Chapter 4 - How to measure PA Flashcards
what do we mean by “activity monitoring”?
measure energy expenditure!
- can convert work (J) into kcals
what are ways to monitor PA in the lab (3)? vs outside lab? (4)
LAB:
1. direct calorimetry
2. indirect calorimetry (open circuit spirometry or closed-circuit spirometry)
3. doubly labelled water
OUTSIDE LAB:
1. questionnaires/self reported information (subjective) (journal, interviews)
2. direct observation
3. pedometers
4. accelerometers
- what does direct calorimetry measure? proxy of what?
- how do they measure?
- good ___________ implications but limited ___________ applications
- disadvantages? (4)
- measures heat production directly. proxy of how much work is being done
- put someone in a really big chamber and make them do exercise
- good theoretical implications but limited practical applications in humans
DISADVANTAGES: time, cost, engineering expertise (room would just not work), cannot be used for most sports, work or recreational activities
- what does indirect calorimetry measure? estimates what?
- 2 types –> explain the one that is most used –> measures what? indirectly reflects what?
- measures O2 consumption during PA –> indirect but accurately estimates energy expenditure (bc E production ultimately depends on use of oxygen)
1. closed-circuit spirometry (rarely used)
2. open circuit spirometry: measures O2 consumption and CO2 production (uses metabolic cart) –> indirectly reflects E metabolism
benefits (3) vs disadvantages (6) of indirect calorimetry
- simple, inexpensive, accurate
DISADVANTAGES: - expensive (equipment, technology)
- gas analysers
- one person at time (vs beep test)
- requires calibration for each participant
- no actual measurements
- mainly in laboratory
- what does doubly labelled water procedure estimates? how/process?
- estimates total daily energy expenditure in real life conditions
1. drink doubly marked 2^(H_2)(O_18) (deuterium) (amount based on weight) - oxygen (labeled) is used to make E for PA (ATP)
2. ask them to come back 2 weeks lates –> urine sample at end of monitoring tells us how much O2 was used over time –> estimates E expenditure
- benefits (2) vs disadvantages (3) of doubly labeled water
- used today?
BENEFITS:
- very precise
- real life activity monitoring
DISADVANTAGES:
- expensive (200$ per dose of deuterium)
- burden is placed on participants
- no info on type of exercise and duration
*not really used anymore today
in self-reported PA:
- what is included in journals?
- what are implications of interviews?
JOURNAL:
- start and end times of duration of activity –> more accurate if you log it in real time
- sleep
- shows daily variability
INTERVIEWS:
- requires qualified interviewer
- depends on memory of participants
- some interview may take several minutes
QUESTIONNAIRES:
- how can they be administered (4)
- what is critical?
- what is a problem?
- not recommended for who?
- how to apply worldwide?
- self-administered, administered by face-to-face OR telephone interview, virtual methods
*not as much investigation as during interviews –> just states the questions - period of interest is critical: last week, last month… (not too far back in time! BUT distant past can be interesting to identify) –> ask “was it a typical week for you?”
- recall bias is a problem
- not recommended for children <12 yo
- develop questions (international PA questionnaire) that could be used worldwide –> make comparisons btw questions, translate
benefits (4) and disadvantages (4)of subjective PA monitoring
BENEFITS:
- ability to study populations (PA patterns over time, population shifts?)
- cost-effective
- qualitative information
- context
DISADVANTAGES:
rely heavily on:
- memory
- perceive level of effort
- knowledge of PA
- recall bias
- how can we do direct observation of PA?
- what is a problem?
- benefits (1)
- disadvantages (4)
- direct observation of people or places of interest (ie park, school, street, shopping mall) –> ie exercise time in Phys ed classes, urban areas (metro, widening of sidewalks)
- reactivity can be a problem! if people know they are being monitored
- BENEFITS: qualitative description of activity
- DISADVANTAGES:
- takes lot of time
- limited sample size
- requires highly qualified personnel
- results vary according to experimenter
- where is pedometer placed?
- measures what? doesn’t measure what?
- how does it work?
- best carried on hip! vs shirt
- produces objective measures of steps (although variable results depending on prise and brand). NOT distance travelled or estimates EE
1. horizontal level arm with spring suspensions moves up and down in response to vertical mvt of waist
2. magnetic proximity sensor with glass slide
3. accelerometer consisting of a horizontal beam and piezoelectric crystal
4 advantages vs 4 disadvantages of pedometers
ADVANTAGES:
- relatively inexpensive, reusable and easy to use –> especially in larger research studies
- easy to understand, and require minimal training for data processing
- can be used as motivational tools for intervention work
- immediate info to wearer (ppl can pace themselves + daily goals)
DISADVANTAGES:
- cheapest ones don’t work well
- does not measure speed
- provied limited info about PA (no context, duration or intensity of exercise)
- pedometers have no way to export or timestamp data
- what are 2 types of research grade accelerometers? where are they places, respectively?
ActiGraph:
- placed on hip, thigh, ankle, wrist
ActivPal
- only worn on thigh –> sticky pads + medical grade take –> don’t take it off for a week
- what does ActiGraph measure? (5) used in what context?
vs what does Activ Pal measure?
ActiGraph:
COUNTS per minute for:
- step count
- time spend in various intensities of activity (light, moderate, vigorous) (different cut offs for different populations)
- sleeping time
- sedentariness (not excellent)
- energy expenditure
*used in many population health studies
*time stamped!!
ACTIVPAL:
- steps
- sedentary time (not physical inactivity, best tool to measure this!)
- standing time
- running time
- transitions from sitting to standing AND transitions form standing to sitting
- overal EE
