Chapter 7 - Energy System and Muscle Fibres

Most important and abundant energy source in nature, essential for human life.

Provide materials to build cell membranes.

Glucose is usual form in which carbs are assimilated by humans.

Stored within skeletal muscles and within liver as glycogen.

Long-term energy storage

Provide more than twice the energy per gram compared to carbohydrates or proteins.

High energy density makes them an efficient fuel source for energy production.

Sustained energy release

Stores excess energy primarily in the form of fat.

Energy that can be accessed during periods of fasting or increased energy demand.

Energy or endurance training

Prolonged exercise requires sustained effort, the body relies increasingly on fats as a fuel source.

Glycogen become depleted, prompting the body to turn to fat stores for energy.

Muscle maintenance and repair

Crucial for the maintenance, repair, and growth of muscle tissue.

Proteins are needed to repair and rebuild tissues, contributing to overall muscle health and function.

Energy production

Proteins can contribute to energy production indirectly.

Amino acids can be converted into intermediates generating ATP

Serves as an immediate energy reservoir for the resynthesis of adenosine triphosphate (ATP).

Allows muscles to sustain maximal efforts for up to 10-15 (anaerobic alactic energy system) seconds by providing a quick source of ATP.

Carbohydrates are the body's main source of energy.

Proteins are primarily used for growth, repair, and maintenance of tissues.

Fats are the most energy-dense macronutrient, providing about 9 calories per gram, providing long-term energy reserve.

Glucose is the primary fuel for most cells in the body, especially the brain and muscles during exercise.

Excess glucose is stored as glycogen in the liver and muscles.

Energy source being used is creatine phosphate.

Pathway uses 1 ATP.

No oxygen is used.

10-15 seconds in duration, with no byproducts.

Examples include sprinting, jumping, throwing.

Limitations include short duration, and muscles store low amounts of both ATP and creatine phosphate.

Energy source being used is glucose.

Pathway uses 2 ATP.

No oxygen is used.

15sec-3min duration, with lactic acid buildup as a byproduct.

Examples include 800m sprint, hockey shift, speed skating.

Limitations include lactic acid buildup and muscle fatigue.

Energy source being used is glycogen, fats, and proteins.

Pathway uses 36 ATP.

Oxygen is used.

3min and up in duration, with water and carbon dioxide as byproducts.

Examples include marathon, triathalon.

Limitations include muscle fatigue and lactic acid buildup, along with a great need for oxygen.

Glycolysis

This is the first stage of subpathways.

In presence of oxygen, pyruvic acid is converted into actetyl-CoA.

Krebs Cycle

Second stage of the subpathways.

2 ATP molecules produced at end of stage.

Electrons sent to process in mitochondria.

Electron Transport Chain

Final stage of subpathways.

36 ATP produced with byproducts being water and carbon dioxide.

Series of electron carriers and protein complexes.

Exercise intensity at which the concentration of lactate in the blood begins to rise exponentially.

Marks the transition from aerobic to combined aerobic-anaerobic metabolism.

Organic acid produced in the muscles during intense exercise when oxygen availability is limited.

Produced during the breakdown of glucose in the absence of sufficient oxygen (glycolysis).

Relax tension slowly, low level of tension for long duration.

Red/Dark in colour.

Contains myosin ATPase to provide instant energy for muscle contractions.

Tense and relax quickly, large amounts of tension and low endurance levels.

Pale in colour.

High levels of glycolytic enzymes.

Activate at twice the rate that slow twitch muscle fibres do.

Three Fibre types

Slow-Oxidative (Type I)

Energy generated at slow pace.

Very fatigue resistant.

Depend on primarily aerobic processes.

Red/Dark in colour.

Most efficient for sports such as marathons, biathalons, swimming.

Fast-Oxidative Glycolytic (Type IIA)

Intermediate muscle fibre type.

Higher speed energy release.

Red/White in colour.

Moderate fatigue resistance.

Most efficient for medium distance running events, hockey shifts.

Fast Glycolytic (Type IIB)

Fast contraction without presence of oxygen.

White/Pale in colour.

Very low fatigue resistance.

Produce quickest burst of energy, shortest duration.

Most efficient in short distance sprints and powerlifting.

Aerobic Energy System

Supports sustained aerobic activity by ensuring a steady supply of oxygen to mitochondria.

Oxygen is present.

Crucial for endurance activities like long-distance running, cycling, and swimming.

Anaerobic Energy System

Not directly involved in anaerobic ATP production, myoglobin helps delay the switch to anaerobic metabolism.

Oxygen is not present.

Activities like sprints or high-intensity interval training where there's a quick shift from aerobic to anaerobic.

Stores oxygen in muscle cells for use during intense activity.

Protein found in muscle tissue that binds oxygen and facilitates its transport within muscle cells.

Endurance training can increase myoglobin content in muscles, enhancing oxygen storage and delivery capacity.

Primary energy carrier in cells, composed of adenine, ribose, and three phosphate groups.

Muscle Contraction

Required for muscle fibres to contract and relax.

Binds to myosin, releasing myosin head from actin, and provides energy for the power stroke.

ATP Resynthesis

Creatine Phosphate: Provides a rapid way to regenerate ATP in the ATP-PC system.

Glycolysis: Resynthesizes ATP anaerobically in the absence of oxygen.

Cellular Respiration: Resynthesizes ATP aerobically using the electron transport chain in mitochondria.