KPE264 midterm

Research Designs

• Longitudinal research involves testing the same subjects and comparing their results over a period of time
• Cross-sectional research involves collecting data from different populations, comparing groups within those populations
• Acute exercise responses refer to the responses to a single session of exercise
• Chronic exercise responses refer to the repetitive responses to exercise sessions

Confounding Variables

• Confounding variables can obscure the true relationship between independent and dependent variables
• Independent variables are what is being manipulated or changed in a study
• Dependent variables are what is being measured and expected to be affected
• X-axis indicates the independent variable on a graph
• Y-axis indicates the dependent variable on a graph

Energy Production

• Bioenergetics is the study of energy transfer through chemical reactions in living tissues
• Chemical energy from food transforms into work
• Energy transfer is also known as thermodynamics
• Energy can take forms such as heat, chemical, mechanical, and electrical
• The first law of thermodynamics states energy cannot be created or destroyed, only transferred
• Breaking down glucose is approximately 40% efficient
• Gas cars are 25% efficient in energy transfer and conversion
• Electrical cars are 80% efficient in energy transfer and conversion

Adenosine Triphosphate (ATP)

• ATP is the primary energy currency in the body
• It contains adenine, ribose (sugar), and three phosphate groups
• ATP converts to ADP (adenosine diphosphate) through the breaking of "high energy" phosphate bond to release energy (hydrolysis)
• ADP converts back to ATP through synthesis for energy storage

ATP and Energy Transfer

• ATP is needed to start things off like activation energy
• Enzymes increase the rate of chemical reactions and are also known as catalysts that do not cause the reaction or alter free energy change
• Enzymes lower the activation energy required for chemical reactions

Enzyme Activity

• Substrate and product concentrations are key regulators of enzymes
• Modulators (e.g., ADP), control when enzymes break down substances, only when needed
• Temperature and pH affect enzyme activity

Substrate Effects

• More substrate result as higher likelihood of enzyme activity
• Vmax is the maximum rate of reaction
• Low substrate concentration results as inactive enzymes, enzymes, and low enzyme rate
• Medium substrate concentrations lead to more binding and increased reaction speeds
• High substrate concentration result as highest enzyme activity and all enzymes are bound

Product and Modulator Effects

• Products of a reaction can stop enzymes from continuing the function through negative feedback
• Stimulators can augment enzyme activity at a given substrate
• Inhibitors can block enzyme binding to the active site

Modulators and Enzyme Activity

• Inhibitors block the enzyme substrate from binding to the active site
• Stimulation involves binding to the enzyme site, opening it and making it more accessible to the substrate

Temperature, pH and Enzyme Function

• Enzymes denature at certain temperatures and are more sensitive to temperature increases
• Normal body pH is 7.1
• Sprinting causes pH to drop, leading to fatigue and slowed enzymes

Sodium Bicarbonate

• Sodium bicarbonate is effective as a buffering agent for short-term and long-term high-intensity exercise
• Buffers can lead to gastrointestinal upset and may not be tolerated well
• Athletes that need to consider sodium bicarbonate include short distance cycling, dragon boating, dancing and hockey (30s shift)
• Sodium bicarbonate decreases muscle activity at rest but increases pH at rest

Bioenergetics and Metabolism

• Bioenergetics studies 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

• The body processes carbohydrates, fats, and proteins through various metabolic pathways
• Lipogenesis, glycogenolysis, glyconeogenesis protein breakdown are some of the important bodily processes

Exercise Metabolism

• Major fuels of exercise include carbohydrates, lipids, and protein
• Carbohydrates are broken down into glucose and stored as glycogen in muscles
• Lipids include fatty acids in the blood and triglycerides stored in adipose tissue and intramuscularly
• Protein breaks down via amino acids
• Key tissues for exercise metabolism are skeletal muscle, liver, and adipose tissue
• Skeletal muscle uses the most oxygen and needs ATP
• Liver stores glycogen
• Adipose tissue stores fat as adipocytes, especially triglycerides

Fuel and Energy Storage

• Average body stores of fuels include both carbohydrates and fats
• Estimates are based on a 65kg person with 12% body fat
• The liver stores approximately 110g of glycogen, offering 451 kcal that help maintain blood glucose
• Muscle glycogen storage offers approximately 500g offering 2,050 kcal
• Glucose accounts for ~15g, 62 kcal stored in body fluids (bloodstream)
• Adipose tissue stores triglycerides (subcutaneous & visceral) -- ~7,800g; 73,320 kcal
• Intramuscular triglycerides totals 161g with ~1,513kcal

ATP Homeostasis

• ATP is broken down into ADP and phosphate (Pi) via ATPase
• ATPase is an enzyme
• Myosin ATPase allows crossbridge formation
• Na+/K+ ATPase helps provide energy to transport sodium
• Energy supply processes include phosphagen breakdown, non-oxidative glycolysis, and oxidative metabolism
• Exercise creates an energy demand or ATP demand and increases ADP while decreasing ATP
• Energy/ATP supply for this demand comes through energy pathways "turned on" by high ADP accumulation and include the PCr system, anaerobic glycolysis, and oxidative metabolism

Muscle Fiber Types

• Type I fibres maintain exercises for prolonged period, require oxygen for ATP production, used for low intensity aerobic exercise and activities
• Type II fibers fatigue quickly, produce more force and ATP anaerobically
• Type IIa fibers are more aerobic compared to Type IIx which are rarely activated

Energy Systems

• Phosphagen, glycolytic, and oxidative are three systems for duration of ATP supply
• Phosphagen supplies a lot of ATP but isn't available for a long period of time
• Glycolytic can be relied on for a longer period of time than phosphagen system
• Oxidative can be relied on for a longer period of time than glycolytic system

Phosphagen Stores, and ATP Production

• Phosphocreatine buffers immediately decreases in ATP
• This instantaneous process quickly depletes these substrates
• Only one unit of ATP formed per unit substrate
• Phosphagen Stores burns quickly

Phosphocreatine

• Creatine comes from meat consumption
• Buffers decline in ATP
• Are at a close site of ADP accumulation
• Creatine supplementation is limited and not effective for a long period of time

Phosphagen System Reliance and Replenishment

• Relied heavily on during the first 15 seconds of intense exercise/forceful movements
• Used during “rest-to-work” transition
• Used during workload transitions
• Takes 5–10 minutes to replenish phosphagen stores

Creatine Supplementation

• Increasing creatine and ATP can lead to greater ADP and PCr
• 90% of Cr storage is in skeletal muscles
• It is effective in those who rely on PCr system, and during brief, intense, repeated exercise
• Older adults may benefit in daily activities
• Concerns include weight gain and fluid balance (supplement retain water in muscles)

Non-Oxidative Glycolysis

• Partial breakdown of glucose/glycogen without oxygen (not as efficient)
• It is rapid but limited by metabolic by-products
• 2-3 units of ATP formed per unit of substrate

Carbohydrates

• Carbohydrate fuels include glucose (C6H12O6) and glycogen which is a glucose polymer
• Glycolysis breaks down 1 glucose to form 2 pyruvate
• Glycogenolysis breaks down 1 “glucose unit" from glycogen to form glucose-1-phosphate

Glycolytic System

• Key points in the glycolytic system are "GLUT" transporter, hexokinase, phosphofructokinase (PFK), substrate level phosphorylation, and NADH
• The "GLUT" transporter allows glucose into the muscle during exercise
• Hexokinase traps glucose in muscle
• Phosphofructokinase (PFK) is a key enzyme
• "Substrate-level phosphorylation” occurs ATP generation in absence of oxygen
• NADH is an important high energy substrate used in ETC to gen ATP
• Net ATP gain from glucose is 2 in glucose or 3 in glycogen
• Liver can take G6-P into glucose

Pyruvate

• Pyruvate can turn into lactate (anaerobic), or acetyl CoA (oxidative)
• To convert to lactate involves lactate dehydrogenase
• NADH is essential to continue this process of glycolysis
• To convert to acetyl CoA involves the pyruvate deydrogenase (PDH) enzyme
• This is an oxidative process in the mitochondria

Lactate Formation

• Lactate formation from Pyruvate regenerates NAD
• Intese excercise causes non-oxidative glycolysis (requires more ATP)
• The "rest-to-work" transition that has low ATP demand also causes elevated lactic acid levels

Increased Lactic Acid

• Increased lactic acid can effect muscle pH
• This results in muscle pH decreasing
• May cause Metabolic inhibition, or contractile inhibition

Lactate

• Lactate is the fulcrum of metabolism
• Lactate anion is formed under fully aerobic conditions for mitochondrial respiration
• Lactate is a major gluconeogenic precursor
• Lactate is also a signaling molecule and stimulates mitochondrial growth

Oxidative Metabolism

• Completes breakdown of Carbohydrates, fattys acids, amino acids to cabon dioixide and water
• Uses all potential energy sources to convert into Cabon dioixide
• Requires Oxgen but provides sustained energy
• Can cause the limitation of ATP to be needed quickly
• Essensial Processes occur in mitochondrion

• 30 units of ATP formed per unit of substrate when there is mitochondrial function

Mitochondria

• Mitochondria is the powerhouse of the cell
• Has an intermembrane that has H+ being pumped accross

Oxidative Metabolism Steps

• Three steps in Oxidative Metabolism -formation of Acetyl CoA (from carbohydrates, fattys acids and amino acids) -Coenzymes can be reduce -Coenzymes are oxidized and Complexes in ETC are reduced

Carbohydrate Oxidations

• Formation of Aceyl coA occurs from carbohydrate breaking Pyruvate (2C)
• Absensce of Oxygen , fate of Prucate = lactic acid
• Pyrucate Dehydroganse -- enzyme in Mitochondria

Acetyl CoA

• Krebs Cycle
• Generates more NADH, FADH2 & ATP
• Important in Oxidation &Reduction by using Electrons with Ox & Red atoms

Oxidative Phosphorylation

• Chemiosmotic Reaction causes Gneration of ATP
• It releases H+ ions accross a membrane

Aerobic Energy Levels

• The body breaks down glucose or glycogen aerobically to create energy during exercise
• Pyruvate Dehydrogenase reaction yields 5 ATP
• The TCA/ETC yields approximately 15 ATP, FADH 3 ATP and approximately 2 ATP

Fatty Acids

• Basic fatty acid structure involves triglycerides, Adipose tissue and Skeletal Muscle
• Involves Lipolysis in the Adipose tissues to get through the body.
• Lipid Catobolism Involve Transport (Albumin protiends), uptakes, activation , beta-oxidation.