Exercise Physiology 4

winniesmith2's version from 2018-01-09 11:24

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). Needed to refuel the cells (e.g. replenish high-energy phosphates and resynthesize lactate to glycogen); increased body temp and hormones can further increase EPOC.
EPOC- summary of mechanismsresynthesize ATP and PCr. Resynthesize lactate to glycogen. Oxidise lactate to energy metabolism. Restore ozygen as myoglobin and blood. Restore thermogenic effects of elevated core temperature. Thermogenic effects of hormones (catecholamines). Restore elevated HR, ventilation and other physiologic functions.