• Introduction
• 2020 World Health Organization guidelines
• Population surveillance and other measurement issues
• References

• The scientific literature linking physical activity and sedentary behaviour to a range of physical and mental health conditions is strong and expanding (2018 Physical Activity Guidelines Committee, 2018; World Health Organization, 2020b).
• Guidelines can be used to educate policy-makers and the general public on these relationships and support/promote healthy behaviours.
• Quantifying a beneficial level of activity provides a marker against which individual, group, and population behaviours can be monitored.
• Guidelines are usually published and endorsed by national governments; the World Health Organization takes responsibility for the global guidelines.
• Guidelines tend to be specific for different life stages, and recently, specific guidelines have been developed for population groups that may require more specific information and targeted support.
• Guidelines have evolved from the American College of Sports Medicine recommendations for improving cardiorespiratory fitness in the 1970s (American College of Sports Medicine, 1978), with the first distinction between the recommendations for fitness and health coming in 1995/6 (Pate et al., 1995; US Department of Health and Human Services, 1996) (see Figure P.1.10; Ding et al al., 2020).

Figure  P.1.10 The evolution of Physical Activity guidelines. Source: Ding et al., 2020

Alongside the specific recommendations detailed below, there are two key messages. (1) Every move counts towards better health (World Health Organization, 2020a), (2) everyone can benefit from undertaking physical activity and limiting sedentary time.

1. Early years (World Health Organization, 2019)

(a) Infants (less than 1 year old)

• Be physically active several times a day in a variety of ways, particularly through interactive floor-based play; more is better.
• For those not yet mobile, this includes at least 30 minutes in prone position (tummy time) spread throughout the day while awake.
• Not be restrained for more than 1 hour at a time (e.g. prams/strollers, high chairs, or strapped on a caregiver’s back). Screen time is not recommended.
• When sedentary, engaging in reading and storytelling with a caregiver is encouraged.
• Have 14–17 hours (0–3 months of age) or 12–16 hours (4–11 months of age) of good quality sleep, including naps.

(b) Children 1-2 years of age

• Spend at least 180 minutes in a variety of types of physical activities at any intensity, including moderate-to vigorous-intensity physical activity, spread throughout the day; more is better.
• Not be restrained for more than 1 hour at a time (e.g. prams/strollers, high chairs, or strapped on a caregiver’s back) or sit for extended periods of time.
• For 1-year-olds, sedentary screen time (such as watching TV or videos, playing computer games) is not recommended. For those aged 2 years, sedentary screen time should be no more than 1 hour; less is better.
• When sedentary, engaging in reading and storytelling with a caregiver is encouraged.
• Have 11–14 hours of good quality sleep, including naps, with regular sleep and wake-up times.

(c) Children 3-4 years of age

• Spend at least 180 minutes in a variety of types of physical activities at any intensity, of which at least 60 minutes is moderate-to vigorous intensity physical activity, spread throughout the day; more is better.
• Not be restrained for more than 1 hour at a time (e.g. prams/strollers) or sit for extended periods of time.
• Sedentary screen time should be no more than 1 hour; less is better.
• When sedentary, engaging in reading and storytelling with a caregiver is encouraged.
• Have 10–13 hours of good quality sleep, which may include a nap, with regular sleep and wake-up times.

2. Children and adolescents 5-17 years of age (World Health Organization, 2020b)

• Children and adolescents should do at least an average of 60 minutes per day of moderate-to vigorous-intensity, mostly aerobic, physical activity, across the week.
• Vigorous-intensity aerobic activities, as well as those that strengthen muscle and bone, should be incorporated at least 3 days a week.
• Children and adolescents should limit the amount of time spent being sedentary, particularly the amount of recreational screen time.

3. Adults aged 18-64 years (World Health Organization, 2020b)

• All adults should undertake regular physical activity.
• Adults should do at least 150–300 minutes of moderate-intensity aerobic physical activity; or at least 75–150 minutes of vigorous-intensity aerobic physical activity; or an equivalent combination of moderate- and vigorous-intensity activity throughout the week, for substantial health benefits.
• Adults should also do muscle strengthening activities at moderate or greater intensity that involve all major muscle groups on 2 or more days a week, as these provide additional health benefits.
• Adults should limit the amount of time spent being sedentary. Replacing sedentary time with physical activity of any intensity (including light intensity) provides health benefits.
• To help reduce the detrimental effects of high levels of sedentary behaviour on health, adults should aim to do more than the recommended levels of moderate- to vigorous-intensity physical activity.

4. Older adults aged 65 years and older  (World Health Organization, 2020b)

• All older adults should undertake regular physical activity.
• Older adults should do at least 150–300 minutes of moderate-intensity aerobic physical activity; or at least 75–150 minutes of vigorous-intensity aerobic physical activity; or an equivalent combination of moderate- and vigorous-intensity activity throughout the week, for substantial health benefits.
• Older adults should also do muscle strengthening activities at moderate or greater intensity that involve all major muscle groups on 2 or more days a week, as these provide additional health benefits.
• As part of their weekly physical activity, older adults should do varied multicomponent physical activity that emphasizes functional balance and strength training at moderate or greater intensity, on 3 or more days a week, to enhance functional capacity and to prevent falls.
• Older adults may increase moderate intensity aerobic physical activity to more than 300 minutes; or do more than 150 minutes of vigorous-intensity aerobic physical activity; or an equivalent combination of moderate- and vigorous-intensity activity throughout the week, for additional health benefits.
• Older adults should limit the amount of time spent being sedentary. Replacing sedentary time with physical activity of any intensity (including light intensity) provides health benefits.
• To help reduce the detrimental effects of high levels of sedentary behaviour on health, older adults should aim to do more than the recommended levels of moderate- to vigorous-intensity physical activity.

5. Pregnant and postpartum women (World Health Organization, 2020b)

• Undertake regular physical activity throughout pregnancy and postpartum.
• Do at least 150 minutes of moderate-intensity aerobic physical activity throughout the week for substantial health benefits.
• Incorporate a variety of aerobic and muscle strengthening activities. Adding gentle stretching may also be beneficial.
• Women who, before pregnancy, habitually engaged in vigorous-intensity aerobic activity, or who were physically active, can continue these activities during pregnancy and the postpartum period.
• Pregnant and postpartum women should limit the amount of time spent being sedentary. Replacing sedentary time with physical activity of any intensity (including light intensity) provides health benefits.

6. Adults and older adults with chronic conditions aged 18 years and older (World Health Organization, 2020b; Dempsey et al., 2020)

• All adults and older adults with the above chronic conditions should undertake regular physical activity.
• Adults and older adults with these chronic conditions should do at least 150–300 minutes of moderate-intensity aerobic physical activity; or at least 75–150 minutes of vigorous-intensity aerobic physical activity; or an equivalent combination of moderate- and vigorous-intensity activity throughout the week for substantial health benefits.
• Adults and older adults with these chronic conditions should also do muscle-strengthening activities at moderate or greater intensity that involve all major muscle groups on 2 or more days a week, as these provide additional benefits.
• As part of their weekly physical activity, older adults with these chronic conditions should do varied multicomponent physical activity that emphasizes functional balance and strength training at moderate or greater intensity on 3 or more days a week, to enhance functional capacity and prevent falls.
• When not contraindicated, adults and older adults with these chronic conditions may increase moderate-intensity aerobic physical activity to more than 300 minutes; or do more than 150 minutes of vigorous-intensity aerobic physical activity; or an equivalent.
• combination of moderate- and vigorous-intensity activity throughout the week for additional health benefits.
• Adults and older adults with chronic conditions should limit the amount of time spent being sedentary. Replacing sedentary time with physical activity of any intensity (including light intensity) provides health benefits.
• To help reduce the detrimental effects of high levels of sedentary behaviour on health, adults and older adults with chronic conditions should aim to do more than the recommended levels of moderate- to vigorous-intensity physical activity.

7. Children and adolescents (5-17 years) living with disability (World Health Organization, 2020b; Carty et al., 2021)

• Children and adolescents living with disability should do at least an average of 60 minutes per day of moderate- to vigorous-intensity, mostly aerobic, physical activity, across the week.
• Vigorous-intensity aerobic activities, as well as those that strengthen muscle and bone should be incorporated at least 3 days a week.
• Children and adolescents living with disability should limit the amount of time spent being sedentary, particularly the amount of recreational screen time.

8. Adults (aged 18 years and older) living with disability (World Health Organization, 2020b; Carty et al., 2021)

• All adults living with disability should undertake regular physical activity.
• Adults living with disability should do at least 150–300 minutes of moderate-intensity aerobic physical activity; or at least 75–150 minutes of vigorous-intensity aerobic physical activity; or an equivalent combination of moderate- and vigorous-intensity activity throughout the week for substantial health benefits.
• Adults living with disability should also do muscle-strengthening activities at moderate or greater intensity that involve all major muscle groups on 2 or more days a week, as these provide additional health benefits.
• As part of their weekly physical activity, older adults living with disability should do varied multicomponent physical activity that emphasizes functional balance and strength training at moderate or greater intensity on 3 or more days a week, to enhance functional capacity and prevent falls.
• Adults living with disability may increase moderate-intensity aerobic physical activity to more than 300 minutes; or do more than 150 minutes of vigorous-intensity aerobic physical activity; or an equivalent combination of moderate- and vigorous-intensity activity throughout the week for additional health benefits.
• Adults living with disability should limit the amount of time spent being sedentary. Replacing sedentary time with physical activity of any intensity (including light intensity) provides health benefits.
• To help reduce the detrimental effects of high levels of sedentary behaviour on health, adults living with disability should aim to do more than the recommended levels of moderate-to vigorous-intensity physical activity.

• The primary factors of consideration for population level surveillance of physical activity and sedentary behaviour can differ from measurement within a research intervention or cohort study.
• A key example of this is the focus on sampling as the issue of representativeness is more critical than for other measurement purposes.
• Another consideration is that trend data are hugely valuable for policy-makers and therefore continuing to use old measurement instruments may be the preferred choice.
• Self-report questionnaires such as the IPAQ or the GPAQ have been typically been used in population level surveillance as they are cheap and easily scalable. In addition, the ability to ask about specific domains of activity is usually of interest to policy-makers.
• Some countries such as Finland, Norway and the United States have incorporated accelerometers [link to accelerometer page] into their surveillance systems for the last 20-30 years, and it is increasingly feasible in a low-and-middle-income country setting (Westgate et al., 2020).
• There is an ongoing debate about whether accelerometers should be used to measure guideline compliance given they are based upon predominantly self-reported data (Migueles et al., 2019). However, alternative metrics have been proposed that exploit the advantages of accelerometry such as the time-stamped monitoring of intensity on a continuous scale (Rowlands et al., 2019).
• The core message of “all physical activity counts” is emphasised by the removal of the previous requirements for physical activity to be done in continuous blocks of at least 10 minutes to enhance health. This poses challenges for surveillance trend data as many questionnaires ask about activities in bouts longer than 10 minutes. Whilst removal of the minimum bout length (i.e. 10 minutes) criterion from questionnaires might result in greater reported physical activity duration, it is also plausible that this will not have a large effect on responses (Ussery et al., 2020), as shorter, incidental bouts of activity are hard to recall.
• Applying a minimum bout length to accelerometer data can have large consequences for the quantification of activity (Orme et al., 2014). However, as accelerometers gain capacity to sample at rates higher than 100Hz, defining a minimum bout length becomes more of a philosophical and physiological question.
• There is a lack of consensus around the measurement of muscle strengthening and multi-component strength and balance activities with various un-validated approaches used in national surveillance worldwide (Milton et al., 2018; Strain et al., 2016). Direct measures of strength (e.g. hand grip) or function (e.g. chair rise) are feasible alternatives (Strain et al., in press).
• Due to the lack of quantified guideline for sedentary behaviour (Dempsey et al., 2020), population levels are usually summarised as mean durations of self-reported sitting time per day (Mclaughlin et al., 2020) rather than a percentage meeting a target. However, it is likely that future measurement and reporting of sedentary behaviour in a surveillance context will be more complex, given ongoing research investigating the importance of sedentary bouts and patterns (e.g. breaks in sedentary time) and interactions with moderate-to-vigorous physical activity (Stamatakis et al., 2019).
• The advent of 24-hour guidelines may require greater integration between physical activity, sedentary behaviour, and sleep [link to sleep page] surveillance whether that is using questionnaires or devices.
• Measurement of energy expenditure [link to energy expenditure] using doubly labelled water is less common in surveillance systems due to the cost and practicalities of administration. However, there are some examples such as in the UK National Diet and Nutrition Survey (Brage et al., 2020).

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