Measurement of PA and SB Flashcards
Give reasons why it is necessary to measure children’s PA and SB
allows researchers to establish links between the two behaviours
allows determination of correlations between behaviours and health outcomes
can then re-measure to determine if an intervention has been successful
Explain why it can be complicated to measure child PA
For different people, activity happens at different times of the day and in different ways
A child will demonstrate lots of different behaviours in one day, so can be hard to capture them all
Children’s behaviour is very sporadic and very short lived (80% of PA bouts are below 10 seconds)
This is very hard to capture, especially with questionnaires
When measuring child PA, what variables need to be measured
Duration
Intensity (HR or speed of movement or energy expenditure)
Time of day when children are most active
Type of activity they’re doing
How can information about the timing and type of PA be used
to design interventions
target times when least PA occurs
Know what type of PA children are doing and therefore clearly like to do
Other than information about the PA, what other variables should be measured
Health outcomes associated with a certain level of energy expenditure
What three things need to be considered when deciding which method to use to determine levels of PA
Accuracy
validity
feasibility
What are the limitations of using questionnaires to determine a child’s level of PA
Large cognitive burden to think about and remember all activity (even more of a problem in younger children)
Children may not understand the wording of a question
Children may get bored and not complete it
Parent report is often used, but the child isn’t often with them all day
Bias, often = over-reporting
Inaccurate recall bc of the sporadic nature of child PA it’s hard to accurately recall
Is the time when you’re recording representative of a normal day
What are the limitations of using accelerators to determine PA levels
People often fail to return the monitors which are quite expensive
People may not comply or may not remember to put on
hard to differentiate between sleep and SB
might not have always been the child wearing it, could have been a friend etc
REACTIVITY (upregulation, not representative)
usually around 5% more activity on day 1 vs other days
how do researchers overcome the issue of reactivity when using accelerometers to capture data?
wear for 8 days and exclude the first day
Give reasons why it is not ideal for accelerometers to be placed on the wrist
over-estimates amount of activity and under-estimates amount of time spent sitting because children do a lot of writing which causes movement
Why is it best to get children to wear the accelrometers for as long as possible
data will be more reflective of the daily average
data will be more reliable
there is a higher correlation between activity on each day
child’s routine is more variable so more days = more representative
Briefly explain how accelerometers were validated
children doing various activities whilst undergoing indirect calorimitry and wearing accelerometers
then determine which number of counts corresponds to which level of PA
regressing analysis relates the amount of counts per minute to the intensity of PA
Why is it hard to compare between studies using accelerometer data?
different threshold values used
so differences in amount of PA at each intensity
A child’s activity would be classified in different ways by different papers
What is an epoch and how are they used to determine the intensity of PA
A period of time, over which the number of accelerations is counted
so a threshold would be a certain number of accelerations in a certain period of time, above which PA is classed as MVPA for example
What are the reasons for using a higher sampling frequency
more sensitive at picking up the sporadic activity of children
easier to differentiate between moderate and intensity activity
What is a possible limitation of using a higher sampling frequency?
Over-estimate sedentary behaviour (bc might not reach threshold even if are moving)
why are questionnaires not desirable for measuring SB in children
struggle to remember how long they sat for
don’t follow a set routine like adults do, therefore also harder to estimate
What is a domain specific questionnaire for measuring SB
and what limitations are there with these
asking how long children spend doing a specific SB e.g watching TV
they may be outdated and not include newer behaviours e.g tablets
time consuming
cognitive burden
tend to over-report due to over-thinking caused by the domains
How are accelerometers used to measure SB
what is the limitation of this
a proxy measure, which measure the absence of movement (<100 counts per min = SB)
could measure <100 when standing so this isn’t technically a SB
How does an inclinometer work
Where it is usually worn
device which measures the angle of inclination
(above a certain angle it is very likely that a person is standing)
mid-thigh
explain how an inclinometer is used
when below a certain angle, a person is considered to be sitting or reclined
participants then asked to complete a diary of when asleep so that this can be partitioned out of the data
what are the limitations of using inclinometers
very expensive uncomfortable to wear people may be allergic to the adhesive forgetting to put it back on time consuming to apply safeguarding and cultural issues to applying device to this are
Why are self-report methods of data collection regarding PA useful
simple and cheap relative to other methods
can get info about the type and context of PA
Can get info from a relatively large sample
What are the limitations of using self-report measures in children
Sporadic nature and short duration of PA, makes it very hard to accurately recall
Children over-estimate the duration and intensity of PA
Low validity in younger children, not really suitable for <10
What is a proxy report and in what age of children should they be used
why are they used in these children
asking teachers or parents to report how much PA a child does
avoids the recall bias caused by their limited cognitive ability
What limitation has been found with the use of proxy measures
not well correlated with objective measures of PA
what three variables can be objectively measured with a HR monitor
frequency
duration
intensity
Provide some critique of the use of HR monitors to measure PA levels
Relatively cheap and non-invasive
limited correlation between HR and energy expenditure at high and low intensities
HR - energy expenditure relationship has many influencing factors such as age, fitness and temperature
An impractical method for large scale studies
HR response is delayed after onset of activity which could mask intermittent activity
Explain how an accelerometer is used to determine PA levels
worn around the waist
records frequency and magnitude of body accelerations
this is then digitalised to give an activity count
activity count is summed over a set period of time and then entered into an equation to give the intensity of PA
discuss the factors which are considered when determining epoch length
long epoch could mask spontaneous and discontinuous play
(will result in an under-estimation of high intensity work)
shorter epochs give a better estimation of time spent and MVPA
What needs to be taken into consideration when deciding how long an accelerometer should be worn for
4-5 days needed to get reliable results and good correlation between PA levels on each day
MVPA varies significantly between weekend and weekday so need to include at least one weekend day
give some limitations of the use of pedometers
only count steps so would miss PA such as riding a bike
what are the advantages of the direct observation method
objective data gives context of PA gives types and intensity of PA can be used in many different settings now computer programmes which can analyse video
what are the limitations of the direct observation method
highly trained people needed
can only do a small sample
In what ways can SB be measured
assess time doing screen based activities via:
self report or survey Parental reports direct observation accelerometers (<100 count) May miss other types of SB such as homework, motorised transport, sitting and talking
