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Efficient Exercise: Are You in One of These Four Zones?

December 20, 2017

Last month, I wrote about the importance of aerobic (cardio) exercise — the type of exercise that gets your heart beating faster.  (See the column here.)

But a heart that is beating faster does not necessarily mean that you are burning more calories or even helping to build your endurance.  In fact, there are defined “zones” of exercise to help make sure that you are exercising efficiently.  In this article, I am going to provide some of the basics of heart-rate zone training.

You should think of these zones as a continuous spectrum with each zone blending into the next. It is actually possible to calculate a range of heart rates that correspond to each of the zones. These heart rates are calculated for each individual based on age, maximum heart rate and other factors. But for the sake of simplicity, you can also get pretty close to this based on how you feel when exercising in each zone. If you’re starting to work on cardiovascular fitness, you should be focusing on Zone 1, and then eventually exercise in a combination of Zone 1 and  Zone 2.  If you’re already fit but looking to improve endurance, you should be thinking about Zone 2 to Zone 4 workouts. Seasoned endurance athletes probably already know about these zones and use each of them in your workouts.

Zone 1: Warmup. Start to exercise here as you begin to work toward cardiovascular fitness.  It is an easy and sustainable zone.  You should feel like exercising in this zone is a place you can be all day.  Zone 1 is where you will start to feel warm, but can maintain a normal conversation.  It is also a recovery zone.

Zone 2: Fat-Burning.  In this zone, most (about 85 percent) of the calories burned are from fat.  This is a level of exercise where you will be aware of your heart rate rising and feel your muscles and body warming up.  You will feel as though you are working in this zone, but your muscles should not feel like as if they are burning or tiring out.  You’ll begin to sweat a little in zone 2, but this level should be sustainable for a long period of time (hours) and you can talk in full sentences.

Zone 3: Endurance.  This zone produces cardiovascular fitness and burns more calories, but is not the most efficient place to burn calories for weight loss, as only about half of the energy needs are met here by using fat as an energy source. Some experts will refer to this zone as a transitional zone, a zone you cross to get to zone 4.  One- to two-word answers are about all that one can speak in this zone.  You really start to sweat here and you are working harder to breathe.

Zone 4: Threshold.  In this zone, you enter anaerobic (without oxygen) metabolism.  The muscles start to use an alternative form of energy that produces lactic acid as a waste byproduct. This lactic acid quickly builds up, giving the “burn” of intense exercise.  The muscles quickly fatigue in this zone, which is sustainable only for a short period of time based on your level of fitness.  At best, you can answer with short single words and prefer not to talk when in this zone.  Although this zone produces endurance needed for runners, bikers and other endurance athletes, this is not the place you want to be when you are first starting out with exercise. Recovery in a lower zone is needed after training in this zone.

Zone 5:  Maximum Effort. This zone is the maximum effort one can produce.  Training here is usually reserved for the most seasoned of athletes, and usually can be sustained only for a short period.  For the rest of us, there really is no reason that to exercise in this zone.

When trying to become more fit, many people make the mistake that more is better. What matters more is that you are working to exercise efficiently.  Using these zones can help you get more out of your cardio workouts to achieve your goals. As always, please remember to consult with your healthcare provider or certified fitness trainer prior to beginning any type of exercise program.

Be well, stay fit and keep moving.

Dr. Darren S. Tishler is director of Metabolic and Bariatric Surgery at Hartford HealthCare.