Lab 7 VO2 Background Reading Flashcards
What is aerobic fitness
ABILITY to EXERCISE CONTINUOUSLY for EXTENDED PERIOD OF TIME WITHOUT TIRING.
Another name for aerobic fitness
CV endurance
Aerobic fitness is important for what sports
ENDURANCE SPORTS e.g distance running, cycling, rowing
What 6 factors influence amt of O2 that can be transported by the body
- Amt of O2 delivered into lungs
- Effective SA of alveoli in lungs
- Saturation lvl of Hb in RBCs w/O2
- Movement of blood thru circulatory system
- Dissociation of O2 from RBCs
- Association of O2 w/tissue in working muscles
What 3 factors affect utilization of O2 by working muscles
- INTENSITY of work being performed
- SOURCES of nrg (carbs and fats) available to the cells in the muscles
- Metabolic pathways used to make nrg required by the muscles
What is VO2max
Maximum O2 uptake (VO2max) is the highest rate of O2 utilization that a healthy person can attain during exhaustive (“maximal”) muscular exercise of approx 6-12 mins duration, when breathing air at approx sea level and working on treadmill, stepping bench, bicycle ergometer or performing similar types of exercise activating large muscle groups
In activities where body mass must be moved against force of gravity (e.g. walking, running, cycling on road, and most other activities) VO2 is most appropriately expressed in what units to more fairly compare people of diff sizes
mL of O2/ kg / min
4 reasons why VO2max is measured
- Good measure of CARDIORESPIRATORY FITNESS e.g. fxnal capacity of the circulation
- Evaluation of ENDURANCE TRAINING PROGRAM
- SCREENING of people for various tasks – work, sport, etc
- CLINICAL EVALUATION of patients w/CV and/or pulmonary disease
What are the 6 methodological criteria for administering a maximum O2 uptake test?
- Work should involved LARGE MUSCLE GROUPS
- CONTINUOUS WORK performed at GRADUALLY INC INTENSITIES. Thus, the approach of fxnal limitations should be detectable w/sufficient discriminatory accuracy
- Work INTENSITY should be selected so that the subject will be EXHAUSTED in 7-10 mins AFTER WARM-UP
- WORK RATE should be sufficiently heavy so that O2 uptake doesn’t entirely correspond w/nrg requirement of work load (non-steady work)
- WORK RATE must be MEASURABLE and REPRODUCIBLE
- Test conditions must be such that RESULTS are COMPARABLE and REPRODUCIBLE
What are the determinants of VO2max? 6 peripheral factors, 6 central factors
Peripheral factors:
- Muscle BF
- Capillary diffusion
- O2 diffusion
- Mitochondria density
- Hb-O2 affinity
- Muscle fibre profiles
Central factors:
- CO
- Arterial pressure
- Hb
- Ventilation
- O2 diffusion
- Hb-O2 affinity
What are the factors affecting VO2max? 6 intrinsic factors, 6 extrinsic factors
Intrinsic:
- Genetic
- Gender
- Body composition
- Muscle mass
- Age
- Pathologies
Extrinsic:
- Training status
- Time of day
- Sleep deprivation
- Dietary intake
- Nutritional status
- Environment
What are the 5 criteria for reaching VO2max
- O2 consumption ceases to inc linearly w/rising work and approaches plateau or drops slightly, the last 2 values agreeing w/in +/- 125 mL (1.5-2.0 mL/kg)
- Blood lactate levels 8.0 mM/L or greater, 3-5 mins after cessation of exercise
- HR close to predicted max (220-age)
- RER greater than 1.15
- Subjective fatigue, exhaustion, and an inability to continue
What is RQ
VdotCO2/VdotO2 at the CELLULAR level
- VdotCO2 = CO2 production in L/min
- VdotO2 = O2 production in L/min
What is RER
VdotCO2/VdotO2 at the LUNG level
- VdotCO2 = CO2 production in L/min
- VdotO2 = O2 production in L/min
What is the highest RQ can go
1.0 (while metabolizing carbs which have equal # of O2 and CO2 molecules)
What the highest RER can go
1.70
Why can RER be higher than RQ
RER exceeds RQ during hyperventilation as additional CO2 is evolved from bodys stores via bicarbonate buffer system
3 equations for VdotO2
- VO2 = O2 inspired - O2 expired
- VO2 = (volume inspired air/min x %O2) - (volume of expired air/min x %O2)
- VO2 = [ VI (STPD) x FIO2] - [VE (STPD) x FEO2]
If the air sample entering O2 analyzer hasn’t been completely dried, will FIO2 be greater or less than 0.2094
Slightly less
Equation to calculate VdotI?
VI (STPD) = VE (STPD) x FEN2 / FIN2
Equation for VdotCO2?
VCO2 = [VE (STPD) x FECO2] - [VI (STPD) x FICO2]
Manual vs. automated method for measuring VO2max?
Manual:
- Expired gas collected in meteorological balloons during exercise. O2 and CO2 content in balloons determined by analyzing small sample of gas. Entire contents of balloon squeezed thru ventilation meter
Automated:
- O2 and CO2 conc of expired air from subject measured using GA. Samples of gas continuously drawn from mixing box to GA. Lung ventilation volumes recorded using spirometer flow head. HR measured with HR monitor. VO2 and VCO2 calculated by computed fxns built into recording software.
