The pat answer would be to work between 60 and 85 percent of your maximum heart. The most well known formula for calculating your maximum heart rate is:

220-your age= x
x times 60-85%=Target Heart Rate

180 X 75%=135

This is a simple and quick method but not always the most accurate for my students and clients who are more experienced exercisers. A bit more complicated but much more precise is the karvonen formula. To use this formula, you need to calculate your resting heart rate. Preferable first thing in the morning or after lying down for a bit at the end of the day, time your pulse rate. This will be your resting heart rate.

To calculate with the karvonen formula:

220-your age=x
x-resting heart rate=y
y x 60-85%= z
z + resting heart = target heart rate

120 X 75%=90

As you can see from the calculations, when you add in your resting pulse rate, you get a more accurate calculation. My target heart rate is 150 calculated with resting pulse rate and 135 based on age, that's 15 bpm higher.

A third option that can be used is the "all out" method. WARNING, this is not to be used by people who are new to exercise or who have medical conditions where over exertion could be dangerous to their health. After a proper warm up, go all out in one aerobic activity for 60 seconds (sprint, cyle, etc). Preferably have a heart rate monitor on, check to see what your pulse rate is at the completion. You may find that your maximum heart rate is greater than the 220. If it is, you adjust the maximum heart rate in the above formulas.

Knowing your maximum and target heart rates is very informational and beneficial. My personal choice is perceived exertion. Quite often in class, I will tell my students to exert their effort to a 6 on a scale of 1-10. Not very scientific but very simple. In addition, the hard numbers you set with the formulas don't allow you the variance for an off day. If you know that your 75% THR is 150 and I ask for an effort of 7 or 8 and you can only get your heart rate up to 140, you may feel defeated. That's why I like rate of perceived exertion (RPE); it gives you the flexibility to adjust to what is going on with you on that day.

Always pay attention to how you're feeling when exercising. Just like in life, they are good days and bad. Just keep on track even when you stumble and you'll get to where you want to be.

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