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AEROBIC CAPACITY II

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					  AEROBIC CAPACITY II

                    APA 2300




AEROBIC CAPACITY II

Functional Capacity

• The extent to which a person can increase
  exercise intensities and maintain these levels
• Determined by persons max ability to convert
  chemical energy to mechanical energy
• Cardiovascular fitness is important component

Aerobic Capacity

• the capacity of the respiratory and cardiovascular
  systems to deliver oxygen to working muscles.
AEROBIC CAPACITY II
Aerobic Metabolism

• Method by which living organisms metabolize
  fuels with the aid of O2 in order to generate
  energy.
• More efficient than anaerobic metabolism.



 Glycolysis                             Electron
                    Krebs Cycle
                                        Transport
                                        Chain




AEROBIC CAPACITY II
Aerobic Metabolism

C6H12O6 + 6O2 → 6CO2 + 6H2O + NRG RELEASED (ATP)



                                        CO2


               Respiration
Fuel + O2                         ATP   + H2O + Heat
AEROBIC CAPACITY II

Endurance

• Ability to perform dynamic muscular work at
  moderate to high levels of intensity for prolonged
  periods of time
• Depends on ability of respiratory, cardiovascular
  and skeletal systems to work together to take in
  O2, transport it to the muscles and use it in
  aerobic metabolism.




AEROBIC CAPACITY II

Maximal Oxygen Consumption (VO2max)

• The maximum amount of O2 an individual can
  utilize during maximum exertion
• Index of maximal functional capacity of
  respiratory, cardiovascular and skeletal muscle
  systems working together
• Considered best measure of cardiovascular
  fitness
AEROBIC CAPACITY II

Maximal Oxygen Consumption (VO2max)

• Expressed as max volume of O2 consumed/min

• Absolute: l·min-1
• Relative: ml·kg-1·min-1

• Normal values - Table 10.1 in lab manual
  (Range: 35 to 75ml·kg-1·min-1)




AEROBIC CAPACITY II

Typical values of VO2max ml·kg-1·min-1

18-25 y old

Excellent                   ≥ 63         ≥ 58
Good                        53-62        48-57
Above average               47-51        42-47
Average                     43-46        39-41
Below average               38-42        34-38
Poor                        31-37        29-33
Very poor                   ≤ 30         ≤ 28
AEROBIC CAPACITY II

Determinants of VO2max

• Cardiac output
  • SV, HR, peripheral resistance
• O2 carrying capacity of blood
  • Muscle blood flow (capillary density)
  • Hemoglobin content


Fick’s Eq. VO2max = HRmax x SVmax x (a-VO2)max




AEROBIC CAPACITY II

Determinants of VO2max

• Ability of muscle to use O2
  • Muscle mass
  • Muscle fiber type
  • O2 extraction (muscle mitochondrial density,
    oxidative enzymes)
AEROBIC CAPACITY II

Factors affecting VO2max

•   Heredity
•   Age
•   Sex
•   Body composition
•   Muscle fiber type
•   Mode & intensity of exercise
•   Training status
•   Altitude
•   Temperature




AEROBIC CAPACITY II

Heredity

• Genetic effect is currently estimated at approx
  20-30% for VO2max, 50% for max heart rate, and
  70% for physical working capacity.

Age

• VO2max begins to decline at about 25yrs (↓ at a
  rate of 1%/yr after age 25)
• BUT, ones habitual level of physical activity has
  far more influence on aerobic capacity than age
AEROBIC CAPACITY II

Sex

• 15-20% difference between men and women,
  even among trained endurance athletes
• Mainly due to differences in;
  • Body composition (musculature, dimensions of 02
    transport system)
  • Hemoglobin concentration
• Differences in training adaptation
      ↑ Cardiac output, mainly due to ↑ SV
      ↑ O2 extraction by muscles (↑ capillarization and more
      mitochondria)




AEROBIC CAPACITY II
AEROBIC CAPACITY II

Body Composition

• Estimated 69% of difference in VO2max scores
  among individuals.
• Mainly influenced by FFM

Muscle fiber type

• O2 consumption capacity varies according to fiber
  type
• Slow oxidative fibers – highest O2 consumption




AEROBIC CAPACITY II

Mode of exercise

• Highest values generally found during treadmill
  exercise, lower on bicycle ergometer
• Values often higher in sports where whole body
  activity is involved and the body mass is not
  supported
• Specificity is very important
AEROBIC CAPACITY II

Intensity of exercise

• O2 consumption is proportional to intensity of
  exercise (% of VO2max)
• VO2 may remain constant at max or drop slightly
  even through work intensity continues to
  increase.
• Estimation of exercise intensity as a percentage
  of VO2max using training heart rate.

            %HRma x= 0.64 * %VO2max + 37




AEROBIC CAPACITY II
AEROBIC CAPACITY II

Training Status

• Exercise that involves large muscle groups, 20-
  60 minutes, 3-5x/wk @50-80% VO2max
• Training can increase VO2max from 15-40%
• Greatest increases in highly deconditioned or
  diseased subjects
• ↑ metabolic capacity of muscle (enlarged
  mitochondria, more mitochondria, more enzymes
  for aerobic nrg transfer, ↑ muscle capilliarization)




AEROBIC CAPACITY II

Altitude

•   ↓ O2 available (PO2) – hypoxia
•   O2 transport capacity ↓ steadily as altitude ↑
•   lower Hb saturation
•   VO2max begins to ↓ at ~ 5000ft (1524m), initially
    ~ 3% every 1000ft but rate of decrease is more
    severe at higher altitudes
AEROBIC CAPACITY II

Temperature

• In general VO2max not affected by a bout in the
  hot or cold
• VO2max is not impaired in heat unless the subject
  is experiencing thermal imbalance when exercise
  begins (↓ 6-8%)
• Severe cold can ↓ VO2max (shivering)




HOT TOPIC

Who has a higher VO2max?

 Soccer player?         Swimmer?              Cyclist?




~ 62 ml·kg-1·min-1   ~ 77 ml·kg-1·min-1   ~ 75 ml·kg-1·min-1
HOT TOPIC

Which type of athlete has the highest VO2max?




                ~ 83 ml·kg-1·min-1




AEROBIC CAPACITY II

Measurements of VO2max must….

• Employ at least 50% of the total muscle mass.
• Be of sufficient duration for cardiovascular
  responses to be maximized.
• Be performed by someone who is highly
  motivated!
AEROBIC CAPACITY II

               Measuring VO2max



      Prediction                     Direct




AEROBIC CAPACITY II
Direct measurement of VO2max

• Indirect, open circuit calorimetry (VE, VO2)
• Automated, computerized equipment
• Symptom-limited maximal graded test to
  exhaustion
• Usually on treadmill or cycle ergometer
AEROBIC CAPACITY II

Direct measurement of VO2max

• HR monitored throughout, often using ECG
• Medical exam required prior to testing
• Physician usually present (tests conducted on
  males 40+ or females 50+ or with 2 or more
  cardiovascular risk factors should be supervised
  by a physician)




AEROBIC CAPACITY II

Direct measurement of VO2max - Advantages

• ↑ accuracy & precision (research, elite athletes,
  assessment or cardiopulmonary status)
• ECG allows direct measurement of HRmax
AEROBIC CAPACITY II

Direct measurement of VO2max – Disadvantages

• Equipment is expensive & requires trained
  technicians to operate
• Subject must be highly motivated to reach true
  max exertion
• Presence of physician may be required
• Not suitable for mass testing
• Overall more time consuming




AEROBIC CAPACITY II

Prediction of VO2max

• Predicted from submaximal tests using exercise
  or post-exercise HR
• Graded exercise test at light to moderately heavy
  intensity (various modalities)
• Uses prediction equations and extrapolation
• Method is within 10-20% of real values
• Useful for documentation of changes in cardio-
  respiratory endurance due to training
AEROBIC CAPACITY II

Prediction of VO2max - Assumptions

• Linear relationship exists between VO2 workload
  and HR




AEROBIC CAPACITY II

Prediction of VO2max - Assumptions

• Similar maximum HR for all individuals
• HRmax is based on the following equation (when
  not measured directly):


          Predicted max HR = 220 - age
AEROBIC CAPACITY II

Prediction of VO2max - Assumptions

• Assumed constant economy or mechanical
  efficiency during exercise
• Small day to day variations in HR (+/- 5 bpm)




AEROBIC CAPACITY II

Prediction of VO2max

Numerous procedures are available:
• Cooper test
• Balke test
• Beep test
• Rockport walk test
• Bruce treadmill protocol
• Åstrand cycle ergometer test

  Some of these tests do not require any physiological
  measurements
AEROBIC CAPACITY II

Example – Bruce Protocol




AEROBIC CAPACITY II

Prediction equations

Men
VO2max(ml/kg/min) = SMVO2 x [(HRMAX – 61) ÷ (HRSM – 61)]

Women
VO2max(ml/kg/min) = SMVO2 x [(HRMAX – 72) ÷ (HRSM – 72)]


Where:       SMVO2 = submaximal VO2 from table
             HRMAX = known HRmax or estimated (220-age)
             HRSM = submaximal HR achieved during test
AEROBIC CAPACITY II

Predicting VO2 max from submax HR




AEROBIC CAPACITY II

Prediction of VO2max - Advantages

• Relatively inexpensive
• Not technically difficult
• Some tests are good for mass testing
• Test duration is usually shorter than direct
  measurements
• Does not require max effort (↑ safety)
• No physician required
• HR & BP can be monitored for appropriate
  responses to exercise at common intensities
AEROBIC CAPACITY II

Prediction of VO2max - Disadvantages

• HRmax, BP and rate-pressure-product are not
  measured
• VO2max not measured directly (prediction errors
  of 10-20%)
• Limited diagnostic use
• True max HR unavailable in prescribing exercise




AEROBIC CAPACITY II

Pre-test screening

•   Select protocol best suited for your subject
•   Follow established protocols
•   Informed consent
•   PAR-Q (Physical Activity Readiness
    Questionnaire) or Submaximal testing readiness
    questionnaire
AEROBIC CAPACITY II




               Questions?




AEROBIC CAPACITY II

Protocols

• http://www.sport-fitness-advisor.com/endurancetests.html
• http://www.exrx.net/Testing/CardioTests.html

				
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Description: The so-called aerobic exercise, also known as "isotonic exercise" means to enhance the body by inhalation, transport and use oxygen for the purpose of the durability of movement. Throughout the course of the campaign, the human body in general and the need for oxygen inhalation of oxygen equal. Aerobic exercise is characterized by low intensity, rhythm, uninterrupted, long duration, and the convenient and easy to adhere to.