Nutrients and Energy
What are the three main nutrients involved in energy production for physical activity?
The three main nutrients are carbohydrates, proteins, and fats.
Define ATP and explain its role in energy production.
Adenosine triphosphate (ATP) is a chemical compound that provides the energy needed for muscle contractions. During physical activity, ATP is broken down to release energy, which must then be resynthesized for continued movement
Discuss how intensity and duration impact the energy systems used during physical activity.
High-intensity, short-duration activities rely on the ATP–PC system. As duration increases to 60-90 seconds, the lactic acid system takes over. For longer, lower-intensity activities, the aerobic system becomes the primary energy source.
Explain the concept of energy system interplay during a marathon.
In a marathon, the aerobic system is the primary source of energy for most of the race. However, the ATP–PC and lactic acid systems may briefly contribute during sprint finishes or uphill runs, where more immediate energy is required.
Define glycogen and explain its importance for athletes.
Glycogen is the stored form of carbohydrates in muscles and the liver. It is crucial for athletes as it provides a readily available source of energy for moderate to high-intensity activities
Explain how carbohydrates are stored in the body and their role in physical activity.
Carbohydrates are stored as glycogen in muscles and the liver. They break down easily, providing a quick source of energy, especially during moderate to high-intensity activities. Glycogen stores can last for 60 minutes of vigorous exercise or 90–120 minutes of moderate activity.
Why is ATP resynthesis essential during physical activity?
ATP stores in the body are limited and deplete quickly during exercise. Resynthesis ensures a continuous supply of energy to sustain muscle contractions, enabling athletes to maintain performance.
Which energy system would be predominantly used during a 400-meter sprint, and why?
The lactic acid system would be predominantly used, as the 400-meter sprint lasts about 45-60 seconds and requires sustained, moderately high-intensity effort.
In what ways does an athlete’s fitness level affect the contributions of each energy system?
A well-trained athlete can use the aerobic system more efficiently for longer periods, delaying the switch to anaerobic systems (ATP–PC and lactic acid) and reducing fatigue.
What are amino acids, and how are they involved in muscle repair and energy metabolism?
Amino acids are the building blocks of proteins. They aid in muscle growth and repair after physical activity. While not a primary energy source, they can be used for energy in extreme conditions.
Why are proteins generally not used as a primary energy source in physical activity?
Proteins are stored as amino acids, which are mainly used for muscle growth and repair. They are only used for energy under extreme conditions, as they take longer to metabolize compared to carbohydrates and fats.
Describe the interplay of the ATP–PC, lactic acid, and aerobic systems during physical activity.
The ATP–PC system is used for short bursts of high-intensity activity (up to 10-15 seconds). The lactic acid system supports activities lasting 60-90 seconds at moderately high intensity. The aerobic system takes over during prolonged, low- to moderate-intensity activity. These systems interact and overlap during various stages of activity depending on intensity and duration.
Explain how training can improve the efficiency of the aerobic system.
Aerobic training increases the body’s ability to deliver and use oxygen efficiently, improves endurance, and enhances the capacity to metabolize fats and carbohydrates for energy, thus delaying fatigue in long-duration activities.
How would you structure a training session to optimize the use of the lactic acid system for a swimmer?
Session: 6 x 100-meter sprints with 60 seconds of rest between sets.
Reasoning: The lactic acid system supports high-intensity activities lasting up to 90 seconds. Short rest periods challenge the system’s ability to clear lactic acid and improve endurance at high intensities.
Explain the difference between chemical energy and mechanical energy in the context of physical activity.
Chemical energy is stored in nutrients (like carbohydrates, fats, and proteins) and is converted into mechanical energy, which powers muscle contractions during physical activity.
Describe the process by which fats are metabolized for energy during physical activity.
Explain the ATP–PC system and the type of activity it supports.
The ATP–PC system provides immediate energy for very short, explosive movements (e.g., 100 m sprint). It relies on stored phosphocreatine (PC) to rapidly resynthesize ATP but lasts only for 10-15 seconds.
How does the body switch between energy systems during physical activities like touch football?
During touch football, the body switches between the ATP–PC system for short sprints, the lactic acid system for sustained efforts, and the aerobic system during recovery periods. The transitions are based on the changing intensity and duration of play.
Justify why a mix of energy system training is crucial for an athlete’s overall performance.
Training all three energy systems (ATP–PC, lactic acid, and aerobic) ensures that an athlete can perform optimally across various intensities and durations, providing both immediate power and long-term endurance.
Describe how triglycerides are used by the body as an energy source during endurance activities.
Triglycerides are broken down into fatty acids and glycerol, which are then metabolized in the aerobic system to provide long-lasting energy for endurance activities.
Identify food sources rich in carbohydrates, proteins, and fats that contribute to energy production.
How does the lactic acid system contribute to energy production during physical activity?
The lactic acid system breaks down glucose without oxygen to produce ATP during high-intensity efforts lasting up to 60-90 seconds. It produces energy quickly but results in the accumulation of lactic acid, which can cause muscle fatigue.
Devise a training session that targets the ATP–PC system and explain the reasoning behind your choices.
Session: Perform 8 sets of 20-meter sprints with full rest between sets (2-3 minutes).
Reasoning: The ATP–PC system is used for high-intensity efforts lasting up to 10-15 seconds, and full recovery allows the system to replenish for the next effort.
Describe how an athlete’s energy needs change as intensity fluctuates throughout an event.
At higher intensities, carbohydrates become the main fuel source via the ATP–PC and lactic acid systems. As intensity decreases, the body shifts to the aerobic system, using a mix of fats and carbohydrates to conserve energy and delay fatigue.
Discuss how understanding the role of fatty acids in energy production can influence an athlete’s diet planning.
Athletes focusing on endurance may increase their intake of healthy fats (rich in fatty acids) to ensure their bodies have a reliable energy source for prolonged, lower-intensity activity, enhancing performance and delaying exhaustion.