Running is demanding. Some Physiological functions such as the cardiovascular system, which is most important adapt very quickly to new loads by running and we experience an improvement in breathing and heart rate after 4-5 weeks of training among other things. But other physiological parts like muscles, tendons and tissues need different and longer adaptation times. Improving endurance workouts with focus on running is the most important factor in marathon training and long-distance running but we also have to respect and find a balance between the differences in this physiological development.
📝Prepare the Endurance Training
So, we want to make a plan for the training that follows these rules and find the balance, particularly between training frequency, training volume, training intensity, variation and recovery in aerobic endurance. A plan will be a program to follow. So you can manage your progress and if you start from your current level, you will be on the right path.
👉 Read more about how a structured marathon training plan can help organize your endurance development.
🫀Improve Aerobic Endurance
If we do that well and keep this balance, we will experience small miracles, because no matter when you start running and no matter which physical state you’re starting from, you will experience progress, the only limit is the “genetic wall”.
In general, when we want to improve something about ourselves, it’s also best not to do it too fast at the beginning with the risk to quit. Your aerobic endurance improves when the pace and length of the distance adapt to your basic training level.
It is necessary to adjust the training distances to the marathon race you want to run. If you want to participate in a marathon race, it is not enough to train at distances up to 10 kilometers. We also have to build up the distance length gradually, so the body slowly adapts to the long runs.
👉 Read more about the key principles behind endurance training and aerobic development.
📊Calculate the Training Intensity in Endurance Training
The intensity of the long runs accomplishes at an easy/moderate pace. This pace also corresponds to the concept of LSD “Long Slow Distance”, there as the words say, performs with lower intensity. The speed should be about 25 – 40 seconds slower per.
Kilometer than the marathon pace or 45 to 75 seconds slower per. Kilometer than the half-marathon pace. A better way to calculate the speed or intensity level is by using the working heart rate.
The heart rate on the long runs should be between 60 to 80 percent of the heart rate reserve. Heart rate reserve (HRR) is a term used to describe the difference between a person’s measured or predicted maximum heart rate and resting heart rate.
If you run long runs with the above intensity, your body will be loaded with the desired training stimulus, and thus adapt to the training. There will be physiological changes in the heart, blood circulation and muscles, as described.
👉 Read more about how heart rate zones can help you manage endurance training intensity effectively.
⚡Economize with the Glycogen Gives More Endurance
To have the energy for a large amount of training it’ll be a good idea with a nutritious diet in the everyday life and it doesn’t have to be a bigger challenge for anyone when we create momentum with the new healthy habits. The muscles glycogen depots must be filled up again after training.
You can influence the glycogen depots to become larger through training. A near depletion of the existing glycogen depots in the muscles entails a stimulus to fill them again. There is indeed a tendency to even bigger glycogen depots after depletion if you consume the carbohydrates in the correct quantity and with proper timing after training.
A good way to complete the long runs is, by starting at a slow pace about 60 % of the heart rate reserve, and then letting the speed increase slowly during the training session so the last third of the run, has an intensity of about 80 % of the heart rate reserve.
👉 Read more about how improved running economy can help you conserve energy during long-distance running.
🏃Endurance training example
For example, if you intend to set your marathon pace at 4:15 min/km, you can choose to run 5.15 min/km as a start pace on the long runs and finish by 4:45 min/km in the last third of the run. The slow start of the run means, that you save on the glycogen in the muscles and thereby, you can run for a longer time.
The Effect of the intensive finish will be, that the glycogen depots in the muscles almost deplete, because you use more glycogen, the faster you run.
The runs will hereby – if carried out properly – stimulate the glycogen depots in the muscles to become bigger. Training with an intensity of about 60 to 80 % of heart rate reserve (HRR) contributes also to improving the body’s capacity to use fat as an energy source.
In that way, you will economize with glycogen, which means that you will be able to keep a higher pace for a longer period.
👉 Read more about how endurance workouts fit into a complete marathon training program.
📅Endurance Training Frequency
This will depend on the recovery requirement. The LSD and easy run does not require a recovery time as more intensive training, where the heart rate is significantly higher. However, after the long runs, the recovery need may be greater than you immediately feel, since muscle glycogen depots deplete or are very restricted.
The body’s other tissues are also loaded by the training. It takes 1-3 days before glycogen stores and your body is fully recovered. It may therefore be a good idea to put in a “low” week in the training schedule like every third week.
In this way, you will also be mentally fresh and avoid over-training. Although you only have 1 – 2 long runs weekly, it does not mean that it is the only two times you train endurance. Endurance training is THE central training type for the marathon.
When you train for a marathon, the many other training days you complete during the week should therefore have an intensity that corresponds to endurance training. The other day’s endurance training takes place at distances, which are between a quarter and a half of the long run.
👉 Read more about how regular long runs contribute to long-term endurance development.
💬FAQ Section
❓What is endurance training in running?
Endurance training focuses on improving your body’s ability to sustain effort over longer periods, helping you run farther and more efficiently.
❓How often should I do endurance workouts?
Most marathon runners include two to five endurance-focused sessions per week, depending on experience level and training goals.
❓What intensity is best for endurance training?
Most endurance training should be performed at an easy to moderate intensity where you can comfortably maintain a conversation.
❓Why are long runs important for endurance?
Long runs help strengthen the cardiovascular system, improve fuel utilization, and prepare both body and mind for marathon distances.
❓Can endurance training improve marathon performance?
Yes. Endurance training is one of the most important factors in marathon success because it increases aerobic capacity, stamina, and fatigue resistance.
💭 Final Thoughts
Training is specific. Therefore, you have to run if you want to be a better runner. The central organs like the heart and lungs will react and adapt in the same way – the heart becomes bigger, the blood volume increases, etc.
On the other hand, the local changes in the muscles will react and adapt to the specific impact. So, if you know you’ll run a Marathon it’s necessary with LSD run as the main element in a long period.
👉 Read more about how oxygen utilization affects endurance performance and marathon success.
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📅 Updated May 2026: This article has been revised to reflect current endurance training principles, aerobic development strategies, and marathon preparation best practices.
