April 21, 2008

Exercise Intensity + Target Heart Rate

Filed under: fitness, howto — admin @ 8:13 am

I’ve had people ask me about target heart rate before. In one case a person said, my trainer suggests I use 128bpm as my target heart rate. In another case someone said, I heard my target heart rate should be 135bpm.

As with everything the truth is always a bit less black and white. The American Council on Exercise says “research shows that optimum exercise intensity for fitness improvement is in the range of about 50 to 85% of maximum oxygen consumption. This corresponds to about 60-90% of maximum heart rate. The ranges are broad because of the effects of the level of fitness, as well as genetic factors. The higher a client’s level of fitness, the higher the appropriate exercise intensity.”

There are a few different methods to calculate all of this, with fancy scientific names, but for simplicities sake we’ll call it percentage of heart-rate reserve method:

rhr - resting heart rate (hr first thing in the morning)

mhr - maximum heart rate (220 - age)

(mhr - rhr) x intensity + rhr

For me, my resting heart rate is 50bpm because I run alot. My mhr is 180.

(180-50) x 0.75 + 50 = 130 x 0.75 + 50 = 98 + 50 = 148.

So if I want to shoot for 75% I’d go with 148bpm. Given the above 60-90%, that means 128bpm at the low end, and 167bpm at the high end.

As anecdotal evidence, I can tell you the best average I’ve hit for one hour of running, really going all out is 147bpm, maxing out at 155bpm. If I do an all-out sprint, a barely push above 160, and how long can a person sprint for?

There is also something called the talk test, which says if you’re at the intensity which is low to moderate, especially for beginners, if you can still carry on a conversation, and breathe comfortably. People with higher fitness levels, and pushing for higher functional capacity may find this method conservative.

In the end a lot of these measures depend on variables such as any smoking history, current weight and percent body fat, and so on. There really is no magic number. Keep in mind that the higher heart rate you exercise at, the greater benefit you will see overall, but to a point. In the beginning especially, don’t over do it. And as always, increase gradually.

What about monitoring your heart rate, what’s the best method?  I recommend a heart rate monitor from the likes of Polar or Garmin.  Polar has some as inexpensive as $60 and at the higher end, Garmin has some $299 models which have GPS, and can give you a lot of data that sync up to your computer.  But primarily what you want is to know what your min, max, and average were for your workout.  You can always write that information down.

As always consult with your physician if you are beginning an exercise program for the first time, especially if you have a pre-existing condition, injury, are a smoker, are overweight, or are an older individual.