The 3 Intensity Zones in Endurance Training

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Intensity Zones in Endurance Training and Sports

A large number of endurance athletes underwent testing in a laboratory that was specifically designed to precisely regulate and monitor the external workload, while also measuring various physiological responses, including oxygen consumption, ventilation, heart rate, and blood lactate levels. The study involved multiple endurance sports, such as cycling, cross-country skiing, rowing, and distance running, with the aim of comparing the athletes’ physiological responses across different modes of exercise. The results of these studies can provide valuable insights for athletes, coaches, and scientists seeking to optimize training and performance, as well as enhance our understanding of exercise physiology. Read the study here: Medicine & Science in Sports & Exercise.

Through meticulous physiological testing, we can differentiate three broad intensity training zones:

  • The Green Zone: This zone corresponds to low-intensity exercise that can be sustained for extended periods without significant discomfort. Athletes in the green zone can maintain a conversation without difficulty.
  • The Yellow Zone: This zone represents high-intensity exercise that requires significant exertion and can be sustained for a shorter duration. Athletes in the yellow zone will find it challenging to hold a conversation.
  • The Red Zone: This zone corresponds to very high-intensity exercise, with a pace that is so demanding that athletes can only sustain it for a brief period. In the red zone, athletes will be gasping for breath and unable to speak.

intensity training zones in endurance sports

Is “No PAIN, No GAIN” the Way the Best Athletes Train?

Based on the research conducted by Dr. Stephen Seiler, who examined some of the best athletes in the world across different sports, different countries, males and females, the answer is definitely not. About 8 out of every 10 of their training sessions are performed in their green training zone.

“They perform a high volume of low-intensity training (LIT) in addition to much smaller but substantial proportions of both moderate-intensity training (MIT) and high-intensity training (HIT) throughout the preparation period. 

The majority of descriptive studies present a “pyramidal” training intensity distribution (TID), with high volume of LIT, substantial MIT, and less HIT, whereas a few studies suggest athletes to adopt a “polarized” TID (reduced volume of MIT, somewhat higher HIT), which have been proposed to give superior endurance adaptations. However, although some evidence suggests superior responses by increased HIT in a clearly polarized TID, there is currently limited empirical data comparing different stimulus ordering approaches for the HIT component of training that is often seen as critical to maximizing adaptations.” (Source: ResearchGate).

Again, many top athletes don’t train very much in that medium-intensity training zone. I will have to quote Dr. Stephen Seiler now:

“…The point is that I can ride at 190 and 200 watts, at 65% heart rate and pretty comfortably for 2 hours. Me and other folks with limited talent and limited training time and real jobs, we could train with a professional cycling team on one of their easy days, on very flat roads for 2 hours of a 5-hour training session… The best athletes in the world do not train in the yellow or red zone every day because they can’t. They train a lot, yes, and sometimes they push themselves to levels of exertion and fatigue that most of us will never experience, but on most days, they train in the green zone at an intensity that is relatively comfortable for them that they can go for a long time and recover and repeat day after day. And that’s what brings success.”

The best endurance athletes train with discipline. Easy training sessions stay easy, whereas hard days are hard workouts.

To conclude, according to Dr. Stephen Seiler, the idea of “No Pain, No Gain” is false. Watch his TEDx Talk Show: How “normal people” can train like the worlds best endurance athletes:

The Polarized Approach Seems to Work Better

To achieve sustainable high performance over time, the training process must be carefully managed. While training has numerous benefits, it can also be a source of stress that may lead to burnout, stagnation, or overtraining.

Athletes have learned that a combination of low-intensity and high-intensity training days can help strike an optimal balance between adaptive signals and systemic stress. This insight is supported by scientific research and has been validated by my own personal experience as an athlete. It is important for everyone, not just professional athletes, to learn from the experience and research of elite athletes in order to optimize their own training.

This is why I continue to publish articles on this topic, as I believe that sharing knowledge and insights can benefit athletes of all levels. By incorporating best practices and avoiding common pitfalls, athletes can achieve their goals while avoiding injury and burnout.

Also read: Is Extreme Running Bad for Health?

Amateur athletes who are time-constrained often try to maximize the benefits of each training session, resulting in a high-intensity approach with little variation. As Dr. Stephen has previously noted:

“…it pulls our good training intentions into a chronic grind in the yellow zone when we slow down on most days and maybe go longer, and then train hard on Sundays because we got the energy and motivation to do it. Performances get better, and the process is more enjoyable and sustainable.”

Many ambitious individuals strive to get the most out of their workouts, often leading to a high-intensity, low-variation approach to training. However, for many individuals, high-intensity endurance training may be too overwhelming, leading them to avoid exercise altogether or turn to less demanding workouts like weight lifting.

As a coach and advocate for general fitness, it is important to promote the best practices for individuals of all fitness levels. Encouraging individuals to jump straight into high-intensity, red zone training without proper knowledge or discernment is irresponsible and potentially dangerous.

The process of becoming fit, muscular, and strong is not about pain, suffering, or brutal training. It is about finding enjoyment in the process and embracing fitness as a lifestyle. Developing virtues such as persistence and patience are essential to achieving long-term success.

As a recommendation, moderate and frequent training in the green zone, with occasional workouts in the yellow and red zones, can be an effective way to achieve fitness goals without overexerting oneself. Combining strength training with cardio can also provide a well-rounded approach to fitness.

Personally, I have found success in doing 2-3 light-moderate workouts per week, along with 1-2 tougher training sessions. This moderate approach has allowed me to maintain great physical shape over the years.

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