Take a look at any selection documentary or ask any person who has been through a selection to describe it. One word comes to mind – HARD. One of the reasons that selection is so grueling is due to the fact that candidates must perform work over and over for long durations. Although this work is hard, candidates are able to repeat efforts because the work being completed is, for the most part, sub-maximal and aerobic in nature. But, as the title says and we’ve established – this work is far from easy.

Aerobic training constitutes working at a rate that has energy demands that can be met without pushing into the anaerobic energy system. The aerobic energy system is the most efficient one, the only drawback is that it takes a while to get going and can’t put as much energy in a short amount of time. For example: competing in a triathlon is grueling and done at a high intensity, but is still aerobic in nature.

Below we explain our different methods of training and why aerobic work isn’t always easy. But first…

Why Hard Work Isn’t Always Smart Work

The issue we commonly find among the combat athletes we train is that everybody loves pushing themselves and proving themselves. This means that often times athletes come flying out of the gate and put out a great time on the first interval or first 5 minutes of a run only be dragging their heels at the end of the workout. To properly progress aerobic training an athlete must put out consistent efforts that are difficult, but not impossible. So yeah, aerobic training can be tough – stupid tough – but if you’re not performing at a sustainable pace then you’re doing it wrong.

Zone 1 Work – The “Easy” Side

Zone 1 primarily works the oxidative aerobic system. This training increases mitochondrial density, capillary density and brings about many more positive adaptations. In fact, Esteve-Lanao et. al in 2005 studied a group of 8 national and regional level endurance runners.[1] The picture below demonstrates the % of training that they completed in either Zone 1, Zone 2 or Zone 3.

The second graph, pictured below is the heart rates that these runners experience during a 10km race. The dotted lines running horizontally across the graphs show the separation between Zone 1, Zone 2 and Zone 3.

As you may well notice, although athletes spend the majority of time training in Zone 1, almost their entire race is performed in Zone 3. In fact, Esteve-Lanao et al. found that those runners who spent the most time performing low level work during training had the best results in competition. This is not to say that athletes do not have to train at higher intensities, they do, just not as often as you think. Think of Zone 1 work as the “eat your broccoli” of aerobic work. You don’t always want to, but you’ll always be better for doing it.

Maximal Aerobic Power (MAP)

Power, by definition, is work/time. As shown in our article, The Truth Behind Anaerobic Training, there are four means by which to determine whether training is Aerobic or Anaerobic: exercise modality, exercise duration, exercise intensity and the individual. The two we’re going to focus on today when talking about aerobic power is the intensity and the duration. For duration, typically we prescribe intervals of 1:1 work:rest ratio. This allows the body to recover so that the athlete can perform consistent, high intensity bouts. This leaves us with intensity.

Image Courtesy: commons.wikimedia.org

Intensity prescribed for MAP work is always done with a % prescription of Aerobic Effort. This is something that is difficult to comprehend and often times takes many trial and error sessions to work out what YOUR 70%, 80%, 90% and 100% is for each modality, on any given day, under varying circumstances. Oftentimes athletes will attempt to associate a percentage aerobic effort with a pace on a rowing erg, or km time when running. The issue with this is that a percentage of aerobic effort is qualitative – based on feeling. This may change day to day based on your diet, sleep, recovery, emotional stress, etc… So deciding that 80% effort on a rower is a 1:45/500m pace may work well on Monday, but Thursday after limited sleep, indigestion and worrying about issues at work you may gas out at 1:50/500m.

The biggest thing to realize with MAP training, or any aerobic training is this: IT IS SUSTAINABLE.  If a MAP session prescribes:

“Run 3:00 @ 80% Aerobic Effort
Walk 3:00
X 5”

Then the athlete should be able to hit the exact same distances for each round of 3 minutes. The same goes is the athlete is given a distance prescription.  If the athlete is told:

“Run 1km @ 85% Aerobic Effort
Walk Equal Time
X 4”

Then each 1km interval should take the exact same amount of time. This takes practice. What we don’t want to see is an athlete blowing the first interval out of the water, then adding 10-15% of time to their next interval because there is a massive build up of lactate in their muscles. Think back to what power is: work/time.

What is Aerobic Capacity

The term Aerobic Capacity is thrown around often because it sounds fancy and useful. Aerobic Capacity only means the maximum amount of oxygen that can be consumed and used. Our bodies think that when we work hard, we need more oxygen. This is true. However, at a certain point our bodies cannot use any more oxygen because the work is being completed by our anaerobic systems. This threshold is known as your VO2 max, which is measured in ml/kg/min. (i.e. how many ml of oxygen can your body use per kilogram of bodyweight, per minute.) The reason why this is important to mention is that as you train your aerobic engine over time, your V02 max will increase, thus, you will be able to complete more work at a given percentage of your Aerobic Effort.  How long an 80% 1km interval takes today vs. a year from now will differ.

We also use this term to describe the work done between aerobic power and Z1 work. This could be 60min and upwards of work done at approximately 70% aerobic effort. It is a consistent work effort in terms of pacing, similar to Z1 but at a significantly higher effort. One way to improve a combat athlete’s ability to do moderately hard work over time is with increasingly long swim/run/ruck or swim/run/bike workouts. This might look like:

@ 70% effort:
15min Swim
20min Run
20min Ruck

And, over the course of several months, we could bring the athlete to the following, for example:

@ 70% effort:
20min Swim
2 Hour Run
2 Hour Ruck

The Middle Distance Myth

In track and field anything up to a 400m run is considered a sprint. However, a quick peak at what the energy systems are doing will show you that the aerobic systems are heavily involved. This graph was taken from Baker et al.’s 2010[2] paper looking at the contribution of energy systems during a maximal exercise test. As you can see as the duration of the test increases the more energy is provided by the Aerobic energy systems (written below as mitochondrial respiration). At 50 seconds, during a MAXIMAL test there are equal energy contributions from both the anaerobic and aerobic energy systems. This shows the extent to which aerobic training can be, and should be hard.


Often times the argument we hear when explaining the importance of aerobic work for the combat athlete is along the lines of: “typical infantry maneuvers and direct action up-and-down assaults are anaerobic in nature”. However, if someone has a large aerobic engine, they will experience 2 things:

  1. They will be able to handle more intense work before their bodies tap into their anaerobic system, thus allowing them to last longer.
  2. When they do ultimately tap deeper into their anaerobic engine (which is not long lasting), they will replenish that system quicker, because they have a well developed aerobic engine. Thus, they are able to quickly get back into the fight.

The video below is a good example of a distance that is traditionally considered an anaerobic glycolytic event. What I want you to notice is the look on the runner’s face when he finishes the event. Almost immediately he is brushing his hair back, breathing through his nose, talking casually. For anyone that has hit a traditional CrossFit workout such as ‘FRAN’ (which IS anaerobic work for even a somewhat trained individual), you’ll know that this is not what you look like at the end of it. Whether he used his aerobic engine almost entirely, OR he was able to recover extremely quickly from predominantly anaerobic work, the fact of the matter is that it was a very well developed aerobic engine that allows him to perform at a very high intensity and quickly recover. This is a massive asset for any combat athlete on the battlefield.

Things to remember:

  • Energy systems training is aerobic when it remains consistent with an equal work to rest ratio
  • Aerobic Training can still be difficult
  • Aerobic Power is determined by work / time and both have to be consistent
  • Z1 work is crucial to aerobic performance

Featured Image: commons.wikimedia.org

[1] Johnathon Esteve-Lanao, Alejandrio F. San Juan, Conrad P. Earnest, Carl Foster, Alejandro Lusia. (2005) How do Endurance Runners Really Train? Relationship with Competition Performance. Medicine and Science in Sport and Exercise.  496-504.

[2] Julien S. Baker, Marie Clare McCormick, Robert A. Robergs. (2010) Interaction among Skeletal Muscle Metabolic Energy Systems During Intense Exercise.  Journal of Nutrition and Metabolism. 1-13.