Most athletes experience the anaerobic threshold zone when they put in some serious work and add power to their workouts. When you reach it, It feels like a burn in the muscles and you will truly have to push yourself to continue. When a lot of power is used over a short period - like in weightlifting, sprints or those exhausting HIIT workouts - your muscles need more oxygen than what your bloodstream can provide. The anaerobic threshold kicks in when the intensity of exercise intensity is highly increased, and the aerobic system can no longer keep up with the energy demand. 

Each muscle consists of contractile tissue and each muscle fiber is comprised of thick and thin filaments that act like cylindrical hydraulics, which makes the muscles contract and enable movement. Everything needs energy including our muscles. Energy used for muscle contraction is called adenosine triphosphate (ATP.)

To fully explain the relationship between aerobic and anaerobic threshold and why a strong anaerobic threshold is good, we need to get a bit scientific and show the basics of how muscles work.  


There are two forms of cell metabolism; aerobic and anaerobic. The most common and slowest of the two is the aerobic metabolism, counting for 90% of your cellular metabolism. Aerobic metabolism occurs when we need energy for daily activities and slower forms of exercise, where the need for energy here is relatively low. 

The required energy is produced when our body converts food into energy by using oxygen - carbohydrates and fats are the two primary sources. They are stored in our bodies in the form of glycogen which during a process called glycolysis, is broken into pyruvic acid. This acid then creates the much-needed ATP to our muscles. This process is constantly occurring in our bodies. 

The by-products carbon dioxide and water are also produced in the process, and the more demanding the exercise, the more by-products generated. That is when we start breathing harder and sweating to get rid of those by-products.


As we start to increase and pick up the pace, things change. To work harder, our muscles start to require more energy than can be produced using oxygen. Our bodies simply cannot supply enough oxygen for your muscles for a burst of energy needed in such high performance. When this happens, we go into anaerobic exercise, a condition where energy is supplemented by contributions from anaerobic metabolism. This means that the body burns glucose and creates energy without oxygen and energy is here produced very quickly to keep up the high intensity.  

In this process, a by-product of energy generation is lactic acid, which breaks into lactate and hydrogen ions, and starts to build up in the blood. These ions contribute to fatigue by interfering and changing the PH of the muscle cell. 


Unlike aerobic metabolism, which provides long-lasting energy, the anaerobic system is far from sustainable. Working at 95% effort, the anaerobic threshold lasts for about 120-240 seconds as it burns through muscle glycogen and lactic acid. Once we reach the limits of our anaerobic tolerance the anaerobic threshold kicks in and the pain and burn level increases. Our muscles will stiffen up and we need to slow down or stop. The bottom line of the physiological processes is that when we push hard, we use more oxygen that we can physically inhale.


The tolerance of lactate and decreasing PH level, which is needed in the anaerobic threshold zone, is limited. However, it can be trained, making you faster and able to perform longer at high intensities.  Training our anaerobic threshold is usually associated with various interval exercises. However, focusing directly on our lungs, training your respiratory muscles will strengthen our ability to hold our breath, called apnea. This ability is also needed in the anaerobic threshold zone, where we lose breath. Therefore, respiratory muscle training benefits your anaerobic threshold. 

By increasing anaerobic tolerance we also increase our bodies’ resistance toward lactate and we will be able to perform at higher intensities for longer periods, decreasing muscle fatigue and lowering our recovery time. 

At Airofit, we have developed special respiratory training programs that allow you to focus directly on abnea, so you can boost your anaerobic tolerance without disrupting your ongoing training schedule.