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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
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AIS Chapter 7Determination 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
