1. Oxygen Uptake and Performance
PSE 4U1
Exercise Science
Unit 6

2. Energy and Performance
Major function of the cardiovascular system during exercise is to deliver oxygen to working muscles
Cardiovascular endurance depends on how efficiently the Cardiorespiratory system works, that is, the ability of the lungs, heart and blood vessels to take oxygen and process it and deliver it to working muscles

3. Performance depends on:
Availability of oxygen in the air (approx. 20%)
Diffusion of oxygen from lungs into blood
Chemical binding of oxygen with hemoglobin (CO has times greater affinity to heme than does O2)
Ability of cells to pick up oxygen from the blood in exchange for carbon dioxide and other waste products
Ability to eliminate carbon dioxide through the lungs and start over

4. Maximal Oxygen Consumption
The rate at which oxygen is delivered and used by the body
Abbrev. VO2max or MVO2
Best indicator of cardiovascular (aerobic) fitness expressed relative to body weight, measured as ml/kg/min
The higher the value, the higher the oxygen available for each unit of body weight; therefore, more work can be performed

5. MVO2 / VO2max depends on
Ventilation: the volume of air that can be taken into the lungs/min
Pulmonary Diffusion: oxygen and carbon dioxide exchange in and out of blood (capillaries)
Transportation of Gases: the ability of blood to carry oxygen (hemoglobin)
Cardiac Output: amount of blood that can be circulated per minute (SV x HR)
Ability of muscles to use delivered oxygen (anaerobic threshold-mitochondria)

6. Indices of Cardiorespiratory Fitness
Maximum oxygen uptake (MVO2 / VO2max)
Resting HR
HR during fixed submaximal exercise/load
Endurance performance
Recovery HR

7. Correlation between HR and O2 uptake
As HR increases so too does O2 uptake

8. Anaerobic Threshold Onset of blood lactate accumulation
Percent of VO2 maximum at which one can exercise without producing lactic acid
Anaerobic threshold is approximately 50% of VO2max in an untrained individual and 65% in a trained individual
10-15% increase in VO2max with training compared to an 80-90% increase in anaerobic threshold

11. Lactate Threshold

12. Testing for Anaerobic Threshold
Talk Test:
Difficult to talk because CO2 is held in
Decrease in O2 uptake; therefore, lactic acid increases
Breathing in interrupts speech; therefore, the talk test is effective
Heart Rate:
Percent of max HR will help determine anaerobic threshold

13. Testing for Anaerobic Threshold
Breath Sound Check
O2 binds with hydrogen ion to form H2O
Hydrogen ions produced by lactic acid increases ventilation thereby increasing oxygen uptake
Hearing your breath during exercise allows you to train at your ventilatory threshold

14. Training Adaptations Increase in the amount of hemoglobin
Increase in maximal cardiac output as heart becomes stronger
Capillarization
Increase in size and number of capillaries around muscle fibres, therefore, increasing blood flow and O2 uptake
Increased efficiency in gas exchange
Increase ability of muscle to use oxygen
Increase in Mitochondria
ATP production increases; therefore, you can train longer and harder aerobically (Krebs, Beta Oxi, ETC)
Can increase about 120% after 24 months

15. 7. Increase a-vO2 difference
8. Conversion of FT(b) to FT(a)
Fast twitch muscle fibres become more aerobic
9. VO2max increase in 10-15%
Increase in anaerobic threshold
10. Fibre size (muscle)
Increase; therefore, more actin and myosin available for contraction

16. a-vO2 Difference
Arteriovenous oxygen difference, or a-vO2 diff, is the difference in the oxygen content of the blood between the arterial blood and the venous blood. It’s a good way to see how much O2 is delivered and used by muscle

17. Physiological Adaptations Due to Endurance Training

18. Factors affecting MVO2 / VO2max
Diet
Exercise
Lifestyle