VO2 max, OBLA etc.

  • Created by: z_mills1
  • Created on: 19-05-15 09:50

VO2 max

VO2 Max factors

  • VO2 max definition – maximum volume of oxygen that can be utilised per minute/unit of time
  • Lifestyle – lack of exercise/smoking/poor diet/fitter
  • Training – continuous/aerobic/fartlek improves VO2 max/stamina/ endurance training
  • Age – VO2 max decreases with age
  • Physiology – number of slow twitch fibres/capillary density/number of mitochondria/haemoglobin content/surface area of alveoli/red blood cell count/efficiency of heart 
  • Genetics – inherited factors of physiology limit possible improvement
  • Gender - men generally have approx. 20% higher VO2 max than women
  • Body composition – higher percentage of body fat decreases VO2 max/poor diet reduce VO2 max/overweight/obese 
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Lactate threshold (OBLA)

Lactate threshold -> when the amount of lactate starts to rapidly increase in the blood

  • always have some lactate in blood -> no effect as it is dealt with quickly
  • Onset of blood lactacid accumulation (OBLA) -> the point at which lactic acid (lactate) starts to rapidly accumulate within the blood (intense exercise)
  • OBLA occurs when blood lactate levels exceed 4mmol 
  • lactic acid enerygy system produces more lactic acid than can be dealt with -> acid starts to accumulate in muscles and blood
  • switch from a predominantly aeobic supply of energy to resynthesise ATP to anaerobic lactate methods occurs because of lack of oxygen in mitochondria to comibine with H ions released during glycolysis and kreb's
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Relationship between VO2 max and lactate threshold

VO2 max – the maximum amount of oxygen utilised per minute  

Lactate threshold – the point at which lactic acid starts to accumulate in the blood (OBLA)

  • Lactate threshold is a percentage of VO2 max
  • The higher the VO2 max, the more the delay in lactic acid build-up (OBLA)/as VO2 max increases, so does lactate threshold
  • Trained athletes can exercise for longer periods at the same/higher intensity compared to an untrained athlete/lactate threshold a much higher percentage of VO2 max
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Factors affecting the rate of lactate accumulation

OBLA – Point at which lactate starts to accumulate in the muscle/blood/lactate threshold

  • Starts at 4 mmol/litre
  • Occurs as body is unable to provide enough oxygen to break down lactic acid/change from aerobic energy system to anaerobic energy system
  • Intensity of exercise -> higher intensity the faster OBLA occurs
  • Fitness of the performer -> physiological adaptive responses due to training, e.g. more mitochondria, greater capillary density, improved gaseous exchange
  • VO2 max of a performer/buffering capacity -> higher the level the more delayed OBLA
  • Respiratory exchange ratio/RER -> closer the value to 1.00 quicker OBLA occurs
  • Muscle fibre type -> if slow twitch fibres used, delays OBLA
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