What is it:
Zone 2 training, also known as aerobic base training or steady-state training, has gained significant attention recently in the realm of fitness and performance optimization. This training method involves exercising at a low-to-moderate intensity where your heart rate is elevated but sustainable for extended periods. The American College of Sports Medicine has adopted a five-zone model based on a maximum heart rate percentage range for the general population. Zone 2 is usually between 60% and 70% of our maximum heart rate, although some fitness experts say it can go up to 80%.
An example of zone 2 intensity would be a relaxed jog or easy bike ride where you can still talk, but every few words are interrupted by an audible breath. Whether you're a seasoned athlete or someone passionate about improving overall health and well-being, understanding and incorporating zone 2 training into your fitness routine can yield remarkable benefits.
Purported claims:
Improved cardiovascular health and endurance
Optimized fat metabolism and glucose utilization
Increased mitochondrial density
Reduced risk of overtraining and injury
Enhanced mental resilience and cognitive function
Better Quality of sleep
Longevity benefits
What the science says:
Zone 2 training targets the aerobic system, strengthening the heart and improving its efficiency in pumping blood and oxygen to the muscles. Regular aerobic exercise has been shown to significantly benefit cardiovascular health by improving vascular function, reducing central adiposity, lowering blood pressure, improving insulin sensitivity, and reducing cardiovascular risk factors such as dyslipidemia, diabetes, obesity, and hypertension.
A study from Finland with several hundred middle-aged men showed that higher aerobic fitness, measured by maximum aerobic capacity (VO2 max), was associated with slower progression of atherosclerosis, the buildup of plaque inside arteries obstructing blood flow. Studies have also shown that regular endurance training may benefit men with low HDL cholesterol, elevated TGs, and abdominal obesity.
Regular Zone 2 training increases the body's ability to utilize oxygen efficiently, improving endurance. However, steady-state training isn't beneficial only for endurance athletes such as cyclists and triathletes. A recent study among professional soccer players found that jogging/running at a low-intensity pace improved energy recovery and general endurance. After the nine-week program, players' blood lactate concentrations and heart rate at the same exercise intensities decreased while the running speed increased.
During low- and moderate-intensity training, most of our fuel comes from fat, so zone 2 training is often called "the fat-burning zone". Therefore, if you want to train your body to burn more fat more efficiently, you must spend time at this intensity level. While all forms of exercise improve insulin sensitivity, some scientists claim that zone 2 creates unique improvements in insulin resistance. Numerous studies have found that acute aerobic exercise within 6 hours of a meal can significantly decrease glucose and insulin concentrations in healthy adults and is an effective strategy to improve acute glycaemic control. With exercise, which is a type of stress, your body gets a signal that it needs to build more tools to break down extra fat and glucose to produce more energy. Here, we see the most significant benefit of Zone 2 training: changes to our mitochondria.
Zone 2 training is the best stimulator for mitochondrial quantity and function. This results in improved energy production and overall metabolic function. Aerobic, endurance-type exercise has been shown in studies to be the most efficient in driving positive mitochondrial adaptations. For example, this type of exercise induces the cells to clear out old, malfunctioning mitochondria through a process called mitophagy while increasing the number of new and more efficient mitochondria. Studies show that elite athletes with high aerobic capacity are more metabolically flexible, meaning they can switch between different energy sources (fat and glucose) more efficiently than less-fit individuals. Metabolic flexibility is essential because it allows you to use and burn fuel more efficiently, whether training, working in the garden, or playing with your kids.
Consistent zone 2 training is also linked to improved mental health and resilience. The endorphins and monoamines released during exercise can boost mood and overall well-being. Studies have shown that long, rhythmic aerobic exercises such as running, walking, swimming, and dancing are the most beneficial for mental health conditions such as anxiety and depression. Some studies have even found regular exercise to improve the quality of life in more severe conditions like schizophrenia.
Studies show that aerobic exercise can change our brain structure, associated with better cognitive performance. Brain plasticity, the brain's ability to change its structure and function in response to internal and external stimuli, is improved by exercise and is usually better in fit individuals. It can make these people more resilient to cognitive impairments such as dementia.
If you have trouble sleeping well, low to moderate intensity could be just what the doctor ordered. Studies show that regular aerobic exercise, such as zone 2 training, improves sleep quality by regulating sleep patterns and promoting restorative sleep, which is crucial for recovery and overall health. A recent study from Canada found that moderate-intensity continuous training or stretching improved sleep quality for older adults who were poor sleepers, whereas high-intensity training did not. Many women experience deteriorating sleep quality during menopause. Some studies have found that consistent aerobic training can improve sleep quality significantly for women experiencing menopause symptoms such as hot flashes.
Studies suggest that aerobic exercise is associated with increased longevity and a reduced risk of chronic diseases such as diabetes, hypertension, and metabolic syndrome. According to CDC data gathered from over 86,000 participants between 18-64 years old, almost half of adults with disabilities are physically inactive, and they are more likely to have one or more chronic diseases. According to research, VO2 max, which increases with aerobic exercise, directly impacts our mortality rates and longevity without an upper limit on benefit (i.e., the fitter you are, the lower your chances of dying of all causes). A 2018 study with more than 120,000 participants found that those with low levels of cardiorespiratory fitness were 4-6 times more likely to die during the course of the study than those with elite levels. Most stunningly, the effects of cardiorespiratory fitness on early death were more significant than smoking.
Our take:
Elite athletes do most of their training in Zone 2 because it's scientifically proven that 'slow' training translates into better race performance when coupled with the right amount of 'fast' or more intense training. For the weekend warrior and the mere mortals, incorporating Zone 2 training into the fitness regimen is essential for performance, overall health, and longevity. Most of your training, about 80%, should be around zone 2 and the rest at zones 3-5. All in all, the versatility and effectiveness of zone 2 training make it a valuable tool for individuals at any fitness level, emphasizing the importance of a balanced approach to exercise and health optimization.
It's also important to remember that the heart rate zones used in Zone 2 training are based on averages and formulas, which may not perfectly align with every individual's physiological response. Age, fitness level, and genetics can influence heart rate, so using these zones as a guideline and adjusting based on personal feedback and performance metrics is essential.
Will this benefit you?
Understanding and implementing Zone 2 training principles can lead to sustainable progress, long-term health benefits, and a fulfilling journey toward reaching your fitness goals. Unlike intervals and other more strenuous efforts, Zone 2 training requires a sustained effort of at least 35-40 minutes. Consulting with your Apeiron Personal Trainer can help tailor a training program that aligns with your goals, fitness level, and overall health considerations. Listening to your body, monitoring progress, and staying adaptable in your approach can maximize the benefits of zone 2 training while minimizing potential downsides.
If you're still interested, here's what to keep an eye on:
While Zone 2 training is generally regarded as safe and beneficial for most individuals, it's crucial to remember that like any exercise routine, there are potential pitfalls and risks. It's possible to overexert yourself, even with low-intensity training (imagine doing cardio for hours every day without rest days). Relying solely on Zone 2 training without incorporating variety (such as strength training, cross-training, mobility work) or progression in your workouts could lead to performance plateaus and monotony. If your fitness goals involve enhancing anaerobic capacity, such as sprinting or high-intensity interval training (HIIT), Zone 2 training alone may not suffice. This is where a personal trainer's expertise, like those at Apeiron Life, can be invaluable in guiding your fitness journey.
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