Heart rate zone training

What are heart rate zones?

Heart rate zones are a series of predetermined ranges of an athletes heart rate relating to a set intensity of exercise. The actual BPM of each zone will vary quite a lot from athlete to athlete, however the actual effort that each athlete is working at will be roughly the same. 

Depending on what literature you read, there can be anything from 5 to 8 hr zones, and other coaches even split the upper zones into "sub zones". When I'm producing zones for the athletes that I coach, I tend to group the 3 sub zones together that are sometimes used in zone 5, although this is mainly for simplicity and ease of use for the athlete.The zones that I use range from Zone 1, which is the easiest level of exercise, up to zone 5 which is Threshold and above. 

I've heard people say things like using zone 1 or 2 for fat burning, but in my opinion, this is the wrong way to look at it for endurance athletes. In it's very crudest form, we'll burn fat at all intensities of exercise and some studies suggest that we'll burn more fat at higher intensities. That said, it also depends on whether you've eaten and what it was, before exercising as this will relate to what fuel source your body will use first. In order to change the way that we think about zones, instead of thinking about their fat burning efficiency, think about what energy system being used in each zone is intended to work on. 

In zone 1 and zone 2 you're working at the bottom end of the aerobic zone and this is the area or intensity that approx 75% of your training should be done in, if you're an endurance athlete. No matter what distance of triathlon you're doing, it's an aerobic sport and so that's the energy system that you need to pay most attention to. When people talk about using zone 2 for fat burning, what's really meant is that if you're doing a long aerobic session on the bike, or a long zone 2 run, in order to maximise the way that your body will utilise fat as a fuel source is to start off in a fasted state, then you're "forcing" your body to utilise fat as a fuel source which is a highly efficient way to fuel yourself during a long race, even though you'll still need to maintain an intake of roughly 60g of carbohydrate per hour in order to keep glycogen stores topped up. On a sprint or standard distance triathlon you can get away with using gels, or similar, as a fuel source, but on a 70.3 or 140.6 distance race you need to pay extremely close attention to how you fuel for it. 

But I digress, back to zones. 

So, now we know that zones 1 and 2 are aerobic zones, this means that when you're training in these zones you're actively developing the efficiency at which your body synthesizes something called ATP. ATP or Adenosine Triphosphate stores and transports chemical energy and is what converts chemical energy into physical energy at a cellular level. Within the ATP are organelles called mitochondria and these are often referred to as the power house of the cells all of which can be developed and increased in number during zone 2 training. Therefore, when you're working in zone 2 you're developing your aerobic fitness at a cellular level, which will yield massive results the more you do and the longer you do it for. It's because of these factors and the way that we develop our aerobic fitness that triathletes and distance runners / cyclists and swimmers do as much as 80% of their training at zone 2. It takes months and months, but with correct structure, progression and recovery, the results speak for themselves.

Zone 3 is also an aerobic zone but it's what we often refer to as tempo and depending on which coaches you speak to, or what literature you read, this can be a bit of a grey zone because it's working at the very upper limits of the aerobic system, but it's not hard enough to push into the threshold and anaerobic systems. So it's not developing your aerobic fitness as well as the zone 1 or 2 stuff and it's not making you faster and stronger as the sessions done at threshold and above are. 

So then we start getting up to zones 4 and 5. Depending on the formula that you use to determine your heart rate zones, your threshold will be somewhere between mid zone 4 and the bottom of zone 5. In these zones you're working hard and although you're not developing your aerobic fitness as much, your speed will improve and your body will get more efficient at processing the lactic acid that you're producing. You'll also become efficient at utilising carbohydrates as a fuel source. As you push above your threshold your heart and lungs are working pretty much to their max and the lactic acid will build up in your blood to a level that you won't be able to continue exercising at. When you reach the point where you can't breathe any faster, you will have reached what's called your VO2 max - your maximum capacity of oxygen use, the higher your VO2 max, the fitter you are. These high intensity interval sessions are good for building up the body's resistance to lactic and will help promote fast twitch muscle fibres to fire and work. However, because the benefits for endurance athletes lie within zone 2 aerobic training, we try to limit the amount of high intensity sessions that we do to a max of 25% of our training. 

Calculating HR Zones

There are quite a few different formulae that can be used to determine your HR zones. The most basic of these is the 220 minus age formula, which will give you your theoretical max heart rate, which you can then use to set your zones as percentages of that. The main issue with this is that it doesn't take into account any underlying issues that you may have. Some people have a slower heart rate, sometimes because of medical reasons and others because of medication. Similarly, others may have a higher heart rate. 

The method I prefer to use is to do a test to determine your max hr and then work it out off that. To do this a running track is ideal because it's so flat, so there are no fluctuations caused by gradients etc. Start off by doing a good warm up for around 20 mins, to include some drills and strides etc. then carry out a 20 minute test. To do the test, the easiest way to do it is to have a run specific watch like a Garmin etc. Start off at a pace that you can just about manage to hold for 20 minutes, after the first 5 minutes, press lap on your watch and continue to run for the next 15 mins. By the time you finish your test you should be at a max effort and should struggle to go much further. Ideally, there should only be a few BPM between your average and max hr, as you'll learn that you can hold a high intensity for the duration of the whole 20 minutes. When you've finished the test take the data from the 15 mins of the test, looking at the average and max hr. These can then be used to set your zones. If you're using the max heart rate, zones can be set as:

Zone 1 - 50-60% max

Zone 2 - 60-70% max

Zone 3 - 70-80% max

Zone 4 - 80-90% max

Zone 5 - 90-100% max

Your average heart rate for the 15 mins of the test is what we refer to as threshold. This isn't the most scientific way of determining your threshold though. To do that you need to do testing in a laboratory environment where blood samples are taken at various intervals to determine lactate levels within the blood. The reason why we don't use the data from the first 5 mins of the test is because for this period you'll be settling into the test and your heart rate will still be rising to near max. 

What you'll notice as you do more and more of the tests is that your max heart rate will gradually become more consistent across the tests as you develop as an athlete and learn how hard you can push yourself

Using the RPE method

RPE refers to Rate of Perceived Exertion and is usually on a scale of 1 - 10 or 1 - 20. This scale is called the Borg scale and can be used to measure how hard your training sessions are. If you think of Zone 1 being the very easiest of exercise, probably a very fast walk and zone 5 being the hardest effort you can imagine and then look at that on a scale of 1 to 10, it'll give you a good indicator of how to grade your effort

Summary

So to summarise very briefly, try and complete at least 75% of your training at zone 2 to increase your aerobic efficiency during a race or training session and complete the other 25% at a very high intensity to promote lactate tolerance and to develop speed. I can't stress enough just how important zone 2 training is though and without it or with not enough of it you'll not reach your potential within endurance sports. 

If you'd like to speak more about your goals and ambitions and how I can help you on your triathlon journey, click on the link below which will take you to my coaching Facebook page, where I can be contacted through

Certa Cito Tri Coaching