Most athletes experience the anaerobic threshold zone when putting in some serious work. When a lot of power is used over a short period of time - like weightlifting or those exhausting HIIT workouts - the types of workouts when your muscles need more oxygen than what your bloodstream can provide. In order to understand the need for high anaerobic tolerance, we need to get a bit science-y and understand the basics of how muscles work. Our muscles are made up of contractile tissue. Each muscle fiber consists of thick and thin filaments that act like cylindrical hydraulics which make the muscle contract, therefore creating movement. Like everything in our lives, muscle contraction requires energy, which in our bodies is stored in a form of ATP (adenosine tri-phosphate).
During a relatively slow exercise, the energy demand is low and your body uses aerobic metabolism - the required energy is created by burning carbohydrates and fats using oxygen. They are stored in our bodies in a form of glycogen, which during a process called glycolysis is broken into pyruvic acid. This acid then creates the much-needed ATP. This process creates two by-products in a form of carbon dioxide and water. More demanding the exercise, the more by-products generated. That's when we start breathing harder and sweating, in order to get rid of those by-products. This is a completely sustainable source of energy, as long as we have consumed enough carbohydrates and fats to burn - also known as eating.
Now, when we pick up the pace, things change. To work harder, our muscles start requiring more energy than can be produced using oxygen. Our bodies simply cannot supply enough oxygen for such high performance. When this happens, we go into anaerobic exercise - the energy is supplemented by contributions from anaerobic metabolism. Without oxygen, H2O and CO2 cannot be created. Instead, during anaerobic metabolism, the by-product of energy generation is lactic acid, which breaks into lactate and hydrogen ions. These ions then contribute towards fatigue by interfering with the contractile processes and by changing the pH of the muscle cell.
Unlike aerobic metabolism, the anaerobic one is far from sustainable. Working at 95% effort, anaerobic threshold lasts for about 120-240 seconds, as it burns through muscle glycogen and lactic acid. Once we're reaching the limits of our anaerobic tolerance, the burn and pain levels increase, our muscles stiffen up and we need to stop, or at least, slow down. The bottom line of all those physiological background processes is that when we push hard, we use more oxygen than we can physically inhale.
Even though the tolerance of lactate and decreasing pH levels is limited, it can be trained. Usually, anaerobic threshold training is associated with various interval exercises. However, focusing directly on our lungs can train our ability to hold your breath - apnea. As we increase our bodies' resistance towards lactate, we will be able to perform at high intensities for longer periods, decreasing muscle fatigue and lowering our recovery time.