VO2max.ppt, Factors affecting VO2 , Exercise and VO2 maxMax, O2 Debt, Age related changes in VO2 max

VO2 Max, Exercise Physiology, O2 Debt,Factors affecting VO2 max

1. PE 254

2. Maximal oxygen uptake
ALSO CALLED:
VO2 max
Peak aerobic power
Maximal aerobic power
Maximum voluntary oxygen consumption
Cardio-respiratory aerobic capacity
Maximal cardio-respiratory fitness
Maximal functional aerobic capacity

3. VO
2
max
A maximum rate at which an individual can
consume O2 during maximal exertion.
Expressed as the maximum volume of oxygen
consumed/min
Absolute: litres per min (L/min)
Relative: milliliters per kilogram per minute
(ml/kg/min)
1 MET = metabolic equivalent = A unit used to
estimate the metabolic cost oxygen consumption) of
physical activity = 3.6 ml O2/kg/min

4. VO
2 max depends on
3 systems: Pulmonary, Cardiovascular, Muscular
Cardiac output: stoke volume, heart rate, peripheral resistance
Muscle blood flow: capillary density
Hemoglobin content (oxygen-carrying red pigment of the red blood
corpuscles)
Muscle mass
Muscle fiber type
Oxygen extraction: muscle mitochondrial density, oxidative enzymes
Pulmonary function

5. Oxygen deficit/oxygen debt
Oxygen Deficit.  While exercising intensely the body is sometimes
unable to fulfill all of its energy needs.  Specifically, it is unable to intake
and absorb enough oxygen to adequately 'feed' the muscles the amounts
of energy needed to adequately perform the tasks the athlete is
requesting from the body.  In order to make up the difference without
sacrificing the output, the body must tap into its anaerobic metabolism. 
This where the body goes into a mix of aerobic and anaerobic energy
production.  While not hugely detrimental, oxygen deficits can grow to a
level that the anaerobic energy system cannot cover.  This can cause
performance to deteriorate.
Oxygen Debt.  This term describes how the body pays back its debt
incurred above after the exercise is over.  You will notice that even after
you are done racing you will continue to breath hard.  At this point your
body is still trying to repay the oxygen debt that was created when you
were working hard.  Technically, it is excessive post-exercise oxygen
consumption. 

6. Oxygen deficit/oxygen debt

7. Factors affecting VO
2
max
Heredity
Age
Sex
Body size and composition
Training status
Types of muscle fibers used during the exercise
Altitude
Temperature

8. Factors affecting VO
2
max
Heredity
It is well established that the limits for
developing fitness capacity are linked to genetic
endowment.
Genetic effect is currently estimated at
approximately 20-30% for VO2 max, 50% for
maximum heart rate, and 70% for physical
working capacity.

9. Factors affecting VO
2 max
Age
Children
Absolute values for girls and boys are similar
until age 12
At age 14 VO2 max value for boys 25% > girls and
by age 16, the difference exceeds 50%.
Relative values for boys VO2 max remains level
at about 52 ml/kg/min from age 6-16
http://jap.physiology.org/cgi/content/abstract/65/3/1147

10. Age related changes in VO
2
max
Average VO2 max in males
18-25y 43-46
36-45y 35-39
46-55y 32-34
>65y 25-28
Average VO2 max in females
18-25y 39-41
36-45y 31-33
46-55y 28-30
>65y 22-24

11. Age and VO
2max in Healthy Subjects

12. Factors affecting VO
2 max
Adults
After age 25 its all down-hill (VO2 max declines
at a rate of 1% per year after age 25)
BUT one’s habitual level of physical activity has
far more influence on aerobic capacity than age!

13. Factors affecting VO
2 max
Sex
Even among trained endurance athletes, the sex
difference for VO2 max = 15-20% mainly due to
differences in:
• Differences in body composition
• Hemoglobin (oxygen-carrying red pigment of
the red blood corpuscles) concentration

14. Factors affecting VO
2 max
Body size and composition
An estimated 69% of the differences in VO2 max
scores among individuals can be explained by
variations in body mass
Mode of exercise
Highest values are generally found during
treadmill exercise, lowest on bicycle ergometer
test; specificity is very important
Muscle fiber type
Slow oxidative fibers – highest oxygen
consumption

15. Exercise and VO
2 max
Moving from rest to exercise = energy requirements
Metabolism increases in direct proportion to rate of
work
As demand for energy increases so does oxygen
consumption (remember the role of oxidation to
produce ATP to do work)
VO2 eventually peaks = VO2 max
VO2 may remain constant at max or drop slightly
even through work intensity continues to increase.
Increased O2 consumption with increasing power
output

16. Other factors affecting VO
2max
Altitude
Low partial pressure of O2 in the atmosphere
Lower partial pressure of O2 in the arterial blood
Lower hemoglobin saturation
http://jap.physiology.org/cgi/content/abstract/91/3/1
113
Temperature
Higher temperature – higher oxygen
consumption

17. Why VO
2 testing?
A measure of cardiorespiratory endurance gives
us an indication of the individual’s aerobic
fitness.
Endurance athletes generally have a larger
capacity for aerobic energy transfer.
VO2 max is generally lower (10-20%) for females
than males.

18. Predicting VO
2 max
Direct measurement of VO2 max requires an
extensive laboratory and specialized equipment
as well as considerable subject motivation.
Direct tests are not suitable for measuring large
groups of untrained subjects outside of the lab.
Direct tests are strenuous and thus could pose a
hazard to adults who are not fit

19. Advantages
Inexpensive
No training required
Short duration
Safety because of submaximal effort
VO2 can be estimated
HR and BP can be monitored

20. Disadvantages
Max HR and BP are not measured
VO2max is not measured directly
Limited usefulness

21. Predictive test for aerobic capacity
Although there are many predictive tests available
we only focus on those used most commonly in
the lab
The treadmill test
YMCA stationary bicycle protocol
Bench step test

22. Predictions based on heart rate
Common tests to predict VO2 max use exercise or
post-exercise HR
These tests make the use of the essentially linear
relationship between HR and VO2 during various
intensities of light to moderately heavy aerobic
exercise

23. Assumptions made in VO
2 max predictions
Linearity of HR-VO2 relationship
Similar maximum HR for all subjects
Assumed constant economy or mechanical efficiency
during exercise
Small day to day variations in HR (+/- 5 bpm)
Method is with 10-20 of real values, good for screening

24. Relationship between HR and VO2

25. Calculating VO
2
max
The formulas:

 Male:
108.844 – [lbs./2.2 (0.1636)] – [time (1.438)] – [HR
(0.1928)]
Female:
100.5 – [lbs./2.2 (0.1636)] – [time (1.438)] – [HR (0.1928)]

26. Calculating VO
2
max
Here’s how you do the calculation: 
If you are male, start with the number 108.844. If you are female, begin with
100.5
Calculate your weight in kilograms by dividing your weight in pounds by 2.2.
Then multiply your weight in kilograms by 0.1636. Finally, subtract the
resulting number from either 108.844 (male) or 100.5 (female). Example:
Kathy weighs 139 pounds. (a) 139/2.2= 63.2 kilograms. (b) 63.2 x 0.1636 = 10.34.
(c) 100.5-10.34 = 90.16
Convert the time it took you to jog the mile into a decimal number. Multiply
this decimal number by 1.438. Subtract the result from the last number
obtained in step #2. EXAMPLE: (a) Kathy jogged her mile in 10 minutes and 15
seconds, which is 10.25 minutes. (b) 10.25 x 1.438 = 14.74. (c) 90.16 – 14.74 =
75.42.
To obtain your VO2max, multiply your heart rate (taken right at the end of the
one mile jog) by 0.1928. Subtract the result from the last number obtained in
step #3. Example: Kathy’s heart rate at the end of the mile was 132. (a) 132 x
0.1928 = 25.45. (b) 75.42 – 25.45 = 49.97. So, Kathy’s VO2max is about 50 milliliters
of oxygen per kilogram of body weight per minute. With a VO2max of 50, she
should be able to complete a 5K in around 29 minutes, a 10K in about 41:20, and a
marathon in 3:11.

27. Prediction equations for bench step
Men
VO2max = 111.33 – (0.42 x HRREC)
Women
VO2max = 65.81 – (0.1847 x HRREC)
HRREC = 15 second recovery HR (bpm)

28. Pre-test screening
Be sure to carefully follow ALL procedures in lab
manual
Subject must answer NO to all questions on PAR-
Q (physical activity Readiness Questionnaire)
and sign it in order to carry on with testing
Subject must complete the submaximal testing
readiness questionnaire

29. Videos on VO
2max tests
http://www.youtube.com/watch?v=u5xiJ1qpMmA
&feature=related
http://www.youtube.com/watch?v=18-Fj8ub7Ik&f
eature=related
http://www.youtube.com/watch?v=xi9ZGl1Ha3o&
feature=related

30. Monday, September 14
th
Read Chapter 2 before Monday,
September 14
th
Please meet at the Fitness Lab, PE
2A (across from the Student
Wellness Center) on Monday,
September 14
th