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Measuring Exercise Intensity and Energy Usage Flashcards

1
Q

Why is measuring exercise intensity valuable?

A
  • Sustainability of exercise
  • Safety of exercise
  • Severity/progression/management of disease
  • Nature and magnitude of stimulus for adaptation
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2
Q

What are common physical ways to measure exercise intensity?

A
  • Speed
  • Power output
  • Resistance exercise: force
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3
Q

What are common physiological ways to measure exercise intensity?

A
  • VO2
  • Mets
  • Heart Rate
  • Blood lactate
  • Ventilation
  • VE/VO2
  • RER
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4
Q

What are common pyschophysical ways to measure exercise intensity?

A

RPE

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5
Q

What is the first ventilatory threshold (VT1)?

A

The first increase in Ve/VO2 indicates VT1, below which prolonged exercise

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6
Q

What does increase in Ve/VCO2 indicate?

A

Indicates severe exercise, heavy motor unit recruitment, glycolysis and imminent fatigue

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7
Q

What is the second ventilatory threshold (VT2)?

A

The point at which breathing becomes rapid and laboured. Somewhat steady state intensities up to VT2, especially if fit.

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8
Q

What is the ventilatory equivalent of oxygen?

A

How much Ve needed for each L of oxygen used (how much do you need to breathe for each L of oxygen)

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9
Q

What is anaerobic threshold?

A

Can refer to initial threshold or usually the second one

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10
Q

What causes an upward inflection in VE and lactate?

A

Happens for multiple reasons, doesn’t relate simply or casually to increase in glycolysis

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11
Q

What is the main thing driving your breathing?

A

The motor cortex

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12
Q

Why are thresholds difficult to identify and to interpret (esp. for lactate)?

A
  • Lactate response inherently a curve
  • Measurement error
  • Time at each stage affects lactate in blood
  • People differ greatly in ability to sustain exercise at any given lactate
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13
Q

What are smart devices not valid indicators of?

A

Intensity, whether that is:
- Sustainable intensity
- Easy, moderate, severe etc.
- Indicating fat (or CHO) burning
- Predicting fitness outcomes

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14
Q

What are the multiple measures/metrics of smart devices?

A
  • Physical: accelerometers, GPS
  • Biophysical: HR, SaO2, skin temperature
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15
Q

What are the pros of smart devices?

A
  • Measure your own fitness testing/performance
  • Track your intensity
  • Provide motivation
  • Relatively cheap
  • Increasingly pretty well validated for energy use and intensity
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16
Q

What are the cons of smart devices?

A
  • Large dataset
  • Generate a lot of data for someone else
  • Can create false ideals
  • Psychological dependence
  • Aren’t necessarily valid
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17
Q

What is RER?

A
  • Respiratory exchange rate
  • VCO2/VO2
  • The first increase indicates VT1
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18
Q

What does RER >1.00 indicate?

A

Increase in anaerobic glycolysis

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19
Q

What is METS?

A
  • Activity met rate/resting met rate (RMR)
  • 1 MET=RMR ~3.5mL/min/kg
  • So METS are just multiples of RMR
  • METS mainly used in health and PA contexts
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20
Q

What is RPE?

A
  • Ratings of perceived exertion
  • Scales relate to physiological strain, regardless of fitness
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21
Q

What are the 3 ways HR is used to indicate intensity?

A
  • Heart Rate
  • Relative to max: %HRmax = HR/HRmax * 100
  • Relative to its available range: %HRR = (HR-HRrest)/(HRmax-HRrest) * 100
22
Q

What is the functional, easy way to indicate intensity with HR?

A

Heart rate

23
Q

What is the better indicator of relative exertion way to indicate intensity with HR?

A

Relative to max

24
Q

What is the excellent indicator of exertion way to indicate intensity with HR?

A

Relative to its available range

25
What is exercise economy?
Energy expended to maintain constant speed or per unit distance travelled (how much energy does it cost you to do the task?)
26
What is exercise efficiency?
- Metabolic cost of work; WR/MR * 100 - Gross and net efficiency both useful - Only possible if know WR, so economy is a more versatile measure than efficiency is (How much do you get out for what you put in?)
27
What factors influence economy and efficiency?
- Speed of movement - Exercise work rate - Fibre composition of muscles - Training status - Posture and familiarity with activity or ergometer
28
Why measure energy usage?
- The energy use of exercise (fit people use more energy) - As aerobic power - Is one aspect and one measure of exercise intensity - Daily energy usage
29
From best to worst, what are the ways to measure total daily energy usage? (8)
- Doubly labelled water - Smart devices - Heart Rate - Accelerometers - Pedometers - Activity log - Activity recall + BMI - Activity recall
30
From best to worst, what are the ways to measure energy usage in an activity? (5)
- VCO2 with VO2 - VO2 - Smart devices - Workrate or HR - Walking/running speed without knowing body mass
31
Where is most energy lost to during exercise?
- Most energy lost as heat as we aren't 100% efficient at converting chemical energy into mechanical energy - ~2/3 of energy lost just to make ATP oxidatively
32
What percent of metabolic rate is work rate?
The absolute best you can get is 25% (<25%)
33
What state can you measure energy usage in?
Only in steady state
34
What is calorimetry?
- The measurement of metabolic energy transformation - The basis for all types of tests
35
What are the 2 types of direct calorimetry?
- Bomb calorimeter - Whole-body calorimeter
36
What is bomb calorimetry?
Measures energy release from combustion of all foodstuffs (but not all is bioavailable)
37
What is bomb calorimetry useful and not useful for?
- Useful for nutrition and dietetics - Not useful for measuring physiological function eg. in clinical ex phys, sport ex phys and ergonomics
38
What is whole body calorimetry?
Measures body heat production. Sealed, insulated unit
39
What is whole body calorimetry useful and not useful for?
- Useful for nutrition, dietetics, clincial ex phys and research - Disadvantages: expensive, requires specialist expertise, restrictive (type of activity and limited time resolution)
40
What is the indirect measure of calorimetry?
Open-circuit spirometry
41
What is open-circuit spirometry?
Indirectly measure rate of energy use by measuring rate of O2 consumed (also can measured VO2 and CO2 produced)
42
What are the advantages and disadvantages of open-circuit spirometry?
- Advantages: Fairly accurate and easily done (VO2 and CO2 is more precise and easy) - Disadvantages: Doesn't give instantaneous energy usage, only useful if steady state, or extrapolate, expensive (VO2 and CO2 has same issues with lag times and more expensive)
43
What are the main problems of using oxygen consumption to estimate energy usage?
- VO2 doesn't instantly reach steady state; incur and early "oxygen deficit" - Different substances give different energy output per O2 used
44
How much energy per litre of oxygen used do you get from fat compared to CHO?
~6% less energy from fat than CHO per L oxygen
45
What does the ratio of carbon produced per unit of oxygen consumed indicate?
- Whether some energy is not from aerobic metabolism (RER>1.00) - Relative use of fat vs CHO being metabolised
46
What is the respiratory quotient (RQ) for CHO metabolism?
- C6H12O6 + 6O2 --> 6CO2 + 6H2) - RQ = 6CO2/6O2 = 1.00
47
What is the respiratory quotient (RQ) for fat metabolism?
- C16H32)2 + 23O2 --> 16CO2 + 16H2O - RQ = 16CO2/23O2 = 0.70
48
What are some considerations when estimating caloric equivalent from RER?
- Respiratory quotient is at cellular level - RER reflects RQ only with aerobic metabolism - RER > 1.00 reflects loss of CO2 from non-oxidative source
49
What is the gold standard for measuring energy usage and fat and CHO usage?
Using RER with VO2
50
What is the fick equation?
VO2 = HR x SV x Ca-CvO2
51
What do you need to realise about the HR vs VO2 relationship?
- Differs between people - Used as a basis for sub-max testing of aerobic fitness - Fittest person = lowest baseline HR and slowest rise
52
Why predict VO2 (and energy usage) from work rate?
- Common 'measurement' unit of exercise volume in fitness industry - Can be inaccurate esp. with diffs in efficiency - Better validity in cycle ergometry and within subjects - Equations apply to a limited range of intensities - Less suitable for clinical use (disease states)

SPEX203 (6 decks)

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