AEROBIC CAPACITY

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 CAPACITYthe 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 VO2MAX AGAINST AGE FOR TRAINED &

UNTRAINED MALES

ONSET OF BLOOD LACTATE ACCUMILATION

OBLAas work intensity increases lactic acid starts to

accumulate above resting valuesat a certain point this produces muscle fatigue and

painthe resultant low pH inhibits enzyme action and cross

bridge formationhence muscle action is inhibitedphysical performance deterioratesthis point governs the lactic aerobic thresholdtrained athletes begin OBLA at higher work intensities and higher values of VO2max than untrained people

FOOD FUEL USAGEFOOD FUEL USAGEthis depends on :

EXERCISE INTENSITYEXERCISE DURATION

SOURCES OF FUELSmain source of CHO for muscular energy during exercise is glucosederived from stored muscle and liver glycogenlack 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 CAPACITYcardiovascular system becomes more

efficientmore haemoglobin is created and is available

in blood for oxygen transportpulmonary systems become more efficientlung volumes increase slightly, greater

volumes of air can be breathed per breathImproved oxygen recoveryHence reduction in DOMSMore myoglobin is created in muscle cellsMore and bigger mitochondria in muscle cells