Download AIS Chapter 7 Determination of Maximal Oxygen Consumption

AIS Chapter 7
Determination of Maximal
Oxygen Consumption (VO2max)
Oxygen consumption
• VO2 = cardiac output (Q) x arteriovenous O2
difference (a-vO2)
• Cardiac output = heart rate x stroke volume
• During incremental exercise, VO2 linearly
related to power output
– VO2max: VO2 not increase despite increasing power
output
– VO2 plateau or even decrease at intensity higher
than VO2max
Oxygen consumption
• Expression
– ml/kg/min, when body weight unsupported,
running
– L/min when total power output is important, rowing
• Estimated 30-50% variation in VO2max
contributed to genetic factors
• Physical training can increase VO2max by 5-30%
in healthy people
• Simulate the movement pattern of competition
during VO2 tests in athletes
Changes in Cardiac Output心輸出量
• Cardiac output increases due to:
– Increased HR
– Increased SV (stroke volume, 心搏輸出)
• Plateau at ~40% VO2max
• Not enough time for ventricular filling
• Oxygen uptake by the muscle also increases
– Higher arteriovenous difference
• In endurance athletes, SV keep increasing
until VO2max
–  venous return,  EDV,  SV
Changes in Cardiovascular Variables
During Exercise