Heart Rate


I had just finished working with a client and was quickly walking back downstairs when I was approached by a woman with a very confused look on her face. “Are you a trainer?”, she asked. “Yes, I am. Is there something I can help you with?” She then proceeded to explain to me that she didn’t understand the difference between heart rate ranges while doing cardio. It confused me at first too. What was the difference, cardio is cardio, right? Wrong.

Our bodies produce energy through a process called the Krebb’s Cycle. Included in this process is a smaller process called glycolysis. Glycolysis can be your friend, if you know how to play by the rules and work at the right intensity level to produce your desired results.

First, you need to know the difference between anaerobic and aerobic exercise. Anaerobic (without oxygen) exercise is when you are pushing your limits. Your breath becomes short and shallow, and there is no way you could carry on a conversation, even if it meant saving your life. Aerobic (with oxygen) exercise is when you are clipping along at a steady but maintainable  pace, breaths are regular and  about 15 minutes in to it, you feel your energy level increase and you know you could go all day. Let me tell you why.

When you’re anaerobic, the glycolytic process takes one molecule of sugar and turns it into 2 ATP (or energy). When you slow it down a bit and go aerobic, the glycolytic process changes. Your body then takes one molecule of fat and turns it into 32 ATP. What a difference oxygen makes, huh?

The difference in the amount of ATP produced through the two different types of glycolysis  easily explains the difference in how you feel while doing the two types of cardio. When you push, give it everything you have, you can only do it for so long. It’s definitely not gonna be an all day event. That’s because your body is only giving you 2 ATP for each molecule of sugar, so you are using more energy than your body is making. However, when you take it down a notch and you feel like you could go all day, your body is making more energy than you are using. You actually have energy left over! Woo-Hoo! How can you pass a deal like that up?

So just how do you go about finding your unique “fat burning” heart rate? It’s easy, I’ll  show you how.

220 – your  age (in years) = Your Max Heart Rate (MHR)

MHR x .60= Your Lowest Fat Burning Target Heart Rate (THR)

MHR x .75= Your Highest Fat Burning THR

MHR x .80= Your Lowest Cardiovascular Training THR

MHR x .90= Your Highest Cardiovascular Training THR

The numbers you got for your lowest fat burning THR and your highest fat burning THR is your unique fat burning zone. As long as you keep your heart rate between those two numbers, you’ll be burning fat while doing your cardio. But what happens when you go higher than that? It’s not that it is a bad idea to do so, in fact it is a very good idea.   Going above your highest THR for fat burning doesn’t mean that you stop burning calories. It just changes the benefit of the cardio you are doing. Exercise at a lower intensity burns fat, where exercise at a higher intensity conditions your cardiovascular system (your heart, lungs, veins, etc.) That’s definitely a good thing. Just make sure that you are in good enough shape to challenge your cardiovascular system before you do so. If you are just beginning or are obese, running would not be the best option. Start with walking or a stationary bike perhaps.

No matter what kind of cardio you choose, make sure to stay properly hydrated. Now that you know how to figure out what your heart rate should be to meet your fitness goals, take into account your current physical condition, do the math and then get out there and burn some calories! 😉

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