ATP Resynthesis Pathways and Creatine Supplementation
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What are the three main pathways for ATP resynthesis?

  • Glycolysis, phosphagen system, and oxidative phosphorylation (correct)
  • Anaerobic respiration, aerobic respiration, and glycolysis
  • Oxidative phosphorylation, glycolysis, and lipolysis
  • Glycogenolysis, protein catabolism, and glycolysis

    • During exercise, how does the rate of ATP replenishment change compared to rest?

  • It is lower during exercise.
  • It is faster during exercise. (correct)
  • It ceases during exercise.
  • It remains constant regardless of activity.

    • Which of the following is the smallest fuel store in a lean individual?

  • Glycogen storage (correct)
  • ATP storage
  • Protein storage
  • Fat storage

    • What is the net ATP gain from glycolysis?

    <p>2 ATP</p> Signup and view all the answers

    What is the enzyme responsible for breaking down glycogen into glucose?

    <p>Glycogen phosphorylase</p> Signup and view all the answers

    What determines the rate at which muscle will take up glucose from the blood?

    <p>Insulin, exercise intensity, and duration</p> Signup and view all the answers

    Which process does not utilize oxygen?

    <p>Glycolysis</p> Signup and view all the answers

    What is the role of mitochondria in replenishing depleted phosphocreatine (PCr) stores?

    <p>Mitochondria facilitate the conversion of ADP to ATP using oxygen.</p> Signup and view all the answers

    Which enzyme is considered rate-limiting in the glycolysis pathway?

    <p>Phosphofructokinase (PFK)</p> Signup and view all the answers

    How many ATP are produced during glycolysis when glucose is converted to pyruvate?

    <p>2 ATP</p> Signup and view all the answers

    What are the two primary fates of pyruvate after glycolysis?

    <p>Lactate formation and oxidative metabolism</p> Signup and view all the answers

    What does oxidation mean in metabolic terms?

    <p>Loss of electrons</p> Signup and view all the answers

    What role do NADH and FADH2 play in cellular metabolism?

    <p>They transport hydrogen into the mitochondria</p> Signup and view all the answers

    Why is lactate formation beneficial during glycolysis?

    <p>It helps maintain a high rate of glycolysis</p> Signup and view all the answers

    What is the main purpose of the citric acid cycle?

    <p>To harvest energy through the oxidation of acetyl-CoA</p> Signup and view all the answers

    What type of carbohydrate is maltose classified as?

    <p>Disaccharide</p> Signup and view all the answers

    What is the primary function of muscle glycogen during physical activity?

    <p>Acts as an immediate energy source for muscle contraction</p> Signup and view all the answers

    How does liver glycogen primarily function during periods of fasting?

    <p>Regulates and maintains blood glucose levels</p> Signup and view all the answers

    Which carbohydrate loading method has notable disadvantages?

    <p>The classical method requiring glycogen depletion</p> Signup and view all the answers

    What is primarily indicated by the glycemic index (GI) of a carbohydrate source?

    <p>The effect of carbohydrate source on blood glucose levels</p> Signup and view all the answers

    Which of the following benefits is associated with carbohydrate ingestion 1-4 hours before exercise?

    <p>Maximizes recovery and endurance</p> Signup and view all the answers

    What is the effect of carbohydrate intake during long-duration exercise?

    <p>Improves motor skills and enhances recovery</p> Signup and view all the answers

    What is the optimal ratio of glucose to fructose for maximizing carbohydrate oxidation during exercise?

    <p>2:1</p> Signup and view all the answers

    What is the recommended approach for maximizing carbohydrate oxidation during exercise?

    <p>Combining two or more types of monosaccharides</p> Signup and view all the answers

    Which of the following is a disadvantage of consuming solid carbohydrates during exercise?

    <p>Requires additional water for digestion</p> Signup and view all the answers

    What is a negative aspect of liquid carbohydrate supplementation during exercise?

    <p>Sloshing around in the stomach</p> Signup and view all the answers

    During what time frame does the rapid phase of glycogen synthesis occur after exercise?

    <p>30-120 minutes</p> Signup and view all the answers

    What is the relationship between insulin and glycogen synthesis during the second phase after exercise?

    <p>Insulin promotes synthesis</p> Signup and view all the answers

    What is the recommended carbohydrate intake for athletes during heavy training?

    <p>5-10 g/kg</p> Signup and view all the answers

    Where is the greatest storage of fat found in the body?

    <p>Adipose tissue</p> Signup and view all the answers

    Which enzyme is primarily responsible for lipolysis?

    <p>Hormone-sensitive lipase</p> Signup and view all the answers

    Which of the following steps is not part of the fat metabolism process?

    <p>Glycogen synthesis</p> Signup and view all the answers

    What is the crossover point in energy sourcing during exercise?

    <p>When 50% of energy comes from carbohydrate and 50% from fat</p> Signup and view all the answers

    How does successful endurance training affect the crossover point?

    <p>It shifts the crossover point to the right</p> Signup and view all the answers

    What role do mitochondrial enzymes play in fat oxidation?

    <p>They increase oxygen utilization and oxidative energy</p> Signup and view all the answers

    What happens to brain metabolism when switching to a low carb, high fat diet?

    <p>The brain adapts to using ketone bodies instead of glucose</p> Signup and view all the answers

    Where are ketone bodies formed and from which macronutrient?

    <p>In the liver from fatty acids</p> Signup and view all the answers

    Why are protein needs increased on a high fat, low carbohydrate diet?

    <p>To meet energy demands due to low glycogen storage</p> Signup and view all the answers

    Which medical condition may benefit from a low carbohydrate, high fat diet?

    <p>Epilepsy</p> Signup and view all the answers

    What is one proven effect of the low carbohydrate, high fat diet on athletes' exercise metabolism?

    <p>Enhanced fat oxidation while sparing glycogen stores</p> Signup and view all the answers

    Study Notes

    ATP Resynthesis Pathways

    • Phosphagen system: Creatine phosphate (PCr) is used to quickly regenerate ATP.
      • Occurs in the cytoplasm of muscle cells.
      • Provides energy for short bursts of intense activity (e.g., weightlifting, sprinting).
    • Glycolysis: Breakdown of glucose into pyruvate, producing a net of 2 ATP molecules.
      • Occurs in the cytoplasm of muscle cells.
      • Important for moderate-intensity exercise lasting up to 3 minutes.
    • Oxidative phosphorylation: Series of metabolic reactions occurring in the mitochondria.
      • Uses oxygen to generate ATP from glucose, pyruvate, and fatty acids.
      • Provides energy for long-duration, low-intensity activities (e.g., jogging, cycling).

    Creatine Supplementation

    • Creatine supplementation can temporarily increase PCr stores in muscles.
    • Effective for improving performance in activities requiring short bursts of high intensity.

    Glycolysis Details

    • Inputs: Glucose.
    • Outputs: 2 pyruvate molecules, 2 ATP, and 2 NADH.
    • Key Enzyme: Phosphofructokinase (PFK) is the rate-limiting enzyme.
    • Sources of glucose: Muscle glycogen, blood glucose (maintained by liver glycogen and food intake).
    • Glucose uptake: Influenced by insulin, exercise intensity, and GLUT-4 transporter.

    Pyruvate Fates

    • Lactate formation: Occurs when oxygen supply is limited.
      • Used to maintain a fast rate of glycolysis.
    • Oxidative metabolism: Enters the mitochondria for further energy production.

    The Citric Acid Cycle

    • Occurs in the mitochondria.
    • Breaks down pyruvate to generate energy.
    • Produces ATP, NADH, and FADH2 which are used in the electron transport chain.

    The Electron Transport Chain

    • Occurs in the mitochondria.
    • Uses electrons from NADH and FADH2 to generate a proton gradient.
    • This gradient is used to produce ATP.
    • Requires oxygen as the final electron acceptor.

    Carbohydrate Digestion and Absorption

    • Monosaccharides: Simple sugars (e.g., glucose, fructose, galactose).
    • Disaccharides: Two simple sugars linked together (e.g., sucrose, lactose, maltose).
    • Polysaccharides: Long chains of simple sugars (e.g., starch, glycogen).
    • Dietary fiber: Indigestible carbohydrates, contribute to digestive health.

    Muscle vs. Liver Glycogen

    • Muscle glycogen: Provides energy directly to muscle cells.
    • Liver glycogen: Regulates blood glucose levels, supplying glucose to the bloodstream during fasting or low energy conditions.

    Carbohydrate Loading

    • Classical method: Depletes glycogen stores followed by high-carbohydrate intake.
    • Modified method: Gradual carbohydrate increase over several days.
    • Disadvantages of classical method: May lead to muscle fatigue and discomfort.

    Glycemic Index (GI)

    • Measure of how quickly a food raises blood glucose levels.
    • High GI foods are rapidly digested and absorbed.
    • Low GI foods are digested and absorbed more slowly.

    Carbohydrate Intake Recommendations Before Exercise

    • 1-4 hours before exercise: High-carbohydrate meals or snacks (e.g., pasta, potatoes, fruit) to maximize glycogen storage and provide glucose for intestinal absorption.

    Carbohydrate Intake During Exercise

    • Duration and intensity: Crucial factors determining the need for carbohydrate intake during exercise.
    • Liquid form: Provides rapid absorption and gastric emptying.
    • Solid form: More energy dense but can cause slower digestion.
    • Combined forms: Mixes of liquid and solid forms of carbohydrates.

    Glycogen Resynthesis after Exercise

    • Rapid phase: Occurs within the first 2 hours after exercise.
    • Slow phase: Occurs from 2 to 24 hours after exercise.

    Factors Affecting Glycogen Resynthesis Rate

    • Insulin: Increases glucose uptake and glycogen synthesis.
    • GLUT-4: Transporter responsible for glucose uptake in muscle cells.
    • Glycogen synthase: Enzyme that catalyzes glycogen synthesis.

    Carbohydrate Intake Recommendations After Exercise

    • Immediate: Consume carbohydrates to facilitate glycogen resynthesis.
    • Later events: Consume carbohydrates to ensure adequate glycogen stores for subsequent exercise.

    Daily Carbohydrate Recommendations for Athletes

    • Moderate to heavy training: 5-10 grams of carbohydrate per kilogram of body weight per day.

    Fat Metabolism

    • Lipolysis: Breakdown of triglycerides into fatty acids and glycerol.
    • Key enzyme: Hormone-sensitive lipase (HSL).
    • Activation: Triggered by hormones (e.g., adrenaline, cortisol) and low insulin levels.
    • Transport: Fatty acids are transported in the bloodstream bound to albumin.

    Crossover Concept

    • As exercise intensity increases, the body relies more on carbohydrates as a primary source of fuel.
    • The crossover point is when 50% of energy is derived from carbohydrates and 50% from fat.
    • Endurance training shifts the crossover point to the right, allowing athletes to utilize fat as fuel for longer periods.

    Fat Oxidation and Training

    • Mitochondrial adaptation: Increases in mitochondrial enzymes improve oxidative capacity.
    • Cellular transport: Improved uptake of fatty acids from the bloodstream.
    • Cardiovascular improvements: Increased blood flow and oxygen delivery to muscles.

    Low-Carb, High-Fat Diet

    • Adaptation: Liver produces ketone bodies from fatty acid breakdown.
    • Brain fuel: Ketones become the primary energy source for the brain.
    • Increased protein needs: Glycogen stores are depleted, leading to increased protein breakdown to provide energy.

    Ketone Bodies

    • Formed in the liver from fatty acids.
    • Used as an alternative fuel source by tissues like the brain.

    LCHF Effects on Exercise Performance

    • Increased fat oxidation: Spares glycogen stores allowing for longer endurance.

    Medical Conditions

    • Epilepsy: Low-carb, high-fat diets may reduce seizures.

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    Description

    Explore the various pathways of ATP resynthesis including the phosphagen system, glycolysis, and oxidative phosphorylation. Learn how creatine supplementation can enhance performance in high-intensity activities and its impact on muscle energy. This quiz is ideal for students studying exercise physiology or related fields.

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