Sedentary behaviour Flashcards
the whole proposition of the sedentary behaviour class?
sedentary behavior (too much sitting) is a deeply-embedded public health problem, which is additional to lack of physical activity (too little exercise)
what is a confounder?
- what are confounders for sitting too much being a risk factor for all-cause mortality?
- a variable that correlates with both x and y –> causes confusion in true relationship
- sex, age, genetics, diet, environment (climate), job, family income, neighbourhood safety, rich vs low income, level of PA
what does it mean if something is an independent risk factor?
means that even if we control for all the other confounding variables, there is sill an association btw x and y
- ie: sitting is a risk factor for all-cause mortality, independent of levels of PA –> even if you control for PA, still an association btw sitting and mortality
how to establish sedentary behaviour ish? vs light vs moderate
- goal of public health PA guidelines?
using METs!
0.9 = sleeping
1.0 - 1.8 = sedentary
- 1.0 = sitting quietly (TV viewing)
- 1.5 = sitting (talking)
- 1.8 = sitting (desk work
2.0 - 3.0 = light
- 2.0 = standing
- 2.5 = slow walking
> 3.0 = moderate
- 3.8 brisk walking
- increase time spent in mod-vigorous activity!
how to apply public health framework to sedentary behaviour research?
4 steps ish
- epidemiology: tracking PA (time surveys) vs sedentary and look at health outcomes –> see if there is an association
- if there it, generate hypothesis –> which leads to clinical/interventional: sample people, check blood work and BP + sedentary + PA levels vs health outcomes
- if you still see a trend, measure effectiveness/efficacy of intervention –> how to decrease risk factors –> change/modify PA levels and sedentary levels –> see if effect on health outcomes
- translational –> how to get the word out? implement public health policy and programs to improve the health outcome
*still early days for sedentary behaviour research (vs domains for PA)
canadian sedentary behaviour guidelines for children 5-11 yo (3 ish)
*1st country in world to come up with sedentary behaviour guideline!
- should minimize time spent being sedentary each day by:
1. limiting recreational screen time to no more than 2h per day –> lower levels associated with additional health benefits
2. limiting sedentary (motorized) transport, extended sitting and time spend indoors throughout the day
*encourage active and outdoors activities!
what counts as being sedentary for children? (5)
- sitting for long periods
- using motorized transportation (bus/car)
- watching television (electronic babysitter)
- playing passive video games
- playing on computer
spending less time being sedentary can help children do what (6)
- maintain healthy bw
- do better at school
- improve self-confidence
- have more fun with friends
- improve their fitness
- have more time to learn new skills
what are 3 things to help children swap sedentary time with active time?
- active transportation (vs driving to school) –> walk to school with groups of kids from neighbourhood
- active play (vs TV) (ie after school) –> limit after school TV watching. plan time outdoors instead + encourage kids to participate in sports
- active family time: instead of video games, introduce family to active games
what objective measurement is changing the research frame in sedentary behaviour? describe
accelerometers!
- Activ graph: small, lightweight, unobtrusive –> can record time, duration, frequency and intensity (light vs mod-vig) of mvt in one-minute epochs
- Activ pal: very good for measuring sedentary time (sitting/lying) + number of transitions btw sitting and standing (reduced for very sedentary people)
NHANES sedentary time in US population –> what is the trend as age increases for time spent in sedentary behaviour?
sedentary behaviour increases!
- lowest = 6-11 yo
- highest = 70-85 yo
BUT 12-15 and 16-19 have higher time than 20-59!
what is the adult’s overall daily behaviour patterns distributed btw physically active and sedentary time? (pie chart)
- 9.3h sedentary time (sitting, studying, in class…)
- 6.5h light-intensity activities
- 0.7h mod-vig intensity activities
describe modern sitting-oriented society
- wake up (7am)
- 15min sitting breakfast + 45min transport to work sitting in car/traffic
- work 3.5h + lunch sitting 30min + work sitting 4h
- transport back home sitting (45min) + 30min dinner sitting
- 4h watching TV + maybe walk 30min
- sleep 11pm
from 2 to 5 –> 15.5h of sitting opportunity…
trends (from 1981 to 2002) in households with entertainment equipment that promotes too much sitting (describe graph)
- VCR/DVD (from 1981), computer (from 1986) and internet (from 1996) increase from 10% to 60% ish throughout the years
- one TV at 70% in 1981, decrease to 30% in 2002
- 2+ TV from 55% in 1981, increase to 90% in 2002
- cable TV from 70% in 1991 to >90% in 2002
prevalence of overweight children vs hours of tv watched per day: describe graph (boys vs girls)
more overweight children as hours of TV watched per day increases!
- <1h/day = around 20% obesity prevalence (more boys than girls)
- 2-3h = 25-30% (more boys than girls)
- >4h = 30-35% (more girls than boys)
sum of 4 skinfolds (adiposity) vs daily television watching habit in children –> describe graph
significantly leaner from 4+ h to 2-3h to <2h
- girls have higher sums than boys for all 3 categories
sum of trunk skinfolds in boys vs thirds of vig activity vs thirds of television watching (staireogram) –> describe!
worst sum = high TV watching and low vig activity
- best = low TV and low vig activity (weird but thats what the graph shows)
what is the trend for television viewing over the years? 2 studies
TV viewing time increases (from 4.5h per day in 1950 to around 8h per day in 2000) in US
- increases from 1.8h (women) and 2.0h (men) in 1992 to 2.0 (women) and 2.6 (men) in 2006. in Australia
avg weekly time spend watching TV in canada –> which 2 groups spend the most time?
18+ yo = around 27h per week
55+ yo = around 39h per week!
- all other ages around 13-17h ish
how is screentime ish separated? (pie chart)
153.2 watching TV
8.1 watching time shifted (recorded TV)
29.2 time on Internet
3.4 watching videos on mobile phone
3.1 watching video on internet
in 2012
what questions are asked for self-reported PA and TV time? from AusDiab Measures: Active Australia. (4)
self reported PA:
- how many times have you walked continuously for at least 10min, in last week?
- what do you estimate was total time spend walking in last week?
self-reported TV time:
- estimate total time last week spent watching TV or videos when it was the main activity –> options for Monday to Friday + Saturday and Sunday
odds of metabolic syndrome
- men vs women
MEN:
- highest (bit below 2x odds) when > 14h TV/week and <2.5h PA/week
- lowest (1x odd) = <14h TV and >2.5hPA
WOMEN:
- - highest (3.5x odds) when > 14h TV/week and <2.5h PA/week
- lowest (1x odd) = <14h TV and >2.5hPA
- low TV + low PA –> still 2x risk
- high TV and low PA also 2x risk ish
cross-sectional and longitudinal studies: high TV time (how many hours) is detrimentally associated with (2), independent of what?
- high TV time (2-4+h per day) –> associated with biomarkers and health outcomes, independent of leisure-time PA
high TV time is associated with which 6 health outcomes?
- CVD risk
- overweight
- diabetes
- metabolic syndrome
- abnormal glucose metabolism and other biomarkers of cardio-metabolic health
- cancer
Canada fitness survey 12-year mortality follow-up 1981-1993
- difference btw physically inactive vs physically for sitting almost all the time, 3/4 of time, 1/2 of time, 1/4 of time, almost none of the time
describe graph!
PHYSICALLY INACTIVE
- almost none of the time and 1/4 of time has lowest age-adjusted all-cause death rate
- then increases pretty linearly with almost all the time having highest all time mortality
PHYSICALLY ACTIVE
(>=7.5 MET-hr/week)
- same trend as physically inactive (increasing death rate as sitting time increases but “none of the time” starts a bit lower and “almost all the time” is at same level as 1/2 of time ish of physically inactive
- not as pronounced but still a significant trend!
meta-analysis
1. level of sitting vs hazard ratio/all-cause mortality –> relationship?
2. level of TV viewing vs hazard ratio
- increase level of sitting = increase hazard ratio, pretty linearly, but some studies see an inverse relationship
- gradual increase despite a few abnormalities. less data than (1), one of the studies has a really big upwards slope
*level of TV viewing = the most risky of sedentary behaviour of all sitting bc associated with more food and alcohol consumption
which health outcomes have a strong level of evidence of association with sedentary behavior?
- what about strong level of evidence for dose-response?
- all-cause mortality, cardiovascular disease mortality, incident type 2 diabetes, incident cardiovascular disease (VS cancer mortality and weight status = limited, incident cancer = moderate)
- all-cause mortality, cardiovascular disease mortality, incident cardiovascular disease
describe heat map of risk of mod-vigorous PA vs daily sitting time
- how is risk of all-cause mortality depicted?
- risk of all-cause mortality is depicted by the color! risk decreases as one moves from red to green
- low PA + low sitting time –> orange/yellow = not good
- low PA + high sitting time = very red = very bad
- as you move towards the right (increase PA), becomes more yellow and green
- BEST = high PA and low sitting
- high PA and high sitting = light green = get protection from high PA
- strong evidence demonstrates that association btw sedentary behaviour and all-cause mortality varies by amount of ____WHAT_____, such that hazardous effects of sedentary behaviour are more pronounced in ________ _________ people
- moderate evidence indicates that effect of ________ vary by amount of sedentary behavior –> explain
- individuals who are highly sedentary need what to achieve same level of absolute mortality risk as people who are less sedentary?
- CONCLUSION?
- varies by amount of mod-vigorous physical activity –> are more pronounced in physically active people
- effects of MVPA vary by amount sedentary behaviour –> those who are the most sedentary experience the greatest relative reductions in mortality risk associated with increases in PA
- highly sedentary –> require even higher amounts of PA to achieve the same level of absolute mortality risk as people who are less sedentary
- therefore, MVPA should be part of every adult’s lifestyle, especially for those who sit for large portions of the day
can you be active but also highly sedentary?
yes!
example of accelerometer data for a week –> mean mod-vig time = 31min/day + 71% of waking hours spend in sedentary
difference btw active couch potato and active non-couch potato
- define both
ACTIVE couch potato:
- mod-vig PA meeting guidelines considered physically active BUT also high level of sedentary behaviour
- activity during the day, but rest of time, METS are btw 1 and 2 = sedentary
ACTIVE NON-COUCH POTATO:
- similar level of mod-vig PA but less sedentary behaviour
- activity during day but rest of time, between 2 and 3 METS –> maybe standing, or takes breaks from sitting
difference between prolonger and breaker?
prolonger:
- long periods of time where sedentary time <100 counts/min (dark band) and some huge chunks of nonsedentary time (>100 counts/min) (light)
- big chunks
BREAKER:
- a lot of alternating between dark and light bands
*even if sedentary time is the same, ppl who have breaks have better health outcomes
which 4 health outcomes/blood markers are more elevated for people in first 2 quartiles of breaks in sedentary time?
- waist circumference
- body mass index
- triglycerides (log)
- 2h plasma glucose
*all higher for first 2 quartiles vs Q3 and Q4 which are decreased
2 bottom-line conclusions from too much sitting
- reducing and/or breaking up sitting time must now be considered as a potential public-health priority
- this is additional to (and not an alternative to) participation in moderate intensity physical activity (because sedentary behaviour is independent to PA)
