The epidemiology of overweight and obesity among Australian children and adolescents, 1995-97

OBJECTIVES

To determine the population prevalence of overweight and obesity among Australian children and adolescents, based on measured body mass index (BMI). To determine if overweight and obesity are distributed differentially across the population of young Australians.

METHODS

Data from three independent surveys were analysed. In each, height and weight were measured by trained surveyors using valid, comparable methods. BMI (kg/m2) was used as the index of adiposity and recently published international BMI cut-off values used to categorise each subject as non-overweight, overweight or obese.

RESULTS

The population prevalence and distribution of overweight, obesity and overweight/obesity combined were generally consistent across datasets. The ranges of the prevalence of non-overweight, overweight, obesity and overweight/obesity combined were 79-81%, 14-16%, 5% and 19-21% (boys) respectively and 76-79%, 16-18%, 5-6% and 21-24% (girls). There were no consistent relationships between the prevalence of overweight/obesity and sex, age or SES. Their prevalence was up to 4% higher in urban than rural areas among boys, but there were no differences between urban and rural girls. The data suggest a higher prevalence of overweight/ obesity among students from European or Middle-Eastern cultural backgrounds.

CONCLUSIONS

Some 19-23% of Australian children and adolescents are either overweight or obese. Although urban/rural, SES and cultural background differentials were noted, only the last warrants a targeted health promotion response.

IMPLICATIONS

Overweight/obesity is a prevalent health risk factor among Australian children and adolescents. More information is needed to understand whether targeted approaches are required for specific ethnic groups in addition to broad, population-based approaches.

Methods of the NSW Schools Physical Activity and Nutrition Survey (SPANS)

The NSW Schools Physical Activity and Nutrition Survey (SPANS 2004) (N = 5407) was a representative population survey, conducted February-May 2004, among New South Wales (Australia) school students aged 4 y-16 y. Physical activity, fitness, fundamental movement skill proficiency and food habits are all related to overweight and obesity and were a focus of this study. The last population-based survey in NSW was conducted in 1997 and use of the same measurement instruments (with the exception of food habits) allowed examination of secular trends. Overweight and obese children are at risk for a number of serious, long-term health problems, and a sub-sample (n = 500) of urban dwelling Year 10 students (mean age 15.4 years) gave a fasting blood sample which was analysed for the presence of risk factors for the metabolic syndrome. This paper describes the methods of the NSW Schools Physical Activity and Nutrition Survey 2004 (SPANS 2004).

Mastery of fundamental movement skills among children in New South Wales: prevalence and sociodemographic distribution

Fundamental movement skills form the foundation for many of the specific motor skills employed in popular sports and leisure activities. Little data exist on the prevalence and socioeconomic distribution of fundamental movement skill mastery among young children in Australia. This study process-assessed performance on six fundamental movement skills in a randomly selected sample of students from Years 1 through 3 in the Sydney metropolitan area of New South Wales. The prevalence and sociodemographic distribution of mastery and near mastery for each skill and each skill component is reported for boys and girls in each school year. The findings revealed that the prevalence of mastery and near mastery of each of fundamental movement skill was generally low. Boys performed significantly better than girls in the run and in the four object-control skills (throw, catch, kick, and strike) whilst girls performed better than boys in the skip. There was no consistent association between prevalence of skill mastery and socio-economic status (SES), with only the kick and vertical jump for boys and catch, dodge, and vertical jump for girls differing across SES tertiles. Based on these results, we recommend that adequate curriculum time, resources, and professional development continue to be devoted to fundamental movement skills in NSW primary schools.

Social, cultural and environmental influences on child activity and eating in Australian migrant communities

AIM

This study set out to examine the socio-cultural, familial and environmental factors influencing health, eating habits and patterns of physical activity contributing to child and adolescent overweight and obesity.

METHODS

Semi-structured, community-based interviews were conducted with contrasting key informant three-generation families; and generation by generation focus groups of grandparents, parents and children from four cultural communities in the state of Victoria, Australia. Purposive sampling occurred from Turkish, Greek, Indian and Chinese communities that have migrated to Australia within the last three generations (n = 160, eight families, 47 children aged 5-15 years, 29 parents, 42 grandparents).

RESULTS

Evidence of two-way influences on eating and physical activity across three generations was evident, with children reporting the greatest cross-cultural diversity. A range of dietary restrictions was reported across all cultural groups. Efforts to foster healthy eating and lifestyle patterns within communities were evident. Parents, as a generation in particular, felt the need for more access to education and support regarding healthy limits for pre-puberty and puberty stages.

CONCLUSION

There is a dynamic influence of culture on many aspects of family lifestyle across three generations. To achieve successful intervention design, childhood obesity researchers need to collaborate with diverse groups and communities. Considering the role and influence of extended family, a multigenerational, whole-of-community approach beyond that of parent and child populations ought to be considered.

Perceptions of the physical environment, stage of change for physical activity, and walking among Australian adults

Data for this study were from a population survey of 1,200 adults ages 40-60 years, sampled from the Illawarra region of New South Wales. Questionnaire items on perceptions of the environment were factor analyzed into: Aesthetic Environment and Practical Environment. For both factors, those in the Contemplation stage had more negative views of the environment than those in Maintenance. Those who walked for 0-20 min/week held more negative perceptions of their environment than those who walked for 21-120 min/week and those who walked for > 120 min/week. The health promotion implications of these findings are that environments perceived as attractive and as providing convenient access to services and facilities may influence motivational readiness for physical activity and time spent walking.

Relationship of physical activity to fundamental movement skills among adolescents

PURPOSE

To determine the relationship of participation in organized and nonorganized physical activity with fundamental movement skills among adolescents.

METHODS

Male and female children in Grade 8 (mean age, 13.3 yr) and Grade 10 (mean age, 15.3 yr) were assessed on six fundamental movement skills (run, vertical jump, catch, overhand throw, forehand strike, and kick). Physical activity was assessed using a self-report recall measure where students reported the type, duration, and frequency of participation in organized physical activity and nonorganized physical activity during a usual week.

RESULTS

Multiple regression analysis indicated that fundamental movement skills significantly predicted time in organized physical activity, although the percentage of variance it could explain was small. This prediction was stronger for girls than for boys. Multiple regression analysis showed no relationship between time in nonorganized physical activity and fundamental movement skills.

CONCLUSION

Fundamental movement skills are significantly associated with adolescents' participation in organized physical activity, but predict only a small portion of it.

The reliability and validity of the physical activity questions in the WHO health behaviour in schoolchildren (HBSC) survey: a population study

OBJECTIVE

To assess the test-retest reliability and validity of the physical activity questions in the World Health Organisation health behaviour in schoolchildren (WHO HBSC) survey.

METHODS

In the validity study, the Multistage Fitness Test was administered to a random sample of year 8 (mean age 13.1 years; n = 1072) and year 10 (mean age 15.1 years; n = 954) high school students from New South Wales (Australia) during February/March 1997. The students completed the self report instruments on the same day. An independent sample of year 8 (n = 121) and year 10 (n = 105) students was used in the reliability study. The questionnaire was administered to the same students on two occasions, two weeks apart, and test-retest reliability was assessed. Students were classified as either active or inadequately active on their combined responses to the questionnaire items. Kappa and percentage agreement were assessed for the questionnaire items and for a two category summary measure.

RESULTS

All groups of students (boys and girls in year 8 and year 10) classified as active (regardless of the measure) had significantly higher aerobic fitness than students classified as inadequately active. As a result of highly skewed binomial distributions, values of kappa were much lower than percentage agreement for test-retest reliability of the summary measure. For year 8 boys and girls, percentage agreement was 67% and 70% respectively, and for year 10 boys and girls percentage agreement was 85% and 70% respectively.

CONCLUSIONS

These brief self report questions on participation in vigorous intensity physical activity appear to have acceptable reliability and validity. These instruments need to be tested in other cultures to ensure that the findings are not specific to Australian students. Further refinement of the measures should be considered.

Impact evaluation of the Royal Australian Air Force health promotion program

BACKGROUND

In 1981, the Royal Australian Air Force (RAAF) introduced an intensive health promotion program (HPP), the purpose of which was to control preventable diseases, particularly cardiovascular disease (CVD), linked to lifestyle-related risk factors. However, the RAAF HPP's effectiveness had not been appropriately evaluated since its implementation.

HYPOTHESIS

The RAAF HPP's interventions have reduced, beyond secular trends, the prevalence of lifestyle-related CVD risk factors.

METHODS

Retrospective cross-sectional risk factor prevalence surveys of randomly selected RAAF pilots and navigators were conducted for the years 1980, 1983 and 1989. The survey results for RAAF subjects were compared with the results obtained for demographically similar subjects participating in National Heart Foundation (NHF) Risk Factor Prevalence Study (RFPS) surveys for the same periods, using chi2 and Mantel-Haenszel (M-H) chi2 tests, and 1-way and 2-way ANOVA.

RESULTS

Over the survey periods, the prevalence of overweight and obesity decreased by 8% in RAAF subjects and increased by 7% in NHF subjects, and mean total serum cholesterol decreased by 8% in RAAF subjects while remaining static in NHF subjects. Participation in vigorous physical activity increased among RAAF, but not NHF, subjects. The results for most other risk factors showed significant differences between RAAF and NHF subjects, but trends were comparable over survey periods.

CONCLUSIONS

On balance, reductions in the prevalence of overweight and obesity, and mean serum cholesterol in RAAF subjects were probable effects of the RAAF HPP. Other observed differences in CVD risk factors between RAAF and NHF groups were attributable to the RAAF aircrew selection process, or other RAAF-specific influences. The study thus provides qualified support for the hypothesis, although effects were less evident in older RAAF subjects.

The relationship between body mass index and waist circumference: implications for estimates of the population prevalence of overweight

OBJECTIVE

Body mass index (BMI) based on self-reported height and weight is a systematically biased, but acceptable measure of adiposity and is commonly used in population surveys. Recent studies indicate that abdominal obesity is more strongly associated with obesity-related health problems than is adiposity measured by BMI. The purpose of this study was to determine the relationships of both measured and self-reported BMI with measured waist circumference in a randomly selected sample of Australian adults.

DESIGN

Cross-sectional survey with self-reported and laboratory-based measures of adiposity.

SUBJECTS

1140 randomly-selected Australian adults aged 18-78 y resident in the city of Adelaide, South Australia.

MEASUREMENTS

Data on self-reported and measured height and weight as well as measured waist circumference were drawn from the Pilot Survey of the Fitness of Australians database. The proportion of men and women with acceptable BMI (BMI</=25 kg/m2) and with excess abdominal adiposity (>/=94 cm for men and >/=80 cm for women) was determined. Differences in the prevalence of overweight based on BMI alone or BMI and waist circumference were also determined.

RESULTS

Compared with the prevalence based on self-reported BMI alone, the prevalence of overweight among men based on self-reported BMI and waist circumference combined was 2.4%, 5.3%, 19.1% and 7.5% greater for men aged 18-39 y, 40-59 y, 60-78 y and for all men, respectively. Among women, compared with the prevalence based on self-reported BMI alone, the prevalence of overweight based on the combined measures was 9.9%, 24.0%, 33.3% and 20.6% greater for women aged 18-39 y, 40-59 y, 60-78 y and for all women, respectively.

CONCLUSIONS

If waist circumference is used as the criterion, then the prevalence of overweight among Australian adults, and probably other Caucasian populations, may be significantly greater than indicated by surveys relying on self-reported height and weight. The development of valid self-reported measures of waist circumference for use in population surveys may allow more accurate epidemiological monitoring of overweight and obesity.

Promoting physical activity in general practice: a controlled trial of written advice and information materials

OBJECTIVE

To investigate the impact of a simple written prescription for physical activity given by a general practitioner and the effect of supplementing this with mailed information materials about physical activity.

METHODS

A controlled trial was conducted in 27 general practices in New South Wales, Australia. Subjects were sequential routine care patients between 25 and 65 years old. Controls (n = 386) were recruited first, and intervention subjects two weeks later. Intervention subjects were randomised to receive a prescription only (n = 380) or a prescription plus a mailed booklet (n = 376). Self reported physical activity levels were measured by interview at baseline, 6-10 weeks, and seven to eight months.

RESULTS

By intention to treat, the average changes in minutes of total physical activity did not differ significantly between the groups. Inactive people in the prescription plus supplementary booklet group were significantly more likely than controls to report an increase in their physical activity by at least 60 min/week after 6-10 weeks (odds ratio 1.58, 95% confidence interval 1.06 to 2.35). No significant short term improvements in self reported activity were shown in the prescription only group. In the supplemented group, the proportion reporting an increase in physical activity to 3,344 kJ/week at 6-10 weeks was not significant, and neither intervention group showed significant increases in any of the outcome measures at seven to eight months by intention to treat. Treatment received analysis showed greater improvements in intervention groups, especially the prescription plus booklet group, in which the odds of inactive people in this group reporting increased activity became significant at seven to eight months.

CONCLUSIONS

A prescription for physical activity from a general practitioner, supplemented by additional written materials, can lead to modest short term improvements in self reported physical activity levels among inactive patients. A prescription alone was found not to be effective.

Social-cognitive and perceived environment influences associated with physical activity in older Australians

BACKGROUND

Regular physical activity in older adults can facilitate healthy aging, improve functional capacity, and prevent disease. However, factors associated with physical inactivity in older populations are poorly understood. This study attempts to identify social-cognitive and perceived environmental influences associated with physical activity participation in older populations.

METHODS

In a randomly selected sample of 449 Australian adults age 60 and older, we assessed self-reported physical activity and a range of social-cognitive and perceived environmental factors. Respondents were classified as sufficiently active and inactive based on energy expenditure estimates (kcal/week) derived from self-reported physical activity. Two logistic regression models, with and without self-efficacy included, were conducted to identify modifiable independent predictors of physical activity.

RESULTS

Significantly more males than females were physically active. Physical activity participation was related to age with a greater proportion of those age 65-69 being active than those age 60-64 or 70 or older. High self-efficacy, regular participation of friends and family, finding footpaths safe for walking, and access to local facilities were significantly associated with being active.

CONCLUSION

Identifying predictors of physical activity in older populations, particularly social support, facility access, and neighbourhood safety, can inform the development of policy and intervention strategies to promote the health of older people.

Mastery of fundamental motor skills among New South Wales school students: prevalence and sociodemographic distribution

Mastery of fundamental motor skills among children and adolescents is a potentially important contribution to satisfying participation in sports, games and other physical activities and may enhance the development of an active lifestyle. However, few attempts have been made to determine the prevalence of fundamental motor skill mastery among young Australians. The NSW Schools Fitness and Physical Activity Survey, 1997 (N = 5518) randomly selected schools proportionally from all three education sectors and selected students in Years 4, 6, 8 and 10. Performance on six fundamental motor skills (run, vertical jump, catch, overhand throw, forehand strike and kick) was assessed qualitatively. The prevalence of mastery and near mastery of each skill and mastery of each skill component is reported for boys and girls in each school year. The findings indicate that the prevalence of mastery and near mastery of each of the fundamental motor skills was generally low. There were no differences between students from urban or rural schools and the prevalence of skill mastery was directly associated with socioeconomic status more consistently among girls than among boys. Greater curriculum time and resourcing and training of teachers is required to increase the proportion of students who have mastered the skills fundamental to common sports, games and other physical activities.

Sociodemographic distribution of measures of body fatness among children and adolescents in New South Wales, Australia

BACKGROUND

Obesity in childhood and adolescence is associated with health problems, increases in cardiovascular disease (CVD) risk factors and a greater likelihood of becoming overweight as an adult. A description of the sociodemographic distribution of overweight and obesity among children and adolescents in the population may allow us to determine if health promotion resources should be differentially allocated to particular groups.

METHODS

The New South Wales Schools Fitness and Physical Activity Survey, 1997 (n = 5518) was a cross-sectional survey which measured height, weight, waist and hip girths and skinfold thicknesses of randomly selected New South Wales students in school years 4, 6, 8 and 10. Height and weight only were measured among Year 2 students. The mean ages of students in school years 2, 4, 6, 8 and 10 were 7.3y, 9.3y, 11.3y, 13.3y and 15.3y, respectively. The values of body mass index (BMI), waist girth, waist-to-hip ratio (WHR) and sum of three skinfolds for students resident in urban and rural areas and in tertiles of socioeconomic status (SES) were compared.

RESULTS

There were no differences on any of the anthropometric measures between urban and rural boys and girls, with the exception that WHR was higher among urban girls. Among boys, there were no differences between the SES tertiles on any of the measures. Among girls, each of the anthropometric measures (except sum of skinfolds) was inversely associated with SES, with body fatness tending to be lower in the high SES tertile, compared with the low and middle SES tertiles. None of the statistical interactions between school year and body fatness was significant, suggesting that the relationship is consistent from childhood to adolescence.

CONCLUSION

On the basis of these results, we suggest that health promotion programs aimed at weight management among Australian girls of lower SES are not warranted. We recommend that health promotion programs emphasize regular physical activity, a healthy diet and acceptance of the normal range of body shapes.

Utility of pwc75% as an estimate of aerobic power in epidemiological and population-based studies

PURPOSE

Studies of physical activity often assess physical work capacity (pwc) and this is usually achieved with extrapolated estimates of maximal aerobic power (VO2max). However, extrapolation beyond the measured values may be problematic, particularly for older subjects. On a population basis, interpolated measures of pwc may provide the same information and avoid the errors associated with extrapolated measures.

METHODS

This study assessed extrapolated (pwc at 150 and 170 beats x min(-1) heart rate (HR) and estimated VO2max) and interpolated (pwc at 75% of maximum HR: pwc75%) measures of pwc in a population sample of 1043 men and women aged 18-78 yr. Each measure was assessed to determine whether it showed the key characteristics of measured VO2max: a decrease with age and an increase with reported physical activity.

RESULTS

Both pwc150 and pwc170 did not decline with age, estimated VO2max (est.VO2max) exhibited a spurious plateau for older age groups, while pwc75% declined approximately 9% per decade of age. All four pwc measures detected a significant difference (approximately 10-15%) between inactive and active groups classified according to a questionnaire of leisure time physical activity.

CONCLUSIONS

Although the pwc75% test requires direct validation, these results suggest that it may be a useful submaximal exercise measure for epidemiological studies of aerobic power.

Effects of physical activity interventions in youth. Review and synthesis

INTRODUCTION

Physical inactivity has been identified as an important public health concern for youth. School and community settings can be important infrastructures for promoting physical activity (PA). This paper reviews studies of physical activity in school and community settings among preschool through college-aged persons to determine characteristics and effects of interventions. Studies in progress are included.

METHODS

Studies from 1980 to 1997 testing physical activity interventions in schools and community settings were identified by computerized search methods and reference lists of published reviews. Studies needed to have used a quantitative assessment of PA, used a comparison or control group, included participants who were preschool through college age, and be conducted in the United States or foreign school or community settings. Significance of effects was examined overall and for various types of interventions.

RESULTS

Twenty-two school-based studies were reviewed, 14 completed and 8 in progress. Three studies were in countries other than the United States. The 8 studies in progress were all in the United States. Only 7 community studies were reviewed, all in the United States. Four studies were in progress. Several community studies involved a high percentage of African-American or Hispanic youth and their families. Studies showing the best results used randomized designs, valid and reliable measurements, and more extensive interventions. Some follow-up results showed PA was sustained after interventions ended.

CONCLUSIONS

The collection of school and community studies is limited for several age groups with none below third grade and only three at college age. There are few community studies. The most is known about upper-elementary-age-students, including the first multicenter randomized trial to report significant results for increasing moderate to vigorous physical activity (MVPA) in physical education (PE) and increase vigorous PA outside of school. A number of older study designs were weak and assessments less than optimal, but studies in progress are stronger. Special attention is needed for girls, middle schools, and community settings for all youth. More objective assessments are needed for measuring PA outside of school and in younger children, since they cannot provide reliable self-report.

Methods of the NSW Schools Fitness and Physical Activity Survey, 1997

Physical fitness, participation in physical activity, fundamental motor skills and body composition are important contributors to the health and the development of a healthy lifestyle among children and youth. The New South Wales Schools Fitness and Physical Activity Survey, 1997, was conducted to fill some of the gaps in our knowledge of these aspects of the lives of young people in New South Wales. The survey was conducted in February and March, 1997 and collected data on a randomly-selected sample of students (n = 5518) in Years 2, 4, 6, 8 and 10. Measures were taken on body composition (height and weight, waist and hip girths, skinfolds), health-related fitness (aerobic capacity, muscular strength, muscular endurance, flexibility), fundamental motor skills (run, vertical jump, catch, overhand throw, forehand strike and kick), self-reported physical activity, time spent in sedentary recreation, and physical education (PE) classes. The methods are described to assist in the development of surveys of other populations and to provoke debate relevant to the development and dissemination of standard approaches to monitoring the fitness, physical activity habits and body composition of Australian children and youth. Finally, we offer comments on some of the strengths and limitations of the methods employed.

Health-promoting schools in Australia: models and measurement

Schools represent a very attractive setting for health promotion. Most children and young people attend school, professional educators are in place, and most school communities are microcosms of the larger community, providing opportunities for children to develop and practice the skills necessary to support a healthy life-style. In response to this opportunity, the precepts of contemporary health promotion have been synthesised into the 'health-promoting school' model, which is guided by a holistic view of health and by the principles of equity and empowerment. Although there are different conceptions of the model, the key components are: the formal curriculum; school ethos (the social climate); the physical environment; the policies and practices of the school; school health services; and the school-home-community interaction. The health-promoting school model offers a comprehensive, systematic approach to health promotion in the school setting, which is widely accepted internationally. There have been few studies in Australia that have attempted to determine the prevalence of activities related to the model or to evaluate interventions. Unfortunately, conceptual and practical advances have far outstripped the development of research and evaluation instruments. There is an urgent need to create valid research tools to support the development and implementation of this potentially fruitful health promotion model.

Physical activity preferences, preferred sources of assistance, and perceived barriers to increased activity among physically inactive Australians

BACKGROUND

Participation in regular moderate or vigorous physical activity substantially reduces risk for all-cause and cardiovascular-disease mortality and confers other health benefits. Efforts to decrease the population prevalence of inactivity will have a greater impact if they are tailored to the needs and preferences of the community.

METHODS

In the Pilot Survey of the Fitness of Australians, a questionnaire was administered to a randomly selected sample of 2,298 adults and included questions on the preferred sources of assistance or support to become physically active, preferred activities, and barriers to regular participation. The responses of those who were identified as insufficiently physically active (n = 1,232; 53.6%) were examined for men and women separately and for those aged 18 to 39, 40 to 59, and 60 to 78 years.

RESULTS

The most-preferred activity was walking (38 and 68% of the youngest and oldest age groups, respectively). The most frequently cited barriers to more-regular participation in the youngest age group were insufficient time, lack of motivation and child care responsibilities. Among those aged 60 to 78 years, injury or poor health were the most frequently cited barriers to activity. The most-preferred source of advice or assistance changed with age: more than 50% of the oldest age group wanted advice from a health professional (compared with 22% of the youngest group) and the opportunity to exercise with a group was the most preferred source of support for the youngest age group.

CONCLUSIONS

The physical activity-related attributes of men and women and of younger and older age groups described in this study may be used to provide more relevant and appealing options for those who might otherwise be missed by "one-size-fits-all" physical activity promotion strategies.

Relationship between a 14-day recall measure of leisure-time physical activity and a submaximal test of physical work capacity in a population sample of Australian adults

This paper reports on the validity of a 14-day recall measure of leisure time physical activity (LTPA) in a sample of Australian adults (N = 986). Submaximal cycle ergometry was used to assess physical work capacity per kilogram of body mass (pwc75/kg). The self-report energy expenditure estimates were used to categorize respondents as vigorously active, moderately active, and low active/sedentary. Multiple regression analyses showed that pwc75/kg increased significantly across energy expenditure categories for adults aged less than 40 years; that the vigorous and moderate activity categories had greater mean pwc75/kg values than the low/sedentary category for 40 to 59-year-olds; and, that there were no differences in pwc75/kg between activity categories for those aged 60 years or older.

Retest reliability of recall measures of leisure-time physical activity in Australian adults

BACKGROUND

Several studies have reported that short-term recall measures of physical activity participation have acceptable repeatability, but in most cases employed convenience samples and did not use optimal statistics. In this Australian study repeatability was assessed on participants recall of activity over two different time periods and over the same time period.

METHODS

Two 14-day recall measures of physical activity participation were administered in two studies to randomly selected population samples of adults in Adelaide, South Australia. Intraclass correlation coefficients (ICC), 80% and 95% limits of agreement and the kappa statistic were calculated.

RESULTS

For a continuous measure of energy expenditure the ICC was 0.86 using recall of the same 2-week period (N = 115), and was 0.58 for activity recalled over different 2-week period (N = 116). For categorized energy expenditure (inactive, low, Moderate and Vigorous categories), kappa was 0.76 for recall of the same period and was 0.36 for different recall periods. Similar results were observed for continuous and categorical forms of a measure of physical activity that recorded frequency of participation in vigorous and moderate activities and walking. The 80% limits of agreement were markedly smaller than 95% limits of agreement, but were still large.

CONCLUSIONS

These data suggest that the variation in repeatability coefficients between recall of the same 2-week time period and activity recalled over different 2-week periods was due to actual variation in physical activity participation over different time periods, and not to poor recall or to poor measurement characteristics. The recall measures appear to have good repeatability for most respondents, but repeatability is poor for a substantial minority of the population.

Spirometric standards for healthy adult lifetime nonsmokers in Australia

The aim of this study was to develop suitable spirometric prediction equations for asymptomatic Caucasian adults in the Australian population. These equations were compared with those of previous studies and constants were presented which, when associated with the prediction equations, permitted the calculation of 5% tolerance intervals for lung function. The 1,302 subjects (aged 18-78 yrs) who underwent pneumotachograph spirometry, using techniques recommended by the American Thoracic Society, were a sample from metropolitan Adelaide, South Australia. The variables recorded were sex, age, height, mass, forced expiratory volume in one second (FEV1), forced vital capacity (FVC), peak expiratory flow rate (PEFR), forced mid-expiratory flow (FEF25-75%) and FEV1/FVC ratio. Complete data were obtained for 614 females and 621 males, but the sample was reduced to 249 females and 165 males when only lifetime nonsmokers with no adverse bronchial symptoms were selected. Prediction equations of normal lung function were obtained from the reduced sample by multiple regression, with age, height and functions of both age and height as predictors. The derived equations did not differ significantly from the majority of previously reported equations and were generally superior in their ability to predict the lung function of the asymptomatic ex-smokers who were part of the original sample. Analysis of the sensitivity, specificity and predictive power of 5% tolerance limits for the presence of symptoms revealed the important roles of FEV1, FEV1/FVC and FEF25-75% in diagnostic testing. The present prediction equations are recommended for use on the Australian population and on populations with similar Caucasian characteristics.

Spirometric standards for healthy adult lifetime nonsmokers in Australia

The aim of this study was to develop suitable spirometric prediction equations for asymptomatic Caucasian adults in the Australian population. These equations were compared with those of previous studies and constants were presented which, when associated with the prediction equations, permitted the calculation of 5% tolerance intervals for lung function. The 1,302 subjects (aged 18-78 yrs) who underwent pneumotachograph spirometry, using techniques recommended by the American Thoracic Society, were a sample from metropolitan Adelaide, South Australia. The variables recorded were sex, age, height, mass, forced expiratory volume in one second (FEV1), forced vital capacity (FVC), peak expiratory flow rate (PEFR), forced mid-expiratory flow (FEF25-75%) and FEV1/FVC ratio. Complete data were obtained for 614 females and 621 males, but the sample was reduced to 249 females and 165 males when only lifetime nonsmokers with no adverse bronchial symptoms were selected. Prediction equations of normal lung function were obtained from the reduced sample by multiple regression, with age, height and functions of both age and height as predictors. The derived equations did not differ significantly from the majority of previously reported equations and were generally superior in their ability to predict the lung function of the asymptomatic ex-smokers who were part of the original sample. Analysis of the sensitivity, specificity and predictive power of 5% tolerance limits for the presence of symptoms revealed the important roles of FEV1, FEV1/FVC and FEF25-75% in diagnostic testing. The present prediction equations are recommended for use on the Australian population and on populations with similar Caucasian characteristics.

Population prevalence and correlates of stages of change in physical activity

Stages of change for exercise, sociodemographic variables, and beliefs about the health benefits of exercise were obtained for a representative sample of Australian adults (N = 4404). Logistic regression analysis was used to examine the relationship between exercise stage of change and sociodemographic variables and beliefs about the benefits of exercise. Thirteen percent of respondents stated that they did not exercise and did not intend to start; 10% stated that they did not exercise but were thinking of starting; 16% stated that they exercise occasionally and were not thinking of doing more; 23% stated that they exercised occasionally and were thinking of doing more; and 38% stated that they exercised regularly and intended to continue. Intention to do more exercise generally decreased with increasing age, but increased with level of education. An increased frequency of exercise and an intention to do more exercise was associated with the belief that exercise would help to prevent heart disease and with a higher level of education. The results provide a useful profile of the exercise habits (and intention to change those habits) of population subgroups. Public communication campaigns on the benefits of physical activity should focus particularly on those who do not intend to exercise, older adults, and the less well educated.

Effects of conditioned stimulus fear-relevance and preexposure on expectancy and electrodermal measures of human Pavlovian conditioning

The present research investigated the effects of fear-relevance of the conditioned stimulus (CS) and CS preexposure on human electrodermal conditioning and on a continuous measure of expectancy of the unconditioned stimulus (US). Both experiments employed 20 preexposure, 8 acquisition, and 8 extinction trials in a differential Pavlovian conditioning paradigm with shock as the US. In Experiment 1 (N = 48), electrodermal conditioning was retarded by CS preexposure, but was not influenced by fear-relevance of the CS. Expectancy of the US was retarded by preexposure only in the fear-relevant condition. In Experiment 2 (N = 48), the CS/US contingencies was embedded in a visual masking task. Preexposure retarded both electrodermal conditioning and US expectancy. Neither measure was influenced by fear-relevance of the CS. However, fewer subjects in the preexposure condition learned the CS/US relationship and those who did, did so on later trial than those in the no-preexposure condition. Thus, the results indicated clear retardation of conditioning as a result of preexposure, but no reliable effect of fear-relevance.

Effects of tumour cell culture supernatants on some biochemical activities of macrophages

The following enzyme activities were measured in cell lysates and supernatants from mouse peritoneal macrophages incubated with products of cultured tumour and other cells: acid phosphatase, beta-D-glucuronidase, N-acetyl-D-glucosaminidase, muramidase (lysozyme), lactic dehydrogenase (supernatant only) and plasminogen activator (supernatant only). There were no noteworthy changes in enzyme activities. Hydrogen peroxide production by appropriately stimulated mouse and/or guinea-pig peritoneal exudate macrophages was variably inhibited by supernatants from some tumour cells and some normal cells. Changes in these biochemical activities of macrophages do not appear to be closely related to the anti-inflammatory activity of tumour cell products.