Measurement of Metabolism
Using the internet or other sources, give the VO2max values for two actual athletes of different sports and provide your source(s) of information.
2. Some of the highest VO2max values every recorded have been in cross-country skiers. Explain why. (FYI it’s not due to training at altitude.)
3. In your own words explain what VO2max represents from a PHYSIOLOGICAL perspective. True, it is a measure of aerobic fitness but it’s also a measurement of what that’s happening inside the body?
Measurement of Exercise Metabolism
Pages 120-122, 123-124, & 125-130.
Objectives
For both VO2 and RER know the following: What is it? How is it measured? Under what conditions is it measured? What can be learned from measuring it?
For both the oxygen deficit and EPOC understand what they are and what each one represents?
Energy Systems
The treadmill said I burned 436 calories. How does it know?
How many of those calories were fat calories?
Measurement of Anaerobic “Energy”: Lactate Threshold
Anaerobic
threshold
Slow glycolysis
Fast glycolysis
Measurement of
Oxidative (Aerobic) Energy
Direct
Calorimetry
40% of energy from ATP is transferred into ATP, the rest is lost as heat
40% of energy from ATP is transferred into ATP, the rest is lost as heat
Indirect Calorimetry
79% N
~17% O2
~4% CO2
79% N
20.97% O2
0.03% CO2
Ventilation
(Liters of air
per minute)
VO2
at rest 3.5 ml/kg/min
VO2max
college aged men 45-50
college aged women 35-40
elite men 80
elite women 70
79% N
0.03% CO2 20.97% O2
VO2
VCO2
79% N
~4% CO2 ~17% O2
Indirect Calorimetry
Measurements made:
O2 content of expired air
CO2 content of expired air
Ventilation
Results:
VO2 – volume of O2 consumed
VCO2 – volume of CO2 produced
Note: does not measure anaerobic energy
Respiratory Exchange Ratio
Respiratory exchange ratio (RER)
RER = VCO2 / VO2
Example 1: Fat (palmitic acid) = C16H32O2
C16H32O2 + 23O2 ↔ 16CO2 + 16H2O + ATP
RER = VCO2/VO2 = 16CO2 / 23O2 = 0.70
Example 2: Glucose = C6H12O6
C6H12O6 + 6O2 ↔ 6CO2 + 6H2O + ATP
RER = VCO2/VO2= 6CO2 / 6O2 = 1.00
Respiratory Exchange Ratio
(RER)
Does not account for the small amount of energy coming from protein or anaerobic energy production
Exercise Metabolism
As exercise intensity increases, so does VO2, and RER
Together, exercise VO2 and RER estimate caloric expenditure
Caloric Expenditure
Assume VO2 = 2.0 liters per minute and an RER of 0.80
Caloric expenditure
= 2.0 liters/min x 4.8 kcals/liter
= 9.60 kcal/min (288 kcal over 30 minutes)
Assume VO2 = 2.0 liters per minute and an RER of 0.95
Caloric expenditure
= 2.0 liters/min x 4.99 kcals/liter
= 9.98 kcal/min (299.3 kcal over 30 minutes)
Carbohydrate: more energy per liter of oxygen
VO2
VO2 is the abbreviation for oxygen uptake or oxygen consumption.
VO2 is the amount of oxygen used by the body for aerobic energy (or ATP) production.
In other words, aerobic metabolism
Basal and Resting Metabolic Rate
How is RMR measured?
What factors influence RMR?
Age, body temperature, stress, hormones, etc.
Exercise Metabolism
Anaerobic
metabolism
Maximal aerobic + Anaerobic
Aerobic + Anaerobic
Aerobic + Anaerobic
Mostly aerobic
Mostly aerobic
slow component of VO2 occurs at intensities above the LT. Takes longer to reach steady state due to the reliance on more type II fibers which are less oxygen efficient.
Maximal Exercise
Metabolic Rate
VO2max
versus
Peak VO2
18-22 year olds: 38-42 for women, 44-50 for men. 77 highest for women, 94 highest for men. Both x-c skiers.
Maximal Exercise
Metabolic Rate
VO2max (maximal O2 uptake)
Untrained young men: 44 to 50 ml/kg/min
Untrained young women: 38 to 42 ml/kg/min
Sex difference due to women’s lower FFM and hemoglobin
Point at which O2 consumption doesn’t increase with further increase in intensity
Best single measurement of aerobic fitness
Not best predictor of endurance performance
Plateaus after 8 to 12 weeks of training
Performance continues to improve
More training allows athlete to compete at higher percentage of VO2max
Maximal Exercise
Metabolic Rate
VO2max normalized for body weight
ml O2 / kg / min (Milliliters per kilogram of body weight per minute)
More accurate comparison for different body sizes
VO2max expressed in L / min (Liters per minute)
Easy standard units
Suitable for non–weight-bearing activities
VO2
VO2 measured at rest = resting metabolic rate (RMR)
Exercise VO2 = submaximal VO2
Highest obtainable VO2 = VO2max or VO2peak
Does regular exercise training increase resting metabolic rate?
How many calories do I burn during recovery from exercising?
Oxygen Deficit and E.P.O.C.
“Aerobic”
supply of
energy
O2 need to preform the activity
Postexercise Oxygen Consumption
Oxygen deficit
Steady-state: all energy needed is provided by aerobic metabolism
Oxygen debt: oxygen taken in above resting values after exercise (EPOC)
Maximizing Recovery
Active recovery
Passive recovery
E.P.O.C.
Low intensity
Moderate intensity
Repeated
high intensity
About 10% of the calories burned during exercise are burned during recovery. May be greater with HIIT.
High Intensity Interval Exercise
Improved insulin sensitivity
Inhibition of glycolysis towards the end of HIIE
Greater increase in catecholamine release
Greater increase in GH
Greater decrease in appetite
Increase insulin sensitivity.
Possible fat metabolism mechanisms:
Inhibition of glycolysis causing an increase in fat oxidation towards the end of HIIE
Greater increase in catecholamine release
Greater increase in GH
Greater decrease in appetite
Ec0n0my of Effort
Training improves economy of effort
Successful Aerobic Athletes
High percentage of type I fibers
High VO2max
High lactate threshold
High economy of effort
Modifiable
Less Modifiable
What accounts for the differences between activities?
Also, need to account for duration of exercise.
Running at 10 mph = 18.2 kcal/min (for 30 minutes = 546 total calories)
Running at 7.5 mph = 14.0 kcal/min (for 60 minutes = 840 total calories)
But can you go more than half as long?
Treadmill exercise burns more calories at a similar level of perceived exertion (discomfort level) than other common types of exercise.
The End