Exercise and Physiology

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  • Created by: Cat
  • Created on: 26-11-12 11:22

Aerobic energy systems

ATP is regenerated from glucose and fats in three stages:

Glycolysis (glycogen-->glucose-->pyruvic acid),

Krebs cycle (pyruvic acid diffuses into matrix of mitichondria and complex cycle of reactions occur; production of 2 ATP +C02 +H, C02 breathed out and H taken to electron transport chain)

Electron transport chain (H is caarried by H carriers this occurs in cristae of mitochondria and H splits into Ions and e- which are charged with potential energy. H+ are oxidised to form H20 while H e- provide energy to re-synthesise ATP. 34 ATP are formed.

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VO2 max

VO 2 max: maximum volume of oxygen that can be taken in and used by the muscles per minute.Factors: Gender, Age, Lifestyle, Training, Body composition. Phyiological adaptations: ^max. cardiac output, ^stroke vol./ejection fraction/cardiac hypertrophy, ^HR range, less O being used for heart muscles, so more is available to other muscles, ^A-VO2 diff, ^blood vol. and haemoglobin/red blood cell/blood count, ^stores of glycogen and triglycerides, ^myoglobin (content of muscle), ^capillarisation (of muscle), ^number and size of mitochondria, ^concentrations of oxidative enzymes, ^lactate tolerance, reduced body fat, slow twitch hypertrophy.

OBLA (Onset of Blood Lactate Accumulation) Lactate is produced when H is removed from the lactic acid molecule. OBLA is when lactate rapidly accumulates in the blood. During intense exercise levels of lactic acid rise dramatically. OBLA gives indication of endurance capacity. Lactate threshold is the point at which OBLA occurs. Untrained person will work at about 50-60% of VO2 max whereas trained endurance performer can work at around 85-90% of VO2 max before OBLA occurs.

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EPOC -recovery process

During recovery the body takes in increased amounts of O. The O is transported to the working muscles to maintain elevated rates of aerobic respiration. This surplus energy is used to help return the body to its pre-exercise state. This is known as excess post-exercise oxygen consumption (EPOC).

Fast replenishment stage (alactacid component): restoration of ATP and PC stores and the re-saturation of myoglobin with O.

Slow replenishment stage (lactacid component): concerned woth the removal of actic acid.

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