Energy Systems and ATP Production

Energy Systems and ATP Production

• Three energy systems create ATP: oxidative, glycolytic, and phosphocreatine.
• Hydrolysis involves the utilization of chemical energy and water.
• Enzymes, proteins, regulate cellular reactions and body functions. Enzyme names often end in "-ase."
• Energy systems operate at different durations and intensities:
  • ATP-PCR (2-30 seconds)
  • Glycolysis (30 seconds - 2 minutes)
  • Aerobic Respiration (>2 minutes; low to moderate intensity)
• Fat and carbohydrate breakdown occur in the mitochondria.
• ATP-PCR is a readily available energy store.
• Intensity, duration, and fitness level all influence energy system use.
• ATP-PCR:
  • Initial utilization in 5-10 seconds, full utilization in 30 seconds.
  • Used in high-intensity, short-duration activities.
  • Provides short-term energy during exercise.
• Work rate (W) is measured in kilogram meters per second (kgm/s).

Carbohydrate Metabolism (Further Detail)

• Stage 2 carbohydrate metabolism produces 12 NADH+, 6 ATP, 6 Acetyl-CoA, and 6 CO2 (3 molecules after stage 2).

Creatine Intake

• Excessive creatine intake can lead to water retention and weight gain.
• Recommended intake for increasing stores: 20g/week, maintenance: 10g/day.
• Glycolysis can be limited by a shortage of NAD.

Glycolysis Regulation

• Four factors regulate glycolysis:
  • Enzyme regulation (3 glycolytic enzymes):
    • Hexokinase/Phosphorylase (HK): Energy deficit (-1 ATP).
    • Phosphofructokinase (PFK): Energy deficit (-1 ATP).
    • Pyruvate kinase (PK): Energy surplus (+1 ATP).
  • Levels of fructose 1,6-bisphosphate (F1,6BP).
  • Oxygen abundance inhibits glycolysis.
  • Redox Potential regulation (step 6 is critical).

Energy Investment Phase (Glycolysis)

• Total energy cost of the energy investment phase is -2 ATP.
• Oxidation/Reduction (Redox) reactions are central to energy transfer.
• NADH+ is reduced during glycolysis.
• Energy generation phase results in +4 ATP.
• Aerobic conditions (70% of the time) follow successful glycolysis.
• Water hydrolysis is used to produce hydrogen.
• Pyruvate kinase facilitates pyruvate production..

NAD (Nicotinamide Adenine Dinucleotide)

• Oxidized form: NAD+
• Reduced form: NADH+H+
• Pyruvate is a product of glycolysis.
• Enzymes determine specific functions in these reactions.
• Step 6 of carbohydrate metabolism requires NAD to take on hydrogens (reducing NAD+ to NADH).

Lactate Production and Maximal Lactate Steady State

• Pyruvate converts to lactate under anaerobic conditions, buffering hydrogen ions.
• Maximal Lactate Steady State (MLSS) is the highest workload for sustained activity without blood lactate buildup.
• Hydrogen buildup contributes to muscle burn during intense exercise.
• Trained individuals develop a better capacity to handle muscle acidity.
• Central limitations: oxygen delivery capacity.

Citric Acid Cycle (Krebs Cycle)

• Two pyruvate molecules are created per glucose molecule, then enter the citric acid cycle. These enter into Acetyl Coa then to the citric acid cycle.

• Two Acetyl-CoA creates (per glucose): two NADH+H+, 2 CO2 From each Acetyl-CoA, per step of citric acid cycle: 3 NADH+H+, 1 FADH2, 1 ATP, and 2 CO2, multiplied by 2 for 2 Acetyl-CoA = 6 NADH+H+, 2 FADH2, 2 ATP, and 4 CO2.

• Oxaloacetate (4 carbons) binds with Acetyl-CoA (2 carbons) to produce a 6-carbon molecule.

• The citric acid cycle functions twice per glucose molecule.

VO2 Max Test and Energy Systems

• The ATP-PCR system is the primary energy source at the highest intensity during a VO2 max test.

Health and Exercise Recommendations

• The recommended weekly exercise time for health benefits is 150 minutes.
• Beta oxidation is used to breakdown of fats for energy, is a main principle.
• Palmitic acid (16 carbons) is a common fatty acid.
• The citric acid cycle can spin 8 times with a 16-carbon fatty acid (palmitic acid).

Explore the intricacies of energy systems and ATP production through this quiz. From the three primary energy systems - oxidative, glycolytic, and phosphocreatine - to the role of enzymes in cellular reactions, test your knowledge on how the body generates and utilizes energy. Understand how different activities influence energy system usage based on intensity and duration.