Introduction
Physical exercise is a complex process that requires a continuous supply of energy. The human body constantly produces the energy required for any physical activity and ensures proper functioning through an interaction of several energy systems. These include the adenosine triphosphate (ATP) and phosphocreatine (PC), anaerobic lactic, and oxygen systems. The interplay between these systems during an extended running exercise will be discussed and evaluated.
The Adenosine Triphosphate and Phosphocreatine, Anaerobic Lactic, and Oxygen Systems
The observed physical activity was a running exercise that required the subject to run for 21 minutes at varying speeds. Heart rate was recorded for the duration of the activity, with pre-exercise and post-exercise rates were also recorded. The lowest pre-exercise heart rate was 80 beats per minute (bpm), with the highest heart rate reaching 187 bpm at 21 minutes. Notably, the observed individual failed to recover rest state heart rate 5 minutes post-exercise, with 155 bpm heart rate being measured. In addition, the onset of blood lactate accumulation (OBLA) point was expected to occur after the athlete reached 200 bpm. However, it was reached at 167 bpm at the 7th minute of the running exercise. It should be noted that the average OBLA point was reached after the first change in running speed.
The ATP-PC system is an anaerobic energy system of the human body. ATP is an organic compound generated from fats and carbohydrates, the breakdown of which releases energy into the muscle cells (Mukhopadhyay, 2021). Whereas PC is a creatine molecule carrying a high-energy phosphate bond that provides energy when hydrolyzed and can resynthesize ATP via creatine kinase protein reaction (Ribeiro et al., 2021). The ATP-PC is the first energy system to respond to exercise-related demand for energy and is associated with high-intensity, short-duration physical activity (Ribeiro et al., 2021). The energy provided by the system lasts until the phosphate stores depletion, approximately 8-10 seconds (Çolak & Başkan, 2020). At the start of the exercise in consideration, as the three energy systems begin to supply energy to cells, the ATP-PC system provides the most energy during the first 10 seconds of running, with the heart rate not exceeding 105 bpm and the OBLA point not being reached. Before and after the exercise, the system can be viewed as inactive due to no intense, immediate energy required before and the phosphate stores depletion after.
Anaerobic lactic (glycolytic) is the second system in the interplay of energy systems during an exercise. The system is realized through the fermentation of carbohydrates, specifically glucose. During glycolysis, glucose molecules are broken down into pyruvic molecules utilized in the citric acid cycle (Mukhopadhyay, 2021). However, if pyruvic molecules are in excess, they are bound to hydrogen molecules, forming lactate (Mukhopadhyay, 2021). According to Ferretti et al. (2022), lactic acid accumulates in contracting muscles as the by-product of glucose breakdown. The OBLA is the metabolic rate of lactate concentration beginning to increase exponentially in the blood (Silva et al., 2021). The lactic system actively supplies the body cells with energy for approximately 45 seconds to 2 minutes (Swanwick, 2018). Thus, for the first 10 seconds of exercise, the system works simultaneously with ATP-PC and oxygen systems. In the exercise under observation, the maximum heart rate was recorded at two minutes at 150 bpm. The lactic system reached its peak activity and began to diminish, with all further exercise being aerobic. In addition, at two minutes, the subject did not exhibit any observable changes in breathing rate, sweating, or skin color.
The oxygen system is the aerobic energy system that becomes dominant after others systems peak, and a steady state of oxygen consumption is reached. The ATP-PC and lactic systems operate on oxygen deficit, as oxygen is not required for their functioning. The oxygen system helps sustain lower-intensity physical activity, during which all the ATP requirements are met at a lower rate of production (Mukhopadhyay, 2021). The energy is generated from carbohydrates, fat, and protein (Swanwick, 2018). During this phase, glycogen sparing can occur if non-carbohydrates are used as the source of energy, for example, blood glucose (Macklin et al., 2019). The breakdown of fatty acids in the presence of oxygen, or aerobic lipolysis, can also transpire. The lactate accumulated in the first two minutes of exercise is further utilized in the citric acid cycle, also known as the Krebs cycle, helping produce new ATP molecules (Alabduladhem & Bordoni, 2022). After the exercise is finished, post-exercise oxygen consumption (EPOC) happens as the interplay of energy systems finishes (Mukhopadhyay, 2021). In the observation, the heart rate peaked at 187 bpm, with the subject exhibiting heavy breathing, sweating, and light red skin color.
Conclusion
In summary, the ATP-CP, lactic, and oxygen systems are the energy continuum of the human body. All systems provide muscle cells with ATP, helping individuals maintain required energy levels during exercise. As anaerobic systems, ATP-CP and lactic systems operate on oxygen deficit, with the heart rate remaining relatively low, as oxygen is not required of ATP molecules synthesis. In comparison, the oxygen system requires oxygen, with the heart rate climbing steadily to satisfy the ATP energy requirements at a lower rate of ATP production.
References
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