Energy Systems in Exercise Biology

Bioenergetics

• Bioenergetics is the conversion of macronutrients into usable energy forms.
• Energy is the ability to perform work.
• ATP (adenosine triphosphate) powers all energy-requiring cellular processes.
• Other energy stores replenish ATP by ADP phosphorylation.

Biological Energy Systems

• Three basic energy systems exist in muscle cells to replenish ATP:
  • Phosphagen (sarcoplasm)
  • Glycolytic (sarcoplasm)
  • Oxidative (mitochondria)

Fuel Substrates Rate vs. Capacity

• Characteristics of various energy supply systems are summarized, including the rate of ATP per second, ATP per molecule of substrate, time to exhaustion, and oxygen necessity.
  • Phosphagen: fast, low capacity, no oxygen.
  • Glycolytic: moderate speed, moderate capacity, no oxygen.
  • Oxidative (from carbs): moderate speed, high capacity, needs oxygen.
  • Oxidative (from fat): slow speed, very high capacity, needs oxygen.

Effect of Event Duration and Intensity on Primary Energy Systems

• Exercise intensity determines the primary energy system used.
  • High intensity = faster ATP production.
  • Low intensity = slower ATP production.
• No single energy system provides the complete energy supply during exercise or rest.
• Different time durations and intensities use different energy systems.
  • Short duration, high intensity events (e.g., 0-6 seconds) rely on phosphagen system.
  • Medium duration, high intensity events (e.g., 6-30 seconds) rely on both phosphagen and fast glycolysis or glycolysis.
  • Long duration, medium to low intensity events (e.g., 2-3 minutes) rely on a combination of fast glycolysis and oxidative systems.
  • Very long duration, low intensity events (e.g., >3 minutes) primarily use oxidative systems.

Review Questions

• Understand the ranking of energy systems based on ATP production speed and efficiency.
• Apply bioenergetics information to various exercises and sporting events with varying intensities.

Figure & Notes References

• Key texts and editions providing details on strength training, exercise physiology, and sports nutrition are listed.

Further Information

• This set of slides details the various energy systems used during exercise.
• The energy system utilized is primarily dependent upon both time (duration) and intensity of exercise.
• A table highlights the primary energy systems utilized by various sports.
• ATP production depends on intensity and duration of activity.

Explore the vital role of ATP and different energy systems used during physical activities. This quiz covers various aspects including the functions of the phosphagen system and the requirements of aerobic energy production. Test your knowledge on how these energy systems interact during exercise and their capacities.