Anyone who runs knows it – and those who don’t should: base training. It’s the type of training that makes the biggest long-term difference: in your heart, your muscles, and the efficiency of every single step. What exactly happens in the body during base training, how intense it should be, and how often you should do it – here’s an overview.
Base training forms the foundation of athletic performance in endurance sports. The two francs for the cliché jar may be justified here—but they’re well spent. After all, it is from this aerobic base work that speed later develops.
Misunderstanding: training period or training method?
First, it’s worth clearing up a common misunderstanding often heard in everyday language. Base training is frequently equated with a training period, such as winter training. In reality, however, base training is less a training phase and more a type of training. Base training refers to the part of endurance training that is performed at low to moderate intensity and mostly aerobically. In other words, the aerobic base is trained throughout the entire year, although it often receives more focus during the winter training period.
What happens in the body during base training?
Long base training sessions at low intensity trigger adaptations that improve performance in the long term—especially in the muscles and the cardiovascular system.
- In the muscles, work is distributed more efficiently and mitochondrial capacity increases. This allows you to perform more economically at moderate intensity and make better use of fat metabolism.
- The cardiovascular system also benefits from base training. The heart works more efficiently and can pump more blood with each beat. As a result, heart rate decreases at the same workload. At the same time, the supply network within the muscles becomes denser because more fine blood vessels develop. This allows oxygen to reach the muscles more efficiently and waste products to be removed more effectively, which in turn improves recovery.
- In addition, base training primarily trains Type I muscle fibers (red, slow-twitch fibers). Over time, these fibers can handle a large share of the workload even at higher speeds. This saves energy and helps maintain performance for longer.
Difference between BASE1 and BASE2
In training theory, a distinction is often made between basic endurance 1 (BASE1) and basic endurance 2 (BASE2). BASE2 is not defined completely consistently everywhere, but it typically lies in the aerobic–anaerobic transition zone (slightly below threshold pace). At this intensity, lactate is produced noticeably, but the body can still break it down at the same time. For well-trained runners, this intensity is close to marathon pace; for less-trained runners, it is often closer to half-marathon pace. The goal of BASE2 training is to improve speed endurance and shift the anaerobic threshold. While BASE1 builds the economical foundation, BASE2 trains the body to sustain higher intensities over longer periods.
Although BASE2 is classified as base training in the model, it should not make up the bulk of weekly training.
How and how often should you do base training?
As mentioned earlier, the intensity of base training should not be too high. You can monitor this either with a heart rate monitor (around 60–75% of maximum heart rate) or estimate it using the simple talk test—meaning you should be able to speak in full sentences while running without much difficulty. Training in the base zone should make up the largest share of your overall training volume, although this also depends on your personal training load. As a rule of thumb, about 70% of training sessions can be performed in the base endurance zone.
Interestingly, many of the physiological adaptations described above occur regardless of the endurance sport you choose. This means you can confidently include alternative endurance sports in your training. However, if your goal is to improve running economy, you should still spend a good portion of your training time running.
Practical training tips
- The vast majority of training should be performed in the BASE1 zone. Depending on your training volume, you can include one BASE2 session every 1–2 weeks.
- BASE2 sessions can, for example, be structured as long intervals. Examples include 3 × 10 minutes or 2 × 20 minutes at BASE2 intensity.