XNB166 Study term week 1 terms

Physical activity

is any bodily movement produced by skeletal muscles that raises energy expenditure above resting level (Caspersen et al., 1985), so it is defined by behaviour and energy cost rather than by purpose, and occupational, domestic, transport and leisure activity all count.

Exercise

is the subset of physical activity that is planned, structured, repetitive and purposive in that its aim is to improve or maintain one or more components of fitness, so the distinction from physical activity rests on intent and structure rather than on intensity.

Physical fitness

is a set of attributes, such as cardiorespiratory endurance and muscular strength, that a person has or achieves, so it is an outcome that exercise can change, whereas physical activity is the behaviour that produces the change.

Sedentary behaviour

is any waking behaviour in a sitting, reclining or lying posture with an energy expenditure of 1.5 METs or less, and it is a risk exposure in its own right, in that a person can meet the activity guideline and still sit for most of the day.

Metabolic equivalent (MET)

is the ratio of working metabolic rate to resting metabolic rate, with 1 MET equal to about 3.5 mL of oxygen per kilogram of body mass per minute, and it lets researchers express the intensity of different activities on one scale.

MVPA

stands for moderate to vigorous physical activity and is activity at about 3 METs or more, and it is the intensity band that the guidelines count toward the weekly target, with adults in the NHANES data averaging only about 0.2 hours, or 12 minutes, of it each day.

Insufficient physical activity

means failing to meet the recommended weekly level, and Strain et al. (2024) pooled population surveys to estimate that about 31 per cent of adults worldwide were insufficiently active in 2022.

Primary prevention

lowers the incidence of disease by acting on a healthy population before any symptoms appear, so public promotion of the adult activity guideline is a population level example.

Secondary prevention

uses early detection, usually screening, to find a risk factor or early disease in an at-risk population and then intervenes to stop progression, in that it aims to limit severity rather than to prevent the first occurrence.

Tertiary prevention

targets people with established disease and aims to limit impairment, prevent recurrence and restore function, and exercise rehabilitation after a heart attack is the standard example.

Dose-response relationship

describes how the size of an outcome changes with the level of exposure, and for physical activity the curve is curvilinear in that risk falls steeply from none to about 2.5 hours a week and then more slowly with diminishing returns.

None to some principle

follows from the shape of the dose-response curve, because the largest marginal gain in health comes from moving inactive people to some activity, so public health messaging should treat any activity as better than none.

Morris et al. (1953)

was published in the Lancet, compared active London bus conductors with sedentary drivers and found lower rates of coronary heart disease in the conductors, so it is a landmark study that identified inactivity as a risk factor for heart disease.

Adult activity guideline

for Australians aged 18 to 64 years is 150 to 300 minutes of moderate or 75 to 150 minutes of vigorous activity a week, which is equivalent to about 500 to 1000 MET minutes, plus muscle strengthening activities on at least 2 days.

24-Hour Movement Guidelines

treat physical activity, sedentary behaviour and sleep as co-dependent parts of one day, in that time given to one displaces time from the others, and they recommend 7 to 9 hours of sleep for adults.

GAPPA

is the WHO Global Action Plan on Physical Activity 2018 to 2030, which sets four strategic objectives delivered through 20 policy actions and a target of a 15 per cent relative reduction in physical inactivity by 2030.

Global inactivity trend

is that the global prevalence of insufficient physical activity is rising rather than falling, at about 31 per cent in 2022, so the world is off track to meet the GAPPA target without a substantial change in policy and environments.

10 000 steps

a day is a target linked to Dr Yoshiro Hatano and to the first pedometer, which Japan produced in 1965 after the 1964 Tokyo Olympics, and students should treat it as a popular benchmark that sits alongside the formal guidelines.

Nutrient Reference Values (NRVs)

are the intake levels set for Australia and New Zealand to prevent deficiency and, where evidence allows, to reduce chronic disease risk, and they are the evidence base from which the food guidance is built.

EAR

stands for Estimated Average Requirement and is the intake that meets the needs of 50 per cent of healthy people in a group, and because it sits at the median of requirement it is the correct reference for judging the adequacy of intake in groups.

RDI

stands for Recommended Dietary Intake and equals the EAR plus 2 standard deviations, so it meets the needs of 97 to 98 per cent of people, and because it includes a safety margin it applies to individuals and would make a well fed group look inadequate.

AI and UL

are two Nutrient Reference Values: the Adequate Intake is used when evidence is too weak to set an EAR and RDI, and the Upper Level is set from toxicity data, so intakes above the UL carry a risk of harm.

AMDR

stands for Acceptable Macronutrient Distribution Range and gives the healthy percentage of total energy that should come from each macronutrient, and it is aimed at chronic disease prevention rather than at preventing deficiency.

Suggested dietary target (SDT)

is an intake set at about the 90th centile of current intake to help lower chronic disease risk, and vitamin C at 220 milligrams a day for men is the example from the lectures.

Core Food Group Analysis

is NHMRC computer modelling of food types and amounts that converts the NRVs into a practical pattern of foods, in that it is the step that links nutrient targets to the Australian Guide to Healthy Eating.

Australian Guide to Healthy Eating

is the food selection guide and main education tool, and it shows the relative share of the five food groups, with water, that a population level diet should contain.

Australian Dietary Guidelines

(NHMRC 2013) give five guidelines for healthy weight, food variety, limiting saturated fat, added salt, added sugars and alcohol, breastfeeding, and safe food handling, and they apply to the whole diet rather than to single foods.

Discretionary foods

are foods and drinks that are not needed for a healthy diet and are usually high in saturated fat, added sugars, added salt or alcohol, and the National Preventive Health Strategy targets a fall in their share of energy intake from over 30 per cent to under 20 per cent.

National Preventive Health Strategy 2021 to 2030

aims to increase investment in prevention, give all Australians the best start in life and achieve health equity for priority populations, with diet targets of 2 serves of fruit and 5 of vegetables a day and a cut in sodium of at least 30 per cent.