THR? RHR? Whaaaaat?

The idea for this post came to me while I was out running with my Saturday morning run group this morning. I started monitoring my heart rate a few months ago and I have seen and felt a tremendous improvement in my time spent doing cardio exercise, so I thought I would share...

When starting an exercise/cardio plan, most people will walk/jog/run as fast or as long as they can (with 30 minutes being the minimum) and call it a day. While this may work at first for a little while, eventually you realize your body isn't changing anymore.

A while back I was having trouble getting motivated because I felt like I was exercising all the time, but I wasn't losing any inches. And we all know that when most people say they want to "lose weight", they probably really mean that they want to "lose inches" (ie, they want to tone up and look thinner). I'm a runner and, while I run often, I noticed that I just couldn't change my body shape. It was then that I really started paying attention to my target heart rate (THR).

Paying attention to your THR and exercising in it can help you maximize the benefits of your cardio and your body's fat-burning potential. In general, your THR is 60-75% of your maximum heart rate. When you exercise and your heart rate goes above your THR, you still work and strengthen your heart, but you end up training your body for endurance exercise instead of working to burn fat.

Finding your THR is pretty simple. The Karvonen Method of calculating THR is the most effective method because it accounts for your resting heart rate.

1. Take your resting heart rate (RHR) as soon as you wake up. Count
your pulse for one minute. Try taking your RHR for several days in a
row and averaging it for a more accurate number.
   Keva Kate RHR = 67

2. Find your maximum heart rate (maxHR) by subtracting your age from 220.
   Keva Kate maxHR = 220 - 26 = 194

3. Next, find your heart rate reserve (HRres) by subtracting your RHR from your maxHR.
   Keva Kate HRres = 194 - 67 = 127

4. Calculate the lower limit of your THR (THRlower). This is 60% of your HRres plus your RHR.
   Keva Kate THRlower = (127 * 0.60) + 67 = 76.2 + 67 = 143.2
   (I round to 143.)

5. Calculate the upper limit of your THR (THRupper). This is 75% of your HRres plus your RHR.
   Keva Kate THRupper = (127 * 0.75) + 67 = 95.25 + 67 = 162.25
   (I round to 162.)

So, that means my THR range is 143 - 162. When my heart rate is in that zone, I am maximizing my fat burning potential.

To help you keep track of your heart rate while you exercise, I highly recommend wearing a heart rate monitor. Personally, I use a Garmin Forerunner 405. This monitor is quite an investment, but has LOTS of neat features like virtual shadow runners, pace timers, and heart rate zone monitors.


However, most people getting started are looking for something a little more low key and affordable. There are several great options out there for under $100. Be sure to check out the Polar FS1, Polar F4, Garmin Forerunner 50, and the Nike Triax C8. All of those are really great and dependable monitors.

I know this was a long post, but I really hope it helps! KEEP IT JUICY!