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The
Health of Children and Young People
 4 Physical activity
4.1 Introduction The health benefits of a physically-active lifestyle are well documented and there is convincing evidence1 that regular activity of even moderate intensity is related to reduced incidence of many chronic conditions, most notably, type 2 diabetes mellitus, obesity, cardiovascular disease, many types of cancers, and osteoporosis.2 For example, it has been shown that inactivity is related to a nearly two-fold increase in the risk for developing coronary heart disease.3 Promoting physical activity has been described to be 'public health's best buy'4 and increasing physical activity among adults has been the subject of public health promotion policies5 and government health strategies since the early 1990s.6,7 In addition there have for many years been internationally-accepted recommendations for the amount and type of physical activity among adults that is beneficial for health.8 For children and young people, on the other hand, there is less evidence of the direct benefits of physical activity, or what the recommended amount or type should be. Evidence of a direct relationship between activity and health among children is generally weak. However, small but beneficial associations have been demonstrated between physical activity and reduced overweight and obesity, psychological well-being, self-esteem, biological CVD risk factors, skeletal health and growth, and other health-related risk factors, and tracking characteristics of childhood physical activity (that is, the extent to which an active child becomes an active adult).9,10,11 The lack of strong links between children's health and physical activity may be due to the lack of clear health and disease end points in children; the difficulties in doing research with children (e.g. ethical clearance, confounding role of sexual maturation); the short length of children's life for inactivity to have a deleterious effect on health; and the lack of variability in the health outcomes assessed.12 It could be thus suggested that the absence of evidence is not necessarily evidence of the absence of a plausible relationship between physical activity and children's health. Overall, as Riddoch argues, although the evidence is weak, the 'conceptual, biological and behavioural plausibility that physical activity is a healthful pursuit for children is high'.13 Blair et al have proposed a hypothetical model on how physical activity may affect children's health. The model identifies three possible routes of how being active as a child improves health:
On the other hand, participation in physical activity can increase the risk of musculo-skeletal injuries, although this is mostly associated with over-exercise and focused participation in competitive sports.15 In 1997 the Health Education Authority initiated a process of expert consultation and review of the evidence surrounding the promotion of health-enhancing physical activity among young people, with the aim of producing a policy framework and recommendations, and produced review papers on key aspects of physical activity among young people.16 The outcome of the Health Education Authority's review process was a set of recommendations on physical activity levels for young people aged 5-18. The primary recommendations are:
A secondary recommendation (which is not addressed in this chapter) is:
This chapter examines the participation in out-of-school physical activity and the physical activity levels of children aged 2-15 and young adults aged 16-24. Although the term physical activity is widely defined as 'any bodily movement produced by the muscles resulting in energy expenditure above the basal level',17 the present chapter is limited to certain types of children's and young adults' physical activity. The physical activities examined are thought to account for the largest part of children's and young adult's total activity. 4.2 The physical activity of children aged 2-15 4.2.1 Children's questionnaire Despite their limitations,18 questionnaires are the most practical and cost-effective way of measuring physical activity in large scale epidemiological research. Questions relating to the physical activity of adults (aged 16 and over) have been included in the Health Survey since its inception (with a break in 1995 and 1996), but 1997 was the first year such questions were included for children (aged 2 and over). Children's physical activity data were also collected in 1998, 1999 (ethnic minorities only sample), and 2002. The Health Survey questions for adults were originally based on a major national study of activity carried out in 1990 (The Allied Dunbar National Fitness Survey19), which included objective measurements of health and fitness (including heart rate monitoring) which were used to validate the physical activity interview questions. No such study existed for children's activity, so the development of the questions for the Health Survey was based on other smaller studies. Extensive piloting of the questions was carried out in 1996, and a further stage of analysis and cognitive interviewing was carried out in mid-1997 (in preparation for the 1998 Health Survey20,21). The children's physical activity set of questions in 2002 is a slightly reduced version of the 1998 questionnaire (minus a set of questions on inactivity). The Health Survey 2002 questions collected details about the out-of-school activity of children aged 2-15 in three main categories: Sports and Exercise, Active Play, and Walking. Children aged 8 and over were also asked questions about their participation in Housework/Gardening. The decision to exclude activities participated in as part of the school curriculum (that is, 'during school lessons') was taken for three main reasons: first, it was assumed that, generally speaking, the amount of activity carried out by children as part of the school curriculum would be similar for all children (according to their age) and so would contribute a 'standard' additional amount of activity for each child; second, activities as part of the school curriculum would generally be compulsory and it was felt that the survey was concerned more with what children would do of their own choice; and third, since a important proportion of our data would be collected by proxy from a parent, it was felt that information about activities during school lessons would be less accurate than about activities during leisure time. However, any activities carried out on school premises but not as part of school lessons (for example after-school clubs) were covered by the questions asked. An important limitation of the Health Survey child physical activity module is that no attempt has been made to validate the questions by comparison with objective measures of activity and fitness, such as heart rate monitoring, use of motion sensors or physiological analysis. Although little is known about the specific cognitive skills required for children accurately to complete self-report measures, it is acknowledged that recalling physical activity is a highly complex cognitive task and it has been estimated that children under 10 cannot recall more than 50% of last week's activities22. The Health Survey module attempts to limit the effects of inadequate recall by confining questions to activity in the 7 days before the interview, and by directing questions at a parent rather than at the child him/herself for children aged under 13. Children would have been present during the interview, so in most cases would have contributed to the answers, but this may not always be the case. Children's physical activity is far more diverse than that of adults and therefore more difficult to quantify. Children's activity patterns have been shown to be characterised by short and sporadic, rather than sustained, bouts of activity,23,24 and are less likely to involve clearly-defined periods of specific activities. For example, a direct observation study has found that the median duration of a low to moderate-intensity activity bout was 6 seconds, and that 95% of children's activity lasted less than 15 seconds.24 This makes the collection of data by structured questionnaire a difficult and complex task. Another important limitation, which should be borne in mind when considering the results presented here, is social desirability. There may be a tendency among some children/parents to over-claim levels of activity in the last week, by quoting what they believe the child should do rather than what was actually done. Alternatively among some children (for example, perhaps, teenage girls) the tendency may be to under-claim activity levels as participation in Sports and Exercise, or particularly 'Active Play', may not be fashionable. For children under 13 it is possible that parents' responses may reflect other stereotypes; for example parents may be more likely to claim high levels of activity for boys than for girls.25 Details of the following activities were collected: Walking Whether the child had done any continuous walks of at least 5 minutes. On how many days the child had done any continuous walks of at least 5 minutes, and the total duration of Walking on each of these days. Housework/Gardening (aged 8 and over only) Whether the child had done any 'Housework or Gardening that involved pulling or pushing, like hoovering, cleaning a car, mowing grass or sweeping up leaves for at least 15 minutes; if so on how many days; and the total duration of Housework/Gardening on each of these days Sports and Exercise activities This category included activities such as swimming, football, tennis, gymnastics, and was intended to cover more 'organised' or structured sporting activities. Whether the child had done any Sports/Exercise and if so, the number of days at the weekend; duration at the weekend; number of weekdays; duration each weekday. Active Play
Defined as 'active things like ride a bike, kick a ball around, run
about, play active games, jump around'. Data for Sports and Exercise and Active Play were collected separately for weekend and weekdays. There was no lower limit for the inclusion of Sports and Exercise and Active Play, but only Housework/Gardening activities that lasted for at least 15 minutes were included. In the section about Walking, children were asked if they had done any walks of at least 5 minutes, followed by more detailed questions. Further details relating to the duration of activities were collected for all four activity types. It should be noted that there are substantial differences between children's physical activity questions in 2002 and in 1997. The main differences are that: a) the questionnaire in 1997 collected information only for activities that lasted for at least 15 minutes and shorter duration activities were discarded (this was the case only for Housework/Gardening in 2002) but Walking set a cutoff at 5 minutes in 2002, and b) no activity duration information was collected for Walking and Housework/Gardening in 1997, therefore all Walking and Housework/Gardening sessions were considered to last 15 minutes. Therefore, data presented in this report are not directly comparable with data presented in the 1997 report. The information collected covered primarily the frequency and the duration of the above types of children's activity, while no information was collected about the specific activity mode. In agreement with the 1997 questionnaire, no information was collected on intensity; it is therefore assumed that all reported activities were of at least moderate intensity. 4.2.2 Children's participation in different activities over the last 7 days All activities Tables 4.1, 4.2, and 4.3 present the key characteristics of children's activity. In considering these tables it should be remembered that no information was collected on activities carried out as part of the school curriculum, so any participation in school curriculum physical activity is excluded from these estimates. The proportion of boys and girls who participated in each activity type over the last 7 days is presented by individual age years in Table 4.1. As previously stated, only Walking sessions that lasted at least 5 minutes and Housework/Gardening sessions that lasted at least 15 minutes were included. There was no lower duration limit for the inclusion of Sports and Exercise and Active Play. As shown in Table 4.1, 99% of both boys and girls participated in some physical activity in the last 7 days. The most commonly reported activity type was Active Play for boys (93%) and Walking for girls (90%), while Housework/Gardening was the least common activity type for both boys and girls (30% of boys and 37% of girls aged 8 and over). Table 4.1, Figure 4A Table 4.3 presents the total and average time children spent in each activity type over the last 7 days. On average, boys reported a total of 14.2 hours of participation in physical activity in the last 7 days, while the corresponding figure for girls was 12.2 hours; this sex difference was statistically significant (p<0.0001). The longest participation duration was reported for Active Play (7.8 hours for boys and 6.4 hours for girls, on average, p<0.001) followed by Walking (3.5 hours, on average, for both boys and girls). Figure 4B shows the average time spent in all activities
by age and sex. Girls participated in physical activities for shorter
periods of time than boys from an early age (from age 4 onwards). Furthermore,
girls' activity time started to decline from age 9, while the time boys'
spent in activity remained relatively stable through to age 15. This replicates
the 1997 Health Survey finding that physical activity declines at an earlier
age for girls than for boys,26 and is in agreement with objective
studies of a smaller scale;27 but it is at odds with observations
from European countries, such as the Netherlands28 and Finland,29
where activity decline during entry in adulthood is steeper for boys than
for girls. Table 4.3, Figure 4B Sports and exercise Overall, 59% of boys and 55% of girls participated in Sports and Exercise in the last 7 days. There was an increase in participation with age up to about age 11 for boys and up to age 9 for girls. The percentage of boys who participated in Sports and Exercise increased steadily from 31% at age 2 to 71% at age 10. From age 12 to 15 participation in Sports and Exercise among boys fluctuated between 63% and 68%. The pattern of participation in Sports and Exercise by age was clearer for girls, where rates increased from 36% at age 2 to 70% at age 9 and tended to decrease thereafter to 50% at age 15. Overall, 16% of boys and 10% of girls participated in Sports and Exercise for 5 or more days in the last week, as presented in Table 4.2. On average, boys spent 2.4 hours and girls spent 1.7 hours doing Sports and Exercise in the last week, a statistically significant difference (p<0.0001). Tables 4.1, 4.2, 4.3 Active Play 93% of boys and 87% of girls participated in Active Play in the last 7 days. Rates of participation were high (at least 82%) across individual years for boys but there was a tendency to decrease with age from age 13 and over (from 93% at age 12 to 86% at age 15). Participation in Active Play decreased with age more markedly for girls than boys. Up to age 10 rates ranged between 89% and 96% but declined rapidly to 59% at age 15, as shown in Table 4.1. Overall, 69% of boys and 60% of girls participated in some kind of Active Play on 5 or more days in the last week. As shown in Table 4.3, boys spent on average 7.8 hours and girls spent on average 6.4 hours on Active Play in the last week (p<0.0001). Mean time spent in Active Play decreased steadily with age for both boys and girls (from 10.5 hours at age 2 to 4.9 hours at age 15 for boys and from 9.5 hours at age 2 to 2.2 hours at age 15 for girls). Tables 4.1, 4.2, 4.3 Walking 89% of boys and 90% of girls participated in Walking (for at least 5 minutes) over the last week. Participation in Walking was high across individual years ranging between 82% and 96% for boys and between 85% and 94% for girls. About three in five boys (59%) and about one in two girls (53%) walked for at least 5 continuous minutes on at least 5 different days in the last week. Both boys and girls walked on average for 3.5 hours in the last week. The average number of hours spent walking increased with age from age 11 for both boys and girls. Tables 4.1, 4.2, 4.3 Housework/Gardening The questions about participation in Housework/Gardening were asked of children aged 8 and over. Participation levels, although lower than for any of the other types of activity, tended to increase with age. Among those aged 8, 19% of boys and 27% of girls did this type of activity, rising to 38% of boys and 45% of girls aged 15. Boys spent 0.5 hours and girls spent 0.6 hours on average doing Housework/Gardening . Tables 4.1, 4.2, 4.3 4.2.3 Patterns of activity among children Table 4.4 shows the time children spent participating in physical activities on each 'active' day (that is, each day on which they did some physical activity), by the total number of 'active' days in the last week. Children who reported no active days are not included in this table. The table shows separate categories for those who were active on 1-4 and 5-7 days. Categories for 1-4 and 5-7 days are broken down according to whether the average time spent active was less than 30 minutes, 30-59 minutes, 60-119 minutes, or 120 minutes or more. This table is based on Sports and Exercise and Active Play activities of any duration, but, as before, only Walking sessions that lasted at least 5 minutes and Housework/Gardening sessions that lasted at least 15 minutes are included. Large proportions of children reported very high levels of physical activity. 42% of boys and 33% of girls were active for at least two hours a day on most days (5 days or more). At all ages over a third of boys were active at this high level. Rates among girls were generally lower than those of boys and declined from age 10 onwards. Table 4.4 4.2.4 Children's summary physical activity levels over the last 7 days In this section participation in the different types of activity has been summarised into a frequency-duration scale, by taking account of the average time spent participating in physical activities, and the number of active days in the last week. There are some limitations as no activity intensity information was collected and therefore it is assumed that all occurrences of these activity types are of at least moderate intensity. The summary physical activity levels categories are as follows:
Table 4.5 and Figure 4C show the proportions of boys and girls in each of these activity groups, by age. The proportions of children in Groups 2 or 3 (that is, achieving at least the lower recommended activity level) are summarised below:
Overall, a higher proportion of boys than girls achieved the recommended levels - 70% of boys were in Group 3, compared with 61% of girls (p<0.0001). A further 13% of boys were in Group 2 (30-59 minutes), compared with 16% of girls (p<0.001). The finding that boys are more physically active than girls is well-documented30,31,32,33,34 and being male has been found to be the strongest predictor for physical activity in children (3-12yrs) and adolescents (13-18yrs).35 Among boys, the cumulative proportion in Groups 2 and 3 did not vary markedly with age and it was over 75% across the individual age years. In contrast, there was a decline in the proportion of girls meeting the recommended activity levels (i.e. Groups 2 and 3) from about age 11. By age 15, 65% of girls met the lower target level of at least 30 minutes'activity per day and 50% met the higher recommendation of at least an hour a day.
 Similar results were reported in the National Diet and Nutrition Survey (NDNS) 2000 where about 70% of boys aged 7-14 met the recommendation for at least 60 minutes of moderate intensity activity a day36 (identical to the percentage found in the Health Survey for boys of the same age range). The corresponding NDNS figure for girls of the same age was under 50%, slightly lower than that estimated in the Health Survey (58%). The decline in physical activity levels with age is one of the most consistent findings in physical activity epidemiology. The biological basis of this decline is supported by evidence that shows that similar declines occur among many other animal species.35 In agreement with the declining pattern of time spent in physical activity (Table 4.3) and activity levels with age (Table 4.5) are a number of prospective studies which found that the most apparent physical activity decreases occur during entry in adolescence, usually around ages 12 -15.28,29,37 The percentages of boys and girls who met the physical activity recommendations presented in Table 4.5 are notably higher than the corresponding figures in the 1997 Health Survey report26 where only 55% of boys and 39% of girls were reported to do so. This difference should not be translated as an upward trend as it may be a result of several fundamental differences in the time-structure of the questionnaire and the data analysis methods. For example, the proportions of children who met the guideline recommendations in 1997 may have been under-estimated, as the 1997 questionnaire collected information only for activities that lasted at least 15 minutes, and shorter duration activities were discarded. Furthermore, in 1997 no duration information was collected for Walking and Housework/Gardening, and as a result, longer sessions were considered to have lasted only 15 minutes. In contrast, the 2002 questionnaire asked about the specific duration of all four types, and lower duration limits were set only for Walking (5 minutes) and Housework/Gardening (15 minutes). The substantial difference between the two Surveys in the proportion of children who meet the activity recommendations implies that much of children's activity is performed in short bouts, as suggested by the literature.24 Physical activity trends between 1997 and 2002 (using re-defined 2002 variables for comparability) are presented later in this chapter. Table 4.5 4.2.5 Variations in children's activity by demographic and socio-economic characteristics This section looks at variations in participation in different activity types (Sports and Exercise, Active Play, Walking and Housework/Gardening) and overall activity levels (Groups 1, 2 and 3) by socioeconomic classification (NS-SEC of the household reference person), equivalised household income, area deprivation (Index of Multiple Deprivation) , Government Office Region, and area type. Tables for participation in different activity types are shown separately for boys and girls in two age groups - 2-10, and 11-15. Though they do not contain equal numbers of children, these age groups were chosen because over the age of about 10, participation in some types of activity (Active Play for both boys and girls, Sports and Exercise for girls), tended to decrease as discussed above (see Table 4.1). Tables for overall activity levels (Groups 1, 2 and 3) are not shown split by age, as age was not related to activity levels as much, especially when Groups 2 and 3 are considered together (see insert table in section 4.2.4). By NS-SEC The socio-economic group of the household reference person of each participating household was defined using the new National Statistics Socio-economic Classification (NS-SEC) which was introduced for the first time in the UK Census 2001. Informants were assigned to 14 functional and 3 residual NS-SEC categories on the basis of the current or former occupation of the household reference person. These were then collapsed to the 5-category version defined as follows: i) managerial and professional, ii) intermediate (e.g. clerical, administrative, sales), iii) small employers and own account workers, iv) lower supervisory and technical, and v) semi-routine and routine occupations.38 Tables 4.6 and 4.7 present the results of the overall activity levels and days participation in different activity types, by NS-SEC, age group, and sex. There was no consistent relationship between overall activity levels and NS-SEC category. Participation in Active Play, Walking and Housework/Gardening did not vary by NS-SEC for either of the age groups of boys and girls. Participation in Sports and Exercise was related to NS-SEC category. The proportion of children aged 2-10 who had at least one day of Sports and Exercise decreased gradually from Managerial and Professional (62% for boys and 65% for girls) to Semi-Routine and Routine households (47% for boys and 42% for girls) but regular participation (on 5 days or more) was relatively consistent across NS-SEC categories. No discernible patterns of participation in any activity type by NS-SEC category were found for children 11-15. Tables 4.6, 4.7 By equivalised household income Children's overall activity levels (Groups 1, 2, and 3) did not differ between equivalised household income quintiles. However, there was a clearly decreasing pattern in participation in Sports and Exercise with increasing equivalised income. The proportions of children, who had done some Sports and Exercise in the last week, by age group, sex and equivalised income quintile, are summarised below:
Interestingly, regular participation (on 5 or more days in the last week) in Walking exhibited a strong inverse relationship with equivalised income quintiles for children of both age groups as shown in the table below:
Among girls, the proportion participating in Housework/Gardening tended to be higher among the lower income quintiles. For example, of girls aged 11-15, 43% and 46% in the two lowest income quintiles had done Housework/Gardening, compared with 27% and 32% in the two highest quintiles. Among boys there was no clear pattern with equivalised income. Tables 4.8, 4.9 By Index of Multiple Deprivation The Index of Multiple Deprivation 2000 (IMD) is based on levels of deprivation in local areas in six domains (income; employment; health deprivation and disability; education, skills and training; housing; geographical access to services).39 The index is presented in quintiles ranging from the first (the least deprived) to the fifth (the most deprived). There was no consistent relationship between area deprivation and children's overall activity levels as shown in Table 4.10. As with equivalised income, a relationship was evident between participation on at least one day in Sports and Exercise and IMD for boys and girls of both age groups 2-10 and 11-15, with lower participation rates in the most deprived quintiles. The table below summarises participation in Sports and Exercise on at least one day, by IMD quintile, age and sex:
Regular Walking (on 5 days or more in the last week) increased consistently across all four age/sex groups (i.e. boys 2-10, boys 11-15, girls 2-10, girls 11-15) from the least deprived to the most deprived quintiles as shown in the table below:
As with equivalised income quintiles, a clear pattern is seen in participation in Housework/Gardening among girls aged 11-15, with a gradual increase from 25% in the least deprived to 48% in the most deprived quintile. Among boys there was no clear association with Index of Multiple Deprivation. Tables 4.10, 4.11 By Government Office Region Government Office Regions have been the primary classification for the presentation of regional statistics since 1996. There are currently nine Government Office Regions:40 North East, North West, Yorkshire and the Humber, East Midlands, West Midlands, East England, London, South East, and South West. Smaller proportions of boys and girls from London had high activity levels (Group 3) than boys and girls from all other regions (64% of boys in London vs 71% of boys in the aggregate of all other regions (p<0.01) and 53% of girls in London vs 63% of girls in the aggregate of all other regions (p<0.0001)). Although there were some differences in the proportions of children participating in each activity type, there was no consistent pattern. Tables 4.12, 4.13 By area type Tables 4.14 and 4.15 present the variations of overall activity levels and participation in the different activity types, by area type. Overall activity levels (Groups1, 2, and 3) were not systematically different between area types. Sport and Exercise Participation on at least one day was lower in inner cities than in the aggregate of all other areas for boys (p<0.0001) and girls (p<0.001) aged 2-10. Similarly, participation in Active Play was lower for boys (p<0.01) and girls (p<0.05) aged 2-10 who lived in inner cities compared with their non-inner city counterparts. The table below summarises participation of boys and girls 2-10 in Sports and Exercise and Active Play by aggregated area type. Tables 4.14, 4.15
4.2.5 Other factors related to children's activity Children's physical activity in relation to overweight and obesity prevalence Table 4.16 shows how mean BMI and obesity prevalence varied by overall activity levels (Groups 1, 2, and 3). Obesity prevalence was calculated using the age and sex-specific International BMI cut-off points, described in detail in Chapter 9 of this report. No apparent relationship was found between physical activity levels and mean BMI or obesity prevalence. When the relationship of overweight (including those who were obese) with overall activity levels were examined, weak inverse relationships were found for boys (r=-0.23, not significant) and for girls (r=-0.20, not significant), as reflected in the table below:
The lack of clear associations between overweight or obesity and children's physical activity is in agreement with some previous studies,41,42 but it is at odds with some others which suggest that lower physical activity levels are strongly associated with overweight or obesity among children.31,32,41,43,44,45,46 It is worth noting that the large majority of studies that have detected significant relationships between physical activity levels and percentage of body fat or overweight /obesity used objective measures (i.e. not questionnaires or interviews) to assess physical activity. This observation is reinforced by a meta-analysis that examined the influence of the type of physical activity measures on the relationships between physical activity and percentage body fat or overweight /obesity among children and adolescents.47 Fifty studies were included in total, covering the whole range of the existing activity measurements (questionnaires, motion sensors, direct observation, heart rate monitors). One of the main findings of the meta-analysis was that that questionnaire studies elicited significantly lower effect sizes compared with studies that used objective measures. The conclusion from the meta-analysis was that non-objective evidence on the relationships between children's activity and body weight status should be interpreted with caution.47 Table 4.16 Seasonal variation in children's activity Environmental changes and monthly precipitation are thought to affect participation in physical activity48. Table 4.17 presents the overall physical activity levels (Groups 1, 2, and 3) by season of the year, age group, and sex. 79% of all boys and 68% of all girls who were interviewed in the summer met the higher recommendation for at least 60 minutes of activity a day, falling to 62% of boys and 48% of girls who were interviewed in the winter. Seasonal variation was lower when the proportions of girls and boys who met the lower activity recommendation (at least 30 minutes on each day) were considered. The table below summarises the proportions of boys and girls who met the higher and lower recommendations of the physical activity guidelines in each season of the year:
Similar seasonal variations in children's activity have been found in some studies49,50 but not in others.51,52 Table 4.17 Children's physical activity and occurrence of major and minor accidents The association between the occurrence of major and minor accidents and levels of physical activity in children is shown in Table 4.18. Informants were asked about the occurrence of 'major' accidents (accidents about which a doctor was consulted or hospital was visited) in the six months prior to interview; and of 'minor' accidents (which include all other accidents to cause pain and discomfort for over 24 hours) in the four weeks before the interview (for details about accidents classification see Chapter 6). Given that data on physical activity are collected for the week preceding the interview, it is likely that those who recently had an accident reduced their physical activity as a result of the accident. This could result in a weaker relationship between physical activity and accidents than that observed in a study which follows individuals over time. In boys, those with high levels of physical activity were more likely to report the occurrence of both a major and minor accident than those with low levels of physical activity: for example, 12% of boys aged 2-10 with high levels of physical activity reported a major accident, compared with 8% of those with low levels. A similar picture emerged for those aged 11-15. In girls the pattern was less clear and the differences in accidents by levels of physical activity were less marked. Table 4.18 Children's physical activity in relation to asthma Several studies have investigated the association between asthma and physical activity. Although physical activity may trigger an attack of asthma, there is no reason to believe that, when the disease is well managed, asthmatics should limit their activity levels because of their condition. Modern management of the disease encourages adequate training, to ensure that asthma should not be a barrier to physical exercise. Physical activity, by contributing to physical and mental well-being, can in fact improve the quality of life of children with asthma.53 Moreover, it has been postulated that physical fitness in childhood may have an inverse relationship with the development of asthma, reducing its incidence.54 While no causal relationship can be investigated in the Health Survey, the physical activity patterns of informants with asthma can be examined. Informants were asked whether they had ever been diagnosed as asthmatic by a doctor, and whether they had wheezing symptoms in the last twelve months (see also Chapter 5). Those who reported a diagnosis of asthma and had symptoms in the last twelve months are considered here as 'current' asthmatics, while those with the diagnosis who did not report symptoms in the last twelve months are considered as 'former' asthmatics. As reported by other studies, children with current or former asthma did not differ in their levels of physical activity from their counterparts who had never been diagnosed as asthmatic. Table 4.19 Logistic regression A multivariate logistic regression model was developed to examine the links between physical activity levels and several socio-economic and demographic factors, self-reported health, asthma and obesity prevalence, and occurrence of major and minor accidents. The dependent variable was membership in Group 3 (at least 60 minutes of activity on 7 days in the last week). The factors entered as independent variables in the initial model were Government Office Region (London compared with the aggregate of all other areas), area type, equivalised household income, area deprivation (IMD quintile) , socioeconomic classification (NS-SEC of household reference person), body mass index status (overweight or obese vs neither overweight nor obese), age group (2-10 vs 11-15), self-reported psychological health (GHQ12), minor accidents occurrence (in the last 4 weeks), occurrence of major accidents that required hospitalisation (in the last 6 months), and lifetime diagnosis of asthma. Separate models were run for boys and girls. Among boys, the only significant variable in the initial backward stepwise models was the occurrence of minor accidents in the last 4 weeks. The only statistically significant variables for girls were Government Office Region and deprivation index quintile. Table 4.20 shows the odds ratios and 95% confidence intervals for variables that exhibited statistically significant associations with physical activity levels. Boys who had a minor accident in the last 4 weeks were about 45% more likely than those who had no minor accident to meet the higher recommendation of the guidelines (active for at least 60 minutes a day on 7 days in the last week). As noted earlier, it is possible that these correlations are an underestimate since those who recently had an accident may have reduced their physical activity as a result of the accident. Girls who lived outside London were about 60% more likely than girls who lived in London to be active for at least 60 minutes on 7 days in the past week. Girls in the least deprived IMD quintile were less likely to be active than all other quintiles but there was no consistent gradient in the odds ratios from the least to the most deprived quintiles. For example, girls in the 2nd and 5th quintiles were 70% and 37%, respectively, more likely to be active for at least 60 minutes on each day of the week than girls in the least deprived quintile. Table 4.20
4.2.6 Comparison of children's activity in 1997 and 2002 As highlighted in the introduction to this section (Section 4.2.1), the structure of the physical activity questionnaires was considerably different between 1997 and 2002. To make 2002 data comparable with the 1997 data, only activities that lasted at least 15 minutes were included in the trend analysis. Furthermore, all Walking and Housework/Gardening sessions in 2002 were capped at 15 minutes (to make the data comparable with 1997). As a result of these adjustments, the re-defined 2002 variables elicited lower values in the percentages of those achieving the recommended level, presented in Table 4.5. The comparison variable between 1997 and 2002 was the overall activity level described earlier in this chapter. Table 4.21 presents the proportions of children with high (Group 3, active for at least 60 minutes on 7 days), medium (Group 2, active for 30-59 minutes on 7 days) or low (Group 1) levels of physical activity in 1997 and 2002, by age group and sex. No differences between 1997 and 2002 were found in the proportions of boys and girls aged 2-10 and 11-15 meeting the higher target of the physical activity recommendations16 for at least 60 minutes of activity per day (Group 3). For example, among boys aged 2-15, 54% in 1997 and 55% in 2002 met this target. However, differences were more pronounced when the lower target of the recommendations was considered: the proportion of those who did at least 30 minutes on each day of the week (Groups 2 and 3) increased by 9 pp for boys aged 2-15 (from 64% in 1997 to 73%) and by 14 pp for girls aged 2-15 (from 51% in 1997 to 65% in 2002). These increases over time were statistically significant for both sexes (p<0.0001). The table below summarises the proportions of boys and girls aged 2-15 who met the higher and lower targets of the physical activity recommendations in the 1997 and 2002 Surveys: Table 4.21
4.3 The physical activity of young adults aged 16-24 4.3.1 Young adults' questionnaire This section reports on the physical activity of young people aged 16-24. The adult physical activity module was developed for the 1991 Health Survey, and was repeated in 1993-1994 with minor changes, while it received more substantial revisions in 1997 and 1998. Shorter versions of the questionnaire were used in 1999 when the focus of the Survey was ethnic minority populations. The 2002 Health Survey used the short 1999 version of the questionnaire. The original Health Survey questions were based on those used in the Allied Dunbar National Fitness Survey (ADNFS) in 1990.19 Physical activity among adults was measured in the Health Survey for England 2002 by examining overall participation, frequency of participation in activities that lasted at least 30 minutes (15 minutes for Sports and Exercise), and type of activity. Information on the specific duration of activities was collected for Sports and Exercise only, while a question related to intensity was asked for Sports and Exercise and Walking only. In 1991, when the Health Survey physical activity module was first developed, the internationally-accepted recommendations were that adults should take part in at least three occasions a week of vigorous activity lasting 20 minutes or more. By the mid-1990s, however, the emphasis had shifted towards encouraging people to take part in regular activity at a moderate level, as described in the 1994 Health Survey report. Although regular vigorous activity has been shown to produce maximum cardiac benefit for an individual, for the majority of the population this may have been an unrealistic target. Moderate activity became more important for health promotion, as it offered greater health benefits in the population as a whole. Recently the emphasis has shifted further, towards encouraging the accumulation of shorter bouts of activity (of as little as 10 minutes) to reach the daily target of 30 minutes. The latest guidelines for adults are that they should take part in at least 30 minutes of moderate activity (at least 5 days a week). 4.3.2 Adult physical activity definitions Types of activity Details on three main types of physical activity were asked about in the questionnaire:
In this report, a summary classification of the number of days' participation in all physical activities of at least moderate intensity, for at least 30 minutes a day is presented. Since data for adults was collected about the four weeks before the interview, this involves averaging the number of occasions in the past four weeks to arrive at an average number of occasions per week (see table below).
Intensity level In order to create a summary classification for this chapter, activities have been classified into intensity levels, based on an estimate of the energy cost of the activities. The levels are:
For Sports and Exercise, activities were classified according to the nature of the activity, and on the informant's own assessment of the amount of effort involved in doing that activity. For example, 'swimming' was counted as 'vigorous' if the effort was usually enough to make the informant 'out of breath or sweaty', otherwise as 'moderate'.63 For Walking, informants were asked to assess their usual Walking pace (slow/steady/ brisk/fast). Walks at a 'brisk' or 'fast pace' were classified as 'moderate'. Walks at a 'slow' or 'steady average' pace were classified as 'light'. For Home activity (Housework, Gardening, DIY) informants were given examples of types of Housework/Gardening /DIY that counted as 'heavy' and 'light'. Heavy Housework and heavy Gardening/DIY were classified as 'moderate', other Gardening/DIY as 'light', and light Housework only as 'inactive'.64 4.4 Young adults' physical activity over the last four weeks 4.4.1 Young adults' participation in physical activities Table 4.22 shows the average number of days' participation per week in at least 30 minutes of Heavy Housework, Heavy Manual/DIY, Sports and Exercise of at least moderate intensity, and Walking of at least moderate intensity, by age and sex. In addition the table shows a summary classification of the number of days' participation in all physical activities of at least moderate intensity for at least 30 minutes a time. The summary classification probably over-estimates the number of active days, as it assumes that each type of activity was done on a different day. So, for example, if an informant had done Walking and Heavy Housework on the same day, it would be counted as two days of activity in the summary classification. The number of days' participation in activities was capped at 7. So, an informant who had participated in Sports and Exercise on 5 days and Walking on 5 days (10 days in total) would be counted as having participated on 7 days when calculating the summary variable. The activity type most commonly reported by both males and females was Sports and Exercise. 73% of males reported at least one day of Sports and Exercise (of at least 30 minutes a time). 22% of males had participated in Sports and Exercise on at least 5 days a week on average. Participation in Sports and Exercise was significantly lower among females than among males (p<0.0001). 57% of females participated in Sports and Exercise at least once, and only 9% had done sports on at least 5 days a week. Among males, Sports and Exercise participation declined with age. Of males aged 16, 82% had done some Sport and Exercise falling to 68% at age 24. Of males aged 16-17, 30% had done at least 5 days a week, falling to 17% of those aged 24. Among females, there was no marked decline in Sports and Exercise participation with age. The second most common activity among young men was Walking, 44% of males had taken at least one walk that lasted for at least 30 minutes. The proportion of young men who had walked on at least 5 days a week fell with age, from 18% of males aged 16 to 12% of those aged 24. Among females, 31% overall had taken at least one walk of moderate intensity, with no variations with age. Among females the second most common activity type (after Sports and Exercise) was Heavy Housework. 44% of females had done some Heavy Housework for at least 30 minutes. Participation in Heavy Housework increased with age: 30% of females aged 16 had done Heavy Housework, rising to 60% of those aged 24. Fewer males (30%) than females (44%) had done Heavy Housework (p<0.0001). As seen for females, participation among males increased with age, from 26% of males aged 16 to 37% of those aged 24. The least common activity was Heavy Manual /DIY, although participation was higher among males (p<0.0001). 16% of males aged 16-24 had undertaken this type of activity, compared with 5% of females. Informants who reported having participated in any activity of at least moderate intensity (at least 30 minutes a time) on 5 days a week or more, on average, met the guidelines for adults. As shown in the summary table below, there were no marked variations in the proportion of young men who met the guidelines. Among young women, there was a slight increase with age.
Figure 4D shows the proportions of males and females who had participated at least once a week on average, in each of the activity types, by age group. Looking at the summary classification for all of these types of activity, males aged 16-24 were more likely than females to have participated at all, and to have participated for a greater number of days. Only 9% of males had not done any activities as defined here (for at least 30 minutes a time), compared with 18% of females (p<0.0001). 51% of males had done some of these activities on at least 5 days a week, on average, compared with 28% of females (p<0.0001). Table 4.22, Figure 4D 4.4.2 Young adults' summary physical activity levels Table 4.23 shows a summary classification of participation in physical activity, by age group (16-18, 19-21, and 22-24), and sex. The summary classification shows the average number of days per week of participation in activities of at least moderate intensity, for at least 30 minutes a time This classification reflects the proportion meeting the current physical guidelines for adults (at least 30 minutes of physical activity at least 5 times a week). It is noted that the summary variable may under-estimate the proportion of adults meeting the guidelines as information on shorter bouts of activity (that may have added up to 30 minutes a day) was not collected. Overall, 51% of males carried out physical activities for at least 30
minutes on 5 days a week or more. This proportion did not vary across
age groups. Fewer than 10% of males had done no physical activity lasting
at least 30 minutes . Among females, the proportion achieving the recommended
level of activity was far lower than that of males, at 28% overall (p<0.0001).
It is interesting to note that this proportion increased somewhat, though
not markedly, with age. Of females aged 16-18, 77% had done physical activity
on at least one day. This increased to 85% of those aged 22-24. This increase
in overall participation with age seems largely to be accounted for by
the increase in the proportions of females doing Heavy Housework, as noted
above. Table 4.23 4.4.3 Variations in young adults' activity by demographic and socio-economic characteristics By NS-SEC, equivalised income quintile, and Index of Multiple Deprivation Tables 4.24-4.26 show the summary classification of participation by males and females in physical activity of at least 30 minutes' duration, by NS-SEC, equivalised household income, and Index of Multiple Deprivation (IMD). There were no consistent patterns in participation in physical activity overall according to NS-SEC; equivalised income quintile, or IMD. However, it should be noted that base sizes for the different groups were generally small and this may have limited the detection of notable differences between groups. Tables 4.24, 4.25, 4.26 By area type and Government Office Region Tables 4.27-4.28 show the summary classification of physical activity by area type and region, respectively. Although there appear to be some differences between the area types in the proportion of young men and young women who engaged in activity on 5 or more occasions a week, there are no consistent trends, and base sizes for each area type (except Suburban/residential) are too small to draw conclusions. The same applies to variations of the physical activity summary classification by Government Office Region where there are only small, and no systematic, differences. Tables 4.27, 4.28 4.4.4 Other factors related to young adults' activity Physical activity in relation to BMI and obesity prevalence Participation in activity for 30 minutes or more was converted into a summary physical activity levels variable to assess relationships between BMI/obesity prevalence and physical activity. The summary physical activity levels measure categories are as follows:
Table 4.29 and the table below show the mean BMI and the obesity prevalence rates by summary activity levels, age group and sex. Obesity was defined as a BMI over 30 kg/m2. BMI tended to be lower among informants in Group 3 (active for 30 minutes and over on at least 5 days a week) than in the lower activity Groups (Groups 1 and 2). Overall, young men who had medium or high activity levels (Groups 2 and 3) had lower BMI (23.6 kg/m2 for both groups) than that of the low activity (24.4 kg/m2). Obesity prevalence was not significantly different between Groups 3 and Group 2 (about 8% for both Groups) but it was notably higher in Group 1 (about 15%). Among young women, BMI increased from 23.6 in Group 3 to 24.4 in Group 1. Obesity prevalence exhibited a strong gradient by activity levels (from about 8% in Group 3, to about 12% in Group 2 and about 14% in Group 1). The non-parametric correlation coefficient between BMI status and physical activity levels was statistically significant for young women (r=-0.54, p<0.05) but not for young men (r=-0.36, not significant). This is reflected in the summary table below where obesity prevalence shows a strong inverse gradient by physical activity levels for young women but to a lesser extent for young men: Table 4.29
Young adults' physical activity and occurrence of major and minor accidents The association between the occurrence of major and minor accidents and levels of physical activity in young adults is shown in Table 4.30. As described earlier, informants were asked about the occurrence of 'major' accidents (accidents about which a doctor was consulted or hospital was visited) in the six months prior to interview; and 'minor' accidents (which include all other accidents to cause pain and discomfort for over 24 hours) in the four weeks before the interview (for details about the classification of accidents see Chapter 6). In young men, those with a high level of physical activity were more likely to report both the occurrence of a major (21%) and minor (18%) accident than those with low levels of physical activity (11%). Among young women, the differences in accidents by levels of physical activity were less marked (10% of Group 3, 9% of Group 2, and 6% of Group 1 reported major accidents). It should be noted that since data on physical activity are collected for the 4 weeks preceding the interview, it is likely that those who recently had an accident reduced their physical activity as a result of the accident. This could result in a weaker relationship between physical activity and accidents than that observed in studies that follow individuals over time. Young adults' physical activity in relation to asthma Table 4.31 shows variations in physical activity levels of young adults by asthma status, and sex. As described earlier in this chapter, those who reported a diagnosis of asthma and had symptoms in the last twelve months are considered here as 'current' asthmatics, while those with the diagnosis who did not report symptoms in the last twelve months are considered as 'former' asthmatics. As reported by other studies,65 adults with current or former asthma did not differ in their levels of physical activity from their counterparts who had never been diagnosed as asthmatic. Table 4.31 Logistic regression A multivariate logistic regression model was developed to examine the links between physical activity levels and socio-economic and demographic factors, self-reported health, asthma and obesity prevalence, and the occurrence of major and minor accidents. The dependent variable was membership in Group 3 (activity of at least moderate intensity for at least 30 minutes on 5 or more days a week). The factors entered as independent variables in the initial model were Government Office Region, area type, equivalised household income, area deprivation (IMD) , socioeconomic classification (NS-SEC), body mass index status (overweight vs obese vs neither overweight nor obese), minor accidents occurrence (in the last 4 weeks), occurrence of major accidents that required hospitalisation (in the last 6 months), lifetime diagnosis of asthma, age group (16-19 vs 19-21 vs 22-24 years), and self-reported psychological health (GHQ12 score). The initial backward stepwise model for young men resulted in all variables being left out of as non-significant, with the exception of GHQ12 and the occurrence of major accidents in the last six months. Statistically significant variables for young women were BMI status, and age group. Young men who had a major accident that required medical treatment or hospitalisation in the last 6 months were about 40% more likely than those who had not had an accident to meet the physical activity recommendation. As noted earlier, this relationship between occurrence of accidents and physical activity levels may have been underestimated in this analysis. It is possible that informants who had a major accident in the last 6 months decreased their physical activity levels due to the physical limitation imposed by the injury. Psychological well-being was assessed in HSE 2002 by the General Health Questionnaire (GHQ12). GHQ12 was originally designed for use in general practice settings as a screening tool but has been used in HSE every year except 1996. GHQ12 is designed to be self-administered and was included in the self completion booklet for informants aged 13-24. The questionnaire comprises 12 questions, asking informants about their general levels of happiness, experience of depressive and anxiety symptoms, and sleep disturbance over the last four weeks. Interpretation of the answers is based on a 4-point scale response scale scored using a bimodal method (symptom present: 'not at all'=0, 'same as usual'=0, 'more than usual'=1, 'much more than usual'=1). A GHQ12 score of 4 or more indicates the possible presence of psychiatric morbidity. A positive correlation was found between GHQ score and activity levels among young men. Young men with a score of 1-3 and 4+ were 63% and 46%, respectively, more likely to belong to the high activity Group (30 minutes or more of at least moderate intensity on at least 5 days a week) compared with those who scored 0. Among females, being obese was correlated with a decreased likelihood of being active. Young women with a BMIover 30 kg/m2 were about 50% less likely to be in the high activity Group. Age group was positively correlated with physical activity in females. Young women aged 22-24 were 51% more likely than those aged 16-18 to meet the activity recommendations. It is likely that this association is moderated by the increase with age in the participation in Heavy Housework/Gardening, as described earlier in this Chapter. Table 4.32 4.4.5 Comparisons in young adults' activity between 1997 and 2002 Table 4.33 shows comparisons between 1997 and 2002 in days of participation, of at least moderate intensity in each activity type, for 30 minutes or more. There were no marked differences between 1997 and 2002 at any level of participation in heavy Housework, Heavy Manual/DIY, or Sports and Exercise. Participation for at least on day a week in Walking was no different between the two years, but frequent walking (on 5 days or more a week) decreased for young men (from 24% in 1997 to 12% in 2002) and women (from 14% to 7%). This difference may be partly explained by the substantial differences in the Walking questions in the two years; in 1997 (but not 2002) there were additional questions about the occurrence of multiple bouts of Walking on the same day. These additional questions in 1997 may have influenced prompted informants to remember more occasions of walking. The summary classification in Table 4.33 shows that overall participation in physical activities was virtually identical in 1997 and 2002. No notable difference between the two years was found when the summary physical activity levels (membership in Group 1, 2, or 3) was considered, as shown in Table 4.34. Tables 4.33, 4.34
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