Chances are that if you’re not a competitive endurance athlete, you’re probably not that concerned about your aerobic or anaerobic status during training. You may not even know the difference between the two, but if you’ve exhausted yourself at any time during exercise or training, you’ve definitely felt the difference–and it’s big. Without getting into an advanced biological or chemical explanation of aerobic and anaerobic exercise, I’ll explain the major differences and how they affect exercise and conditioning.
Define Our Terms
According to Merriam Webster’s dictionary, aerobic exercise occurs “only in the presence of oxygen.” This is not referring to the amount of oxygen we breathe in, which is about 21%; rather, it refers to the body’s status during exercise. It means the body has a sufficient amount of oxygen at its current exercise intensity level to operate “normally.”
During aerobic exercise, the body’s activity is fueled by glycogen reserves, fat reserves or a combination of both, depending on the intensity level of the given exercise. The byproducts of aerobic exercise are carbon dioxide, water and of course, energy. One of the major benefits to aerobic conditioning is an increase in the heart’s stroke volume, which is the amount of blood the heart can pump with one beat. The more blood the heart can pump with one beat, the more efficient the cardiovascular system. This is why those who exercise regularly generally have a lower resting heart rate.
Conversely, anaerobic is defined as occurring “in the absence of oxygen.” Again, this does not refer to the amount of oxygen in the air we breathe, but rather the body’s status during exercise in which its demand for oxygen exceeds its supply. At this intensity, the byproducts are no longer carbon dioxide and water, but lactic acid, which accumulates in the muscles and is difficult to expel, leading to fatigue more readily. Symptoms of lactic acid build-up include a burning sensation in the lungs and muscles.
Aerobic Capacity
According to Wikipedia, aerobic capacity is defined as “the maximum amount of oxygen the body can use during a specified period, usually during intense exercise. It relates to cardio-respiratory performance and the maximum ability to remove and utilize oxygen from circulating blood.” The important thing to note about this is that everyone’s aerobic capacity 1) is different, 2) is primarily a result of exercise, conditioning and genetics, and 3) can be altered. The obvious goal when doing cardiovascular exercise is to maximize our aerobic capacity. Not only does this benefit our work capacity, but also our work efficiency as firefighters.
The standard for measuring aerobic capacity is by VO2 max testing, in which the participant exercises (usually on a treadmill) with a mask over their mouth and nose to measure oxygen consumption. The intensity of the exercise is raised until the participant reaches exhaustion. Note: Although this is the standard means of measuring aerobic capacity, it is exhausting; therefore, it requires a respirometer, and participants should receive clearance from a doctor before taking the test. Other, less intense tests are available that calculate aerobic capacity based on a sub-max test. A sub max test simply means that the participant is not exercised until exhaustion or to the “max.” Rather, the test is concluded when a pre-calculated heart rate based on age is achieved.
The Aerobic Benefits the Anaerobic
There’s no doubt that when we’re called to mitigate an emergency, we tax our bodies and very possibly exceed our aerobic capacity and operate in the anaerobic zone. Knowing this, it’s important to ready ourselves by regularly pushing our level of exercise intensity into the anaerobic zone. This is what is meant by the phrase “no pain, no gain,” and doing it increases our ability to operate anaerobically, both physically and mentally. That said, limiting aerobic exercise and only doing anaerobic training may lead to a limited aerobic capacity and cause us to reach anaerobic status more quickly.
As previously stated, once the anaerobic zone is reached, the body’s byproduct becomes lactic acid, which leads to fatigue more quickly. The longer you stay in the aerobic zone, the longer you’re able to work before moving into the anaerobic zone. In his article, “Aerobic Base Training: Going slower to get faster,” author and coach Matt Russ writes, “Prolonged aerobic training produces muscular adaptations that improve oxygen transport to the muscles, reduces the rate of lactate formation, improves the rate of lactate removal and increases energy production and utilization.” It is because of these adaptations that heart rate training is possible.
Finding the Aerobic Zone
The most un-scientific method of determining when you’re in the aerobic zone while exercising is the “talk test.” Simply put, you exercise at up to an intensity that still allows you to maintain a conversation without gasping for more air. The theory is that if you’re still able to carry a conversation, the body’s demand for oxygen while exercising is being fulfilled. On the other end of the spectrum is the VO2 max test which, as stated earlier, requires a capable facility and a knowledgeable tester.
In addition to those tests, there are aerobic tables that calculate a predicted maximum heart rate based on age. You simply plug your age into the equation to derive your maximum heart rate. Once you calculate your maximum heart rate, you exercise at about 70% —80% of that maximum rate to stay in the aerobic zone. Note: There are several different fitness organizations and authors, each with their own tables that result in slightly different final heart rates, but remember that you’ll be exercising within a zone and not at an exact number. Examples of some aerobic tables include:
- 226 — age = max heart rate
- 209 — (0.9 x age) = max heart rate
- 206.3 — (0.711 x age) = max heart rate
- 217 — (0.85 x age) = max heart rate
Again, these tables are intended to predict maximum heart rate without having to go through the VO2 max testing. This is not only safer, but more convenient for those who are just beginning to exercise or those with less than optimal fitness levels wishing to increase their intensity. Note: Fitness levels are not factored into these equations, which may alter final numbers but, although not exact, these tables will give baseline numbers from which to improve.
Heart Rate Monitors
The easiest way to monitor your heart rate during training is to purchase a heart rate monitor, which are available at most sporting goods stores and common retail stores. They consist of a chest strap that sends heart rate information to a wrist receiver that looks like a watch. There are also watches that serve as heart rate monitors that don’t require the user to wear a chest strap. Both options are an inexpensive and easy way to know your exact heart rate at any given time. Some monitors are even programmable and can notify you when you’ve reached a pre-set heart rate or zone.
Train for Both!
Aerobic training is an essential aspect of building aerobic capacity. The key for firefighters who must routinely operate in both aerobic and anaerobic conditions is to train in both aerobic and anaerobic ways. Training within the aerobic zone not only improves cardiovascular efficiency by way of stroke volume, it also allows the body to recover from constant anaerobic training. Although it may seem counterintuitive that working less intensely can actually improve performance at higher intensities, when done correctly, that’s exactly what happens.
