physical inactivity Flashcards
physical inactivity
- bodily movement generated by skeletal muscles resulting in energy expenditure (heat production).
- amount of energy you are using in exercise (energy metabolism)
- 2 divisions
- non-exercise activity thermogenesis (NEAT)
- voluntary physical activity
- an insufficient physical activity level to meet present physical activity recommendations
- different all depending on how an individual lives
metabolic cart
- amount of O2 being used
- not as convenient to measure O2
metabolic chamber
- longer O2 testing
- can be done from days - weeks
- uses sample gas
- how much O2 is used over time
doubly labelled water technique
- consume a water with H2O and O2 (isotopes) to see how the different isotopes are excreted in different ways
- released through urine , evaporation, sweat
- how much of this release was due to metabolism
- not time bound
METS
- 1 MET = amount of oxygen consumed at rest , standardizes physical activity in VO2
- normalizes the metabolic demand of a given activity / across activities
- 1 MET = 3.5 ml O2 / kg / min
- originated from the resting VO2 from one 70kg, 40 year old man and his value ^^
- MET compendium website to convert the cost of VO2 –> METS
classifying energy expenditure through FIT
- frequency x duration x intensity x body mass
- equals different levels of energy expenditure depending on how you combine them
classifying movement behaviors
- spectrum of movement behaviors
- also includes activities in other categories like sleep, sedentary behavior
- holistic view on physical activity
sitting
- a position in which one’s weight is supported by one’s buttocks rather than one’s feet, and in which one’s back is upright
- there is sitting doing nothing and sitting but doing something
lying
- being in a horizontal position on a supporting surface
standing
- a position in which one has or is maintaining an upright position while supported by one’s feet
sedentary behavior
- any waking behavior characterized by an energy expenditure of less than 1.5 METS, while in a sitting, reclining, or lying posture
sedentary behavior patterns
- have to take into account all aspects of the activity spectrum
- there is not just active and not just sedentary
total 24hr movement behavior
- 4 different possibilities in the range of sedentary - physical activity
- can be in both category
- NOT mutually exclusive
reasons to measure physical activity levels
- direct relationship with disease endpoints (morbidity/mortality)
- indirect relationship with disease through the effects of activity on diet or body weight (nutrition)
- ability to study physical activity patterns , determinants, and barriers in different groups
- more relevant for a wider segment of the population
- to evaluate physical interventions
weekend warrior
- challenges vigorous physical activity
- as long as you get 150 min of activity per week it reduces mortality, CVD, and cancer mortality
- 1-2 sessions per week to meet the 150min requirement
interaction between types of activity (Tv study)
- 240,000 adults (50-71)
- moderate to vigorous activity
- TV viewing time as sedentary behavior and CVD risk
- tv time vs exercise
- 100% risk if you watch a lot of TV but exercise a lot
classifying inactivity by energy expenditure (METS)
- sedentary activity : 0-1.5
- light PA: 1.5-3
- moderate PA: 3-6 (most common with athletes and gen pop)
- vigorous PA: 6+ (usually combined with moderate)
methods for assessing physical inactivity
- gold standard is to measure over 7 days
- best is also to assess over periods of time
- use reliable and valid assessment methods
- reliable : reproducible, giving the same results for a given amount of physical activity
- valid: accurately measures what it is intended to measure
physical activity questionnaires
- self reporting
- IPAQ
self reporting questionnaires, pros and cons
- pros –> easy to use (implementing/scoring), inexpensive, easy to deliver on a large scale
- cons –> social desirability (BIAS, not full truth, socially accepted by sounding better) , memory/ recall (harder over longer periods of time), familiarity with terminology.
IPAQ
- developed over past 20+ years
- actually captures what people are doing
- short and long versions for epidemiological and research purposes
- many validation studies across a variety of populations
- translated into 15+ languages
- incorporates sedentary behaviors
- large range of validity in comparison objective measures
subjective assessment
- self-report measures of physical activity
objective measurements of activity
- pedometers (step counters)
- accelerometers (motion in 3D)
- heart rate monitors
pedometers
- detect vertical accelerations of the body and record a “step” when vertical acceleration exceeds a threshold value
- accurate for recording the number of steps taken and distance walked
- increased reliability for faster walking and running paces because stride is longer and there is a clear heel strike
- accuracy not affected by walking or running surface
- relationship between step counts and energy expended strongest for moderate-intensity activities
- step count is more accurate than kilocalorie estimates
problem with pedometers
- decreased sensitivity if tilted away from the vertical plane (not worn properly)
- hard to track for obese people if they walk slower if the belt is tilted
- ankle device is sensitive enough to detect frail, slow, shuffling steps
accelerometers
- measure movement based on acceleration and deceleration of the body
- can be work on trunk or limbs
- measurements are proportional to muscular forces (picks up gravitational acceleration)
- most results in proportion to energy expenditure
- provides FIT of PA
- best types measure in three planes (vertical, horizontal, mediolateral)
activPAL
- picks up sedentary behavior
- worn on the thigh
- helps with sitting activities (swimming and cycling)
parameter
- can be worn on sports bra / chest
- ECA waveforms
actigraph
- research grade
- very good
- worn on the hip and wrist
advantages of accelerometers
- small size and ability to record data over long periods of time
- ability to download data and to segment physical activity time periods
- same accelerometers can be worn repeatedly by different participants
limitations of accelerometers
- requires more time and resources
- technical expertise, hardware, and software needed to calibrate
- single-plane models may not accurately detect movements from activities such as bicycling, weightlifting, or swimming
- unable to detect increased activity level resulting from upper body movement, carrying a load, or surfaces
- equations that estimate energy expenditure may not apply to free-living situations (need well studied devices and validity)
heart rate monitoring
- HR is linearly related to VO2 during submaximal aerobic activities
- HR is good for telling us how how hard we work = exertion
- good method of physical activity assessment
- very practical in the field
- able to store data
- is able to estimate frequency, intensity, and time of physical activity for days-weeks
calorimetry
- indirect is highly correlated (0.87) with HR monitoring
- there is a stronger correlation with accelerometers than calorimetry for lifestyle activities
- wearing an accelerometer and a HR monitor together may improve energy expenditure estimation and classification and time spent in light, moderate, and hard activity
limitations of a HR monitor
- HR is increased by temp, humidity, and high altitude so these may result in overestimation of energy expenditure.
- emotional state, hydration status, and type of contraction (static vs dynamic), and the amount of muscle mass recruited will affect HR, independent of physical activity
monitors that use multiple inputs
- combos of accelerometers and physiological signals to predict/calculate energy expenditure
- SenseWear Armband
- Actiheart
GPS monitoring
- provides accurate assessments of speed from slow walking to fast running
- can be used indoors and outdoors
- cannot be used for stationary activity
physiological sensors
- can be embedded into clothing with wearable digital camera
objective measures of activity
- different charts of advantages and disadvantages of pedometers, accelerometers, and HR monitors