Question

In children under 5 years of age what dose (i.e., durations, frequencies, patterns, types, and intensities) of physical activity, as measured by objective and subjective methods, is associated with favourable health indicators?

Summary of evidence

The 2017 systematic review of the relationship between physical activity and health indicators in the early years (0–4 years) (26) assessed 908 full text articles and identified 96 studies, from 36 countries with 71,291 unique participants, that met the inclusion criteria. One additional study (31) (301 participants) was incorporated up to March 2017 for the update to inform the Australian guidelines process and an additional six studies (2,327 participants) for the update to December 2017 (32–37). These included randomized-controlled trials (RCTs) (n=8), cluster RCTs (n=5), non-randomized interventions (n=10), cross-over trials (n=3), longitudinal (n=12), longitudinal with additional cross-sectional analysis (n=5), case-controlled (n=4), case cross-over (n=1) and cross-sectional (n=55) studies. One meta-analysis was conducted (four studies, 1100 participants) examining adiposity as a health indicator. The GRADE table for physical activity is available in Web Annex Evidence Profiles, section 1.1.

Physical activity was associated with improved motor and cognitive development, psychosocial and cardiometabolic health in randomized and non-randomized intervention studies and with improved motor development, fitness and bone and skeletal health in observational studies. Moderate- to vigorous-intensity, vigorous-intensity and total physical activity were beneficially associated with several health indicators and although it was not possible to determine the most favourable frequency or duration of physical activity, more physical activity appeared to be better.

In infants less than 1 year of age, 30 minutes per day of prone position was favourably associated with health indicators.

For the critical outcomes, there was moderate quality evidence for cognitive development, low quality evidence for psychosocial health, motor development and adiposity and very low-quality evidence for fitness. The overall quality of evidence was rated as very low using the GRADE framework.

Rationale

The recommendation for 180 minutes per day of physical activity was first proposed by Australian guidelines in 2010 (38), based on expert consensus and included in the United Kingdom (39) and Canadian guidelines of 2012 (40). The current evidence available is from studies that assessed compliance with a 180 minutes per day duration of physical activity vs non-compliance and the former shows an association with better health outcomes. No evidence was found favouring less physical activity. For children who are currently inactive, progressive increase in activity to reach the target through additional time for free active play will have health benefits.

The recommendation for 60 minutes of moderate- to vigorous-intensity physical activity per day for 3–4-year-olds aligns with the recommendation for 60 minutes per day of moderate- to vigorous-intensity physical activity in children 5 years of age and older (1), and is associated with desirable health indicators.

The GDG discussed extensively the use of the term physical activity or active or energetic play, recognizing that in young children, physical activity will most likely take the form of energetic play rather than organized exercise, physical education or sport. The GDG decided to use the term physical activity and moderate- to vigorous-physical activity as these are the terms used in guidelines for older children and can be quantified in terms of Metabolic Equivalent of Task (METs) that are used in the measurement of physical activity. In the implementation of the guidelines, the term energetic play may be preferred (see glossary for definitions).

The GDG made a strong recommendation as the desirable outcomes of promoting physical activity outweigh possible harms. For infants, benefits of at least 30 minutes of prone position (tummy time) while awake include improved motor development and reduced likelihood of deformational plagiocephaly. The benefit of at least 5 hours of unrestricted movement per day is reduced adiposity. Evidence for psychosocial health was equivocal. For children 1–4 years of age, the benefits of increased levels of physical activity include improved motor and cognitive development, and fitness. Most studies showed a favourable or inconclusive association with adiposity, and very few studies showed an unfavourable association. In addition, there is no evidence that physical activity is associated with serious risk of harms or injury in any age group.

While the GDG acknowledged that in some settings there may be additional resource requirements to ensure young children meet physical activity recommendations, the panel considered resource implications to be minimal due to the type and variety of physical activities that young children can engage in (such as free, energetic play) to meet physical activity recommendations at home or in child care settings. As such, the GDG concluded that the potential benefits of promoting physical activity outweigh the costs. No evidence was available on the values and preferences, acceptability or feasibility of the recommendations in low and middle-income settings. The GDG discussed that there may be some variability on how some groups value adiposity in children. Physical activity can be increased in various ways requiring minimal facilities or equipment, but safe environments should be ensured. The GDG noted that for infants, interactive floor-based play would require appropriate supervision and a safe environment. Tailored communication and/or resources may be required for certain settings (such as low resource settings) and special populations (children with disabilities). The GDG noted that studies in Canada (33, 34) and Australia (35) indicated that most children 1 to 4 years of age and about 30% of infants were already meeting the recommendations for physical activity and prone position (tummy time) respectively and considered this evidence to support the feasibility of the recommendation. The GDG concluded that the physical activity recommendations were feasible and that promoting more physical activity in the longer-term would probably increase health equity by improving health outcomes, although no evidence was available.

Question

In children under 5 years of age what dose [i.e., durations, patterns (frequency, interruptions), and type] of sedentary behaviour, as measured by objective and subjective methods, is associated with favourable health indicators?

Summary of evidence

The 2017 systematic review of the relationship between sedentary behaviour and health indicators in the early years (0–4 years) (27) assessed 334 full text articles and identified 96 studies, from 33 countries with 195,430 unique participants, that met the inclusion criteria. Three additional studies (41–43) (2,592 participants) were incorporated up to March 2017 for the update to inform the Australian guidelines process and an additional four studies (32, 34, 37, 44) (2,222 participants) for the update to December 2017. In total, these included RCTs (n=2), case-control (n=3), longitudinal (n=31), longitudinal with additional cross-sectional analysis (n=5), and cross-sectional (n=62) studies. The GRADE table for sedentary behaviour is available in Web Annex Evidence Profiles, section 1.2.

There was no association between objectively measured sedentary time and adiposity or motor development. There was a predominantly unfavourable, or a null association between screen time and adiposity, cognitive or motor development and psychosocial health. There was a favourable or null association between time spent with a caregiver reading or storytelling and cognitive development. There was a predominantly unfavourable, or null association between time spent seated (in pram or stroller, for example) and adiposity or motor development.

For the critical outcomes, there was moderate to very low-quality evidence for screen time and adiposity, motor and cognitive development and psychosocial health and very low-quality evidence for overall sedentary time and adiposity, motor development and psychosocial health. The overall quality of evidence was rated as very low.

Rationale

Previous Canadian guidelines on sedentary behaviour for this age group published in 2012 were derived from expert consensus (14). Current evidence available is from studies of sedentary screen-time and time spent restrained (when children are not able to move around freely and play for an extended period), that assessed compliance with this 2012 recommendation vs non-compliance. The former shows an association with better health outcomes. No evidence was found favouring prolonged restrained time.

The GDG recognized that sedentary time may include time spent engaged in quiet play without electronic media. These pursuits, such as puzzles, block building drawing, colouring, cutting out, singing, music etc. are important for child development and these activities have cognitive benefits. In developing the recommendation, the GDG discussed the importance of reflecting the value of sedentary interactive time with a caregiver in particular. An attempt to comment on all possible beneficial sedentary activities would risk leaving out an activity that is important in a particular setting.

The GDG made a strong recommendation as the desirable outcomes of reducing sedentary screen time and time spent restrained outweighed possible harms. The benefits of less screen-based sedentary behaviour (TV viewing, watching videos, playing computer games) include reduced adiposity, improved motor and cognitive development and psychosocial health. The benefits of less time spent restrained (car seats, prams/strollers, high chairs, or strapped on a caregiver’s back) include reduced adiposity and improved motor development. The benefit of more time spent with a caregiver reading or storytelling (while sitting or lying) is improved cognitive development. There was no evidence of risks of harms associated with reducing screen-based sedentary time and time restrained. There is an absence of evidence on values and preferences, feasibility and acceptability of the recommendations. The GDG concluded that, although there may be some variability on how some groups value adiposity in children and that in some contexts there may be issues about reducing time spent restrained for infants, due to cultural norms and values and caregivers’ multiple responsibilities, the potential benefits of reducing sedentary screen time and time spent restrained outweigh the possible harms or costs and may increase health equity by improving health outcomes.

Question

In children under 5 years of age what duration of sleep, as measured by objective and subjective methods, is associated with favourable health indicators?

Summary of evidence

The 2017 systematic review of the relationship between sleep duration and health indicators in the early years (0–4 years) (28) assessed 133 full text articles and identified 69 studies, from 23 countries with 148,524 unique participants, that met the inclusion criteria. Three additional studies (45–47) (1,300 participants) were incorporated up to March 2017 for the update to inform the Australian guidelines process and an additional five studies (48–52) (9,401 participants) for the update to December 2017. In total, these included randomized trials (n=5), non-randomized interventions (n=1), longitudinal (n=22), longitudinal with additional cross-sectional analysis (n=7), and cross-sectional (n=42) studies. The GRADE table for sleep duration is available in Web Annex Evidence Profiles, section 1.3.

Shorter sleep duration was associated with higher adiposity, poorer emotional regulation, impaired growth, more screen time and higher risk of injuries. There were no clear associations between sleep duration and cognitive and motor development or physical activity.

For the critical outcomes, there was high quality evidence for cognitive development and emotional regulation (although these were very small RCTs restricting daytime naps), low quality evidence for adiposity and very low-quality evidence for motor development or growth. The overall quality of evidence was rated as very low.

Rationale

Previous sleep duration recommendations have been derived from expert consensus (28, 53, 54). Current evidence available is from studies that assessed compliance with sleep duration recommendations vs. non-compliance and the former shows an association with better health outcomes. No evidence was found favouring shortened sleep duration or inadequate sleep. The GDG made a strong recommendation as the desirable outcomes of ensuring adequate sleep and preventing shorter sleep duration outweigh possible harms. Shorter sleep duration is unfavourably associated with adiposity, emotional regulation, growth, and some measures of cognitive development. Shorter sleep duration is associated with more TV viewing and time spent playing computer games and with an increased risk of injury. The GDG noted that there may be some resource implications to meet the recommendations for adequate sleep in homes and childcare settings with limited space and where behaviours and routines of the children and their parents are not conducive to sufficient sleep and regular sleep and wake times. Implementing these recommendations may require changes to the behaviours and routines of the children, their parents and caregivers, and physical environment in places where children sleep. However, in the view of the GDG the potential benefits of ensuring adequate sleep outweigh the costs and ensuring young children sleep an adequate number of hours per day would probably increase health equity by improving health outcomes.

Question

In children under 5 years of age, what are the relationships between each of the following combinations of movement behaviours and health indicators?

• Sleep & sedentary behaviour
• Sleep & physical activity
• Sedentary behaviour & physical activity
• Sleep & sedentary behaviour & physical activity

Summary of evidence

The 2017 systematic review of the relationship between combinations of movement behaviours and health indicators in the early years (0–4 years) (29) assessed 277 full text articles and identified 10 studies, from five countries with 7,436 unique participants, that met the inclusion criteria. No additional studies were incorporated up to March 2017 for the update to inform the Australian guidelines process and an additional three studies (32, 55, 56) (568 participants) for the update to December 2017. In total, these included cluster RCTs (n=5), non-randomized interventions (n=1), longitudinal (n=3) and cross-sectional (n=4) studies. The GRADE table for combined movement behaviours is available in Web Annex Evidence Profiles, section 1.4.

The most ideal combinations of sedentary behaviour and physical activity, thought to be beneficial for health (less sedentary time, more physical activity) were favourably associated with motor development and fitness in pre-school children, both favourably and not associated with adiposity and not associated with growth. The most ideal combinations of sleep and sedentary behaviour (more sleep and less sedentary time) were favourably associated with adiposity in young children.

The evidence showed that replacing sedentary time with moderate- to vigorous-intensity physical activity is likely to improve health indicators in children. However, there was no information available that considered all three movement behaviours (physical activity, sedentary and sleep time).

For the critical outcomes, there was moderate quality evidence for growth, low quality evidence for motor development and adiposity and very low-quality evidence for fitness. The overall quality of evidence was rated as very low.

Rationale

The GDG considered the value of a 24-hour approach to recommendations on physical activity, sedentary behaviour and sleep. Although the GDG discussed each aspect of the recommendations individually, they expressed a preference for the three areas to be presented together for each age group with clear reference to the contribution each makes to the 24-hours of a child’s day. The GDG emphasized that the recommendations do not attempt to account for each hour of the child’s day and that these will necessarily include quiet play and sitting time (during meals, for example).

The GDG made a strong recommendation, as favourable outcomes outweigh possible harms of combinations of more physical activity, less sedentary screen time and longer sleep duration, and that the greatest benefits result from meeting all three behaviours. In children 1–4 years of age the benefits of the less sedentary screen time and more physical activity are favourably associated with motor development and fitness, with no significant association with growth. Combinations of longer sleep duration and less sedentary screen time, and longer sleep duration and more physical activity were favourably associated with cognitive development and adiposity. Meeting all three recommendations of the Australian 24-hour movement guidelines for the early years was associated with favourable adiposity (57). Compositional analysis from Canada using objective monitoring indicates that lower levels of sedentary behaviour and higher levels of moderate- to vigorous-intensity physical activity while preserving sleep are associated with favourable health outcomes (58). The benefits of replacing sedentary time with moderate- to vigorous-intensity physical activity are increased fitness in children 3–4 years of age. There was no evidence of risks of harms associated with meeting any of the combinations of more physical activity, less sedentary screen time and longer sleep duration.

In the view of the GDG, although in some settings there may be additional resource requirements to ensure young children meet all recommendations, the potential benefits of meeting all the recommendations outweigh the costs. The GDG determined that the integration of the movement behaviours may enhance the feasibility of implementation of individual movement and sleep recommendations by providing parents and caregivers with opportunities to gradually replace undesirable behaviours with more desirable behaviours and recognizing the importance of quality interactions with caregivers and preserving sufficient sleep.

Dissemination and local adaptation

The guidelines will be published and available online and as print copies in all six official languages. The release of the guidelines will be widely publicized through regional and country offices, the WHO global and regional websites and by reaching out directly to relevant UN agencies and partners. These guidelines will be launched at a suitable international event to increase awareness of the recommendations. It will be disseminated through health and early childhood educator networks.

WHO can support local adaptation of the guidelines through WHO country offices, with support from regional and headquarters offices.

A summary advocacy brochure will be prepared to help disseminate information and raise awareness of the importance of movement behaviours in young children and the existence of global guidance. In addition, a practical guide, with links to resources, such as standards for physical activity in early child education and care settings, and case studies will be developed and made available as an online toolkit, such that it can be kept up-to-date. The aim of this will be to support Member States and NGOs in developing interventions and approaches to promote healthy physical activity, sedentary and sleep time behaviours in young children.