KPE264 Module 1: Research & Exercise Metabolism

• KPE264 Module 1 notes cover research designs, confounding variables, energy production, ATP, enzymes, effects of temperature/pH, and exercise metabolism.

Research Designs

• Longitudinal research tests the same subjects over time and compares the results.
• Cross-sectional research collects data from different populations and compares groups within those populations.
• Acute exercise responses refer to the body's reactions to a single exercise session.
• Chronic exercise responses refer to the body's reactions to repeated exercise sessions.

Confounding Variables

• A confounding variable influences both the independent and dependent variables, creating a spurious association.

Energy Production

• Bioenergetics studies energy transfer through chemical reactions within living tissues.
• Chemical energy from food is transferred to work.
• ATP must be created to do work
• Energy transfer follows the principles of thermodynamics.
• The first law of thermodynamics states that energy cannot be created or destroyed, only transferred from one form to another, with some energy lost as heat.
• The efficiency of energy transfer varies: 40% for glucose breakdown, 25% for gas cars, 80% for electrical cars.
• ATP (Adenosine Triphosphate) is the primary energy currency.
• ATP consists of adenine, ribose (sugar), and three phosphate groups linked by high-energy bonds.
• ATP becomes ADP through hydrolysis, which breaks down ATP.
• ADP becomes ATP through synthesis.

Importance of ATP in Energy Transfer

• ATP is needed to initiate processes.
• Enzymes control reactions, lowering activation energy.
• ATP is regenerated by fuel sources.

Fuel Sources to Regenerate ATP

• Phosphocreatine (PCr)
• Carbohydrates (glucose, glycogen)
• Fats
• Proteins

ATP Storage

• Only small amounts of ATP are stored because approximately 1 kg of ATP is consumed per hour at rest.
• ATP use can increase 100-fold during exercise.
• ATP supplements may or may not be effective.
• Benefits may only provide ~0.04s of energy.
• The supplement's ability to survive the digestive system is a consideration.

Bioenergetics

• Chemical reactions are facilitated by enzymes.
• Enzymes increase the rate of chemical reactions without being consumed ("catalysts").
• Enzymes do not cause the reaction, alter free energy change, but require lower "activation energy”.

Enzyme Mechanisms

• Substrates bind to the enzyme's active site, forming an enzyme-substrate complex.
• The enzyme-substrate complex transitions to a "transition state" instantaneously.
• The complex then forms a product

Factors Affecting Enzyme Activity

• Substrate and product concentrations are key regulators.
• Modulators (e.g., ADP) control the rate of breakdown.
• Temperature
• pH.

Effect of Substrate on Enzyme Activity

• More substrate leads to a higher likelihood of enzyme activity.
• Vmax represents the maximum rate of reaction.
• Low substrate concentration means inactive enzymes and a low enzyme rate.
• Medium substrate concentration increases binding and reaction speed.
• High substrate concentration maximizes enzyme activity, with all enzymes bound.

Effect of Product on Enzyme Activity

• By-products can stop an enzyme from continuing its function through negative feedback.

Effect of Modulators

• Stimulators augment enzyme activity at a given substrate.
• Inhibitors reduce enzyme activity.

Modulators

• Inhibition blocks the enzyme's active site.
• Stimulation binds to the enzyme.

Effect of Temperature and pH on Enzyme Activity

• Enzymes denature at certain temperatures.
• Enzymes are more sensitive to temperature increases.
• Normal body pH is 7.1.
• Enzymes operate best at 7.0 pH.
• pH drops and causes fatigue during sprinting, slowing down enzymes.

Ergogenic Effects of Sodium Bicarbonate

• Sodium bicarbonate effectively buffers both short-term and long-term high-intensity exercise.
• Buffers can cause GI upset.
• Athletes who may benefit are: short distance cyclists, dragon boaters, dancers, and hockey players (30s shift).
• Sodium bicarbonate decreases muscle activity at rest and raises pH.

Bioenergetics and Metabolism

• Bioenergetics is the study of energy transfer through chemical reactions in living tissues leading to metabolism.
• Metabolism is the sum of all chemical reactions in the body.
• Catabolism is the breakdown of molecules during exercise.
• Anabolism is the synthesis of molecules during recovery.

Cellular Metabolism

• Includes the interactions between fats, carbohydrates, and proteins in the body and processes like lipogenesis, lipolysis, and glycogenesis.

Exercise Metabolism

• Major fuels include carbohydrates (glucose, glycogen in muscle), lipids (fatty acids in blood, triglycerides stored in adipose tissue and intramuscularly), and protein (amino acids).
• Skeletal muscle uses the most oxygen and needs ATP; by-products end up in the liver (lactate).
• The liver is also important.
• Adipose tissue stores fat in adipocytes and triglycerides.

Average Body Stores

• Average body fuel stores for a 65kg person with 12% body fat include carbohydrates (4cal/gram of energy)
  • Liver glycogen (110g; helping maintain blood glucose levels during exercise)
  • Muscle glycogen (500g; largest storage)
• Glucose in body fluids (15g).
• Fat (9cal/gram)
  • Adipose tissue triglycerides (7,800g)
  • Intramuscular triglycerides (161g).

ATP Homeostasis

• ATP homeostasis balances supply and demand.
• ATP + H2O is converted to ADP + Pi by ATPase
• Ca2+ ATPase and Myosin ATPase are types of ATPases involved in muscle function.
• Na+/K+ ATPase transports sodium.

ATP Supply

• Energy/ATP comes from phosphagen breakdown, non-oxidative glycolysis, and oxidative metabolism, turned on by high ADP accumulation.

Energy Demand

• Exercise creates an energy demand or ATP demand.
• ADP increases, and ATP decreases.
• ADP generates ATP in the energy pathways.

Muscle Fibers

• Type I fibers (slow twitch) maintain exercise for prolonged periods.
• They require oxygen for ATP production.
• They are primarily recruited for low-intensity aerobic exercise and daily activities and are heavily relied on.
• Type II fibres (fast twitch) fatigue quickly and produce more force.
• These fibres produce ATP anaerobically and include Type IIa and Type IIx.
• Type IIa fibres are more aerobic, while Type IIx fibres are rarely recruited.

Fibre Characteristics

Module 1 covers research designs like longitudinal and cross-sectional studies, confounding variables, and energy production principles. It also explores ATP, enzymes, temperature/pH effects, and exercise metabolism. Bioenergetics studies energy transfer, essential for bodily functions.