Heart Rate Zones

Important: I’m not a doctor, have no medical or sports training or expertise and the information in this post has been mainly been gleaned from the internet. DO NOT follow any advice in this post blindly. You should seek medical advice or the advice of a sports specialist yourself.

One of the main reasons I have started doing indoor rowing is to lose weight. Ignoring fads, crash diets, etc. I’m adhering to the core concept that to lose weight you need to expend more calories than you consume each day. This can be done be eating differently, exercising or doing both. This isn’t rocket science. If you don’t change what you eat but you start exercising you’ll expend more calories than you did before and either lose weight or, if you are still consuming more calories than you are expending, at least slow down your weight gain. Similarly, if you eat less or change your diet then you will either lose weight or at least slow down any weight gain.

On the eating side I’m trying to eat smaller portions, eat better foods (fewer processed and more fruit and veg) and cut down on snacking. I’m kind of keeping a food diary and doing some calorie counting too but this isn’t the focus of this blog post. Instead I want to focus on exercise and, more specifically, effective exercise.

When you are working out you can optimise your exercise sessions by making use of heart rate zones. Each zone has a different overall effect on your body.

The Recovery Zone: Training in this zone develops basic endurance and aerobic capacity. Your heart becomes stronger, muscles are fed more efficiently and your body learns to metabolise fat as a source of fuel.

The Aerobic Zone: Training in this zone helps develop the cardiovascular system, essentially training your heart. It is also in this zone that you improve your body’s ability to transport oxygenated blood to your muscles and carry carbon dioxide away.

The Anaerobic Zone: Training in this zone develops the lactic acid system. Here fat stops being the main fuel and rather glycogen from muscle is used which produces lactic acid. When your body cannot remove lactic acid faster than it creates it you have reached your anaerobic threshold. Training in this zone pushes the anaerobic threshold higher.

The Maximum Zone: Training in this zone is only possible for short periods and it should only be done by people who are very fit.

Which zone is the best one for burning fat? Training in the Aerobic Zone was traditionally thought to be the best one. However that myth has now been dispelled. After exercising your body will replenish and rebalance your energy stores which means that if during a workout you are burning carbohydrates rather than fat then your body will convert fat into carbohydrates once you have finished exercising. Also the key thing is that you are burning calories. If you do a long, low intensity workout you may well burn fewer calories than you would during a higher intensity, shorter workout.

What is perhaps more important than exercising in one particular zone is to get the balance right. You are better off exercising in all of the zones each week than focusing on, say, the aerobic zone. Whilst aerobic exercises should be done at least once a week and will probably form the backbone of your weekly plan you should probably do a workout in the anaerobic zone once a week and follow that the next day with a recovery workout.

The maximum zone should only be dipped into (if at all) which brings up the subject of interval training. I believe that there isn’t a specific scientific reason why but interval training seems to be the most effective way to burn fat. This is when you mix bursts of high-intensity exercise (anaerobic or maximum) in with an aerobic workout. For example, you might do 30 seconds of rowing as hard and fast as you can followed by two minutes at a much more relaxed rate and intensity.

So far the zones have all been described fairly loosely but fortunately they can be more tightly defined in terms of heart rate and more specifically, working heart rate. The zones are generally thought of as being:

  • The Recovery Zone: 60-70% Heart Rate Reserve
  • The Aerobic Zone: 70-80% Heart Rate Reserve
  • The Anaerobic Zone: 80-90% Heart Rate Reserve
  • The Maximum Zone: 90-100% Heart Rate Reserve

Your working heart rate is simply your maximum heart rate less your resting heart rate.

You can get your resting heart rate by taking your own pulse when you are relaxed and resting (perceived wisdom is to take it when you wake up). It is worth measuring it over several days and taking the lowest figure. If you don’t want to take your pulse then use a heart rate monitor but the sort that clips onto a finger or is wrist-based might be more convenient than a chest strap.

Unless you attend a specialist clinic to have it measured you will probably have to simply calculate your maximum heart rate. There are a plethora of formulas you can use. Note that they may not be very accurate which can throw the zone heart rates off and different sports and activities can have different maximum heart rates too.

Once you have both you can subtract your resting heart rate from your maximum heart rate to get your working heart rate. Remember that you should recalculate it over time too since, as you get fitter, your resting heart rate will probably drop.

Putting all of this into an example, assume that I have a resting heart rate of 70 and a maximum heart rate of 180. That means that my working heart rate is 110. To calculate your heart rate zones you take the percentage of the working rate and add the resting heart rate. Using the above figures my recovery zone would span from a heart rate of 70 + (110 x 0.6) to 70 + (110 x 0.7) or from 136 BPM to 147 BPM. The aerobic zone would span from 70 + (110 x 0.7) to 70 + (110 x 0.8) which is 147 BPM to 158 BPM. The anaerobic zone is 158 BPM to 169 BPM and the maximum zone is 169 BPM to 180 BPM.

All of this means that I’d now know that if I wanted to have an hour-long aerobic workout I should row at a stroke rate and with an effort which will result in my heart rate being between 147 and 158 beats per minute. I also know that if I approach 180 beats per minute then I need to ease off unless it is a planned burst as part of an interval training session. Also, if mu heart rate is below 136 beats per minute than I’m probably not burning many calories or giving my heart much exercise.