Monday, 15 October 2012

Heart Rates Part 3: Heart Rate Reserve and Target Zones

Well done if you have worked out your resting heart rate and your maximum heart rate! You are well on the one to constructing a workout program that is best for your body. The final step in this process is understanding the target zones for exercising in and your heart rate reserve.

Let me start with the concept of target heart rate zones, which most of you might know about already but bear with me. The idea argues that there are a series of zones between your resting heart rate and your maximum heart rate which develop different aspects of your fitness. Ideally, you should be creating a program that involves working at a number of different levels across the cycle.

For most simple programs these zones are based on a percentage of your maximum heart rate. Here is a sample chart which demonstrates the concept:

Fitness Target Zones: Heart Rates

Exercise LevelBenefitsIntensity Level
(Max HR %)
Light ExerciseHealthy Heart
50% - 60%
Weight LossBurn Fat & Calories60% - 70%
Base - AerobicIncrease stamina & endurance70% - 80%
ConditioningFitness conditioning, muscle building, and athletic training80% - 90%
Athletic - eliteAthletic training and endurance90% - 100%

From the website Heart.

As you have now worked out your maximum heart rate, you can develop or understand programs that work on this model.
Please keep in mind that these divisions are very simplified and only indications. For example, obviously all exercise must burn calories, it is just that the lower heart rate levels allow the body to rely on its fat burning processes rather than using other processes. However, any process has to burn something to create the energy and so will use calories in one form or another, it might just not use your fat stores first.

This method relies only upon your maximum heart rate and as general fitness does not affect maximum heart rate as much as resting heart rate, these zones do not take into account your own fitness very much.

Another method takes into account the available spread of heart rates that an individual can work within. This spread is based on the range between your resting heart rate (which can vary up to 60 or 70 bpm between a fit and unfit person) and your maximum heart rate.

If you are not very healthy at all, you could have a resting heart rate of 100 and a maximum heart rate of say 180, therefore an active range of 80bpm. On the other hand, an athlete might have a resting heart rate of 50 and the same maximum of 180, so has an active range of 130 bpm. So how can we take into account this range?

This is where Heart Rate Reserve comes into play. Your heart rate reserve is just this, your active heart rate range. It is calculated by subtracting your resting heart rate from your maximum heart rate.
Our not so healthy person: 180 (MHR) - 100 (RHR) = 80 (HRR).
Our athlete: 180 (MHR) - 50 (RHR) = 130 (HRR).

Based on this theory, target heart rate zones are calculated based on a percentage of the heart rate reserve which is then added back onto the resting heart rate (being your bottom line.)

This is used by a lot of more developed training programs, such as the rowing programs on the Concept 2 webpage, who define the different target zones as follows (based on Heart Rate Reserve):


 Band  Type of Work % HRWhat it is good for How you Feel 
 UT2Utilisation 2. Light aerobic, low intensity work. Sustainable and fat burning. 55-70General CV fitnessRelaxed. Able to carry on a conversation.
 UT1Utilisation 1. Heavy aerobic work using more oxygen. 70-80 Higher level of CV fitnessWorking. Feel warmer. Heart rate and respiration up. May sweat. 
 ATAnaerobic Threshold. Harder work. On the aerobic limit. Pushing into anaerobic area. 80-85High level of CV fitness. Building mental and physical tolerance.Hard work. Heart rate and respiration up. Carbon dioxide build up. Sweating. Breathing hard. 
 TROxygen Transportation. Working hard. Unsustainable for long periods.  85-90Developing oxygen transport to the muscles under stress. Increasing cardiac output. Stressed. Panting. Sweating freely.
 ANAnaerobic (without oxygen). Short bursts of maximum effort. Unsustainable. Burning carbohydrate.  90-100Anaerobic work. Increasing speed. Accustoming the body to work without oxygen.Very stressful. Gasping. Sweating heavily.

From Concept 2.

So, let us compare the two methods for our two examples the not so fit (NSF) person and the athlete. Say that both of them want to build up a good cardiovascular (CV) base by doing some conditioning work staying in the aerobic band.

According to our first and second chart:
Base - AerobicIncrease stamina & endurance70% - 80%

UT1Utilisation 1. Heavy aerobic work using more oxygen. 70-80

(Keep in mind that the two charts do not align against each other perfectly, but the example shows the variance between a fit and an unfit person.)

So, for our NSF person with a max of 180
Chart 1: 126 - 144 bpm is the range they should be working in.
(180 x 0.7 - 180 x 0.8)

Chart 2: 156 - 164 is the range they should be working in.
Reserve = 80.
Resting = 100
So (80 x 0.7) + 100 and (80 x 0.8) + 100 
56 + 100 and 64 + 100. 

And our athlete?
Chart 1 will be the same: 126 - 144

Chart 2: 141 - 154 is the range.

Reserve = 130
Resting = 50
So (130 x 0.7) + 50 and (130 x 0.8) = 50.
91 + 50 and 104+ 50.

What can we learn from this?
First, when working out your zone, make sure whether the program is referring to % of maximum or % of reserve, as there is a big difference.
Second, generally as you get fitter the target heart rate you are working at will need to drop to stay in the lower zones. Your body will become more effective, and so if you keep working at a higher rate, you will be in a different zone.
Third, using a percentage of your heart rate reserve gives you a more personalised program.

Even if you don't use it, take time to sit down and work out your target zones based on your heart rate reserve and Concept 2's bands just so you can get a feel for how it might be different to what your treadmill chart might be asking you to do.

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