VO2 Max WHAT IS YOUR AEROBIC POTENTIAL?
VO2 Max - "the highest rate of O2 consumption attainable during maximal or exhaustive exercise”.
“Aerobic power”, “aerobic capacity” and “maximal oxygen uptake” = VO2 max
Factors affecting VO2 max GENETICS: heredity can account for up to 25-50% of the variance seen between individuals. (e.g. skeletal muscle composition, structure of cardio respiratory). There is a genetic upper limit beyond which, further increases in either intensity or volume have no effect on aerobic power AGE: in general VO2 max is the highest at age 20 and decreases nearly 30 percent by age 65. GENDER: differences in body size and body composition (%body fat), blood volume and hemoglobin content, a woman's VO2 max is in general about 20 percent lower than a man's VO2 max. ENVIRONMENT: Altitude - Because there is less air pressure, the pressure difference between lungs and blood is decreased and less O2 enters the blood, VO2 max decreases as altitude increases above 1600m (5249ft) FITNESS LEVELS: maximal oxygen uptake increase to training. The increase is specific to the training (training type, intensity, timing)
THEORIES OF VO2 max Training Two theories have been proposed: • Utilization Theory: sufficient amount of oxidative enzymes within the cell's mitochondria. The body's ability to utilize the available oxygen that determines VO2 max • Presentation Theory: the ability of the cardiovascular system to deliver oxygen to active tissues. VO2 max is improved with: • Increased blood volume, • Increased cardiac output (due to increased stroke volume) • Better perfusion of blood into the muscles
Review: Cellular Respiration AEROBIC SYSTEM • Glycolysis: 2 ATP (substrate-level phosphorylation) • Kreb’s Cycle: 2 ATP (substrate-level phosphorylation) • Electron transport & oxidative phosphorylation: 2 NADH (glycolysis) = 6ATP 2 NADH (acetyl CoA) = 6ATP 6 NADH (Kreb’s) = 18 ATP 2 FADH2 (Kreb’s) = 4 ATP • 38 TOTAL ATP/glucose
TRAINING AND VO2 max VO2 max change - depends on the starting point. The fitter an individual is to begin with, the less potential there is for an increase VO2 max plateau - further improvements in performance can still occur. • Two major reasons for this are improvements: • in anaerobic threshold • economy in sport technique.
ANAEROBIC • Fermentation: • lactic acid~ pyruvate to lactate
Anaerobic – energy in the absence of O2 There are two systems within Anaerobic metabolism 1. ATP-PC System • The breakdown of ATP increases ADP triggering an enzyme known as CreatineKinase to initiate the breakdown of PC providing the energy required to resynthesise ATP at a fast rate. • We only have 120g of Creatine within our bodies and so this repeated breaking down of PC in order to produce energy to resynthesise ATP is temporary and can only last a maximum of 10 seconds. Therefore the ATP-PC system is used mainly for bursts of speed.
ANAEROBIC Con’t 2. Lactic Acid System • Sometimes also known as Anaerobic Glycolysis due to the initial process being the same as aerobic glycolysis only without oxygen. • Carbohydrate broken down to Pyruvic acid and 2 molecules of ATP. • To try to prevent an increase in acidity the pyruvic acid accepts the H+, forming Lactic acid. • Lactic acid is thought to interefere with muscle contraction due to disrupting the binding of Calcium to Troponin. Acidity also stimulates free nerve endings within the muscle, causing pain. Due to lactic acid production, this energy system can only be predominant for up to 2 minutes.
Lactic Acid vs. Blood Lactate • Not the same thing • Lactic Acid is the endproduct of anaerobic glycolysis • Blood lactate is a salt produced from the recombination of lactic acid and ions • Lactate is an importance substrate that can be used during submaximal exercise, recovery and rest • Training accelerates lactate clearance
Predictor of Performance VO2 max is NOT a good predictor of performance More significant than VO2 max is the speed at which an athlete can run, bike etc. at VO2 max. A high VO2 max may be a prerequisite for performance in endurance events at the highest level BUT…… other markers such as lactate threshold are more predictive of performance
LACTATE THRESHOLD • the speed at lactate threshold is more significant than the actual value itself. • The point during exercise of increasing intensity at which blood lactate begins to accumulate above resting levels, where lactate clearance is no longer able to keep up with lactate production.