Energy Systems in Firefighting

It is a widely accepted fact that firefighters should be in excellent shape. What that is exactly is a highly debated topic. In one camp you have those that say firefighting is all about endurance and training should consist of mainly long-duration exercise. On the other side you have people that believe the only way to train for firefighting is by doing high-intensity intervals because this mimics the demands of the job more. Both sides make very good arguments to support their claim and in the next few paragraphs I hope to bring some clarity to what is actually needed to prepare most effectively.
First off let’s look at what the energy systems actually are and what they do…
It is important to note that no energy system acts independently or turns on or off. They up-regulate and down-regulate based on the activity intensity and duration meaning that all systems are always “on” but contributing to varying degrees. Our body creates energy both with the use of oxygen and without – aerobic and anaerobic. The anaerobic system is also broken down into two subcategories- alactic and lactic.
Here is a breakdown of each system:

Anaerobic Alactic
Duration: power: 0-2 sec, capacity: 10-12 sec
Intensity: High
Work to rest ratio: 1:12-1:20
Fuel source: ATP generated from readily available phosphate molecules attached to creatine molecules.

Anaerobic Lactic
Duration: power: 20-60 sec, capacity: 60-90 sec
Intensity: High
Work to rest ratio: 1:3 to 1:5
Fuel source: glycogen

Aerobic
Duration: power: 2-6 min, capacity: hours
Intensity: low to high
Work to rest ratio: 2:1 to 1:3
Fuel source: glycogen and fat

As I said, no energy system operates on its own and they all influence each other. It is irrefutable that firefighters require a high level of endurance. The most effective way to increase your endurance is to improve your aerobic system. Training your aerobic system improves both oxygen delivery and oxygen utilization. Improving the delivery is accomplished by increasing your stroke volume and the strength of the heart itself and improving the utilization is accomplished mainly by increasing the number of mitochondria in the muscle cells. Most people think only about the cardiovascular system when discussing conditioning. Without addressing both sides we are leaving alot on the table.

Why is the aerobic system important for firefighting? Here are a few things that the aerobic system would influence directly:
General air management – how long a cylinder will last
Recovery between cylinders
Recovery between events
Recovery between shifts
Ability to concentrate while under stress
Longer duration searches
Extensive Overhaul
Ability to lower heart rate and conserve air if trapped
This is not an exhaustive list but there are some pretty big points here.
The anaerobic system (lactic and alactic) will typically be the dominate system during activities such as:
Pulling hose before entry
Breaching walls
Forcible entry
Primary search
Initial stages of overhaul
The thing is that you never complete only one of these actions and then receive adequate recovery before doing it again. You absolutely need a well developed aerobic system to be able to complete task after task. What I have often heard is that conditioning should consist of high intensity intervals because they are “purely anaerobic”. Tabata training often gets referenced as anaerobic conditioning. Looking at the capacity and work to rest intervals for each system I think it’s clear that many of the formats we mistakenly use to train the anaerobic system are highly aerobic in nature. The first 20 second interval would be highly anaerobic but with only a 10 second rest we start moving towards a more aerobic based activity. In other words the aerobic system continues to up-regulate and provide a higher percentage of energy as the intervals progress and the anaerobic system is taken to and past its limits. This is true for many of the tasks I have just included in anaerobic tasks. They certainly are anaerobic in nature, if you did that one task but as soon as you have to complete it again, move to another task or it takes longer than 90 seconds your aerobic system will contribute more than your anaerobic systems.
Now you might be thinking that all we need to do is train using tabata intervals because we would both train at a high intensity and develop the aerobic system. Sounds pretty specific to firefighting. If you did this and only this you’re still not developing the aerobic system to its full capacity. As stated above there are two main ways to develop the aerobic system: oxygen delivery and utilization. Next blog post I will go into detail about the parameters and methods for developing the aerobic system but at this point what you need to know is the main point about how to improve your oxygen delivery.
Low intensity, steady state cardio and low intensity interval training, such as tempo intervals.
It gets overlooked all the time. It’s the ugly duckling of training. It’s not very well liked because it doesn’t hurt as much and no pain=no gain, or so we are told.
Increasing your stroke volume means your heart can stretch more and fill with more blood, resulting in more blood pumped with each beat. This is known as cardiac eccentric hypertrophy. The thing is though, eccentric hypertrophy occurs at heart rates below 150. Once you pass this point the heart beats too fast to stretch and fill to its full capacity. If you are only doing high intensity intervals then you may not see these benefits. It is true that high intensity interval training is very effective at improving the aerobic system but if you are so deconditioned that your heart rate is elevated at rest these two methods may be the best place to start.
This is where block training and periodization is highly effective. Spending a full two month block training at lower heart rates will improve your oxygen delivery by increasing stroke volume. We can then utilize this adaptation when working at higher intensities in a later training block.
In my next post I will dive into specific training methods to improve oxygen delivery. Following that we will look at various methods to improve oxygen utilization. Finally, I will get into how to properly develop the anaerobic system. With any sport or activity we should be looking at what the demands are and plan our training to improve our physical abilities to meet those demands. However, we have to make sure we take the appropriate steps, meaning our training should flow from general to specific. If we program for sport/activity specific movements or systems too early we will often not see the full benefits as much as we could have if we progressed properly.

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