Exercise Physiology

winniesmith2's version from 2017-10-28 19:30

Section 1

Question Answer
What is the efficiency of substrate metabolism 40% of substrate energy--> ATP. 60% of substrate energy--> heat.
How does a calorimeter work Heat production increases with energy production – Can be measured in a calorimeter – Water flows through walls of calorimeter – Body temperature increases water temperature (thermometer accuracy: 0.01°C)
Pros of direct calorimetry – Accurate over (long!) time – Good for resting metabolic measurements
Cons of direct calorimetry – Expensive, slow – Exercise equipment adds extra heat – Sweat creates errors in measurements – Not practical or accurate for exercise
What is the respiratory exchange ratio (RER)VCO2/VO2.
What is the equation for pure carbohydrate oxidation (glucose) O2 + C6H12O6 --> 6 CO2 + 6 H2O (+32 ATP). RER = 6 CO2 / 6 O2 = 1.0
What is the equation for pure fat oxidation (palmitic acid)23 O2 + C16H32O2 --> 16 CO2 + 16 H2O (+129 ATP) RER = 16 CO2 / 23 O2 = 0.7
Each litre of oxygen consumes makes available what amount of energy 5 kcal
If we are using 100% fats to derive energy, what is the RER (respiratory exchange ratio)0.71
For each litre of oxygen consumed when using fat , how much energy becomes available 9 kcal/g
For each litre of oxygen consumed when using carbohydrates, how much energy becomes available 4 kcal/g
How much energy does pure carbohydrate oxidation require32 ATP
How much energy does pure fat oxidation require129 ATP
If I run at a ܄ሶ O2 of 2.0 L/min, how many calories will I burn in 30 minutes?300 kcal. because each litre of oxygen consumed makes 5kcal. 5X2 =10 . 10x 30 mins =300
Indirect calorimetry: limitation • CO2 production in cells may differ from CO2 exhalation (for example, hyperventilation) • RER does not take into account protein oxidation (protein may contribute up to 5% of total energy expended  RER is sometimes referred to as “nonprotein RER”) • Gluconeogenesis (catabolism of amino acids and fats in the liver) produces RER < 0.70 • RER > 1.0: Anaerobic metabolism, hyperventilation  Energy expenditure calculations only valid for RER values between 0.7 and 1.0

Section 2

Question Answer
What is basal metabolic rate (BMR)rate of energy expenditure at rest.
Under what conditions can you measure BMR– In supine position – Thermoneutral environment – After 8 h sleep and 12 h fasting
What does basal metabolic rate showthe minimum energy requirement for living.
What is BMR effected by – Related to fat-free mass, therefore women have lower BMR than men of a similar body mass – Also affected by body surface area, age, stress, hormones, body temperature
What affect does ageing have on basal metabolic rate 2-3% decrease/decade. – Decrease in fat free mass – Increase in body fat – Depression of metabolic activity of lean tissue
What is resting metabolic rateenergy expenditure at rest. – Less stringent rules than for basal metabolic rate – More applicable in many laboratory settings.
At what exercise intensity do i oxidise as much fat as possible (Romijn)65% V02 max.
At what exercise intensity do i oxidise as many plasma FFA as possible (Romijn)85% V02 max
Describe Fat and carbohydrate (CHO) oxidation during incremental cycling (male triathletes, VO2max= 59+5 mL/kg/min. Gonzalez-haro. Page 3, slide 16.
Describe Fatmax and trainability: Untrained vs trained women (܄ሶ O2max = 42 ± 2 and 54 ± 1 mL/kg/min)Fat oxidation, moderate intensityUntrained 0.31 +- 0.01. Trained: 0.38 +- 0.04. Fat oxidation at high intensity; Untrained 0.20+.0.02. Trained 0.27+- 0.04.

Section 3

Question Answer
Describe energy expenditure: energy cost of various activities • Calculated from VO2 and RER; expressed in kcal/min • Values ignore anaerobic aspects, energy expenditure following exercise • Daily expenditures depend on: – Activity level (largest influence) – Inherent body factors (age, sex, size, weight, fat free mass)
What is a MET • Defined as multiples of resting metabolic rate • 1 MET = 3.5 mL/kg/min oxygen uptake
What is V02 for the average sized women200 mL/min. (57 kg x 3.5 ml/kg/min)
What is V02 for the average sized man 250 mL/min (71 kg x 3.5 ml/kg/min)
MET vs kcal • Recap: 1 litre of oxygen consumed: 5 kcal • 1 MET = 3.5 mL/kg/min Resting Vሶ O2  for average sized woman (57 kg): 3.5 mL/kg/min x 57 kg = 200 mL/min, therefore: 1 kcal/min which is 60 kcal/h which is 1500 kcal/day. Running for one hour at 5 MET would result in energy expenditure of ~ 300 kcal.
The compendium of PA tracking guide slide 23. examples: Running at 6mph = 10 METs. Basketball game = 8 METs. Vacuuming = 3.5 METs.
What is the definition of mechanical efficiency (External work accomplished) / (energy expenditure)
What is the mechanical efficiency average value for cycling, running, walking 20-25%. (example: • Cycling: 160 Watts = 2.29 kcal/min • Oxygen uptake at 160 Watts: 2.0 L/min • 2.0 L/min equal to around 10 kcal/min (as 5 kcal per litre O2)  Mechanical efficiency: 2.29/10 = 22.9%). Swimming (more drag); <20%.
How to plot mechanical efficiency page 25. • Homogenous group of athletes (similar Vሶ O2max ) • x‐axis: oxygen consumption at 16 km/h (energy expenditure) • y‐axis: race time (measure for external work accomplished)
Refuelling after exercise OR: Why do we keep breathing heavily after we have stopped exercising?Excess post‐exercise oxygen consumption (EPOC)
EPOC- summary of mechanismspg 28