Unit 3 Section A Physiology

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ENERGY SOURCES AND SYSTEMS
ENERGY SOURCES
Sources
Glucose ­ a carbohydrate, the main form of carbohydrate found dissolved in plasma and
used as an energy source to resynthesize ATP by cells and muscles.
Glycogen ­ a carbohydrate, the stored form of carbohydrate that is found in muscles and
the liver used as an energy source.
Triglycerides and fats ­ main form of stored fat used as a source.
Protein and lactate.
Phosphocreatine
Effects of high intensity activity on ATP and PC stores
ATP and PC levels decrease during exercise.
Insufficient Stores don't fully recover and there is not enough ATP and PC being
resnythesised in 30 seconds of rest.
During exercise ATP / PC is supplying energy, where the PC breakdown is for ATP
resynthesis.
Then during recovery ATP / PC is resynthesized, but 30 seconds is insufficient recovery
time to fully replenish as it takes 23 minutes for full recovery.
Energy sources and level of intensity
At low level of exercise energy comes from a mixture of fats and carbohydrates.
These are broken down aerobically, using oxygen and the aerobic system.
Glycolysis occurs to break glucose down, into pyruvate.
Beta oxidation breaks down triglycerides.
The Krebs cycle involves the oxidation of acetylcoenzymeA and citric acid production.
In the Electron transfer chain, water is formed with hydrogen ions.
At high levels of intensity carbohydrates are only energy source and as intensity increases,
more carbohydrates are used.
At high intensities fat use is limited by oxygen availability as no fats used anaerobically.
Energy release from fats is slower / quick release of energy from carbohydrates.
Lactic Acid System has no oxygen and anaerobic glycolysis occurs, where glucose is broken
down forming pyruvate and lactic acid formed.
THE ATP SYSTEM
Adenosine triphosphate.
Immediately useable energy source for the first 02 seconds of exercise.
ATP ADP = P = ENERGY
Breaking bonds creates energy.
THE ATPPC SYSTEM
ATPPC system
Uses phosphocreatine.
PC P + C + ENERGY
Breaking bonds creates energy.
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Producing enough energy to resynthesize two molecules of ATP.
Used for the first 2 to 8 seconds of exercise.
PC stores take 3 minutes to replenish
Cons of PC the system
Limited stores of PC.
High intensity exercise can only be completed for brief period of time (8 ­ 10
seconds.)
Full recovery takes up 23 minutes.
Pros of the PC system
Energy is released quickly and doesn't require oxygen.
ATP is resynthesised quickly and the phosphocreatine stores recover quickly.…read more

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OXYGEN CONSUMPTION
Stages of consumption
Resting consumption.
Oxygen deficit.
Oxygen requirement.
Steady state oxygen consumption.
Aerobic capacity.
Oxygen deficit
Energy is provided anaerobically.
Insufficient oxygen is available at the start to provide all ATP aerobically.
This is due to the high intensity demands which is hard for the heart and circulatory
system to meet.
Steady state oxygen consumption
The period of exercise when oxygen consumption matches energy being used.
Aerobic capacity
The maximum rate of which a person can consume oxygen.…read more

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Restore and resynthesize ATP and PC levels.
Reduce lactic acid to normal levels.
Reload myoglobin and haemoglobin.
Restore muscle glycogen.
ATP ­ is constantly restored and it will take 48 to 72 hours to resynthesize to normal. This
requires energy from glycose.
PC ­ the breakdown of PC is reversible, restoring it requires energy from glucose.
Lactic acid ­ 65% converted to pyruvate, 25% converted to glucose, 10% converted to
protein.
Myoglobin ­ oxygen must be reloaded after exercise, creating an oxygen demand.…read more

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They have an increased oxygen carrying capacity and more red blood cells carry oxygen to
the muscle.
OBLA
OBLA
Onset of blood lactate accumulation.
The point at which lactate starts to accumulate within the blood, followed by a huge
increase in it.
This is reached at 4 mmol.
Endurance athletes will take longer to reach 4 mmol.
The higher the VO2 max, the longer time taken to reach OBLA.
This is where the lactate threshold is reached.…read more

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The higher the VO 2 max, the more the delay in lactic acid buildup, meaning as VO
2 max
increases, so does lactate threshold.
Trained athletes can exercise for longer periods at the higher intensities compared to an
untrained athlete.
MUSCLES
STRUCTURE
Skeletal muscles cause our bodies to move.
Muscle fibers contain myofibrils, mitochondria and the sarcoplasmic reticulum.
Muscle fibers contain myofibrils.
The myofibrils contain sarcomeres.
The sarcomere contains the actin and myosin proteins.
Actin is make up of tropomyosin and troponin.…read more

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Slow oxidative.
Fatigue and contract slowly.
Small diameter.
Long twitch duration.
Low force.
High mitochondria, capillary density, triglycerides, oxidative enzymes, capillarisation, and
myoglobin.
Fast twitch (type 2a)
Fast oxidative glycolytic.
Between type 1 and 2b.
Medium force and duration.
Fatigue resistant.
High in oxidative and glycolytic enzymes.
Fast twitch (type 2b)
Fast twitch glycolytic.
Rapid forceful twitches.
Easily fatigued.
Anaerobic and high in PC and glycogen stores.
Fast speed of contraction.
High force of contraction.…read more

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SPECIALISED TRAINING
THERMOREGULATION
Types
Conduction ­ transfer of heat through direct contact.
Convection ­ transfer of heat though gases.
Radiation ­ losing heat through infrared rays.
Evaporation ­ as sweat evaporates heat is lost.
How
Vasodilation
Vasoconstriction
Hypothalamus ­ the thermoregulatory centre in the brain.
Thermo receptors ­ detect changes in heat.
Hyperthermia ­ a condition where body temperatures are elevated.
Hypo hydration ­ a condition where there are very low levels of water in the body.…read more

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Physiological explanation
Muscle spindles detect changes in muscle fibers.
This causes the stretch reflex.
Designed to prevent overstretching.
The aim of PNF stretching is to override the stretch reflex.
The golgi Tendon organs detect overstretching of muscles.
This causes muscles to relax, this is known as autogenic inhibition.
This allows greater range of movement than the initial stretch.
PLYOMETRIC
Aim
It aims to develop power and explosive strength.
This can involve hopping, bounding, depth jumping and medicine ball work.…read more

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The body produces EPO.
Increased concentration / red blood cells.
Increased concentration of haemoglobin and myoglobin.
Increased capacity to carry oxygen.
Increased tolerance to lactic acid and delayed OBLA.
Benefits last for up to 6 to 8 weeks.
Disadvantages
Alternative methods are now available.
This includes hypoxic tents, altitude tents and train low, live high.
Altitude sickness.
Training at same intensity difficult, causing a loss of fitness.
Benefits lost within few days back at sea level.…read more

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