Distance Training: Why Long Runs Are Essential
Summary: This article explains why low-intensity distance training remains a cornerstone in endurance sports, even though high-intensity intervals often yield quick improvements. The main question is why the elite dedicate so much of their training to easy sessions when intervals seem so effective in studies. By reviewing research on training volume, performance factors, and work economy, the picture becomes clearer: distance training contributes in ways that are harder to capture in short studies but are crucial over time. The conclusion is that you need both volume and intensity — and that long sessions often allow you to endure, repeat, and develop hard training.
Introduction
We always strive to follow and highlight new research to provide you with the tools to perform better in training and competition. We have often highlighted which form of training is most effective, and questions about high-intensity interval training keep coming up — 4×4, 40/20, or 4×8, which is most effective, and how often should you do them?
There has also been much research on both amateurs and elite athletes regarding high-intensity interval training. Improvements are often quick, making it easy to attract participants to the studies — and we like that! But we've also talked and written extensively about the importance of polarized training with high continuity where low-intensity distance training constitutes the majority. Unfortunately, there's not as much research on low-intensity training — it takes time, costs more, and it's harder to find study participants who stick it out. But research exists, and that's what we're diving into now.
Background: Why Distance is "Necessary"
A few years ago, three of Sweden's leading authorities on endurance training released the article "The Necessary Distance Training". These were Mikael Mattsson, Filip Larsen, and Professor HC Holmberg. In the article, they review the research on distance training and attempt to explain why it is so vital for success at a high level in endurance sports. We highly recommend reading the entire article!
Below is a review of the key points.
First, so we know what we're talking about: Distance training means low-intensity training, either in the form of standalone distance sessions or as the time spent between high-intensity intervals. Low-intensity training is usually done at about 60–75 percent of maximum heart rate with a perceived exertion level (Rating of Perceived Exertion, RPE) of 11–13 on the Borg scale — conversational pace for most people. The duration can vary from about 1 hour up to 7–8 hours.
Distance training makes up the majority of the total training load for virtually all endurance athletes. If research shows that intervals are often very effective, why do elite athletes train 700–1,200 hours per year where 85–95 percent is low-intensity training?
One explanation could be tradition: almost all endurance athletes spend around 90 percent of training time in the low-intensity range — regardless of whether competition time is 3–4 minutes or 4–5 hours. You may have read about athletes who build their training around more intervals, but since the time over 90 percent of maximum heart rate often only constitutes 5–8 percent of training volume, total high-intensity training still seldom exceeds about 10 percent. Thus, it still falls within the framework of polarized training with a significant majority of low-intensity work.
Why Does the Elite Train So Low-Intense?
If the goal is to develop and perform, training should positively impact performance factors — otherwise, it's just a waste of time. Although arguments for low-intensity training are hard to demonstrate in direct interval‑vs‑distance tests, there are clear indications that training volume correlates with performance in elite athletes.
Completing a marathon in 3 hours requires, on average, 70–80 km of running per week. The elite, who run under 2.5 hours, are around 150 km per week. The figure below shows a clear correlation.
We understand that achieving high performance requires considerable volume, and that low-intensity training constitutes the majority of the intensity distribution. Many athletes notice they perform better in high-intensity workouts when they have a strong aerobic foundation.
A fundamental training principle states that what is quickly gained is also quickly lost (cheerful, right?). To maintain stable performance, slow, continuous progress over time is essential — that's why many incorporate endurance training into their daily routine. High-intensity training offers quick gains, but they are quickly lost if you stop. This is one reason why high-intensity, anaerobic intervals are often scheduled close to competition season or during peak conditioning periods.
Additionally, focusing solely on high-intensity training would make the training load unmanageable. Recovery and low-intensity sessions are required between intense efforts.
What governs your physical ability?
The physiological ability to perform for an endurance athlete is primarily determined by three factors, besides mental and nutritional aspects:
– Maximum oxygen uptake (VO2max)
– Utilization (i.e., what percentage of VO2max you can maintain over an extended period)
– Economy of movement (how energy-efficient your movement is)
Among these, VO2max has garnered notably more attention in literature and research. High-intensity training is far superior in enhancing oxygen uptake. Endurance training has a significantly poorer effect on this, and for individuals who are already well-trained, purely low-intensity training can sometimes even decrease VO2max.
Low-intensity training, however, is more effective at developing the economy of movement and is roughly comparable to high-intensity training when it comes to enhancing utilization. Research on low-intensity training takes a long time to show results, making it less “appealing” for quick studies.
An extreme study putting things in perspective
An extreme study was conducted in 2014: nine athletes engaged in cross-country skiing for 6 hours a day for 42 consecutive days, at about 60 percent of maximum heart rate. (What a dream to be part of this experiment.) Despite the high volume, no improvements in VO2max or mitochondrial capacity were observed. However, capillary density in the arms significantly increased, and performance capacity improved by 20 percent.
Many experience the same effect at training camps. You increase the volume a lot, for example a cycling camp in Mallorca, and even if VO2 measurements don't show dramatic changes, the body feels tougher and performs better further into the camp.
If 42 days of distance training didn't improve VO2max but still increased performance capacity, what improved then? Part of the puzzle is spelled work economy.
Work Economy
Work economy is how energy-efficient you are in your sport, meaning how much energy you consume at a certain intensity. Work economy is influenced by several factors:
– Anthropometry: height, weight, body shape, tendon attachments, and so on. In practice, weight is typically the only thing you can affect. Some individuals are better suited for certain sports and distances.
– Technique: how well you perform the movement. The significance of technique varies between sports—cycling technique may not differ much between athlete and elite, whereas running can differ 20–30 percent in work economy and swimming can differ even more because technique is so crucial. Technique can be improved with training.
– Biochemical efficiency (work efficiency): what portion of the energy the body creates becomes mechanical work. During cycling, the physiological efficiency is about 20 percent, meaning only about 20 percent of the energy is converted into mechanical work while about 80 percent is lost as heat.
In simple terms, more well-trained individuals who have been active for several years often have higher work efficiency. It seems difficult to make large improvements in this area, but even small improvements can significantly impact performance.
Together, these factors influence the work economy. There is still debate and research on how much work economy can be altered, but the best studies follow individuals over a long time—often several years.
In one study, well-trained cyclists were followed over five years, where VO2max remained constant but work economy improved by 14 percent. The woman world record holder in the marathon recorded a similar improvement of about 15 percent over twelve years. VO2max didn't increase; what changed was the mileage per week from 40–50 kilometers up to over 200 kilometers. This suggests that work economy plays an important role in performance and that low-intensity training volume is a way to achieve these improvements.
Another example of the importance of distance training comes from sprint skiing, where the competition time is often only 3–5 minutes. In a Norwegian study, eight national team skiers were compared with eight skiers just outside the national team. There was no difference in the amount of high-intensity training, but the national skiers completed more low-intensity hours: on average 340 hours versus 254 hours over a six-month period.
Summary
As always in science, there are rarely simple, straightforward answers. To develop and perform, you need all parts of the intensity scale: high-intensity intervals, threshold training, and low-intensity distance sessions. In a study from 2014, three groups trained exclusively at one of these intensities over nine weeks. There was also a fourth group that trained all three variants, i.e., polarized training—and they achieved the best effect on most variables.
What is the benefit of distance training then? The answer is that it leads to physiological improvements, particularly at the local muscular level, to improved work economy (either metabolic or technique-related improvements), and to the ability to perform and withstand more high-intensity training.
You need both high volume and high intensity to become really great—a truth that is sometimes forgotten. So, heading into winter: don't forget the long sessions when you're pushing high watts on the exercise bike or running 4 minutes on the treadmill!
Read more about: