Physical Activity Flashcards
Define Physical Activity (PA) including PA categories.
Any body movement provided by skeletal muscles that results in an increase in energy expenditure above resting levels (McArdle et al. 2015)
PA contributes around 25% of TEE
-Leisure
-Occupational
-Household
-Travel
Define exercise.
Exercise is physical activity that is planned, structured, repetitive and purposeful (McArdle et al. 2015).
Define health and explain how physical activity contributes to health.
Health is defined as physical, mental and social well-being not simply the absence of disease.
There is a positive relationship between health and physical activity and an inverse relationship between mortality and PA.
Elements of PA and exercise that contribute to overall health include:
- Maintaining healthy weight (important to note that exercise accounts for only ~20% of weight maintenance - diet accounts for ~80%)
- Improve muscle mass and strength
- Improve cardiorespiratory fitness (Improving cardiorespiratory fitness has the greatest effect on reducing risk of CVD)
- Mental wellbeing/stress management
- Improves cognitive health e.g., reduced risk of dementia.
- Decreased risk of acute illness.
Describe some difficulties in measuring PA levels.
PA is difficult to assess accurately without changing one’s behaviour (as this is the exact thing we are trying to measure).
There are also multiple characteristics to consider when assessing PA including:
- Study characteristics
- Population characteristics
- Instrument characteristics
- Activity characteristics
How is the relationship between physical activity, fitness and health complex?
Relationship between PA and mortality is ‘inverted J’ curve:
Those who go from doing nothing to increasing PA see the most benefits, those at the other end of the scale completing extreme amounts of PA have increased risk of mortality.
As exercise intensity increases, risk of injury increases (negative effect on health).
- however, is mortality an appropriate measure? Should the relationship concern PA and aspects that improve QoL?
Describe the benefits of PA across age groups.
Children - bone health, cognitive function, CRF, muscle development, weight status, mood.
Adults - CVD, cancer, neurological disorders (dementia, anxiety/depression), sleep, weight.
Older adults - frailty, sarcopenia, osteoporosis, decreased risk of falls.
Describe the impact of physical inactivity
PI is the fourth leading global cause of death (Kerr & Booth, 2022).
- major contributor to metabolic and endocrine diseases
Regular PA been shown to reduce risk of poor health.
Physical inactivity has been shown to increase risk of over 40 chronic diseases including:
- Metabolic disorders (T2D, obesity, HTN, CVD)
- Cancer
- Poor mental health
People who are PI are:
- 1.75 times more likely to develop CVD
- 1.4 times more likely to develop dementia
Define sedentary behaviour (SB)
Any waking behaviour in a sitting or reclining position with an energy expenditure equal to or less than 1.5 MET (metabolic equivalent task).
Describe the relationship between PA and SB.
SB and PA are separate entities that co-exist.
Individuals can be ‘physically active’ i.e., they meet the recommended guidelines for PA, however, still engage in high levels of SB meaning that the positive effects of PA are lost.
Canada fitness study (17,000 men and women followed for 12 years) showed that SB was independently and positively associated with all cause mortality despite level of PA.
CVD risk also increased as daily sitting time increased.
Describe why rates of SB are increasing?
What are the sociocultural aspects of sitting behaviour?
It is well understood how physically active our early ancestors were (hunting/gathering) however we cannot know how sedentary they were.
Industrial revolution: Machines replaced tools = increased levels of PA.
Introduction of cars and computers has further increased levels of SB.
Sociocultural aspects:
Infants like to move a lot - only restrained by car seats, high chairs etc.
Sitting represents institutional discipline and is the predominant posture in schools, university and workplaces.
Western society therefore very much promotes being sedentary as people spend the vast majority of the day in a seated position (school, 8 hour workday..)
Rates of SB & PI are thought to have increased further as a result of COVID-19 pandemic - more people WFH, fallen out of habit of going to gym etc.
What are the PA guidelines in the UK for children and adults?
Children (5-18):
60 minutes of PA each day across the week.
- playing
- walking
- swimming
- climbing
Adults (19+):
150 minutes of moderate/vigorous intensity exercise
OR
75 minutes of high intensity exercise
Strength training at least 2x week
Also:
- reduce time spent sedentary
- improve balance (especially for older adults)
Describe the role of PA in the management of T2D
Exercise has shown positive effects on the management of T2D and can help put T2D into remission.
- exercise increases insulin sensitivity and lowers HbA1c levels by 0.7% (shown in RCT of adults consuming varied diets who did not lose any weight so effects can be attributed to exercise)
- shown to decrease the amount of insulin needed to achieve glucose homeostasis by 50%
- Both aerobic and resistance exercise help to control blood glucose levels and reduce HbA1c levels (best effect is when the both types of exercise are done)
- Most beneficial effects of PA on blood glucose are postprandial (after meal ingestion) as blood glucose levels have more potential to reduce however important to check blood glucose level before exercise
The favorable effects of exercise training are limited not only to the prevention, but also to the control of the prognostic determinants of the diabetes, such as the glycaemia, blood pressure, and lipid profile.
Also reduced risk of diabetes complications associated with HTN such as microvascular disease.
Describe the role of PA in the prevention/management of hypertension
management of overweight/obesity:
- BP increases as adiposity increases
- weight loss results in decrease in BP
Regular PA has direct effect on BP: Increasing PA reduces BP and BP increases when PA level is reduced.
- The first randomized controlled study that evaluated the effects of exercise on BP was the PREMIER Clinical Trial in 2003 (810 patients).
- The results of this study strongly support the concept that exercise in combination with other lifestyle modifications can lower BP at same extent of some drugs.
Exercise needs to be aerobic to have antihypertensive effect however does not have to be high intensity e.g., walking
- some research does support that dynamic resistance training can have effect on reducing BP.
Yoga shown to increase odds of maintaining normal BP
exercise = stronger heart = heart can pump more blood with less effort = force on the arteries decreases. This lowers blood pressure.
Describe the effect of PA on HDL levels.
An RCT by healthy older adults that a 2-year period of aerobic physical training enhanced the plasma levels of HDL-cholesterol level by 3–9%
- later studies confirm this and add that it is the amount of PA rather than intensity of PA that has greatest effect.
Describe the relationship between exercise and mental wellbeing.
(Harris, 2018).
RCT - Community-wide, gamification-based PA intervention found increases in mental wellbeing were significantly greater for the least active prior to the intervention. Strong, positive correlation between increase in PA and increase in mental wellbeing was observed throughout.
