Kin 4310-Exam 3
Health status
-Individual Health Status -Observer (e.g., physician) -Self-report ---------------------- Health of a population -Life expectancy at birth -Death rate -Prevalence of disease -Pollution
Air Displacement(indirect technique)
-Individual sits inside small chamber -Computerized pressure sensors determine the amount of air displaced by the person -Body volume is calculated by subtracting the air volume with the person inside the chamber from the volume of the empty chamber (air in the lungs is taken into consideration) -Body density and percent body fat are then calculated -Less cumbersome to administer -Takes only about 5 minutes
Physical intensity
-METs: multiples of the metabolic equivalent of sitting quietly for one hour -Sedentary < 1.5 METs -Light 1.5 < 3.0 METs -Moderate 3 - 6 METs -Vigorous > 6 METs
Accelerometers:
-Measure accelerations of the human body -Record activity patterns over a period of time -Benefits: small, non-invasive, large storage capacity, can be used widely in field settings Different types: -Actigraph GT3X+ -ActivPAL -FitBit -Jawbone -Nike Fuelband ...---------------------------------- Strengths -Measures actual movement -Valid & reliable in lab & field -Determine intensity of PA continuously in real-time -Easy & quick for data collection & analyses -Provide real-time data to personal electronic devices ---------------------------------------------------------- Limitations -Sensor location may involve less movement in certain activities -Cost (large samples) -Reactive
Direct Observation
-Measure behavioral aspects of physical activity -Provides information on specific activities occurring in a variety of settings over time -Quantitative & qualitative information -Useful with younger children -Requires trained observers Pen and paper instruments ------------------------------------------ Strengths -Detailed quantitative & qualitative data -Describes PA in real time -Low financial cost -Computer software allows for immediate recording & analysis of data ------------------------------------------------ Limitations -Time-intensive training -Time & labour intensive data collection -Limited sample sizes -Observer presence (reactivity) -Limited validation against physiological criteria
Heart Rate Monitors
-Measures cardiorespiratory response to physical activity -Transmitter and belt worn around the upper body -Data commonly displayed on a wrist receiver -Downloaded via interface for analysis -------------------------------------------------- Strengths -Measures physiological relationship with energy expenditure -Valid & reliable in lab & field -Describes intensity of PA -Easy & quick for data collection & analyses ------------------------------------------------------- Limitations -Cost (large samples) -Data attrition -Discomfort over long periods -Age, sex, training status affect HR -No information on context of physical activity
Body Mass Index (BMI)
-Most common measure of body composition -Incorporates height and weight to estimate critical fat values at which disease risk increases
body composition conti..
-Percent body fat (%BF): Weight of fat in the body relative to the person's total weight -Essential fat: Minimal amount of body fat needed for normal physiological functions; constitutes about 3-5% of total weight in men and 8-12% in women -Storage fat: Body fat in excess of essential fat; stored in adipose tissue -Lean body mass: Body weight without body fat
Aerobic Power Output
-Rate of mechanical work used to define exercise intensity -Usually expressed in Watts -Cycle ergometers (arm or leg) -Treadmills
Dietary Assessment - Methods(24 Hour Recall)
-Requires trained interviewer -Interviewer helps subject remember all foods consumed and assists in determination of portion sizes -Common technique: -Interviewer asks what subject first ate and drank upon waking THAT day, and works forward to time of interview -Interviewer then begins at point exactly 24 hours ago and works forward to time of waking
Estimating Food Portion Sizes
-Significant problem with interpretation of portion sizes -Subjects should give as accurate description as possible, possibly by comparing to other objects (i.e. - deck of cards) -Food models or pictorial representations can also be used -Subjects can also be taught how to record net weight or volume on food labels and report proportion of the food that was consumed
Bioelectrical Impedance(indirect technique)
-Simple to administer, but accuracy is questionable -Sensors are applied to the skin and a weak electrical current is run through the body to estimate body fat, lean body mass, and body water -Based on the principle that fat tissue is a less-efficient conductor of an electrical current -The easier the conductance, the leaner the individual -Body weight scales with special sensors on the surface may also be used to perform this procedure Hydration status can influence results
Dietary Assessment - Methods (Unweighed/Estimated Food Record/diary)
-Subject cooperation and literacy skills required -Less invasive - tends to be more acceptable to subjects -Some accuracy lost, but often balanced by better subject participation and adherence
Dietary Assessment - Methods(Food Record/Diary)
-Subject records, at time of consumption, the types and amounts of food and beverages consumed for a period of time ranging from 1-7 days -Weighed food record -Food and beverages weighed -Preferred method - considered more accurate -Unweighed/estimated food record -Portions estimated using household measures such as cups, teaspoons, tablespoons, etc.
Dietary Assessment - Methods(Duplicate Food Collection)
-Subjects collect identical portions of all food and beverages consumed over a specified period of time -Duplicate portions are then chemically analyzed for nutrient content ------------------------------------------------------------ Strengths -Avoids coding errors and errors involved in the use of food composition tables -Can be used for nutrients and contaminants found in very small amounts for which food composition databases are incomplete -------------------------------------------------------------- Limitations -Very expensive -Considerable subject burden -May underestimate intake
Aerobic Fitness
-The ability of the heart, lungs and blood vessels to supply oxygen to the working muscles -The ability of the muscles to use the available oxygen -A major component of fitness! -There is a significant relationship between aerobic fitness and mortality rates -VO2 max -------------------------------------------- (field tests) -1.5 mile-timed quarter mile run track -pacer shuttle run-children running back and forth at a increasing pace
drawbacks of hydrostatic weighing(indirect technique)
-Time consuming -Not feasible to test large number of people -Requires measurement of residual lung volume (if unknown, can be estimated) -Difficult to perform on the aquaphobic
Hydrostatic Weighing(indirect composition)
-Underwater weighing -Most common technique used for decades -A person's "land" weight is compared with underwater weight -Fat is more buoyant than lean tissue -Most other indirect techniques have been validated against hydrostatic weighing
MRI (magnetic resonance imaging)direct technique
-Used primarily by research and medical facilities -2nd "gold standard" technique -Uses high powered magnets and imaging software -Measures total and regional adiposity -Safe; no problems with radiation exposure, etc. Limits-Procedure can be time consuming and is very expensive
accessing body compositions
-indirect techniques involve measurements outside or on the surface of the body to estimate what is inside: -Hydrostatic weighing -Air displacement -Skinfold thickness -Bioelectrical impedance BMI, WC, WHR
The T-test steps
1)Determine the test statistic 2)calculate degrees of freedom 3)find the critical value 4)reject or fail to reject the null hypothesis
Physical activity
"Any bodily movement produced by the skeletal muscles that results in energy expenditure."
Measuring Physical Activity
-30+ different instruments and/or methods -Pros and cons of each, depending on what information you are trying to capture -Characteristics assessed: -Frequency -Intensity -Duration
Definition of Health:
-Absence of: -Physical pain -Physical disability -Conditions likely to cause death -Emotional well-being -Satisfactory social functioning
Dietary Assessment - Methods(Food Frequency Questionnaires)
-Assesses energy and/or nutrient intake by determining frequency of consumption of a limited number of foods known to be major sources of the dietary component under investigation -Lists approximately 100 food or food groups -May ask for indication of portion size -Portion numbers and sizes are statistically analyzed to estimate nutrient intake ------------------------------------------------------------ Strengths -Can be self-administered -Scannable computer scoring available -inexpensive -May be more representative of habitual intake -Allows for examination of diet-disease relationships ------------------------------------------------------------- Limitations -May not represent typical food or portion sizes consumed -Relies on ability of subject to describe diet
Dietary Assessment - Methods(Diet History)
-Assesses subject's usual dietary intake over an extended period of time -Collect general information on subject's health habits -Question subject about usual eating patterns -Verify accuracy of data provided -Subject also completes d-day food record --------------------------------------------------- Strengths -Assesses usual nutrient intake -Can detect seasonal changes -Data on range of nutrients can be collected -Correlates well with biochemical markers of intake (i.e. - protein intake and nitrogen excretion -------------------------------------------------------- Limitations -Time consuming and expensive -Labor intensive - requires highly trained interviewers and complex coding systems -May overestimate nutrient intake -Requires cooperative subject with ability to recall usual diet
Skinfold Thickness(indirect technique)
-Based on the principle that approximately half of the body's fat tissue is directly beneath skin -Reliable measurements can give a good indication of percent body fat -Skinfold test is done with pressure calipers -Several sites are measured and percent fat is estimated from the sum of the three sites -All measurements should be taken on the right side of the body
CT scan(direct technique)
-Computed tomography (CT) -Measures regional adiposity by imaging multiple cross-sectional slices -Measures fat layers within body cavity, limbs or organs -images are segmented into adipose and nonadipose tissue pixel values measured in Houndsfield units (HU) -Uses higher-dose X-ray energy -Radiation exposure can be a drawback -Procedure is simple; time required depends on number of slices taken
Accessing Body Composition
-Direct techniques involve looking inside the body and measuring the different tissues by volume (or area) -Dual energy X-ray absorptiometry (DXA) -Magnetic resonance imaging (MRI) -Computed tomography (CT)
DXA(direct technique)
-Dual energy X-ray absorptiometry (DXA) -Most frequently used by research and medical facilities -Considered the "gold standard technique" for body composition assessment -Uses low-dose beams of X-ray energy -Measures fat mass, fat free mass, and bone density -Procedure is simple; takes only 15 minutes to administer -Safe; no problems with radiation exposure, etc.
If H0 is true,the F statistic is:
A random number with a positively skewed distribiution
what is 1 MET?
A unit of oxygen consumption equal to sitting at rest.
Accelerometers
Are the gold standard for physical activity measurement
what is the gold standard measurement of body composition?
BF% as determined by dual x-ray absorptiometry
156 adolscent girls are tested with the Eating Attitudes Test and the Goldfarb Fear of fat Scale. Which hypothesis test should you use to determine if the scores on these two tests are related?
Correlation test
body composition
Definition: The different components that make up the human body -Fat -Muscle -Bone Important in assessing health status and disease risk
156 adolescent girls are given the Eating Attitudes Test.Then,they are shown a series of images from a fashion magazine.After a short break,the test is repeated.Which t-Test should you use to determine if there is a difference between the girls' test scores before and after viewing the imagery?
Dependent t-Test(paired data)
What can a t-test be used for?
Determining if there is a significant difference between two groups.
what is the gold standard for measurement of body fat %?
Dual X-ray Absorptiometry
Excercise
Exercise " A sub-category of physical activity, that is planned ,structured ,purposeful and repetitive."
Which methods are prospective?
Food diary,duplicate food collection
which diet assessment method would work best in a study where subjects and researchers communicated only by mail?
Food questionaire
what is the gold standard measure of aerobic fitness?
Laboratory VO2max test
what is the gold standard for aerobic fitness testing?
Laboratory Vo2 max test
Methods to Assess PA
Objective Measures: -Accelerometers Marker of movement Heart rate monitoring Physiological response to PA -Pedometers Number of steps taken -Direct observation Observed or videotaped -GPS systems Newer application; measures population movement
Dietary Assessment - Methods(Food Record/Diary)
Strengths -Does not rely on memory -Can provide detailed data on intake and eating habits -Multiple day data more representative of usual intake -Valid up to 5 days ---------------------------------------------------------- Limitations -Requires high degree of cooperation -Subject must be motivated and have average literacy level -Subjects willing to complete food records may not be typical -Quality of record declines in relation to the number of days studied Reactive
24 Hour Recall conti..
Strengths -Requires only 20-30 minutes -Fairly inexpensive -Provides detailed quantitative and qualitative data -Low subject burden Low reactivity-not reacting to the measurement ----------------------------------------------------- Limitations -Time-intensive training -Time & labour intensive data collection -Seldom representative of usual intake -Under/over reporting can occur -Requires cooperative subject; data can be withheld or altered
Methods to Assess PA
Subjective Measures: -Physical activity logs (PALS) -24 hour recall -7 day recall -Previous month recall -Previous year recall Questionnaires ---------------------------------------- -All are self-administered or interviewer administered, either in-person or on telephone
A 2-way ANOVA
Tests the main effects of both factors as well as the interaction between factors
If there is no correlation in a population
There may be a significant correlation in a sample of that population,but it is unlikely
What is a limitation of hydrostatic weighing for determining %BF?
Time consuming -Not feasible to test large number of people -Requires measurement of residual lung volume (if unknown, can be estimated) -Difficult to perform on the aquaphobic
What is the purpose of a 2-way ANOVA?
Two factors,Ex:older blood pressure vs younger blood pressure -are two independent factors -Used when we want to learn about the main effects of each factor individually, but also want to understand how they interact
which of the following methods of assessing aerobic fitness is most reliable?
VO2max test
Heath-related physical fitness includes
body composition aerobic fitness flexibility muscular endurance
A linear correlation coefficient
can be weak and statistically significant
Which method is the most reliable?
duplicate food collection
which diet assessment method is the most reactive?
food diary
Which method is the cheapest to administer?
food questionaire
130 adolescent boys and 156 adolescent girls are given the Eating Attitudes test.Which t-Test would you use to determine if there is a difference between the scores of the boys and the girls?
independent t-Test
Aerobic fitness is ______ correlated with mortality rate
negatively
What is a limitation of air displacement for determining %BF?
not as accurate as direct methods
consider this statement:there is no relationship between flexibility and body composition.what kind of hypothesis is this?
null hypothesus
What are Disease Adjusted Life-Years (DALY)?
number of years that you died prematurely,living with disease
What is the basal metabolic rate?
rate of energy expenditature,heart and lungs
Which of the following is NOT a component of health-related physical fitness?
reaction time