Midterm Flashcards
epidemiology
- study of health-event (frequency), health-characteristics (why) or health-determinant patterns in a society (prevent)
- it is the cornerstone method of public health research & helps inform policy decisions and evidence based medicine by identifying risk factors for disease and targets for preventative medicine
traveling & health
increases health problems by transferring germs/diseases throughout countries
first ACSM recommendation
in 1978, 3-5x/week, 50-85% of VO2max or 60-90% of HR, 15-60 min each time
London bus study
- 1949, bus drivers vs conductors
- annual rate of CHD for drivers= 2.7/1000; conductors= 1.9/1000
- could be due to drivers being more sedentary
- this is really where PA and exercise research began
sports
actions/movements exerted in direction of game, struggle and effort, and whose practice involves a methodical training, respect for certain rules
exercise
actions/movements organized manner to maintain or develop the qualities or entities
physical activity
any bodily movement produced by skeletal muscles that result in higher energy expenditure
physical inactivity
not meeting national guidelines for PA
sedentary
- sitting too much - 75% of our lives spent sitting
- any waking behaviour characterized by an energy expenditure that is less than equal to 1.5x resting metabolic rate while in a sitting or reclining posture
incidence
number of new cases of a particular disease
prevalence
total number of affected persons present in a population at a specific time
confounder
- variable with an effect that’s entangled with effect of PA which can’t be easily separated and studied independently
- confounders need to be controlled for using statistical procedures to ensure accurate results
- ex: effect of PA on chronic conditions= confounders= age or sex
cohort
a group followed over a period of time
p-value
used to quantify degree to which change may account for an association that was observed in a particular study
interaction
- a variable has an impact on how another one will react to an outcome
- 2 groups aren’t responding same way to same thing
- ex: men and women at 80 have different PA levels
bias
any trend that affect to interpretation of results and put you away from the truth
risk factors
aspect associated with health-related conditions increase or not, the probability to develop a disease
MET
- a measure of exercise intensity used in epidemiology studies
- it is an absolute measure (doesn’t consider age or muscle mass)
- vigorous exercise 6+ METs
- moderate exercise 3 METs
- rest 1 MET
- metabolic equivalent of task
- metabolic rate consuming 1 kilocalorie per kg of BW per hour= 1 MET
- ex: 60 kg= 1440 kcal/day
oxygen levels
- 1 MET= 3.5 ml/kg/min O2
- 10.5 ml/kg/min O2 is minimum required level to be considered healthy
MET minutes
4 METs x 200 min= 800 MET min
physical fitness
set of attributes that people have achieved that relates to ability to perform physical work, related to VO2max
wellness
holistic concept describing a state of positive health including physical, social, and psychological
disease
reduced, abnormal or lost structure of function cells, organism or systems of body
body compositions 1981 –> 2008
body compositions increased but fitness levels decreased
guidelines for 18-64 years
- aerobic exercise 150 min/week
- 2 sessions of resistance training/week - strengthens heart
- kids= ~300 min/week
exercise reduces risk of 7 chronic conditions
hypotension, CVD, diabetes, stroke, osteoporosis, breast cancer, mortality
life expectancy
- W: 84 years (72 health, 9 disabled)
- M: 79 years (68 healthy, 8 disabled)
- men more likely to die sooner due to gravity
- just because you put more money into health system does not mean it will increase life expectancy
cost of disease
tend to put more work towards diseases that cost government more
aerobics center longitudinal study
- impact of PA on mortality and chronic disease
- 80 000 people since 1970 at Cooper Institute in Dallas
- unique VO2max testing, more than 100 studies
- each minute of increased treadmill time between the 2 times reduced mortality risk by 7.9%
gold standard measure
- measure that we agree to use and trust answers the tool gives (ex: BP cuff)
- we don’t have one for PA that’s accurate
what do we want to measure?
- calories (METs, metabolic equations)
- intensity (HR monitor, accelerometer)
- time active (pedometer)
- time sedentary (ActivPaL)
- bouts of PA (accelerometer)
- purpose: weight loss, portrait of population
questionnaires
- before 60’s PA based on occupational class
- 1st questionnaire specific to leisure PA in 1975 for community health study
- now more than 60 PA validated questionnaire
- pros: use for a lot of people, not expensive, can send questionnaires to remote areas
- cons: some people can’t read/write, language barriers
validated questionnaire
when you look at how much PA someone does and measures it with questionnaire and it matches
measures of PA
- self reports of PA are easiest methods for measuring PA in national surveys and surveillance systems
- men over estimate, women under estimate
- correlation coefficient between self-reported variables and accelerometer measures of PA is 30%
direct calorimetry
- best way to measure O2 consumption
- in a room exercising, producing CO2
- increasing VO2 is also increasing CO2
- REQ= CO/O2 –> not good when CO2 is higher than O2
- expensive
indirect calorimetry
estimate energy expenditure from O2 consumption and CO2 production - mask on face
doubly labeled water
- best overall measure of total daily energy expenditure
- subject consumes water containing known concentration of stable isotopes of H+ (2H-deuterium) and O2 (18 O or oxygen-18)
- costs $1000 and need spec mask to analyze
- only way to lose O 18 is through sweat
- how much O 18 left is how much energy you used
heart rate monitors
- measure electrical activity of heart
- conversion of HR to measure energy expenditure based on linear association between HR and O2
- public health wise this is not the best solution
pedometer
- need 10 000 steps a day to reach 30 min/day of PA
- can get 6000 steps/day without trying
- walking cadence - steps/min, measures intensity, need 100 steps/min for general (~120 steps/min older adults)
accelerometers
- need to wear 10 hours/day to be valid
- under 100 counts/min - assume they’re sedentary
- need to wear 3 days in week and once on weekend
- measures movement on 3 axis
- best on hip to measure accurate movement
- cons: don’t know posture, biking shows increased METs but decreased counts
- ActivPaL costs 500 euros and measures posture
- not gold standard measure but best we have
other popular activity monitors
Fitbit 1, Fitbit zip, and Withings Pulse performed best, methods is most important part of paper
popular body composition measures
densitometry, plethysmograph, absorptiometry (DXA), MRI & CT Scan
bioimpedence
- methods of estimating body fat 1st validated by GSM & then equation created
- Heyward (2001) said several precautions to optimize reliability of technique
premise
- lean body mass consists of 60-75 average (73% H2O)
- volume of body fat mass and free fat mass are constant
- segments comply constant proportions from 1 person to another, all precautions taken - don’t use with pacemaker
Heyward precautions
- don’t eat/drink 4 hours before test
- no exercise 12 hours before test
- urinate 30 minutes before
- no alcohol 48 hours before
- don’t use diuretics during 7days leading up to test
skin folds
- estimation of body fat using skin folds is possible because in adults 50-70% of body fat is located between skin and viscera
- reliability of this technique depends mainly on level of adiposity of subject and expertise of evaluator
- triceps is a good location for kids
- not valid for BMI > 30
BMI
- measures bone, fat, and fat free mass
- kg/m2
- waist circumference W: >88cm M: >102cm
- 3 steps for public health:
1. BMI
2. waist
3. if 1 and 2 are elevated - body composition
densitometry
- measures bone density
- similar to absortiometry (DXA)
- more expensive and uses radiation but can account for different body segments
- 4% difference can be seen due to body hair
plethysmograph
- measures changes in volume within organ or whole body
- the more air you push out the more body volume you have
- no way to measure fat mass and free fat mass
MRI & CT Scan
no measurements, just estimates
gold standard measure for BMI
cadavre
basic principles of fitness
- specificity
- overload
- initial value
- inter-individual variability
- diminishing returns
- reversibility
specificity
- physiological and metabolic adaptations to exercise
- training are specific to type of exercise and muscle groups involved
- includes specific angles, specific fatigue, etc.
- impossible to think that best way to improve leg strength is to do elliptical machines
overload
- to improve our anatomy and physiology
- must overload body beyond what it’s usually required to do
- once body has adapted to particular training load
- new load becomes regular challenge and to get further improvement “overload” must be imposed
- you have best adaptation within first 6 weeks
initial values
- new exercisers improve faster because initial value is lower and takes less to improve
- ex: VO2max= 12% improvement in first month
inter-individual variability
- biological age
- initial level
- genetics
- gender
- health
- training state
- fatigue
- the dose-response relationship is highly individualistic
impact factor
- putting in order which journal is most prestigious
- scale of 0-4, the higher the IF the more prestigious
- 4 means it is well respected in science
- # of citations/# of articles
smokers
give patches to smokers to help them stop smoking because we invest so much in diseases caused by smoking (i.e., cancer, COPD)
CRF
measured by doing a VO2max test
genetics or environment?
- spaniards train more but sleep less than Ethiopians
- spaniards don’t perform as well as ethiopians
best way to prescribe intensity
heart rate reserve (HRR) because it takes into consideration your age and resting heart rate
diminishing returns
- each person has a genetic ceiling
- as fitness level increases, more work or changes are needed to observe gains
- less likely to improve if you’re already at max
reversibility
- use it or lose it
- you can maintain your fitness level even if you need to reduce the frequency even for several months
- in general, you need to exercise at about 70% of your VO2max at least once a week
- resistance training more maintenance
periodization
- in its simplest form, the year training is divided in 3 phases:
1. preparation
2. competition
3. transition
VO2max
- rate of O2 uptake during an effort that reflects the capacity of the heart, lungs, and blood to deliver O2 to the working muscle
- unit for cardiorespiratory fitness:
1. express by absolute VO2max - L/min
2. express by relative to weight (ml/kg/min)
3. VO2max between 40-60 is good, VO2max of 20 is not
4. people that have high VO2max- skiers, people who train at high altitudes, genetically inclined people
VO2max tests
- maximal test (ex: bruce protocol, MCAFT)
- sub-maximal test- need equipment (treadmill, step test)
- field test- don’t need equipment (ex: beep test)
moderate:
- METs
- %HRR or %VO2R
- % HRmax
- %VO2max
- RPE (6-20)
- METs: 3-5.9
- %HRR or %VO2R: 40-59
- %HRmax: 64-76
- %VO2max: 46-63
- RPE (6-20): 12-13
people using beta blockers should use what?
RPE
difference between HRmax and resting HR
- HRmax typically uses 220-age
- proposed new formula 206.9-(0.67 x age)
difference between %HRR and %HR to prescribe intensity of training
%HRR is greatly correlated to maximum capacity
Intensity equivalence (RQ)
- goes between 0.70-1.00
- 0.70= fat; 1.00= glucose
- RQ= CO2/O2
resistance training guidelines - endurance
- % 1RM: 60-70
- reps: 12-20
- # of sets: 2-3
- rest: 20-30 secs
resistance training guidelines - hypertrophy
- % 1RM: 70-80
- reps: 8-12
- # of sets: 3-6
- rest: 30-90 secs
resistance training guidelines - strength
- % 1RM: 80-100
- reps: 1-8
- # of sets: 3-5+
- rest: 2-5 mins
% 1 RM
percentage of max rep
ex: max weight for 1 rep is 200 lbs, do 80% of that = 160 lbs
sedentarity consequences
associated with mortality from all causes, CV disease, and diabetes
odd ratio
- cross sectional
- might have the condition or not
relative risk
- longitudinal
- did not have the condition at baseline
- more important and higher on pyramid
- long time & expensive
objective- measurement studies
- sedentary time- larger waist circumference and more adverse 2 h-h plasma glucose and triglyceride levels
- breaking up sedentary time might help
- study shows waist circumference increases when you don’t break up your time spent sedentary
prospective studies
- testing associations observed in observational studies
- after 6.5 years- for each increment of 1 hour in TV time –> 11% increased risk in all-cause mortality and 18% increase in CVD related mortality AFTER controlling for PA, diet, smoking, BP, waist circumference
- study done over 21 years:
- – time in car: 10h vs less than 4h per week = 84% more risk of dying from CVD
- –time in car + TV: 23h vs less than 11h per week= 64% greater risk
walking vs standing
- breaking up prolonged sitting with light intensity walking results in superior improvement in glucose tolerance, compared with breaks spent standing
- less energy expenditure
- treadmill work stations are likely to avoid some known problems with prolonged standing, namely pooling blood, headaches, and backaches
kids 0-2 TV recommendations
shouldn’t watch TV
kids 2-4 TV recommendations
should watch TV less than 1 hour a day
kids 5-11 TV recommendations
should watch TV less than 2 hours a day
kids 12-17 TV recommendations
should watch TV less than 2 hours a day
treadmill workstation research
- improvement in some risk factors for CV disease
- reduction in BW
- no significant impact on job productivity
- interesting results but costly, require a lot of space, misconceptions, and many outcomes have not been explored
pilot study main outcomes
- PA level
- health related measures
- treadmill use
- participants’ expectation and experience
pilot study conclusions
- women seem more interested in this intervention
- preliminary results show that sharing a treadmill workstation:
- –feasible and generally well accepted
- – improve sleep
- – improve BP
- might have more health impacts if:
- –adherence is improved
- –length of interventions is increased
which one is more convincing/important? PA or fitness
- fitness level & mortality risk because you have a better VO2max with a good fitness
- fitness is the physiological condition and PA is the behaviour
95% CI less than 1.0; more than 1.0
- reduced risk
- increased risk, if interval crosses 1.0 then it is not significant (0.89-12.00)
mortality rate in US railroad workers
significantly lower for most active men
Harvard Alumni Health Study
men aged 35-79 that expended more than 2000 kcal/week gained 2.15 years on their life compared to men that expended less than 500 kcal/week
what determines how many calories you burn?
BW is difference in calorie expenditure when doing the same exercise as someone with a different weight
Iowa women’s health study
- stronger study since it has RR
- might not be accurate since it used questionnaires
- reduction of 33% (95% CI= 0.77) by doing mod-high PA compared to low PA
CV health study
- one of the first studies to incorporate different ethnicities
- 12% died after 5 year follow up
- those who expended more than 980-1890 kcal/week had 30% reduction risk
- higher risk if income less than $50 000/year, low weight, male, BP, smoking, lack of PA
Finnish twin study
- can genetics explain effects of PA against premature death
- RR for occasional exercisers was 0.80; for conditioning exercisers it was 0.76
- dose-response reduction in risk of dying with increasing quintiles of estimated energy expended on exercise, not necessarily due to genetic factors
veteran’s study
for each MET increase in peak exercise, RR of dying was decreased by 18%
lifetime risk of developing hypertension is __%?
90%
coronary heart disease
- disease in which a waxy substance called plaque builds up inside the coronary arteries
- also called coronary artery disease
coronary heart disease possible consequences
- angina
- myocardial infarction (average age for men 65, women 70)
- in US 935 000 events per year - 425 000 will die
- CHD represent 50% of all death from cardio-vascular diseases
main risk factor for many health problems?
age
risk factors of coronary heart disease
- related to behaviour
- tobacco smoke
- high cholesterol
- high BP
- physical inactivity
- diabetes melitus
- obesity
- stress
- high triglycerides
- alcohol abuse
atherosclerotic process
in coronary arteries, begins in childhood
multiple risk factor intervention trial
- tested 12 000 high risk men
- 16 years later, men doing less than 5 minutes per day of PA increased their risk of CHD by 22%
- if doing more than 20 minutes then no difference in RR
women’s prospective study
- studied female nurses for 8 years
- inverse association between total energy expenditure and CHD risk (more exercise = less risk)
- women’s study was more linear compared to mens (multiple risk factor intervention)
weight training/intensity prospective study
- men
- weight training 30 minutes/week = 18% reduced risk of CHD
- walking pace associated with 18% reduced risk of CHD
lipid research clinics prevalence study
- submit treadmill test
- white males
- strong association between cardiorespiratory fitness and lower CHD incidence and mortality
cardiac rehab
- all cause mortality 20% reduction
- cardiac mortality 26% reduction
- problem is after they tend to stop exercising since there is no support in case something happens
cerebrovascular disease
group of conditions that affect the circulation of blood to the blood, causing limited or no blood flow to affected areas of the brain
stroke
- serious medical condition where one part of the brain is damaged by a lack of blood supply or bleeding into the brain from a burst blood vessel
- 3rd leading cause of death in Canada
- more women die than men
- every 7 minutes a Canadian suffers a stroke
signs of a stroke
- facial weakness
- arm weakness
- speech difficulty
- time loss is brain loss
5 most important risk factors for stroke
- high BP
- abnormal obesity
- tobacco smoking
- heart disease
- diabetes
PA and stroke
- 25-30% risk reduction
prospective athletes study
- for each km run/day = 7.% reduction in stroke incidence
- runners who averaged at least 4km/day had 55% reduction in stroke
blood pressure
- primary: not sure why we have it (92-94%)
- secondary: have a specific gene or organ related to hypertension (3-5%)
- risk if high BP, but haven’t found evidence for risks of low BP
- a lot of people don’t know they have high BP
hypertension
- affects about 40% of canadians
- most common reason to visit doctor and taking medication
- BP is #1 risk factor for stroke and a major risk factor for heart disease
treating hypertension
- drug treatment
- weight management
- reduction in sodium intake
- regular PA
- limit alcohol
- maintain adequate dietary potassium
- diet
how much reduction in BP can you expect when you start exercising?
- 4.6 mmHg
- reduction of only 3 mmHg leads to reduction of 8% of strokes death, 5% of CV mortality and 4% all-cause mortality
average age to reach max weight
- 55-65
- after age 19 you tend to gain 1 pound/year
fitness & cancer
- Harvard: 50% less risk of cancer if spending more than 500 kcal/week
breast cancer survivors and CRF
had better survival rate if you had high CRF
colon & rectal cancer
- RR of 0.76 (0.72-0.81) when comparing most active vs least active
- 30-60 mins/day of mod-big PA may be necessary to significantly reduce risk of getting colon cancer (24%)
lung & endometrial cancer
- both seem to have a reduced chance of developing when engaging in PA
rectal & prostate cancer
- little support that PA reduces chances at developing these cancers
risk factors for cancer
- age
- race (most common in white American women)
- sex (most common in males- about 20% higher)
- family history
