Aerobic base training, also known as base building or base mileage, is a fundamental phase of training in running. It focuses on developing and strengthening the aerobic energy system, which primarily utilizes oxygen to generate energy for sustained exercise. During aerobic base training, the emphasis is placed on building endurance, improving cardiovascular fitness, and increasing the body’s capacity to efficiently use oxygen.
The primary purpose of aerobic base training is to establish a solid foundation of endurance and aerobic fitness. It strengthens the heart, improves lung capacity, enhances oxygen delivery to working muscles, and increases the body’s ability to utilize fat as a fuel source.
Aerobic base training sets the stage for subsequent phases of training, such as speed work and race-specific workouts. It lays the groundwork for improved performance by allowing the body to handle higher training loads, resist fatigue, and sustain a steady pace over longer distances.
What are the benefits of base training?
1. Increases Aerobic Efficiency
Aerobic means “with oxygen” and in base training, one of the primary goals is to improve your ability to take in and utilize oxygen. The more energy you can produce from your aerobic energy systems, the easier you can race. In the base phase, both your capacity to take in and utilize oxygen (called VO2max) and your efficiency at utilizing it (called Running Economy) are improved.
Improving your aerobic system is done in two stages. When you first begin running (or return to running), your body responds by increasing the number of red blood cells in your blood. You’ve probably heard that the red blood cells are what carry the oxygen through the body so having more red blood cells means that you can carry more oxygen – a very helpful adaptation. Another early adaptation is that the left ventricle of your heart (the one that pumps the blood out to your body) increases in volume. This allows it to eject more blood with each beat. More blood. More oxygen. Better performance. (Runners see this change as a lowering of their resting heart rate. Each beat sends more blood to the body so fewer beats are required than before to circulate the same amount of blood through the body.) There are a few more quick changes the body makes during base training but those are two of the most important early stage changes.
After you’ve trained for a while, there are some more foundational and structural changes that occur in your body to again, help improve your aerobic system. First, your body builds more capillaries around your muscle cells. Capillaries are the smallest arteries in our bodies and having more of them means you can get more blood to the working muscles.
Second, within the muscle cells, you build more mitochondria. Mitochondria are the organelles within the muscle cells where the energy is actually created from our oxygen-dependent (aka aerobic) energy pathways.
Third, within the mitochondria, the body adds more aerobic enzymes. Enzymes are required to make the energy pathways work so having more of them means the pathways can work better.
ll of these changes, the early stage and the later stage changes, result in your ability to better utilize oxygen. Your VO2max will increase (particularly in new runners), your running economy will improve and your ability to delay the build-up of lactic acid (aka lactate threshold) will be pushed to a faster pace. All of these changes make you a better runner.
2. Lowers The Risk Of Injury
Running is a high-impact sport, and without the proper preparation, the body runs the risk of not being able to handle that impact. Because base training running is done at an easy pace, the body can recover from each run instead of experiencing fatigue and running on shot legs. This will weaken you more and open up the opportunity to experience overuse injuries such as shin splints, runner’s knee, and stress fractures or over-training. So the base training improves injury resistance by challenging the musculoskeletal system to better handle the stresses of running.
Over time, the legs grow stronger so you can better handle these long runs and as a result, can better handle any fatigue challenge in future training. (If you’ve done speed training, then you know that feeling when the legs fatigue late in a workout. Stronger legs from the base phase delay that fatigue so you get more from your speed workouts.)
3. Increases Glycogen Stores and Fat Burning Capacity
The bulk of the energy for distance running comes from our two oxygen-dependent (aka aerobic) energy systems. One system breaks down fat for energy (this is our most efficient energy system for distance running) and the other breaks down carbohydrate for energy. Since fat is our most efficient (i.e., we get the most energy with the least amount of negative consequences), a key adaptation for runners during base training is that they get better at burning fat for fuel. And this is a highly desirable adaptation.
Better fat burning is typically achieved by consistent training (remember the aerobic adaptations mentioned above?) as well as during the longer runs, particularly runs lasting over 90 minutes. It’s at this point in the run, after around 90 minutes, that the carbohydrate stores are running low so the body begins to burn even more fat for energy. Therefore, a big part of base training is getting in runs that purposely burn through your stored carbohydrates (called glycogen) and force more fat burning.
Another benefit of depleting the muscle glycogen stores is that it stimulates your body to increase the stores for the future. The body essentially says, “Okay, if you are going to keep doing this – burning through my carbohydrate stores, I’ll simply increase the fuel tank!” The result is a larger store of glycogen and again, this is critical for faster training and racing.
You can probably see how a bigger fuel tank would be very beneficial for longer distance runners, like half and full marathoners, as they would have more fuel on board and would delay or avoid the dreaded “wall” in their races.
4. Improvements to Your Mental Toughness and the state of Tireless
A good block of base training improves your body physically, but it also helps your mind. You’ll see, you won’t always be wishing you were at your last mile but won’t even notice you’re running.
You mind that will be so used to running that it’ll become more resistant to fatigue. You may remember this from when you first started to run. Those first runs were accompanied by a strong urge to stop. The mind sent loads of fatigue feelings because it wasn’t used to running.
But, after a month or so, you started to feel pretty good running. You still got tired, but your brain was no longer screaming at you to stop. And over time, you got to where you could endure longer and longer runs. And, you sort of liked the mental challenge of pushing yourself.
Tips to remember
- Always stay at conversation pace
- Forget about pace
- Run with a friend or in a group
- Be Patient
How do you build an aerobic base?
Building an aerobic base requires consistency and time. In order to do so, runners will need to plan a few weeks or months prior to the start of their training plans, during which they can focus on the basics. Here are some key aspects of aerobic base building.
- Intensity is low to moderate
- Speed remains consistent
- Distance builds very gradually over time
- Strength training is supplemental
- Incorporate longer base training prior to harder goals
- Beginner runners begin very slowly and gradually
- Never push to the point of pain
Shall I do other workouts during base building?
Yes you can. You can mix other cross or strength training as part of your non-running days. Because your base training is at a low intensity, you can perform other activities to supplement you. But keep them at level that you can recover easily than being sore for multiple days. If you are a beginner, I would suggest starting with body weight exercises and then slowly adding weight based exercises.
You also add short intervals of tempo and speed workouts to play with speed and introduce your body to small challenges. But remember, the goal of base training is to keep your training at low intensity. So that will be your majority. Once your base training goes well you can increase intensity and perform race specific workouts during the other phases of training.
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