What is Oxygen Uptake?
What is VO2 Max?
OXYGEN UPTAKE - VO2
 amount of oxygen consumed per unit of
time (usually 1 minute)
 expressed as VO2
 mean value at rest
= 0.2 to 0.3 l min-1
 VO2 increases proportionally to work
intensity
 up to a maximum value - called VO2max
DRAW A GRAPH TO
ILLUSTARTE THE
DIFFERENCE BETWEEN A
TRAINED AND UNTRAINED
ATHLETE IN RELATION TO
THEIR VO2 MAX
Trained Athlete
Untrained Athlete
AEROBIC CAPACITY
 the ability to do physical work which is
dependant on the aerobic mechanism of
energy supply
STEADY STATE
• the demands of the body for oxygen is
balanced exactly by oxygen uptake
FACTORS AFFECTING VO2 MAX
• Availability of O2 in the tissue
– Is haemoglobin saturated with oxygen at muscle
•
•
•
•
tissue
– Varies individual to individual
– Myoglobin in muscle cells is fully saturated with O2
(has sufficient recovery time elapsed?)
reduction in VO2max will cause decline in aerobic
performance
Age – reduction by 10% per decade
Aerobic training can improve by 10%
Women tend to have greater reductions in VO2 max
DRAW A GRAPH TO ILLUSTARTE VO2
MAX AGAINST AGE FOR TRAINED &
UNTRAINED MALES
ONSET OF BLOOD LACTATE ACCUMILATION
OBLA
 as work intensity increases lactic acid starts to accumulate






above resting values
at a certain point this produces muscle fatigue and pain
the resultant low pH inhibits enzyme action and cross
bridge formation
hence muscle action is inhibited
physical performance deteriorates
this point governs the lactic aerobic threshold
trained athletes begin OBLA at higher work intensities
and higher values of VO2max than untrained people
FOOD FUEL USAGE
FOOD FUEL USAGE
this depends on :
EXERCISE INTENSITY
EXERCISE DURATION
SOURCES OF FUELS
main source of CHO for muscular energy
during exercise is glucose
derived from stored muscle and liver
glycogen
lack of CHO fuel is the limiting factor for
aerobic endurance performance
main source of fat for muscular energy
during exercise is free fatty acids (FFA)
derived from triglycerides stored as
adipose tissue under the skin and in
muscle tissue
FOOD FUEL USAGE FOR AEROBIC ACTIVITY
ADAPTATIONS TO AEROBIC CAPACITY
 cardiovascular system becomes more efficient
 more haemoglobin is created and is available in
blood for oxygen transport
 pulmonary systems become more efficient
 lung volumes increase slightly, greater volumes
of air can be breathed per breath
 Improved oxygen recovery
 Hence reduction in DOMS
 More myoglobin is created in muscle cells
 More and bigger mitochondria in muscle cells