Test 1 Flashcards
Relative risk
Probability of an event (ex. cancer) in exposed (ex exercise) group compared to the probability of that event in non exposed (ex no exercise) group
Relative risk example
17% of physically inactive women develop breast cancer, while 1% of physically active women develop breast cancer
RR= 17%/1%
Physically inactive women are 17X more likely to develop breast cancer than physically active women
Randomized control trial
Participants are randomly allocated to receive one of the other treatments under study
Studies risk factors (ex. blood pressure, insulin resistance etc.)
Types of randomized control trials
- Efficacy trial
- Effectiveness trial
Efficacy trial
Concerned with what happens when you exercise (internal validity)
Measures a trait under ideal settings
Ex. Does exercise reduce risk of morbidity and motality?
Effectiveness trial
Concerned with behaviour change (external validity)
Measures translation of traits to real-world setting
Ex. How can we get people to regularly adopt and sustain PA?
Prospective cohort study
Follows of a group of individuals over time who differ with respect to certain factors under study to determine how these factors effect a certain outcome (ex cancer, morality, diabetes)
Strengths of a prospective cohort study
Large sample
Generalizable
Multiple outcomes can be studied
Limitations of a prospective cohort study
Expensive
Confounding variables
Changes in exposure (diff levels of PA)
Principal assertion of 24 hour movement guidelines
The composition of movement behaviours (sleep, sedentary, behaviour, physical activity) are mutually exclusive (the behaviours co-exist)
If you change one behaviour anther behaviour must change
Provide opportunities to engage in movement behaviours in a way that reflect individuality, variability and personal preferences
Recommendation 1: MVPA
- 150 min MVPA per week
- No longer needs to be in greater than 10 bouts
- Muscle strengthening activity at least twice a week
- PA that challenges balance for 65+
Three key observations of relationship btwn MVPA and all-cause mortality
- Steep inverse dose-response relationship (greatest benefit) occurs when going from little MVPA to some
- No lower threshold for benefit
- Intensity doesn’t matter
- No evidence of risk at high end of exercise dose
Hazard ratio
Measure of how often a particular even happens in one group compared to another; estimate of relative risk
Why doesn’t intensity matter in the guidelines?
There is no evidence of an upper threshold effect (the harder you work doesnt determine your hazard ratio of mortality)
Guidelines are based on outcomes (ex. mortality), not risk factors,
Recommendation 2: LPA
- Associated w a reduction in risk in a dose-respone manner
- Any amount of LPA counts
- Reallocating sedentary time into LPA is associated with benefit
Recommendation 3: Sedentary time
- High sedentary behaviour is associated with negative health outcomes
- There is a positive dose-response relationship btwn sedentary time and mortality
- Reallocating sedentary time into any of the other movement behaviours is associated with benefit
Public health implications of guidelines
- Promoting participation of MVPA of any length provides more options and increases engagement
- Promotes engagement in exercise of less than 10 min bouts
- LPA encourage participation in routine activities, feasible, supports public health initiatives (stairs, walking, standing)
- Limiting sedentary time will reduce the risk of chronic disease, mortality
Dose response relationship btwn MVPA and health outcomes
- MVPA is associated w substantial reduction in health risk
- Any amount counts
- Reallocate time into MVPA
**MVPA benefits health regardless of sedentary behaviours and LPA
Dose response relationship btwn LPA and health outcomes
- LPA is associated with a substantial reduction in health risk is dose response later
- Any amount of LPA counts
- Reallocating some sedentary time into any of the movement behaviours is associated w benefit
Approaches for integrating movement behaviours
- Examine effects of one intensity of movement within levels of another (ex. more PA=more you reduce the effect that sedentary has on health)
- Independent effects of two movement behaviours (ex. direct effects of sedentary independent of MVPA)
- Compositional data analysis (CoDA)
Cardiorespiratory fitness 3 points
- CRF reduces your risk of mortality, independent of risk factors (ex. metabolic syndrome)
- CRF can be measured pragmatically in clinical settings (step test, treadmill test, non-exercise method)
- CRF can be improved by performing PA and following guidelines (intensity matters)
Estimating CRF
- Using a non-exercise model/algorithm
- estimated CRF associated with measured CRF
- estimated CRF is associated with/predicts CVD and all cause mortality similar to measured CRF
Association btwn exercise amount and intensity on insulin resistance/ blood glucose
Increasing intensity has more of an effect on 2-hour glucose than increasing amount
Why is CRF a strong predictor of mortality?
Effects risk factors such as cigarette smoking, hypertension, high cholesterol, T2D
