PE 254

Maximal oxygen uptake

ALSO CALLED:VO2 maxPeak aerobic powerMaximal aerobic powerMaximum voluntary oxygen consumptionCardio-respiratory aerobic capacityMaximal cardio-respiratory fitnessMaximal functional aerobic capacity

VO2 maxA 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

VO2 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

Oxygen deficit/oxygen debtOxygen 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. 

Oxygen deficit/oxygen debt

Factors affecting VO2 maxHeredityAgeSexBody size and compositionTraining statusTypes of muscle fibers used during the

exerciseAltitudeTemperature

Factors affecting VO2 maxHeredity

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.

Factors affecting VO2 maxAge

ChildrenAbsolute values for girls and boys are similar

until age 12At 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

Age related changes in VO2 maxAverage VO2 max in males18-25y 43-4636-45y 35-3946-55y 32-34>65y 25-28

Average VO2 max in females18-25y 39-4136-45y 31-3346-55y 28-30>65y 22-24

Age and VO2max in Healthy Subjects

Factors affecting VO2 maxAdults

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!

Factors affecting VO2 maxSex

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

Factors affecting VO2 maxBody 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 exerciseHighest values are generally found during treadmill exercise, lowest on bicycle ergometer test; specificity is very important

Muscle fiber typeSlow oxidative fibers – highest oxygen consumption

Exercise and VO2 maxMoving from rest to exercise = energy requirementsMetabolism increases in direct proportion to rate of

workAs demand for energy increases so does oxygen

consumption (remember the role of oxidation to produce ATP to do work)

VO2 eventually peaks = VO2 maxVO2 may remain constant at max or drop slightly

even through work intensity continues to increase.Increased O2 consumption with increasing power

output

Other factors affecting VO2max

AltitudeLow partial pressure of O2 in the atmosphereLower partial pressure of O2 in the arterial bloodLower hemoglobin saturation

http://jap.physiology.org/cgi/content/abstract/91/3/1113

TemperatureHigher temperature – higher oxygen consumption

Why VO2 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.

Predicting VO2 maxDirect 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

AdvantagesInexpensive

No training required

Short duration

Safety because of submaximal effort

VO2 can be estimated

HR and BP can be monitored

DisadvantagesMax HR and BP are not measured

VO2max is not measured directly

Limited usefulness

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 testYMCA stationary bicycle protocolBench step test

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

Assumptions made in VO2 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

Relationship between HR and VO2

Calculating VO2max

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)]

Calculating VO2max 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.

Prediction equations for bench step

MenVO2max = 111.33 – (0.42 x HRREC)

WomenVO2max = 65.81 – (0.1847 x HRREC)

HRREC = 15 second recovery HR (bpm)

Pre-test screeningBe 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

Videos on VO2max testshttp://www.youtube.com/watch?v=u5xiJ1qpM

mA&feature=related

http://www.youtube.com/watch?v=18-Fj8ub7Ik&feature=related

http://www.youtube.com/watch?v=xi9ZGl1Ha3o&feature=related

Monday, September 14th

Read Chapter 2 before Monday, September 14th

Please meet at the Fitness Lab, PE 2A (across from the Student Wellness Center) on Monday, September 14th