Heart Rates: Part II

Last week we covered the basics. In Heart Rates: Part II, we’re going to zoom past the terminology and learn how to calculate maximum and target heart rates. We’ll also be discussing the various heart rate zones and which one is appropriate for you and your workout (hint: it depends on what your fitness goals are!).

We’ve all seen that ridiculously generic chart in the gym. You know, the colorful one with your age along the x-axis and a bunch of percentages up the y-axis. Perhaps there’s a bolded area entitled “Target Zone.” You think to yourself, “What does that even mean?”

It’s a graphic representation of what level of intensity your work out should be at depending on your fitness goals. Understanding this chart and using it to its full potential all starts with knowing your own maximum heart rate.

Calculating Maximum Heart Rate

There are two methods. The first and predominantly default method is a simple formula. This is what most workout machines utilize when metrics like calculating calories burned.

Maximum Heart Rate = 220 – Age

This means as a 25 year old, my max heart rate is 195.

According to WebMD, this method can overstate the maximum heart rate for individuals older than 40. If you’re younger than 40, this equation will work reasonably well, providing you with an approximate estimate of your maximum heart rate.

The second and more accurate method was recently published in the Journal of the American College of Cardiology back in 2001.

Maximum Heart Rate = 208 – (Age * 0.7)

This means as a 25 year old, my max heart rate is approximately 191.

WebMD cautions that for any person, these formulas can be off by as much as plus or minus 10 to 20 beats per minute. That means if I use the first formula, my true maximum heart rate could be as high as 215 or as low as 175. So it’s important to remember that these formulas will only give you a reasonably close estimate of what your maximum heart rate is.

Note: The only sure fire way to determine your maximum heart rate is to perform a test with a licensed medical professional. Basically they stick you on a treadmill and increase the speed, all while recording your heart rate, until you collapse with exhaustion. Whatever heart rate you were at just prior to collapsing is your maximum heart rate. I wouldn’t advise any of you to try this, especially not at home.

Heart Rate Zones

Four main heart rate zones exist – endurance, aerobic, anaerobic and VO2 Max. Depending on your fitness goals, each of these zones has different pros and cons. By identifying which zone you want to train in, you can optimize your workout.

  • Endurance: training within this zone occurs at 60-70% of your maximum heart rate and is ideal for those individuals looking to lose weight or boost endurance. Essentially, you’re training your body to utilize fat as fuel. This zone can also be classified as the energy efficient or recovery zone.
  • Aerobic: training within this zone occurs at 70-80% of your maximum heart rate. The aerobic zone is ideal for those individuals looking to improve their overall fitness level and maintain their current weight. Unlike the endurance zone, your body is utilizing both fat and carbohydrates for fuel.
  • Anaerobic: training within this zone occurs at 80-90% of your maximum heart rate and is ideal for those individuals looking to maintain consistent speeds. Your body will experience increased lung capacity and lactate tolerance, also known as increased anaerobic threshold.
  • VO2 Max: training within this zone occurs at 90-100% of your maximum heart rate. The VO2 Max zone develops an individual’s speed by working out their fast twitch muscle fibers. Realistically, exercising in this zone is only sustainable for short periods.

Calculating Target Heart Rate

Calculating your target heart rate depends entirely on which zone you want to exercise in. Once you determine what your goals are, finding your target heart rate is really just simple math.

If you’re looking to lose weight, you’ll need to train in the endurance zone or at 60-70% of your maximum heart rate. That means for me, with max heart rate of 195, my endurance zone ranges from 117 to 137.

If you’re looking to improve your general level of fitness or maintain your current weight, you’ll need to train in the aerobic zone or at 70-80% of your maximum heart rate. That means for me, with max heart rate of 195, my aerobic zone ranges from 137 to 156.

If you’re looking to maintain your current speed or level of fitness, you’ll need to train in the anaerobic zone or at 80-90% of your maximum heart rate. That means for me, with max heart rate of 195, my aerobic zone ranges from 156 to 176.

If you’re looking to build speed (think interval training), you’ll need to train in the aerobic zone or at 90-100% of your maximum heart rate. That means for me, with max heart rate of 195, my aerobic zone ranges from 176 to 195.

I know what you’re thinking – this is so much math! If you’re like me though, you want to know if your work outs are effective. Going on a three mile run or lifting weights for half an hour is all well and good, but if your heart rate is too low or conversely too high, then you aren’t performing at your best.

Knowing your maximum heart rate and which zone you want to train in will guarantee optimal performance during each and every one of your workouts. Who doesn’t want that, right?

Join me next week as we conclude the third installment of Heart Rates! I’ll be covering training with a heart rate monitor. Really, it’s the best workout buddy a girl could ask for 🙂

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