Exercise in the zone – what your heart rate tells you

By
Charl Greeff
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You get on the treadmill. You’re motivated. All around you people are jogging, running and walking… What do you do? Become a copycat?… No!  Listen to your heart to exercise in your best training zone.

What your heart decides

When you exercise, your heart beats faster to supply oxygen and fuel to your muscles. Your heart rate (number of times your heart beats per minute) will increase as the intensity of your exercise increases to boost the supply.

As you train, your muscles need fuel to work harder. The harder you exercise the more fuel your muscles will need.  Your body can use different fuel sources for different needs. During prolonged, low intensity exercise, your body mainly uses your fat stores for energy. During shorter, higher intensity exercise, glycogen and carbohydrates become your primary energy source.

Your exercise goal is important

It’s important to have a goal when exercising, such as increasing your fitness, losing fat, toning, increasing muscle strength, or managing your health condition. Your exercise intensity and heart rate will be relative to your exercise goal, which in turn will determine the fuel source you will use.

How to determine your resting heart rate and maximum heart rate

Resting heart rate:  Find your pulse on your wrist first thing in the morning. Count the beats for 15 sec and multiply by 4. The value is your resting heart rate (beats/min.).

Maximum heart rate (MHR): MHR = 220 – (your age). For example, the MHR for a 54 year old person is 220 – 54 = 166 beats/min.

Target heart rate: The heart rate between your resting and maximum heart rate that would allow you to function at optimal capacity to achieve your specific exercise goal.

Training according to your target heart rate zone:

Very Low Intensity: 50 – 60% of MHR
The intensity is very low at this level, but enough to increase your fitness. You will gain the health benefits, without the risk, making it safer if you’re elderly, have heart problems or if you’re a beginner. This zone is also used for recovery after overtraining. In this zone your main fuel source is fat.
Low Intensity: 60 – 70% of MHR
In this zone your heart works slightly harder. An example would be running for longer distances to maintain muscle endurance. Fat is still your primary source of energy. Having strong muscles is key so don’t attempt this if you’re a beginner!
Moderate Intensity: 70 – 80% of MHR
In this zone you will focus on increasing your muscle strength. This is also the most effective heart rate zone for cardiovascular fitness if you don’t have heart problems. You will really push your heart to supply the muscles with nutrients and oxygen and as your fitness increases, you will be able to cover more distance in less time. At this level, half of the calories you burn will come from fat and half from carbohydrate.
High Intensity: 80 – 90% of MHR
At this level your body changes from using oxygen (aerobic) to having muscles contract to use less or no oxygen (anaerobic). This happens because you’re training at a higher intensity. In this zone, your goal will be to increase your performance. Your breathing will be heavy and your muscles will tire easily as you condition your body to cope with these stressors to become fitter. Your primary fuel source will be carbohydrate and less will come from fat.
Maximum Intensity: 90 – 100% of MHR
In this zone you use such little oxygen that the body can only handle it for short bursts such as sprints. Your benefit in this zone is increasing power, speed and agility.

What heart rate zone is important for losing weight

You will burn a higher proportion of calories from fat when exercising at lower intensities (50 – 60% of MHR). However, if you exercise for the same period of time at a higher intensity (70-90% of your MHR), you will burn a greater number of total calories, which is more significant for losing weight.

By following these simple guidelines, you can train within a specific heart rate zone to optimally focus on your needs and achieve your training goals.

Photo by Mike Baird

 

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About Charl Greeff

Charl Greeff is a biokineticist at Virgin Life Care.