Overview
This lecture covers the phosphagen (ATP-PCr) system, focusing on ATP structure, energy release, creatine phosphate's role in ATP resynthesis, and key aspects of anaerobic energy metabolism relevant to high-intensity, short-duration activities.
ATP Structure & Energy Release
- ATP is composed of adenosine and three phosphate groups with strong negative charges causing repulsion.
- Hydrolysis of ATP releases energy due to the repulsion between the negative phosphate groups.
- Conversion of ATP to ADP (adenosine diphosphate) involves release of one phosphate and energy.
The Phosphagen (ATP-PCr) System
- The ATP-PCr system provides rapid energy for 10-15 seconds during high-intensity activities like sprinting and heavy lifting.
- Phosphocreatine (PCr) donates a phosphate to ADP to quickly regenerate ATP.
- The enzyme creatine kinase catalyzes the transfer of a phosphate from PCr to ADP.
- This system operates in the cytosol and mitochondria, not requiring oxygen (anaerobic).
- Used during explosive movements such as sprints, jumps, and short bursts of exercise.
Creatine Supplementation & Performance
- Creatine supplementation increases PCr stores, allowing greater ATP regeneration and improved performance in short, high-intensity tasks.
- Consistent dosing is necessary for benefits; inconsistent use reduces effectiveness.
- More PCr leads to more available ATP, supporting increased power and muscle work.
- Supplements do not replace effort; they support greater work capacity.
Anaerobic vs. Aerobic Metabolism
- The ATP-PCr system is anaerobic, meaning it does not require oxygen.
- "Aerobic" means with oxygen, "anaerobic" means without oxygen.
- Anaerobic metabolism is predominant during short, intense physical activity.
Key Terms & Definitions
- ATP (Adenosine Triphosphate) — The main energy carrier in cells with three phosphate groups.
- ADP (Adenosine Diphosphate) — ATP after losing one phosphate group and releasing energy.
- Phosphocreatine (PCr) — A molecule that donates a phosphate to ADP for rapid ATP resynthesis.
- Creatine Kinase — Enzyme that catalyzes phosphate transfer from PCr to ADP.
- Anaerobic — Metabolic processes that occur without oxygen.
- Aerobic — Metabolic processes that require oxygen.
Action Items / Next Steps
- Review the posted practice quiz and exam outline found at the top of Canvas under resources.
- Prepare questions for the review session and decide whether to send them via email or discussion post.
- Study Module 3, 4, and the relevant Module 5 videos included in Modules 4 and 5.