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Heart Rate Workout Zones

When I worked at Hanscom Air Force Base, I had the good fortune of working with the athletic trainers that keep our military in tip-top shape. That’s when I first learned about working out in designated heart rate zones.

Most recently, Orangetheory fitness has capitalized on this type of training using five color-coded zones to work out in. I haven’t personally used their program but dietitian colleagues have assured me that there are qualified coaches that guide members based on what shape they are in. I can’t stress the importance of not diving into a fitness program, especially if you’re a little older and a little out of shape! As always, check with your physician before starting an exercise program. They know your medical history and can offer activity limits the best. Many people don’t realize how their medications come into play with exercise. For example, some cardiac medications (aka beta blockers) slow the heart rate, which will prevent the increase in heart rate that typically occurs with exercise.

So, what’s the science behind heart rate zone training? While we exercise, our body burns a combination of the following energy sources: glucose (aka blood sugar), glycogen (carbohydrates stored in the muscles and liver), and fat (we know where those deposits are!). What type of exercise, its intensity, and its duration determine which of these will be used as primary energy suppliers. The higher the heart rate, the more you are depending on quick energy suppliers, like stored carbohydrate. Endurance athletes (like marathon runners) generally prefer to have a heart rate where they are relying on fat for energy since that is a more sustained source of energy for them for longer periods of time demands.

The American Heart Association generally recommends you work out at your own Target Heart Rate (THR) — that’s the level at which your heart is being exercised and conditioned, but is not overworked. To calculate your desired target heart rate zone, you have to determine your Maximum Heart Rate (MHR) first.

Maximum Heart Rate calculation:

Subtract your age from 220 to get your Maximum Heart Rate. Example: a 50 year old has a MHR of 170 and should not exercise above that heart rate.

Here are the different levels of THR exercise zones per the American Heart Association:

  • Low Intensity Zone: Here, you are working out at 50-60% of your maximum heart rate. This is the least strenuous zone where most can comfortably work out. 85% of calories burned is fat.

  • Moderate Zone: Here, you are working out at 60-70% of your maximum heart rate. This is typically a warm up or cool down zone. 65% of calories burned is fat.

  • Vigorous Zone: Here, you are working out at 70-85% of your maximum heart rate. 45% of calories burned is fat.

Getting in shape is NOT a race, so take it slow. Start out at 50-60% of your MHR (low intensity) and slowly progress. An ideal program for weight loss is exercising at 70-85% of your MHR for 30-60 minutes, 4-5 times a week. Aerobic exercise helps to improve cardiac and metabolic systems like cholesterol, blood pressure, and blood sugar. Strength training, while considered anaerobic exercise, is also essential for muscle building, good posture, improving flexibility, and bone health, so include that, as well in your fitness plan.

The key to setting up fitness goals and designing a healthy program is what works best for you. Not the person on the machine next to you. Chances are, they have NO clue what they are doing and they are just pressing arbitrary buttons on the panel. Working with a certified personal trainer or physical therapist is a good investment if you are thinking of heading back to the gym.

In Good Health,


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