Energy Systems (IB Biology & Sports Science)

Energy Systems

The systems in the body responsible for producing energy for muscular contractions during physical activity.

ATP-PC System

Also known as the alactic system; provides immediate energy for high-intensity, short-duration activities.

Lactic Acid System

Also known as anaerobic glycolysis; used for moderate- to high-intensity activities lasting 30 seconds to 2 minutes.

Aerobic System

Also known as the oxidative system; provides energy for low-intensity, long-duration activities.

Adenosine Triphosphate (ATP)

The immediate energy source for all muscular contractions, composed of adenosine and three phosphate groups.

Phosphocreatine (PC)

Stored in muscles; used to rapidly regenerate ATP for immediate energy.

Anaerobic

A process that occurs without oxygen.

Glycogen

Stored form of glucose used as fuel for energy production.

Muscle Fatigue

Decreased ability of muscles to generate force due to lactic acid accumulation.

Krebs Cycle

A series of enzymatic reactions in the mitochondria that generates ATP, NADH, and FADH2 from pyruvate.

Electron Transport Chain (ETC)

A series of complexes in mitochondria where electron transfer occurs, producing a large amount of ATP.

High-Intensity Activities

Activities that rely heavily on the ATP-PC system for immediate energy.

Low-Intensity Activities

Activities that primarily utilize the aerobic system for sustained energy.

Moderate-Duration Activities

Activities lasting from 30 seconds to 2 minutes, mainly utilizing the lactic acid system.

Oxygen Availability

A critical factor determining whether anaerobic or aerobic pathways dominate in energy production.

VO2 Max

The maximum rate of oxygen consumption; an indicator of aerobic capacity.

Lactic Acid

The byproduct of anaerobic glycolysis; can lead to muscle fatigue.

Training Adaptations

Physiological changes in response to regular training, improving the efficiency of energy systems.

Mitochondrial Density

The number of mitochondria in a cell; higher density improves aerobic metabolism.

Phosphocreatine Stores

Limited reserves in muscles, which deplete quickly (within 10-15 seconds) during high-intensity efforts.

Anaerobic Glycolysis

The breakdown of glucose without oxygen, producing ATP and lactic acid.

Explosive Movements

Activities requiring immediate energy, typically generated by the ATP-PC system.

Sprinting

An example of a sport that predominantly relies on the ATP-PC system.

Endurance Sports

Sports like marathon running and cycling that rely primarily on the aerobic system.

Energy System Interplay

The collaboration of different energy systems during various types and intensities of exercise.

Fitness Level

A factor influencing energy system usage; trained athletes utilize oxygen more efficiently.

Carbohydrates

One of the fuel sources for aerobic metabolism; can be converted to ATP.

Fats

Another fuel source for the aerobic system; used in prolonged exercise.

Protein

Occasionally used as a fuel source in the aerobic system, especially during prolonged exercise.

Fatigue and Discomfort

Common consequences of lactic acid buildup during high-intensity activities.

Enzyme Activity

The increase in specific enzyme levels through training that enhances ATP production.

Short Bursts of Activity

Activities lasting less than 10 seconds primarily utilizing the ATP-PC system.

Moderate to High Intensity

Activities typically relying on the lactic acid system for energy.

Tailored Training Programs

Training designed to develop the dominant energy system required for specific sports.

Immediate Energy Production

The rapid generation of ATP necessary for quick, high-intensity efforts.

Explosive Strength

Strength needed for activities like weightlifting, which benefits from the ATP-PC system.

Endurance Training

Training aimed at improving the efficiency of the aerobic system.

Recovery Time

Time needed to replenish energy stores after high-intensity exercise.

Energy Consumption

The process of utilizing stored energy sources for physical activity.

Fatigue Threshold

The point at which muscle fatigue begins during high-intensity activity.

ATP Resynthesis

The process of creating ATP from ADP and inorganic phosphate, mainly using energy released from PC.