When you compare various cars, the source of energy can vary into 3 different categories, diesel, unleaded, and electric. Our body also uses different energy source and depending on the purpose, the process will be different.
Our body can utilize 3 nutrients, carbohydrate, fat and protein, that can be convert into energy that our body can use called ATP or adenosine triphosphate. Think of ATP as currency. For our body to utilize those nutrients into energy they must be converted into ATP.
Rate and Duration of Energy Production
When you look at various sporting events, you’ll find that certain events do require higher rate of energy production such as weightlifting, powerlifting, and track and field where performance is done in less than 10 seconds. For these events, although energy production rate may be high, however, duration that the athletes can sustain that amount of energy is short. Whereas soccer, MMA, marathon, cycling, hiking requires longer duration of energy production, but amount of energy production is lower compared to weightlifting, powerlifting, and track and field. In other words, there always will be a tradeoff between rate of energy production and duration of energy production.
Aerobic Energy and Anaerobic Energy
Our body has mainly 2 different energy pathways, aerobic and anaerobic energy production. These processes are necessary for us to survive and runs 24/7/365 ever since we were born and will continue until we die. Both will be creating ATP which is required not just for muscular work but for all cellular functions. Higher the performance is more ATP is required.
Aerobic System
Aerobic system provides most of the energy for any activity that last longer than 60 seconds regardless of intensity level. Aerobic energy system is also responsible for recovery. This is not just for while you are resting but also recovery during the performance.
Pitcher in baseball for example, uses anaerobic energy production while throwing but need to recover quickly in between pitches or power production will decline. This recovery in between pitches is determined by their aerobic fitness.
Aerobic system also provides ATP that is necessary for use to live 24/7/365 throughout our entire life. Because of that process to create energy or ATP in aerobic system can convert glucose (carb) and fatty acids (fat) into ATP. This process is done within mitochondria within our cells. When necessary, amino acids (protein) can be converted into ATP through same system.
There is a strong correlation with increase in aerobic fitness to decrease in risk of cardiovascular death. Therefore, it is important to improve your aerobic fitness not only for athletic performance but also for minimizing the risk for heart failure.
Anaerobic-Lactic System
Compared to aerobic system, anaerobic-lactic system is shorter in energy production duration but is higher in energy production rate. This means when performing more strength required activities, body will switch from aerobic system to anaerobic-lactic system. Anaerobic-lactic system contributes the most power output around 30 seconds then declines after that.
Anaerobic-lactic system creates ATP from glucose through aerobic pathway or from lactate through anaerobic pathway. When the person is conditioned properly, they can recycle the lactate and create energy quickly without accumulating. Whenever glucose is being used as energy source, the body will be creating some level of lactate. Depending on how fast the body can utilize in anaerobic metabolism, will dictate how much of lactate can be found in the bloodstream.
Lactate is transported to the brain, the heart and other working muscles in the body. During the exercise it is primary fuel source for the heart. Otherwise, the heart cannot meet the demand of large volume of blood throughout the body during physical activity.
Lactate often consider as cause of fatigue, but fatigue is caused by multiple factors. In fact, cause of fatigue is not lactic acid but due to change in muscle temperature, blood pH, change in substrate, calcium ion (Ca2+) change in muscle and so on.
Anaerobic-Alactic System
Lastly, anaerobic-alactic system, also known as ATP-PC and able to generate the fastest ATP because of less chemical step, therefore can produce the most power energy output. However, it can only produce high amount of energy for a few seconds. In other words, fatigue will kick in faster than other energy system.
The training method for alactic system must be short. 3-6 seconds of maximum effort with 1-3 minute resting period. This could be 1-3 repetitions of maximum effort of weightlifting or 3-6 seconds of sports related movement such as throwing the ball, kicking the ball, throwing javelin, and so on.
To improve the ability of alactic system high level of aerobic fitness level will be needed to speed up the energy contribution. This can be observed in sports. Although the trainee may have trained in alactic system for fighting match, however, because the aerobic fitness level is too low that cannot last 3 rounds.
Summary
Each sports and activity varies in how our body can create energy. This also point out the importance of understanding power output and work to rest ratio. Training outcome should be lined with how well the body is able to adapt to the environment and maintaining the homeostasis. Which means, for those who hike at higher elevation will need different training methods compared to sports such as soccer and basketball.
At any sports or activities that last for more than 60 seconds, the aerobic fitness or aerobic energy system becomes the foundation of both anaerobic lactic and alactic system. In terms of frequency of the training, aerobic fitness will be more frequent compared with anaerobic fitness.
Kota Shimada
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