aerobic capacity Flashcards
1
Q
power vs. capacity
A
- power is the maximum rate at which energy can be utilized
- capacity is the total number of work that can be performed
- you may have an increase in VO2, but might not be able to maintain it
2
Q
why measure aerobic capacity
A
- ultra endurance athletes may have a similar VO2 max as middle distance athletes but the latter cannot match aerobic capacity
- more important to day-day living than other physiological variables used to assess aerobic fitness, especially for exercise prescription
- may have athlete and clinical/health application
3
Q
aerobic capacity
A
- the total amount of work that can be done using aerobic energy sources
- tests need to be of a specific duration to determine / predict the limits of aerobic energy power output
- very difficult to determine validity
4
Q
what is aerobic capacity dependent on
A
- hydration
- glycogen (energy stores)
- lactate clearance (higher ability to clear lactate = better exercise for longer
- muscle soreness
5
Q
what types of tests for aerobic capacity
A
- boulay test
- anaerobic threshold
- submaximal endurance tests
6
Q
boulay’s aerobic capacity test
A
- 90 minute continuous exercise on a cycle ergometer
- intensity set at HR of 10 bpm below PREVIOUSLY determined AT
- want to avoid working above AT
- pedal revs no less than 60 but can be higher
- resistance adjusted throughout the test to maintain the HR intensity
- results in kj/kg
- higher ceiling = increased output and more total work
7
Q
rationale behind the boulay test
A
- VO2 max does not predict the maximal amount of energy that can be generated aerobically
- 90 min significantly stresses mechanisms related to aerobic energy production
- test actually has to be long enough to actually engage aerobic metabolism
- duration does also not require intake of food
- intensity does not engage anaerobic glycolysis if HR is set below AT
8
Q
reliability of the boulay test
A
- ICC for relative work done (kj/kg) = 0.99 and 0.93 for mean HR
- test retest varied less than 2.5%
- validity is hard to compare to normative data
- have to test multiple times
9
Q
limitations of the boulay test
A
- length of the test
- requires determination of AT prior to test; not practical for mass testing, have to do it a second day
- requires precise control of resistance
- dehydration and cardiovascular drift may negatively influence score
- substrate (glycogen) depletion may influence score (variable day-day)
- lack of comparative data available
10
Q
assessment of anaerobic threshold
A
- the highest exercise intensity that you can sustain for a prolonged period without lactate substantially building up in your blood.
- has 2 components : lactate threshold and ventilatory threshold
11
Q
lactate threshold
A
- graded, incremental protocols to near max from VO2 tests
- should use 3-4 minute increments to accurately determine blood lactate levels
- need to produce lactate to measure it
- requires equipment to determine blood lactate which is easy to require
- want to find out when lactate accumulates at what speed
12
Q
single lactate threshold determination
A
- point that proceeds a sustained change in blood lactate greater than 1mM
- graphical method is the most common way to measure
- ## bla vs power output over time
13
Q
regression analysis in single lactate threshold determination
A
- LT is the interaction of 2 regression lines formed above and below inflection
14
Q
d-max method in single lactate threshold determination
A
- largest deviation between the lactate acid vs the W curve and the line connected the end points
- indicates point where LA starts to build (LA threshold
- onset of blood lactate of 4 mM
15
Q
maximal Lactate steady state
A
- assess the maximum blood lactate that can be maintained
- is a functional measurement of intensity
- very time consuming
- requires a series of tests at different intensities preceded by a LT test (requires several days)
- BLa vs. Power output or time
16
Q
ventilatory threshold
A
- graded, incremental protocols to near max
- increments can be 2-3 min
- vo2 in real time, changes in real time to VT
- requires equipment to measure ventilatory threshold
- easier to measure
- helps to buffer lactate accumulation
17
Q
threshold analysis for ventilatory threshold
A
- V-slope method
- VCO2 vs VO2
- uses a metabolic cart `
18
Q
reliability for Ventilatory threshold
A
- LT usually occurs at a similar time or precedes VT by one workload
- test retest is 0.95
- subjective criteria is 0.65
19
Q
field testing anaerobic threshold
A
- uses repetitive intervals of exercise increasing speed over a predetermined distance and measures HR and actual velocity at the end of each interval
- graph HR vs. Velocity and determine the deflection (breakaway) point in HR response
- predicts AT
- validity = 0.93
- reliability = 0.90
20
Q
the PWC170 test
A
- physical work capacity at a heart rate of 170bpm
- suggests to be a capacity test
- two consecutive 6 min POs on a cycle ergometer at 50 - 60rpm
- HR between 120 and 140
- Plot HR vs. PO and extrapolate to HR of 170 and determine PO at 170 or PWC 170
- ROUGHLY predicts power output
21
Q
limitations of submaximal endurance tests of aerobic capacity
A
- makes assumptions on thresholds (170bpm can be above or below capacity)
- usually not long enough to stress AC
- variables selected may not indicate AC
- possible that some submax test intensities are higher than AT
22
Q
does AT actually indicate aerobic capacity ?
A
- in intensity of exercise below AT is attained through aerobic energy sources and above AT, there is an increased need for energy from anaerobic glycolysis , then AT may set the upper limit for AC
-below AT, exercise endurance time is greatly increased and above AT, greatly reduced - endurance athletes completing in events stressing the capacity of the aerobic system have high AT’s
23
Q
can aerobic threshold predict performance
A
- attempted to predict from marathon finishing times
- the 2hr marathon time
24
Q
2hr marathon physiological parameters
A
- VO2 max
- lactate threshold
- ## running economy: vo2 used in a given work intensity
25
Q
exercise economy
A
- influenced by “internal factors” : joint biomechanics , respiratory entertainment (breathing vs. running gate), VO2 drift
- influenced by “external” factors : win resistance, friction, energy absorption, external load
