Cardio Training Zones – What Exactly Are They?

We’ve all heard about training zones for cardio exercise – these are basically ranges of intensity for doing cardio exercise, measured by your heart rate. The idea is that exercising within each of these ranges produces a different effect on your body, and therefore a different outcome.

Generally speaking, there are 5 training zones, shown below:

Probably the most well-known training zone is the Fat Burning Zone. This is defined as being 60-70% of your Maximum Heart Rate (MHR), and is the range in which your body is burning mostly body fat to fuel the exercise.

There are a few different ways of working out your maximum heart rate. The simplest is to just subtract your current age from 220, but there are also several formulas you can use which give you a more accurate result. The most common formula is probably one called the Karvonen Formula.

From my experience there’s still a lot of confusion around regarding training zones. Even though they’re quite well understood these days in industry circles, there are still a lot of myths floating around among women. Many of these generally stem from older thinking – from the days when even experts weren’t sure about how they worked.

Probably the two most common misconceptions I hear about training zones are these:

1. To maximize your weight loss, you need to train in the Fat Burning Zone.
2. If you train with too much intensity, you’ll lose muscle.

Both of these, of course, are not true.

The one significant thing that we’ve learned about cardio exercise is that the major factor which determines how efficiently you lose weight is intensity.

Even though low intensity exercise (in the Fat Burning Zone) causes your body to focus on body fat for fuel, it’s the number of total calories burned by exercise that determines how much weight you ultimately lose.

High intensity exercise has been shown to cause an after-effect, where your metabolism remains elevated for hours after the exercise has finished. During this time, your body continues to burn calories and therefore continues to lose weight.

High Intensity Interval Training, otherwise known as HIIT, allows you to train at high intensities (in the Anaerobic and Maximum Effort Zones) by having you alternate between periods of high exertion and low exertion for recovery.

This is why HIIT has become so popular for weight loss.

In fact, HIIT is now recognized as the very fastest way of losing weight. It’s been shown to shed body weight several times faster than low intensity cardio exercise.

In terms of muscle loss, as long as you ensure that you have adequate carbohydrate fuel in your body before training, there’s simply no reason for your body to turn to your muscles for its energy needs during high intensity exercise.

Serious endurance athletes such as marathon runners often place very high demands on their bodies’ carbohydrate fuel sources, and when these run low they will start to shed muscle. This however isn’t related to high-intensity activity – it’s simply a way for the body to get energy when other sources become inadequate.

By ensuring your energy levels are always topped up and making resistance training a part of your regular exercise routine, you’ll never need to be concerned about losing any muscle tissue – something that’s very undesirable on a weight loss program.

My approach to using cardio exercise training zones is very simple:

1. Warm up at 50-70% MHR (Warm Up Zone and Fat Burning Zone), depending on your fitness level.
2. Do most cardio training as HIIT, for anaerobic fitness, aerobic fitness, and maximum calorie burning. This will take you into the Anaerobic Zone and Maximum Effort Zone, depending on the length of intervals you use – the shorter the intervals, the higher the intensity level.
3. Do some lower intensity cardio training as well (Cardio Zone) for aerobic fitness and calorie burning.