1102 - study review Flashcards
what modern trends are associated with the increased prevalence of chronic disease
physical inactivity, obesity, aging populations
definition of physical activity (two)
- casperson def: any bodily movement produced by contraction of skeletal muscles that substantially increases energy expenditure
- the new holistic def: people moving, acting and performing within culturally specific spaces and context, and influenced by a unique array of interests, the motions, ideas, instructions, and relationships
definition of physical inactivity
performing insufficient amounts of moderate to vigorous physical activity
definition of sedentary behaviour
any waking behaviour characterized by a energy expenditure less than or equal to 1.5METs while in a sitting or reclining posture
definition of exercise
a subcategory of leisure time, physical activity, in which planned, structured, and repetitive bodily movements are performed to improve or maintain one or more components of physical fitness
definition of physical fitness
a set of attributes (cardio respiratory endurance, power, etc.) that people have or achieve that relate to their ability to perform physical activity
definition of health (two)
- a state of complete physical, mental, and social wellbeing, and not merely the absence of disease or infirmity
- the ability to adapt and self manage in the face of social, physical, and emotional challenges
UK double decker bus study purpose
to discover the length between physical activity and heart attacks
UK double decker bus study design
UK double decker bus study findings (two points)
- conductors on double decker busses climb 600 stairs per day; drivers on the bus sat for 90% of their shift
- the incidence of coronary heart disease in conductors was less than half of that of drivers
harvard alumni studies (result)
when alumni in their 40s take part in vigorous exercise (and more exercise in general) it is critical for longevity and lower risk of cardiovascular disease
harvard alumni studies (purpose)
purpose was to examine the relationship between physical activity and incidence of heart attack
definition of obesity epidemic
growing number of people globally. more than 1.9 billion adults and 41 million children under the age of 5 who are overweight or obese and who often have accomaning medical illness such as chronic disease and disability
characteristics of an epidemic vs pandemic
- epidemic is a disease that affects a large number of people within a community, a population, or region at expected or normal levels.
- pandemic is an epidemic that spread over multiple countries or continents
WHO(world health organization) maps- double burden of disease
refers to the rise of communicable (illnesses that spread from one person to another, animal to person, surface or food) and non communicable diseases (come from unhealthy behaviour)
main findings from participACTION report - total daily steps (three points)
- about 50% of canadian adults take at least 7,500 per day which falls under the physically active lifestyle
- percent meeting this guideline decreases with age and is lower in women
- adults with one or more chronic condition are less likely to meet this guideline
- in 2019, our grade was a C
main findings from participACTION report - physical activity (two points)
- 56% of adults (18-79 years) living in canada get at least 3 hrs per day of physical activity (LPA)
- the percentage of adults achieving at least 3 hrs of physical activity (LPA) a day does not generally vary significantly by age, gender, having a chronic disability or ethnicity
main findings from participACTION report - moderate to vigorous physical activity (three points)
- 49% of adults (18-79 years) living in canada obtain at least 150 minutes of MVPA
- 1 hr of MVPA per day can reduce cancer related fatigue during and after cancer treatment
- both cardiovascular and strength training have been shown to be effective in reducing depressive symptoms and may also further prevent future depression
international society for physical activity and health - 8 investments for physical activity
- whole of school program
- active travel
- active urban design
- healthcare
- public education including mass media
- sports and reaction for all
- workplaces
- community wide programs
definition of epidemiology
the study of the distribution and determinants of health related states or events in specified populations and the application of this study to the control of health problems
physical activity and epidemiology
- specific study of the relationship between physical activity/exercise and various diseases and conditions within a populations
- evidence showing that physical inactivity in a major risk factor for several chronic diseases
assumptions of epidemiology (three points)
- human disease does not occur at random
- human disease has casual and preventative factors that can be identified through scientific investigation
- the primary goal of epidemiology is to identify the determinants of disease to decrease mortality and morbidity within a population
incidence
the number of new cases of a disease or a disorder within a population over a period of time
prevalence
the number of existing cases of a disease in a population at a given time
cost of illness
expenditures on medical care, work related costs, educational costs, cost of support services required by medical conditions
burden of disease
the total significance of disease for society beyond immediate cost of treatment. measured in years in life lost to ill health or difference between total life expectancy and disability adjusted life expectancy (DALY)
Disability adjusted life expectancy (DALY)
this is a summary measure of the health of a population. one DALY = one lost year of healthy life
measure of prevalence
- the number of individuals with a disease at a certain point in time (point prevalence)
- ex: 2.8 million people are obese in a country of 10 million. the prevalence of obesity is 28% (2.8 divided by 10 x 100)
measure of incidence
the number of new cases of a disease that develop during a specified time interval/ population at the beginning of the time
- ex: 5 individuals get a disease in a year and the population on january 1st was 1000 (so the cumulative incidence is 5 per 1000)
types of epidemiological study- case report and case series
- quick and inexpensive
- recognize new and emerging health problems
- may generate hypotheses based on similarities among groups
- give insights into disease mechanisms
types of epidemiological study - correlational study
the researchers can’t manipulate either the variables involved
types of epidemiological study - cross sectional study
- compares different population groups at a single point in time
- does not involve manipulating variables
- allows researchers to look at numerous characteristics at once
types of epidemiological study - case control study
data on potential risk factors are collected retrospectively and as a result, may give rise to bias
types of epidemiological study - cohort study
- the investigator identifies subjects at a point in time when they do not have the outcome of interest and compares the incidence of the outcome of interest among groups of exposed and unexposed subjects
types of epidemiological study - randomized control trials
they are controlled randomized and usually blinded and the significance of the results is determined statistically according to a predetermined algorithm
epidemiological studies vs lab studies
- Epi: manly observational
- Epi: allow nature to take its course and analyze relationships between indices of health status and other variables
-Lab: manly experimental
-Lab: intervene to see what happens to some/ all individuals
Harvard alumni study - purpose type of study and outcomes assessed
the canadian 24 hour movement guidelines
-replacing sedentary behaviour within additional physical activity and trading light physical activity for more moderate to vigorous activity while preserving sufficient sleep can provide greater health benefits
benefits:
- lower risk of mortality
- cardiovascular disease
- hypertension
- type 2 diabetes
- several cancers
- anxiety
- depression
- dementia
- weight gain
- adverse blood lipid profile
subjective measures of physical activity
depend upon the ability of participants to recall and/or report their own physical activity/inactivity
- examples:
- questionnaires
- physical activity records
- interviews
- surveys
- recall diaries
objective measures of physical activity
include measures that directly assess one or more dimensions of physical activity and have the ability to capture a variety of metrics such as: number of steps, minutes of activity, intensity of activity, bouts of activity
- examples:
- frequency
- intensity
- time
- type
advantages and disadvantages of subjective measures of physical activity
dis:
- bias
- misleading
ad:
- easy to obtain
- easy to categorizes
- inexpensive
advantages and disadvantages of objective measures of physical activity
dis:
- expensive
- more timely
- some uses of measure are inaccurate
ad:
- more specific results
- no bias
- more validity
importance of reliable and valid physical activity/ fitness measures
- reliability and validity of a measure determines whether or not it will produce accurate measures
- accurate measures provide researchers with the tools to effectively study, predict and promote physical activity behaviour
- examples:
- specific amounts of physical activity for health benefits
theories of physical activity - success of interventions
relationship between accelerometer measured physical activity and questionnaire measured physical activity
Acc:
- measure the rate and magnitude of movement in up to 3 axis
- store movement counts in specific time intervals
- can assess frequency, duration, and intensity
limitations: can’t assess energy expenditure related to stationary activities such as cycling, resistance training, and paddling sports. can’t account for the excess energy expenditure related to incline, load bearing, or uneven surface locomotion
Ques:
- simplest method
- can range from just a couple of questions to link the surveys
- can be specific or general and most often require recall
randomized control study
- overall study population
- random allocation (physical activity intervention group, and a control group)
- compare outcomes between randomized groups
parallel experimental design study
an experimental study design in which each subject is randomized to one of two or more distinct treatment/intervention groups
crossover experimental design study
two or more treatments (examples: drugs, procedures) are provided to subjects at different time periods and the sequence of treatments is randomized for each subject
before after experimental design study
measured outcomes in a group of participants before introducing a product or other intervention and then again afterwards
errors
- evaluation of validity of the findings of a study depends on the extent to which these could also be explained by chance, bias, or confounding variables
- random error can occur due to sampling error, and measurement error
random error- due to chance
- biological variation
- sampling error
- measurement error
bias - results differ systematically from true values
- selection bias
- measurement bias
confounding
observed association is due to a third (confounding) factor related to the exposure that independently affects the risk of developing the disease
accuracy and precision
- data are accurate if they are close to the true values
- precise if the same measurement when repeated consistently yields similar values
- good data has to be both accurate and precise, neither is sufficient alone
establishing causality and epidemiology
- appropriately sequenced - activity/fitness measure must precede onset of disease
- plausibility - is association consistent with other knowledge?
- consistency in different populations
- strength of association (relative risk)
- dose response
- reversibility
- strong study design
US railroad employees - purpose
a study was conducted of death rates among clerks, switchmen, and sectionmen employed in the railroad industry for the purpose of obtaining information on the relationship of physical activity of exercise and coronary heart disease
meta analysis - accelerometer measured physical activity and all cause mortality
this showed individuals participating in different levels of physical activity over the span of a year. we saw that the longer someone spent participating in physical activity, the lower their mortality rate was
US railroad employees - methods
- cohort study
US railroad employees - results
the men in sedentary occupations have more coronary heart disease than those in occupations requiring moderate to vigorous activity
other meta analysis - examining physical activity and all cause mortality
- studies mainly based on questionnaire data are reassuringly consistent for aerobic physical activity and data is accumulating for muscle strengthening activities
- risk of inactivity is independent of other known risk factors
- studies using questionnaires are likely to underestimate the true relationship between physical activity and mortality due to inaccurate recall
- objective assessments of physical activity (examples: doubly labeled water, and accelerometers) are becoming more common and typically show stronger relationships with mortality than self reported activity
changes in physical activity and risk of mortality (harvard alumni study)
- death rates 25-33% lower among alumni expending 2000 calories per week + compared with those expending less
- findings remained significant even after controlling for smoking, hypertension, extreme/gains for body mass, and early parental death - inverse association between physical activity and mortality risk held for different age bands
meta analysis - association between sitting times and mortality according to physical activity level
people who sat for more than 8 hours a day were more likely to die
measures of physical fitness and epidemiological studies assessing relationship between fitness and mortality
- physical activity is inversely associated with mortality and observational studies even after adjustment for confounders
- most studies have measured physical activity using self report questionnaires which may underestimate the relationship with mortality due to inaccurate recall. stronger associations have been observed with more objective measures of physical activity
- accumulating evidence suggests that participation in muscle strengthening exercise as well as aerobic physical activity is associated with a lower risk of mortality
- it has been estimated that almost 10% of deaths worldwide can be attributed to physical inactivity
aerobic center longitudinal study
- one of the first studies to show association between physical fitness and all cause mortality risk
- 10,224 neb and 3.120 women
- time to exhaustion on treadmill test
- followed for 8 years
- quintiles (lowest to highest fitness)
- lowest risk of death seen in those with highest fitness (men) and quintile four (women)
- concluded that high levels of PF delay all cause mortality due to lowered rates of CVD and cancer
myers study - fitness and risk of mortality in men with and without CBD
individuals who have cardiovascular disease have lower METS and will have an increased risk of death than those without. However, with an increase in exercise this number for risk of death decreases
meta analysis - inverse association between fitness and all cause of mortality
people participating in low fitness have a higher mortality rate than those who participate in intermediate and high fitness
UK biobank study - role of strength and fitness in moderating relationships between PA and mortality
- strength moderates the association between physical activity and mortality; people with low grip strength have higher mortality rate than those with high grip strength
- fitness moderates the association between physical activity and mortality; people with low fitness has a higher mortality than those with higher fitness
- grip strength, showed a consistent decline/incline and fitness was more broad as any level of fitness would help decrease mortality rate
ACLS - strength of association between low fitness and mortality with other risk factors, in normal weight in obese individuals
- individuals who are obese and have CVD and low fitness have a higher mortality rate than those with diabetes, hypertension, smokers, and high cholesterol
- high fitness appears protective against the adverse effects of obesity on mortality
ACLS - changes in fitness over time and risk of mortality
- changes in levels in physical activity or cardiorespiratory fitness are associated with changes in risk of mortality
- a high level of physical activity does not fully protect from the adverse effects of obesity on mortality risk
nurses health study - influence of physical activity on risk of mortality by weight classification
