1) PA and Health

What is physical activity

Any bodily movement produced by skeletal muscles that results in energy expenditure

What is physical activity What is exercise

A type of physical activity that is planned, structured, repetitive, and purposeful, usually performed to improve or maintain fitness

What is physical activity What is sedentary behaviour

Any waking behaviour involving very low energy expenditure (1-1.5 METs) while sitting, reclining, or lying.

What is physical activity What does it mean to be physically active in terms of METs

Generally, PA involves energy expenditure above sedentary levels

• activities around 3-4 METs are commonly considered moderate-intensity

METS What does MET stand for

Metabolic Equivalent of Task

METS What does a MET measure

The energy cost of an activity relative to a person’s resting metabolic rate

METS What does 1 MET represent

~the amount of energy the body uses at rest

METS Why are METs useful when studying PA

They provide a standardised way of describing the energy expenditure/intensity of different activities

How much PA should we do What are the general global PA guidelines for adults

At least:

• 150 mins of moderate-intensity activity per week

• 75 mins of vigorous-intensity activity per week

How much PA should we do Can moderate and vigorous activity be combined to meet guidelines

Yes

• Moderate and vigorous activity can be mixed and matched to reach the recommended amount

How much PA should we do Is the same amount/type of PA optimal for every health outcome

NO

• The amount and type needed can depend on the target outcome, such as cardiovascular health, mental health, or disease prevention

How much PA should we do What is the key public-health message about PA

Doing some PA is better than doing none

How much PA should we do Does PA have to occur in long, continuous exercise sessions to benefit health

NO

• Health benefits can occur when PA is accumulated in different patterns of bout duration, intensity, and daily/weekly frequency

How much PA should we do What does research suggest about different patterns of PA

PA accumulated across different durations, intensities, and frequencies is associated with a range of beneficial health outcomes in adults

Why should we do PA How has research on PA and health developed

It has grown substantially, with early influential evidence coming from studies comparing physically active and sedentary occupations, such as London bus conductors and drivers

Why should we do PA What did the London bus driver/conductor study demonstrate

Sedentary bus drivers had a greater risk of cardiovascular disease than bus conductors, who were more physically active during their work

Why should we do PA What broader conclusion came from the London bus study

People who move more tend to have better health outcomes than those who are more sedentary, highlighting the importance of regular movement

Why should we do PA What is cardiorespiratory fitness (CRF)

The ability of the cardiovascular and respiratory systems to supply oxygen to the body during sustained PA

Why should we do PA Why is CRF importance for health

Low CRF is:

• one of the strongest predictors/contributors to mortality & disability

• associated with poorer health independently of body weight

Why should we do PA Is the relationship between PA/fitness and health dependent only on body weight

NO

• CRF is an important health predictor independent of body weight, meaning being physically fit can provide health benefits regardless of body size

Population-level impact What is the estimated cost of physical inactivity

The cost of inaction is ~$47.6B per year

Population-level impact Why is physical inactivity considered a public-health intervention target

Increasing PA could prevent substantial numbers of deaths and years of poor health, potentially reducing healthcare and societal costs

• Worldwide, 499.2 deaths could be avoided by 2030

Population-level impact What could happen if PA levels increased globally

Large numbers of premature deaths could potentially be avoided, demonstrating the population-level impact of increasing PA

Population-level impact What could happen if PA increased by only 10-25%

• 533 000 and 1.3mil deaths could be avoided

• Life expectancy increases by 0.68years

• Inactive people would gain 1.3 – 3.7 years

Population-level impact Who would benefit most from increasing PA

Currently inactive people, who gain particularly large improvements in life expectancy and health from becoming more active

Population-level impact What is the public-health inplication of the effects of physical inactivity

Investment in preventive PA interventions may reduce disease burden and healthcare costs, rather than relying solely on treatment after disease develops

Do we do enough PA Is physical inactivity equally prevalent across men and women

NO

• women tend to be more inactive than men across the lifespan

Do we do enough PA What can contribute to differences in PA between women and men

Environmental determinants, among other social and contextual factors

Why is PA complex What are the 4 major types of PA

1. Aerobic - biking, swimming

2. Strength - resistance/weight training

3. Flexibility - yoga, pilates

4. Balance

Why is PA complex Do different types of PA necessarily produce the same health outcomes

NO

• Different types may produce different health outcomes, creating challenges when comparing research

Why is PA complex Why might researchers have difficulty cross-referencing studies examining different types of PA

Because studies may investigate different types of activity, which may not produce the same health outcomes

Characteristics of PA What are the 4 key characteristics of PA

FITT:

1. Frequency

2. Intensity

3. Time

4. Type

Characteristics of PA What does frequency mean

How often PA is performed

Characteristics of PA What does intensity mean

How hard the activity is

Characteristics of PA What does time mean

How long the activity lasts

Characteristics of PA What does type mean

What kind of PA is being performed

Characteristics of PA Why do differences in PA characteristics make research difficult to interpret

People can differ in frequency, intensity, time, and type, making it difficult to group evidence together and make broad statements about the health benefits of “physical activity”

Domains of PA What are the 4 domains of PA

1. Leisure

2. Work/school

3. Household

4. Transport

Domains of PA What is leisure-domain PA

PA performed during free time, such as sport or recreational exercise

Domains of PA What is work/school-domain PA

PA occurring as part of employment or education

Domains of PA What is household-domain PA

Activity associated with household tasks, such as cleaning and gardening

Domains of PA What is transport-domain PA

Activity used to travel from one place to another, such as walking or cycling

Domains of PA Why do PA domains matter

The same amount of PA can potentially have positive or negative outcomes, depending on the context/domain in which it occurs

What are the two broad categories of PA measurement

• objective

• subjective/self-report

measures

Objective Measures What is an accelerometer

A device that objectively measures movement/acceleration to estimate PA

• e.g. ActiGraph

Objective Measures What is a posture monitor

A device that measures body posture and movement

• activPAL

Objective Measures What is wearable technology used to measure physical activity?

Devices such as a Fitbit can track activity-related measures such as movement and steps.

Objective Measures What is a pedometer?

A device that measures the number of steps taken.

Subjective Measures What are examples of subjective/self-report measures?

• Questionnaires

• Interviews

• Time-use diaries

• Proxy reporting

Subjective Measures What is proxy reporting

When someone reports another person's physical activity, e.g., a parent reporting activity for a child.

Subjective Measures What is a major limitation of self-report measures?

People tend to over-report how active they are.

What are three important criteria for evaluating a physical-activity measurement method?

Reliability, validity, and feasibility.

What is reliability?

The consistency of a measurement — whether it gives similar results when repeated under similar conditions.

What is validity?

Whether a measure accurately measures what it is intended to measure.

What is feasibility?

How practical and manageable a measurement method is to use, considering factors such as time, cost, burden, and accessibility.

What is a key difference between objective and subjective measures?

Objective measures provide a more direct measurement of movement but may be less feasible/costlier, whereas subjective measures are generally easier and cheaper but are more vulnerable to recall and reporting bias, including over-reporting.