Perhaps you have just acquired your first fitness tracker, or maybe you have decided that it’s time to use more of the data that you have been “wearing” for some time. Or maybe you have been hearing a lot about “Heart Rate Based Training”, but not quite sure where to start?
In this post I will look at the precursor of Heart Rate Zones and that is to determine your Maximum Heart Rate and to suggest a slightly more accurate way to calculate it.
(If you are not so worried abut understanding the background and theory then Click Here to jump straight to the formula)
Intensity & Performance
Let’s consider two types of fitness training: Strength & Conditioning (S&C) and Cardiovascular Training (CV). In both, intensity of training can be manipulated by a number of variables for instance; duration, repetition of exercise. Conveniently in S&C, we can also increase intensity by adjusting weight, but of course that is not so relevant in Cardio training. So what is the equivalent? Enter “Heart Rate Zones”. But before we can establish “work zones” we need to have determined our Potential Maximum Heart Rate.
MaxHR is Sport Specific
At first glance the Maximum Heart rate for a given person should be a single number. One person, one heart and we are looking for the maximum number of times that it can “beat” in a minute? However, MaxHR does not quite mean that.
If we consider Cardio exercise and specifically when we are using our “aerobic” energy system. This means that our muscles are using Oxygen to convert glucose and “fats” into Adenosine triphosphate (ATP). ATP being the fuel that our muscles can use. The harder we make a muscle work (within the aerobic energy system) the more oxygen it will require. Oxygen obviously is transported to the muscle in our blood, therefore it follows that we will need to increase the amount of oxygenated blood reaching the muscle.
In thinking about the flow of blood around our body and what determines the flow rate, we start to consider “Cardiac Output”. This is controlled by two factors; the volume of blood leaving the Left Ventricle each time the heart beats, and the number of times the heart beats in a minute.
Therefore one of the markers of how hard we are “working” is how fast our heart is beating. However, consider that different types of sport use different muscles and groups of muscles (meaning that different amounts of muscle mass will need oxygenating) and as such when working at “maximum capacity” will have the potential to need a different cardiac output. Given that the size of our left ventricle will be constant (although we can increase it over time as a consequence of training!), then what changes per sport, is our Heart Rate.
The consequence being that an individual, at any given point in time, will have a MaxHR per sport. Some will be similar (or potentially the same) but the important point is that MaxHR is relative to the activity.
Calculating MaxHR simplistically
To calculate MaxHR you subtract your age from 220.
Well no, not really! Although this is the commonly sighted formula, it transpires to actually be inaccurate for many people much of the time. It’s origin is from the work of Fox et al. (1971) where Fox reviewed a number of studies and concluded that no single formula could adequately represent the decline of HR with age. However ‘220 minus age’ defined a line not far from many of the data points’. He was therefore offering this as no more than an approximation.
Using a Maximal Stress Test
The most accurate way to determine MaxHR is to follow a sport specific testing protocol in a laboratory with medical supervision. But in practice, other than for Elite Athletes, most others would not have access or resources to be able to do this.
Also, performing a ‘maximal’ test is hard and unpleasant as you are required to reach complete exhaustion. This can also be dangerous unless you are physically fit and conditioned.
There are various ‘field based’ stress tests that can be used. Their accuracy however is determined by the subjects ability to meticulously follow the testing protocol. Reproducibility is also an issue. Therefore you using this approach will only lead to an approximation of maxHR. Given the inherent safety risks and accuracy of the result, I would suggest not worth doing.
So what other options do you have?
Alternative Calculations
There are more accurate calculations that we can use and others have conducted research after the work of Fox.
Whyte et al. (2008) proposed a more refined formula that took account of the difference between men and women.
- Male athletes – HRmax = 202 – (0.55 x age)
- Female athletes – HRmax = 216 – (1.09 x age)
A different study by Londeree and Moeschberger (1982) found that whilst there was no difference between genders, there was a variance based on activity levels and training background.
Further studies found that there was a calculable difference between different types of sport in terms of the MaxHR that could be potentially reached.
As you can see many studies have been done but there is conflicting information and ultimately no clear cut answer. Which is possibly why the ‘220 minus age’ formula remains popular and often considered good enough!
Using MaxHR to define training Zones
Perhaps another consideration is to return to why we are trying to understand MaxHR in the first place? After all there are other markers we use to estimate fitness and performance.
Unlike S&C where we have the ability to add or remove weight as one lever of intensity, in Cardio exercises we don’t have that. But we believe that we can cause different physiological adaptions depending on the extent to which we invoke different energy systems. This translates to ‘training zones’ and in turn these training zones can be mapped against % of MaxHR. So for cardio training it can be a very helpful number to know!
We should remember though that as good as modern technology is, there is still a relatively high degree of error introduced by the different measuring techniques. Generally a trade off against accuracy and convenience!
What are the key takeaway messages?
Firstly outside of Elite level sport “MaxHR” is not an exact science as we are not using maximal testing methods in a lab controlled environment. Wherever we end up will be an approximation.
Secondly the sports watches, trackers and even chest straps all introduce a margin for error in the data we are collecting. This adds to what is already an approximation. It is therefore worth giving some though to what equipment you are using and how accurate it is. Also to how carefully and consistently you use it.
That being the case we could conclude that ‘220 minus age’ is good enough. Personally, I think we can do better by using the following approach which is derived from findings across a number of different studies:
Based on the Whyte formula:
- Male athletes – HRmax = 202 – (0.55 x age)
- Female athletes – HRmax = 216 – (1.09 x age)
And then adjusted using approximations from Londeree and Moeschberger
- Subtract three beats for elite athletes under 30
- Add two beats for 50-55 year-old elite athletes
- Add four beats for 55+ year-old elite athletes
- Use this value as the HRmax for running
- Subtract five beats for bicycle training
