How to Find Your Aerobic Training Zone

aerobic training zones

Hiking and mountaineering are predominantly endurance activities performed at a low intensity for long durations, often for many days in a row. In order for this to be an enjoyable activity and to prevent unnecessary stress and overuse injuries, you must focus your training on developing the energy system that is responsible for handling this kind of activity – the aerobic system.

In this post, you’ll learn how to find your aerobic zone, get a basic understanding of the two energy systems that you have at your disposal and how they can be used to your advantage. I also share some practical tips and tools to help you implement this training system, so you can make the most of your training and increase your enjoyment of the mountains.

The primary focus will be on the aerobic energy system, which is one of two energy systems we have available to us as humans to fuel our activities, the other is anaerobic. But it’s important to note that the two aren’t always mutually exclusive – they are often used together, let’s dive in and find out how.

It’s just Hiking, is this really necessary?

While hiking or mountaineering may not be activities that draw a great deal of investigation in the area of sports science, it’s still possible to apply a basic understanding of how the human body changes and adapts as the intensity and duration of our adventures increase. 

During a long day of hiking, or a long training session, there are key points of change that occur, which have a significant impact on the effectiveness of our training. For this reason, it is important to understand these points of change and to use this information to our benefit.

Those two points of change are the aerobic threshold and the anaerobic threshold. Without getting too bogged down in the science, let’s look at how and when these changes occur.

Aerobic vs. Anaerobic – what is the difference?

When you perform an exercise using your aerobic system you are likely to be breathing steadily, you feel calm and your stress levels are relatively low. As you continue to increase the intensity of an exercise, you will move past a point called the aerobic threshold, where you begin to use a mix of both the aerobic and anaerobic systems to fuel your activity. If you push yourself even further past the next point of change, the anaerobic threshold, you will begin using the anaerobic threshold exclusively. This basic graph will help illustrate my point.

training systems

Note: This graph is designed to illustrate some of the most important terminology in this article. The heart rate numbers you see here are arbitrary and are only used as an example. The determining factors are the level of blood lactate and the metabolization of fat and sugar.

The Energy System Graph

As you can see, at the lower end of the intensity spectrum, we utilise the aerobic system to support our activities. If you were to develop your aerobic fitness with intelligent training, you will be able to perform much more intense activities but still, be able to feel relaxed whilst doing so. In essence, your blue line will move further to the right, meaning you are increasing your aerobic threshold, and thus, your overall aerobic capacity.

The advantage of understanding and developing aerobic fitness is that you can do more work with less effort – that results in a more enjoyable time in the mountains and also less muscular stress-related injuries. Now let’s look at the two systems in more detail.

aerobic run in the Pyrenees

That’s me on an aerobic run in the Pyrenees, taking it slow and steady in the mountains. @chase_mountains

The Aerobic System

Every mountain sport, whether it’s hiking, mountaineering, skiing or climbing (perhaps the only exception is bouldering) is predominantly an aerobic activity, meaning that oxygen is an essential part of the production of the energy your body will use to fuel these activities. When training and being active aerobically, we are predominantly using the following three components:

  • Oxygen
  • Slow-twitch muscle fibres
  • Fat as a fuel source

During aerobic activity, your body will utilise oxygen at the same rate you are capable of supplying it, via your breathing, to the working muscle fibres, which are in this case slow-twitch muscle fibres.

Slow-twitch muscle fibres are those related to our endurance-based muscle. Picture the muscles of a marathon runner; lean, sinewy muscle that is neither bulky nor particularly impressive. Those are the muscles that our long-duration activities rely on. 

When exercising aerobically the body utilizes both glycogen (sugar) and fat as a fuel source, but the percentage of fat utilised will always be higher, this is perhaps the defining factor of aerobic activity.

What are the benefits of aerobic training?

The benefits of aerobic training for endurance-based activities such as hiking, or any other mountain sport are as follows:

  • You’ll be able to do more work and it will feel much easier and more enjoyable
  • You’re much less likely to crash in energy as you begin to learn your limits
  • Your body operates under lower stress meaning injuries are much less likely
  • You teach your body to burn body fat as the predominant fuel source
  • You won’t need to constantly snack in order to fuel your activity throughout the day
  • Improved general health, wellness and vitality

The primary benefits here are obvious. With aerobic training, our trek, hike or expedition becomes far more enjoyable. Particularly important is the lower likelihood of injury which coupled with adequate mobility will make you basically mountain proof!

The secondary benefits such as reduced body fat may be appealing to you, but perhaps what’s more important is the reduced reliance on constant snacking and glucose to fuel your activity. But in order to achieve this or any other benefit of aerobic training, it must be done with some precision, which I’ll get into shortly.

Have you experienced this?

Have you ever noticed a drop in energy after about one or two hours of hiking, especially if you haven’t eaten anything?

If that’s the case, then it is likely that your aerobic system is not very well trained and you are relying on glucose to fuel your hiking.

The Anaerobic System

When do I need the anaerobic system and when should I train it?

The other system of energy production in the body is the anaerobic system. As opposed to using fat as a fuel source, the anaerobic system uses more glycogen (sugar) for energy production. When training anaerobically, we are likely to be using the fast-twitch muscle fibres which are responsible for short, powerful efforts. Think sports like sprinting or Olympic lifting. Anything that requires short, fast and powerful bursts of energy.

On the other hand, when we train aerobically we’re more likely to be using slow-twitch muscle fibers. These are the muscle fibres responsible for powering many hours of low-intensity activity, such as hiking or long arduous mountaineering ascents.

athlete Trae Williams
Athlete Martin Fiz

Athletic Bodies: On the left, Australian Sprinter Trae Williams displaying some serious fast-twitch muscle fibres. On the right, Basque Marathon runner Martín Fiz. It’s still an athletic physique, just a different type of muscle fibre for an entirely different purpose.

When do we use the Anaerobic System?

Our ability to utilise the anaerobic system is very limited, especially when concerned with endurance-based activities. If you’re a hiker or a mountaineer the majority of your training should be aerobically based.

As a trekker and hiker, it’s basically unnecessary to train at a very high intensity. Having said that, it may be both necessary and enjoyable under certain circumstances, and for that reason, I almost always include some anaerobic training in the later stages of my programs once the aerobic base has been well established.

What about High-Intensity Interval Training (HIIT)?

When I began my career as a coach, High-Intensity Interval Training (HIIT) was at its highest point of popularity. There were even several studies that suggested that one could raise their aerobic threshold by training for shorter times in these faster, more high-intensity bursts. In a way, this is still correct, but it is only relative to short term increases in endurance that aren’t really beneficial in the long term. So if you have less than 4 weeks to train for a mountain, HIIT may be the only real option for you to gain some improvement in such a short amount of time, but the risks could see you injured and unsuccessful. 

If you want to give yourself the best chance of success in the mountains, training predominantly in the aerobic zone is going to yield far better results than HIIT.

What is the Aerobic Zone?

The aerobic zone is an optimal level of training to increase aerobic efficiency. It is generally thought to be within 10 beats per minute of your aerobic threshold. For me, my aerobic zone is between 135 and 145 beats per minute, but it is different for each individual depending on your age, your lifestyle stress, training history and many other factors. I go into more detail on how to establish your aerobic zone using the Maffetone Method very soon.

What is the Aerobic Threshold (AeT)?

Aerobic Threshold is the point at which fat is no longer the primary fuel source that is powering your movement. Anything below this point, you will be training aerobically, anything above this point you will be using a combination of fat and glycogen.

What is Anaerobic Threshold? (AnT)

Aerobic Threshold is the point at which glycogen becomes the predominant fuel source, and fat is no longer a significant factor in powering your movement. If you train at or above this point, you will be training aerobically, which you’ll only be able to sustain for very short periods.

testing based on blood lactate

Aside from performing vigorous testing based on blood lactate the best way to determine your aerobic threshold is by using the -180 method set out by endurace expert Dr. Phil Maffetone.

Where to begin? – Establishing an Aerobic Base

Priority number one is to gradually and steadily improve your aerobic development and the percentage of calories burned from fat. This is best done by simply increasing your walking/hiking mileage per week – but if you are short on time, live in the city or don’t have a lot of hiking friendly areas nearby, there is plenty you can do that I’ll discuss below.

Whether you are hiking in the mountains, stuck in the gym on a treadmill or anything in between, you need to bring a certain level of structure and science to your training in order to make the improvements I mentioned earlier, so here are my recommendations for establishing your aerobic base.

  1. Perform the vast majority of your training on your feet, walking, hiking or running in your aerobic zone.

What is the Best Heart Rate Zone to Train in?

In general, I recommend training in the aerobic zone, which is often referred to as Zone 2, but could also be called Zone 3 – already you’re starting to see the issue that we face with zone training, there are countless variations. What’s even more troublesome is that unless you are willing to go and undertake an expensive threshold test held in laboratory conditions under the supervision of a qualified exercise physiologist, then it is quite likely that you are training in a different zone to the one you intended.

How do I Establish my Aerobic Zone?

The most common way to establish your aerobic zone is with the 220 minus your age calculation. However, I do not recommend using this system as it is incredibly arbitrary and is only accurate about 30% of the time. Not only that, but there are countless opinions on which system of training zones to use, many of which contain conflicting information which only creates more confusion.

Rather than working off a percentage of your heart rate to find your aerobic zone, I recommend using your maximum aerobic heart rate as the determining factor in establishing your training intensity.

how to find your heart rate

Many modern watches come with built-in heart rate monitors on the watch itself, but the technology is not quite accurate enough yet to be a trustworthy source with which to base your training on.

How to Establish Your Maximum Aerobic Heart Rate (and therefore your Aerobic Zone)

The simplest and most effective method that I have found is the 180 formula (see below for details). Developed by Dr. Phil Maffetone, one of the world’s leading experts on training for endurance sports. Once you have established your maximum aerobic heart rate, my recommendation is that you start by doing all your cardiovascular training within -10 bpm of that level for at least one month (even up to 3-6 months). Do your best to never exceed it during that time. This is what I referred to above as your aerobic base training.

Using myself as an example, my assumed maximum aerobic heart rate according to the 180 formula is 145 beats per minute (bpm). This means that I try to maintain my heart rate between 135-145 bpm as closely as I can during my aerobic workouts. For me to reach this level I have to run quite fast on the flat or hike up a steep uphill with a pack. 

Sometimes I unintentionally go above 145 bpm when going up a steep hill but I immediately drop the pace to a crawl to drop back into my aerobic zone as quickly as possible.

For you, it may be that walking on flat or slightly hilly terrain puts you in the ideal aerobic zone, this may be true for many who are above 50 years of age and/or are new to training.

However, if you have been training consistently for some time, then you will likely need a more intense method in order for you to stay in your aerobic zone. I’ve listed some options here in my order of relevance to hiking, but it’s worth noting that any activity that keeps you in your aerobic zone will ultimately be beneficial.

In order of relevance here are my recommended aerobic training methods:

  1. Hiking with a backpack
  2. Stair climbing with a backpack
  3. Treadmill walking with a backpack (5 to 15 degree incline)
  4. Trail Running
  5. Elliptical or cross trainer


I’ve listed these as my top 5 as they are most relative to hiking. They are all performed on your feet, they all place gravitational forces on the body, and with the exception of the last option, all demand balance, stability and neuromuscular coordination in general. While other forms of cardio such as cycling, rowing or swimming are useful for building your aerobic base and are excellent options for cross-training and keeping things varied, I strongly recommend you do the vast amount of your aerobic training using any, or a mix of the 5 options listed above. 

Training for Hiking at Home under quarantine, using a heart rate monitor to guide my level of exertion.

How will I know when I’m training outside of my aerobic zone?

The short answer is to buy a heart rate monitor, which I’ll get into soon. But until then, here are some indications that you can use to recognise your aerobic zone without the use of heart rate watch technology:

Nose Breathing – you should be able to breathe in through your nose comfortably when training in your aerobic zone. Towards the higher end of your aerobic zone, close to your aerobic threshold, your breathing will become noisy and laboured, but you will still be capable of inhaling through your nose. You will feel more tightness in your chest and your breathing will become heavier as you begin to step outside of your aerobic zone.

Conversation Pace – if you can hold a conversation with a training buddy during the workout then that is a good indication that you are certainly below your aerobic threshold. ‘Conversation pace’ is a commonly used term among cyclists and runners who often train in groups and chat while they train – keeping them below aerobic threshold. But beware, you might be going a little too easy to get the benefit we are after – that’s where heart rate watches come in handy.

Light to moderate breathing – as mentioned above your breathing can become noisy and laboured in the higher end of your aerobic zone, but for the most part, your breathing should be deep, steady and consistent.

Light sweating – this obviously depends on the weather and your physiology (some of us sweat more than others) but in general, if you’re profusely sweating, it’s safe to say you’ve left your aerobic zone! In the cooler months here in Spain, I often come home from an aerobic run with little to no sweat at all.

Feeling of maintenance – outside of the breath, the best indication I get from my body that I’m in my aerobic zone is the feeling that I could maintain this level of effort for hours. After going uphill for more than 30 seconds or so, I usually begin to feel those telltale signs that signal my inability to maintain the pace, so I glance at my heart rate watch which confirms my suspicions (over 145 bpm) and I slow my pace until I’m back in my aerobic zone (below 145 bpm).

My best advice is to listen to your body when you’re training, monitor your breathing and begin to learn what it feels like to leave your aerobic zone.  Pay attention to the signs your body gives you as you cross the aerobic threshold. By far the best tool that can help you in developing your optimal endurance and better fat-burning is a heart rate monitor that straps around your chest getting the most accurate data from your workouts.

Most people use their heart-rate monitors to see how high they can push their heart rate during a workout, but this is really a fraction of the value that these simple devices offer and not the best use of this incredible training tool.

Are heart rate watches without chest straps still useful?

You may already have a high tech watch that tracks your workouts directly from your radial pulse, but the reality is that radial pulse reading technology is not quite accurate enough (yet, in 2020) to produce data that is sufficiently accurate. So I recommend buying a heart rate monitor with a chest strap to accurately monitor and test your improvement.

Chest strap heart rate monitor

Using a chest strap heart rate monitor on a trail run on Montserrat.

What Heart Rate Monitor Should I buy?

When shopping for heart rate monitors, try not to get carried away with the technology. The watches with full-spec features such as GPS maps, cadence and LCD screens can cost all the way up to $700 or $800- and those tools are great, but it’s really not necessary for just training for hiking. The most important and most usable feature is the chest strap which you can even buy independently (of a watch) and will send accurate heart rate data directly to an app on your phone. Heart rate watches with a chest strap included can be found second hand for little as $20 and are absolutely worth the investment. 

The model that I use is nothing fancy, the Polar F4. It’s over a decade old but is still going strong! It’s no longer in production but you can find them second hand very cheaply – people have no idea of their true value!

A note for those experienced in Aerobic Zone Training using the MAF Method

If you’re a regular runner or cyclist who already performs long aerobic zone work on a regular basis, you may already have a good aerobic base with which to enjoy multiple days trekking at altitude, and so you may continue your aerobic base training as you have done in the past. But if you are an inexperienced hiker, I recommend transitioning to more hiking specific methods of aerobic training as soon as possible. Trail experience takes time, effort and practise, and those who lack this experience quickly become fatigued and frustrated by their comparative inefficiency on the trail compared to other experienced hikers who appear to be “less fit” than themselves.

In any case, it’s possible that your training has been more anaerobic than you thought, so it’s worth implementing the instructions provided in this article for at least 3 months in a hiking specific manner, to experience the benefits we’ve already discussed.

Trail Experience

A lack of cardiovascular fitness, muscular endurance and joint stability can be made up for if you have a good deal of trail experience. Trail experience involves the nuanced movement patterns, subtle technical skills and proprioception that can only come from hundreds if not thousands of hours of hiking on difficult terrain. I know many hikers that are seriously lacking in all three of the aforementioned categories, but they thrive on the trail simply because of their vast experience.

Experienced hikers have the mind-body connection that enables their feet to negotiate difficult terrain without becoming tired. They move efficiently over snow, rocks, slippery and steep surfaces with grace and ease, spending little to no mental or physical energy to surmount these small obstacles.

the importance of trail experience

Experienced hikers and climbers are often much more efficient when negotiating difficult terrain.

What should hikers be working on?

So, would these aforementioned experienced hikers benefit from doing some mobility work, strength training or cardiovascular training? Yes absolutely! But I’ve often had a hard time convincing the experienced hiker to follow any of the above advice until the point where they get injured and can no longer hike.

Inexperienced hikers, on the other hand, will spend vast amounts of mental and physical energy assessing and analysing the difficult sections of the trail as they move over obstacles. Often, the inexperienced hiker finds him/herself unbalanced on technical trails. This may be due to a lack of core strength and balance, two factors which contribute to an unstable mechanical axis that is only accustomed to navigating predictable environments like footpaths and hallways. The end result is that inexperienced hikers spend precious energy correcting mistakes from misplaced feet and awkward negotiation of obstacles, leaning to fatigue of both the mind and the body.

For this reason, all of my full-service programs include agility drills, stability movements and balance challenges to prepare the inexperienced hiker for the small but frequent challenges presented when negotiating uneven terrain.

Of course, it’s also necessary to get out and experience the trail first hand, but having some increased stability, balance and agility makes for both more efficient hiking and drastically reduces the chance of injury.

In Summary

Aerobic fitness is perhaps the element that will most directly impact your enjoyment of a trek.  Increased aerobic fitness will improve your body’s oxygen utilisation, meaning you are breathing more efficiently with each breath, performing more work with less stress and utilising fat as opposed to glucose as a fuel source. It is clear that the anaerobic system serves little use to hikers and trekkers and so your focus should be on the former. 

It’s important that this aerobic training is performed in a precise manner, firstly by establishing your maximum aerobic heart rate via the instructions below and secondly by monitoring your heart rate with a chest strap type HR monitor. Keep your training specific to hiking, measurable in terms of intensity and watch your hiking improve surely and gradually over time. It is also clear that many hikers, regardless of their experience are not developing the core strength, balance or proprioception that would greatly improve their performance and the overall enjoyment of their time spent in the mountains.

Appendix – How to establish your maximum aerobic heart rate with the 180 formula.

The following are guidelines directly from the website of Dr. Phil Maffetone who developed the 180 formula and who is one of the world’s leading experts on building endurance. Follow these steps to establish your maximum aerobic heart rate and find your aerobic training zone.

The 180 Formula

To find your maximum aerobic training heart rate, there are two important steps.

  1. Subtract your age from 180.
  2. Modify this number by selecting among the following categories the one that best matches your fitness and health profile:a)  If you have or are recovering from a major illness (heart disease, any operation or hospital stay, etc.) or are on any regular medication, subtract an additional 10.b)  If you are injured, have regressed in training or competition, get more than two colds or bouts of flu per year, have allergies or asthma, or if you have been inconsistent or are just getting back into training, subtract an additional 5.c)  If you have been training consistently (at least four times weekly) for up to two years without any of the problems in (a) and (b), keep the number (180–age) the same.d)  If you have been training for more than two years without any of the problems in (a) and (b), and have made progress in competition without injury, add 5.

 

For example, if you are 30 years old and fit into category (b), you get the following: 180–30=150. Then 150–5=145 beats per minute (bpm).

In this example, 145 must be the highest heart rate for all training. This allows you to most efficiently build an aerobic base. Training above this heart rate rapidly incorporates anaerobic function, exemplified by a shift to burning more sugar and less fat for fuel.

Initially, training at this relatively low rate may be difficult for some athletes. “I just can’t train that slowly!” is a common comment. But after a short time, you will feel better and your pace will quicken at that same heart rate. You will not be stuck training at that relatively slow pace for too long. Still, for many athletes, it is difficult to change bad habits.

If it is difficult to decide which of two groups best fits you, choose the group or outcome that results in the lower heart rate. In athletes who are taking medication that may affect their heart rate, wear a pacemaker, or have special circumstances not discussed here, further consultation with a healthcare practitioner or specialist may be necessary, particularly one familiar with the 180 Formula.

Exemptions:

  • The 180 Formula may need to be further individualized for people over the age of 65. For some of these athletes, up to 10 beats may have to be added for those in category (d) in the 180 Formula and depending on individual levels of fitness and health. This does not mean 10 should automatically be added, but that an honest self-assessment is important.
  • For athletes 16 years of age and under, the formula is not applicable; rather, a heart rate of 165 may be best.

Once a maximum aerobic heart rate is found, a training range from this heart rate to 10 beats below could be used. For example, if an athlete’s maximum aerobic heart rate is determined to be 155, that person’s aerobic training zone would be 145 to 155 bpm. However, the more training closer to the maximum 155, the quicker an optimal aerobic base will be developed

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