Bioenergetics and Anaerobic Metabolic Pathways

• Chapter 2 discusses, "Essentials of Bioenergetics and Anaerobic Metabolic Pathways".

Learning Objectives

• Students will define the three main metabolic substrates and how they produce energy.
• Students will be able to determine which metabolic substrates are dominant during rest and various types of exercise.
• Energy production from the adenosine triphosphate-phosphocreatine system and glycolysis will be explained.
• Positive and negative aspects of phosphagen and glycolytic pathways will be covered.
• How these energy systems adapt through training will be clarified.

Metabolism Applications

• Sprinters can only sprint "all out" for a short time period.
• Marathoners can sustain a race pace for over 2 hours.
• Limiting performance factors should be addressed, and energy origins should be identified.

Why Energy Is Needed

• Muscle contraction demands energy.
• Digestion depends on energy.
• Reproduction draws its energy from somewhere.

What Energy Is

• Energy is the ability to do work.
• Work is a capacity.

Food As Energy

• Food makes energy.

Metabolism

• Metabolism, also known as bioenergetics, transforms food into energy.
• Metabolism encompasses the sum total of all chemical reactions within cells.

Energy Origin

• Plants convert sunlight to carbohydrates.
• Humans and animals consume plants which contain carbohydrates.
• Breakdown of carbohydrates, proteins, and fats yields energy.

Energy Conversion

• Chemical energy from food turns into mechanical energy.
• This results in bodily movement and muscle contraction.
• The 3 types of chemical energy consumed comes from: -Carbohydrates broken down into simple sugars like glucose, fructose, and galactose. -Fats broken down into triglycerides and fatty acids. -Proteins broken down into amino acids.

Macronutrients

• Macronutrients digest into forms usable by the body.
• Carbohydrates break into simple sugars (glucose, fructose, galactose).
• Fats break into triglycerides and fatty acids.
• Proteins breaks into amino acids.

High-Energy Compounds

• Usable forms of nutrients break down into high-energy compounds like ATP.
• Breakdown of ATP releases energy for muscle contraction.

Adenosine Triphosphate (ATP)

• ATP is the energy currency and a biologically useful energy form.
• Energy is released for biological work when bonds like phosphate bonds break.

ATP Breakdown

• Energy releases when a phosphate breaks off.

ATP Supply

• Continual ATP supply needs to match demand.
• Muscle activity slows down due to a lack of intensity and fatigue if ATP production is less than ATP demand.

ATP Supply Challenge

• ATP supply should meet muscle needs.
• ATP has limited storage and is good for ~1-2 seconds of all-out effort.
• ATP resynthesis or replacement is required to allow working the muscle to continue to contract.
• Nutrient breakdown releases energy and achieves this.

Fuel Requirements

• Fuel (substrate) chemical energy must store in chemical bonds.

Substrates Used

• Carbohydrates, fats, proteins, and creatine phosphate (CPR, PC, CP) are substrates used.

Carbohydrates

• Carbohydrates offer rapid and readily available energy sources.
• Carbohydrates contain approximately 4 kcal/g.
• Three carbohydrate forms:
  • Monosaccharides (single).
  • Disaccharides (two).
  • Polysaccharides (many).

Monosaccharides

• Glucose is considered blood sugar, and the primary fuel for energy in the brain.
• Fructose is fruit sugar, it converts to glucose in the liver.
  • Examples of sources includes fruit, honey, and high fructose corn syrup.

Disaccharides

• Disaccharides form by monosaccharides that bond together.

Polysaccharides

• Many monosaccharides bond together to form polysaccharides.
• Includes: Starch, glycogen, and fibre.
• Cellulose forms insoluble fibre.
• Only starch and glycogen digest.
• Glycogen is a storage form of glucose in mammals that stores in the liver and muscles (muscle glycogen).

Glycogenesis

• The term, "genesis" means to make or form.
• Glycogenesis is the process of forming glycogen from glucose.

Glycogenolysis

• The term, "lysis" means to break apart.
• Glycogenolysis is the process of breaking down glycogen into glucose.

Glycogen

• Provides glucose to the muscles. It is found in muscle.
• It helps to maintain blood sugar. It is found in the liver.
• Glucose and glycogen are important substrates during rest and exercise.

Carbohydrates and Energy

• Carbohydrates act as an important fuel source during exercise.
• Glucose constitutes the main brain energy source.
• ATP produces readily, quickly, and rapidly. The con: Depletion can occur after ~2 hours of prolonged exercise.

Carbohydrate Intake

• Carbohydrate content in one's diet influences exercise.

Fats

• Fats metabolize for energy.
• Triglycerides store fat.
  • Consists of 1 glycerol.
  • Consists of 3 fatty acids (4-24 carbon atoms).

Lipolysis

• "Lipo" is lipid.
• "Lysis" breaks down.
• Fatty acids are liberated and produce/make energy.

Fats During Workout

• Fats contain an important resource for energy, as well as protection and insulation.
• Fats transport/store fat-soluble vitamins.
  • ATP is produced slowly.

  • 1/2 ATP is provided at rest.

  • During intense exercise, it offers little production value.

"Not" Depletable

• Fat stores "not" depletable.

Proteins

• Proteins consist of a small energy amount.
• They are acids that link together to form amino.
• Composition between protein, carbohydrates, and fats vary.

Enzymes

• Enzymes enable chemical reactions to occur.
  • Speeds up reactions.
• Enzymes consists of unique shapes and end in -ase. Examples of -ase's encompass:
  • Protease
  • Lipase

Energy Systems/Pathways

• Energy comes from chemical reactions that transform substrates into products.
• Anabolism refers to the process of making newer molecules from smaller ones.
• Catabolism refers to the breaking down of molecules of larger size into smaller molecules.

Anabolism

• Underlies growth and repair.

Catabolism

• Begins with the digestion of foods.
• Substrates are further broken down, causing what happens to release energy.
• This synthesizes ATP.

Muscle Contractions

• Triglycerides break down to create atp in metabolism.

Condensation and Hydrolysis

• Two molecules joins while losing water.

Stored ATP

• Enough stored ATP is kept for 1-2 seconds of activity.

ATP Regeneration

• ATP-PC system creates the ATP.

Energy For High-intensity Efforts

• The phosphocreatine (PCr or PC) system.
• PC is composed of phosphocreatine and creatine, and stores in sarcoplasm.
• ATP production involves a small amount of steps.

ATP Production and PC

• A small number of steps in the ATP-PC system as well as within the muscle, enables quick ATP formation.

Substrate

• The energy source is for activities which require a high intensity and quick energy source.
• Brief duration for 3-15 seconds dominates all out effort by creatine in the inorganic substrate phosphocreatine.

ATP-PC Mechanism

• Energy releases from breakdown of phosphocreatine.
• Pcr Cr + P + energy
• ADP + P + energy ATP
• ATP ADP + P + energy +H

PCr Breakdown

• ATP production is fueled by creatine kinase.

Important Reaction

• ATP increases if enzymes or substrates are increased.

ATP Decline

• Phosphagen declines more rapidly than ATP because its concentration in muscle is initially much greater. As phosphagen is depleted, the rate of glycolysis increases because there is less ATP available to inhibit it.

Fatigue

• The recall that ATP ADP + P + energy +H
• Accumulation of H+ increases acidity, causing fatigue
• H+ is needed for ATP formation
• If ATP breakdown exceeds production then H+ accumulates

Reducing Fatigue

• Production is important.

PC Stores

• Replenishing happens during times of recovery only.
• Depleted, other systems must generate ATP (anaerobic/aerobic metabolism).

Sprinter's Breath

• Accumulation of hydrogen being reduces, and fatigue causes the sprinter to run "all out" for a short duration of time.

Adapting To Exercise

• Mixed results show about changes during creatine kinase activity following training.
• With certain type of training, ATP & PC may increase. Results are mixed.
• Endurance training: has no effect.
• Elevations in content of intramuscular ATP & PC may increase performance in short term, high-intensity.

Creatine Supplements

• Creatine monohydrate exists, and would be beneficial to energy creation in brief high intensity exercises.

Ergogenic Effects

• Short-term benefits emerge with a 5-7 loading period, including high power output and multiple sets.
• Chronic training increases power via building muscle tissue with improved strength.

Creatine

• Muscle PCr increases.
• Creatine with ATP makes phosphocreatine (Pcr) + ADP
• The catalyst for this transformation is Creatine Kinase.

High-Intensity Efforts

• Glycolysis increases with exercise exceeding the capacity of the ATP-PC system.

Glycolysis

• Involves breakingdown glucose and glycogen which leads to pyruvate
  • Referred to as "glucose splitting" Occurs: Sarcoplasm and does not require oxygen.

Glycolysis Production

• 6 carbon molecule splitting turns into;10/11 steps to create ATP

Oxygen Deficient

• Pyruvate is converted into lactate.

Available Oxygen

• Pyruvate converts through glucose/glycogen using the enzyme glycolsis. It makes ATP, Lactid and Acetyl.

Glycolysis Overview

• Anaerobic (fast): not using oxygen
• Aerobic (slower): using oxygen
• Use is dependent on exercise factors: intense level, duration, and fuel type. Glycolysis (Glucose Into Pyruvate) In the same way, these will occur fast or slow.

Glycolysis Details

• Glycogen phosphorylase cleaves glucose to generate glucose 6- P through glycogenolysis.
• Hexokinase catalyses glucose to glucose 6- P.

ATP Usage

• Glucose to glucose 6 phosphate uses ATP unlike glycogen to convert to glucose 6 phosphate.

Enzyme

• The enzyme limiting rate: Phosphofructokinase.
• In order it requires more than one hydrogen as it provides what an aeroic process needs for its glycolysis.

Glycolysis Requirements

• Lactate needs NAD+ in order to continue.
• Mitochondria oxygen is key, but NADH donates h+ to pyruvate.

Why Lactate Matters

• There are 2 options for removing H+, including using O2 or pyruvate to make lactid acid.

Lactate

• Caused by activity of increasing acidity in muscle due to sprint that is accumulated.

Anaerobic Glycolysis

• This leads to the fatigue from the working muscles, such is a burn and pain.
• It will occur due to the oxygen debt that forms due to aerobic metabolism during heavy short bursts.

Recovery

• Occurs in 2-3 minutes and full recovery may be 30 mins

Addressing Fatigue

• Sodium bicarbonate (baking soda), combats build up of acidity.

Glycolysis: Key Points

• Glucose causes ATP to be generated that is short-term. It causes limited time due to build in the system from exercising
• The dominant system for 20-30 seconds of high out put.

Common Adapations

Improved enzyme function leads to better substrate levels.

Enzyme Adaptations

To improved what will increase a high rate comes in muscle and limits fat loss, through Lactid.

Adaptating

Factors that are adapt; in frequency, volume, duration, and intensity Muscle Hypertrophy or weight training has will decrease PFK

Glycogen

With the increase you see the amount in body by starting longer.

Adaptating Buffer

It helps by providing long performance through recovery

Anaerobic Versus Aerobic

Anaerobic : short high intensity Aerobic: long low

Sprint Speed & Energy

• It involves 87% of ATP and 3% are for a small amount of time
• Short distances

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