Tim Olds

• BA(Hon) BSpSC PhD (Sydney) PhD(UNSW)
• Professor at University of South Australia

Objective To investigate associations between early-life diet trajectories and preclinical cardiovascular phenotypes and metabolic risk by age 12 years. Methods Participants were 1861 children (51% male) from the Longitudinal Study of Australian Children. At five biennial waves from 2–3 to 10–11 years: Every 2 years from 2006 to 2014, diet quality...

Background: Childhood obesity is associated with an increased risk of adult obesity and related chronic disease. Our aim was to identify modifiable exposures that are independently associated with obesity in the preschool age group. Methods: A prospective cohort study of 5734 children in New Zealand with anthropometric measurements was completed a...

Study objectives Sleep plays an important role in cardiometabolic health. While the importance of considering sleep as a multidimensional construct is widely appreciated, studies have largely focused on individual sleep characteristics. The association between actigraphy-derived sleep profiles and cardiometabolic health in healthy adults and childr...

Background Few studies have investigated associations between academic achievement and meeting recommendations from the 24-h movement guidelines. The specific guidelines associated with the most benefit academic achievement are unknown. Utilizing both self-report and objective movement data, this study examined associations between academic achieve...

Study objectives Sleep, physical activity and sedentary time are all known to play a role in cardiometabolic health. Compositional data analysis (CoDA) enables us to examine associations between 24-hour use of time and health outcomes. Methods Data were collected in the Child Health CheckPoint study, a one-off national population-cohort study cond...

Aims To investigate relationships between takeaway food and sugar-sweetened beverage (SSB) consumption with cardiometabolic phenotypes during childhood and mid-adulthood. Method Design: Cross-sectional Child Health CheckPoint within the national population-representative Longitudinal Study of Australian Children. Participants: 1838 children (mean...

Microvascular changes may contribute to obesity-associated cardiovascular disease. We examined whether body mass index (BMI) and waist-to-height ratio (WHtR) (1) at multiple earlier time points and (2) decade-long trajectories predicted retinal microvascular parameters in mid-childhood/adulthood. Participants/design: 1288 11–12 year olds (51% girls...

Objectives: To examine how overweight and obesity at specific ages and overall BMI growth patterns throughout childhood predict cardiometabolic phenotypes at 11 to 12 years. Methods: In a population-based sample of 5107 infants, BMI was measured every 2 years between ages 2 to 3 and 10 to 11 years. We identified 5 BMI trajectories using growth c...

Background Good sleep is a growing public health focus. Given the multidimensional nature of sleep, it is of interest to examine population sleep profiles and determine sociodemographic and lifestyle correlates. Methods This study uses actigraphy-measured sleep data collected between February 2015 and March 2016 in the Child Health CheckPoint stud...

Cardiometabolic disease is a leading cause of adult morbidity and mortality globally. There is considerable evidence that childhood adversity is associated with markers of cardiometabolic disease risk in childhood, including obesity, blood pressure trajectories, and chronic inflammation. Experiences of racial discrimination may be an important, yet...

Background: An international physical activity (PA) questionnaire is beneficial to make cross-country comparisons among children and adolescents. This study assesses the validity of the PA questions in the World Health Organization Health Behavior in School-Aged Children (WHO HBSC) survey in Japanese children and adolescents. Methods: Participan...

Traditional retinal microvascular parameters (smaller arteriolar and greater venular caliber) are associated with cardiovascular risk factors, pre-clinical vascular phenotypes and clinical cardiovascular events in adults. Although novel retinal microvascular geometric parameters showed analogous associations in adults, less is known whether these p...

Background The success of a mobile phone app in changing health behavior is thought to be contingent on engagement, commonly operationalized as frequency of use. Objective This subgroup analysis of the 2 intervention arms from a 3-group randomized controlled trial aimed to examine user engagement with a 100-day physical activity intervention deliv...

Background Existing research has documented inconsistent findings for the associations among breakfast frequency, physical activity (PA), and sedentary time in children. The primary aim of this study was to examine the associations among breakfast frequency and objectively-measured PA and sedentary time in a sample of children from 12 countries rep...

Background: Emerging evidence suggests that children become fatter and less fit over the summer holidays but get leaner and fitter during the in-school period. This could be due to differences in diet and time use between these distinct periods. Few studies have tracked diet and time use across the summer holidays. This study will measure rates of...

Objectives: Snacks contribute to overconsumption of energy-dense foods and thence obesity. Previous studies in this area are limited by self-reported data and small samples. In a large population-based cohort of parent-child dyads, we investigated how modification of pre-packaged snack food, i.e. (a) item quantity and variety, and (b) dishware (bo...

Objectives: This study aimed to investigate sleep patterns in adolescent males over a 12-week period (a 10-week school term and pre and post term holidays). Design: Intensive longitudinal design, with sleep data collected daily via actigraphy for 81 consecutive days. Setting: Five Secondary Schools in Adelaide, South Australia. Participants:...

Background: Homophily is the tendency to associate with friends similar to ourselves. This study explored the effects of homophily on team formation in a physical activity challenge in which "captains" signed up their Facebook friends to form teams. Methods: This study assessed whether participants (n = 430) were more similar to their teammates...

Background Although gender is an important determinant of health behaviour with males less likely to perform health-protective behaviours, samples in health behaviour research are heavily biased towards females. This study investigated the use of online social network, Facebook, to reach and recruit inactive males to a team-based, social, and gamif...

Background Recently, a small number of studies have suggested that gains in fitness and reductions in body fat achieved during the school term are reversed or stagnate during the holiday period. This may be associated with changed activity patterns. The aim of this study was to compare 24-h activity compositions between school and holiday periods i...

BACKGROUND The success of a mobile phone app in changing health behavior is thought to be contingent on engagement, commonly operationalized as frequency of use. OBJECTIVE This subgroup analysis of the 2 intervention arms from a 3-group randomized controlled trial aimed to examine user engagement with a 100-day physical activity intervention deliv...

Sleep is essential for children's health and well-being. Characteristics of children's sleep such as sleep duration, timing, quality and variability are increasingly being associated with a wide range of health outcomes. The purpose of this study is to conduct a meta-review (systematic review of systematic reviews) to examine the relationship betwe...

Background and objectives This study explored whether, for people with chronic obstructive pulmonary disease (COPD), changes to the 24-hour composition of physical activity (PA), sedentary behaviour (SB) and sleep were associated with changes in symptoms and health-related quality of life (HRQoL); and how time re-allocations between these behaviour...

Association with change in a) fatigue; and b) breathlessness unpleasantness when re-allocating the time from one energy expenditure band (+) by taking the time from another energy expenditure band (-). EE, energy expenditure; ES, effect size; LPA, light physical activity; MVPA, moderate to vigorous physical activity; S, sleep; SB, sedentary behavio...

‘One-for-remaining’ models: effect on a) breathlessness unpleasantness; b) depression; and c) fatigue when re-allocating time to each MARCA activity ‘superdomain’, by taking the time from the remainder of the composition. EE, energy expenditure; ES, effect size; LPA, light physical activity; MVPA, moderate to vigorous physical activity; S, sleep; S...

Participant raw data and standardized effect sizes for associations between time re-allocations and health outcomes. (XLSX)

Objectives: Estimates of adults' moderate-to-vigorous physical activity (MVPA) based on self-report are generally higher than estimates derived from criterion measures. This study examines a possible explanation for part of this discrepancy: the cutpoint bias hypothesis. This hypothesis proposes that inter- and intra-individual variability in ener...

Background: Facebook has over 1.8 billion users and offers unique opportunities for health intervention delivery due to its popularity, flexibility, high engagement, and social connectedness. Methods: This study aimed to determine the effectiveness of the Mums Step It Up (MSIU) Facebook app, a team-based, 50-day physical activity intervention fo...

The 2018 AHKA Report Card on Physical Activity for Children and Young People was developed using synthesised data from a number of national and state/territory based surveys. The AHKA Research Working Group evaluated all the data in order to assign letter grades to each of the 12 indicators using pre-determined criteria and benchmarks and provided...

BACKGROUND To date, many online health behaviour programs developed by researchers have not been translated at scale. To inform translational efforts, health researchers must work with marketing experts to design cost-effective marketing campaigns. It is important to understand the characteristics of end-users of a given health promotion program, a...

Background: To date, many online health behavior programs developed by researchers have not been translated at scale. To inform translational efforts, health researchers must work with marketing experts to design cost-effective marketing campaigns. It is important to understand the characteristics of end users of a given health promotion program a...

Previous data have indicated relative stability over time of paediatric jumping performance, but few data exist since the early 2000s. This study quantified the 30-year secular changes in jumping performance of Australian children aged 11−12-years using data from the Australian Schools Health and Fitness Survey (1985, n = 1967) and Growing Up in Au...

Purpose: This study investigated the relationship between outdoor time and physical activity (PA), sedentary time (SED), and body mass index z scores among children from 12 lower-middle-income, upper-middle-income, and high-income countries. Methods: In total, 6478 children (54.4% girls) aged 9-11 years participated. Outdoor time was self-report...

Background: Hearing loss is a disabling condition whose prevalence rises with age. Obesity-a risk factor common to many non-communicable diseases-now appears to be implicated. We aimed to determine: (1) cross-sectional associations of body composition measures with hearing in mid-childhood and mid-life and (2) its longitudinal associations with 10...

Starting university changes the way students must structure their day. This study describes the patterns of time use of 444 Australian first year students and explores differences between gender and age groups. Overall, students were studying on average four hours per day (h/day), sleeping eight h/day and meeting Australian physical activity guidel...

Sleep is important for the physical, social and mental well-being of both children and adults. In this paper, we discuss the need to consider sleep as a component of 24-hour activity. First, we make a case for considering sleep as a multidimensional construct, whereby all characteristics of sleep (including duration, quality, timing and variability...

Our aim was to identify the best anthropometric index associated with waist adiposity. The six weight-status indices included body mass index (BMI), waist-to-hip ratio (WHR), waist-to-height ratio (WHTR), and a new waist-by-height0.5 ratio (WHT.5R). The association between three waist skinfolds and the six anthropometric indices was conducted using...

Background Retirement is a life transition involving an obligatory change in how people use their time. Because there are strong associations between use of time and health, different changes in time use following retirement may have different impacts on mental health. Methods 105 participants were followed from 6 months before retirement to 12 mo...

Complete dataset. The complete dataset on which this analysis was based. (XLSX)

Background: Active travel (walking or cycling for transport) is associated with favourable health outcomes in adults. However, little is known about the concurrent patterns of health behaviour associated with active travel. We used compositional data analysis to explore differences in how people doing some active travel used their time compared to...

PurposeHealth-related quality of life has been related to physical activity, sedentary behavior, and sleep among children from developed nations. These relationships have rarely been assessed in developing nations, nor have behaviors been considered in their true context, as mutually exclusive and exhaustive parts of the movement behavior compositi...

The ability to compare published group-level estimates of objectively measured moderate-to-vigorous physical activity (MVPA) across studies continues to increase in difficulty. The objective of this study was to develop conversion equations and demonstrate their utility to compare estimates of MVPA derived from the wrist and hip. Three studies of y...

BACKGROUND The popularity and reach of social media make it an ideal delivery platform for interventions targeting health behaviors, such as physical inactivity. Research has identified a dose-response relationship whereby greater engagement and exposure are positively associated with intervention effects, hence enhancing engagement will maximize t...

Background The popularity and reach of social media make it an ideal delivery platform for interventions targeting health behaviors, such as physical inactivity. Research has identified a dose-response relationship whereby greater engagement and exposure are positively associated with intervention effects, hence enhancing engagement will maximize t...

Background Little is known about how to achieve enduring improvements in physical activity (PA), sedentary behaviour (SB) and sleep for people with chronic obstructive pulmonary disease (COPD). This study aimed to: (1) identify what people with COPD from South Australia and the Netherlands, and experts from COPD- and non-COPD-specific backgrounds c...

Participant feedbackfrom pilot of Round 1 Delphi questionnaire with research team action NR, no response; RX, respondent number.

Item considered as unimportant to each participant group for improving physical activity, sedentary behaviour and sleep in people with COPD: Rounds 2 and 3

Proposed amendments and action taken to allocation of items to themes by participants in Round 1b COPD, chronic obstructive pulmonary disease; RX, respondent number.

What is important to: (1) be more active; (2) spend less time sitting and lying and; (3) improve sleep quality—group average Likert-score for each item by theme (1) COPD, chronic obstructive pulmonary disease; Employ., Modify/understand employment commitments; GP, general practitioner; PA, physical activity. (2) CFE, concerns/fears/expectations; CO...

Objective Studies examining associations between movement behaviors (i.e., physical activity, sedentary behavior, and sleep duration) and obesity focus on average values of these movement behaviors, despite important within‐ and between‐country variability. A better understanding of movement behavior inequalities is important for developing public...

Aim: To examine cross-sectional associations of children's bone health (size, density, strength) with moderate-vigorous physical activity (MVPA) and sedentary behaviour by considering: (1) duration of activity, (2) fragmentation, and (3) duration/fragmentation combined. Methods: Design: Population-based cross-sectional study. Participants: 11-...

Background: Active travel (walking or cycling for transport) is associated with favourable health outcomes in adults. However, little is known about the concurrent patterns of health behaviour associated with active travel. We used compositional data analysis to explore differences in how people doing some active travel used their time compared to...

Descriptions of time use patterns in people with chronic obstructive pulmonary disease (COPD) are scarce and the relationship between use-of-time and COPD severity remains unclear. This study aimed to describe a typical day for people with COPD and to explore the differences in time-use patterns across the Body Mass-Index, Airflow Obstruction, Dysp...

Background Daily activity data are by nature compositional data. Accordingly, they occupy a specific geometry with unique properties that is different to standard Euclidean geometry. This study aimed to estimate the difference in adiposity associated with isotemporal reallocation between daily activity behaviours, and to compare the findings from c...

Objective: Older adults' health has been linked with time in moderate-to-vigorous physical activity (MVPA), and recent studies suggest time in sedentary behaviour may also be important. Time-use behaviours (MVPA, light physical activity, sedentary time and sleep) are co-dependent, and therefore their associations with health should be examined in...

The purpose of this multinational and cross-sectional study was to investigate whether nighttime sleep duration was associated with physical activity (PA) and sedentary time (SED) the following day, whether daytime PA/SED were associated with sleep duration the subsequent night, and whether the associations were modified by sex and study sites. Dat...

Objective: To examine the relationships between socioeconomic status (SES; household income and parental education) and objectively measured sleep patterns (sleep duration, sleep efficiency, and bedtime) among children from around the world and explore how the relationships differ across country levels of human development. Design: Multinational...

Purpose: To examine the associations between participation frequency in Physical Education (PE) classes and objective measures of physical activity (PA) and sedentary behavior (SB) in children from 12 countries at different levels of development. Methods: This multinational, cross-sectional study included 5,874 children aged 9-11 years from site...

Acute exercise studies using transcranial magnetic stimulation (TMS) can provide important insights into the mechanisms underpinning the positive relationship between regular engagement in physical activity and cortical neuroplasticity. Emerging evidence indicates that a single session of aerobic exercise can promote the response to an experimental...

The purpose of this study was to describe children’s daily compliance with moderate-to-vigorous physical activity (MVPA) recommendations across a week in different parts of the world, and to identify individual- and school-level correlates that may explain differences in daily MVPA compliance. The sample included 6553 children aged 9–11 years from...

Background: In 2017, the Australian Government funded the update of the National Physical Activity Recommendations for Children 0-5 years, with the intention that they be an integration of movement behaviours across the 24-h period. The benefit for Australia was that it could leverage research in Canada in the development of their 24-h guidelines...

How people use their time has been linked with their health. For example, spending more time being physically active is known to be beneficial for health, whereas long durations of sitting have been associated with unfavourable health outcomes. Accordingly, public health messages have advocated swapping strategies to promote the reallocation of tim...

Background Physical inactivity is a leading preventable cause of chronic disease and premature death globally, yet over half of the adult Australian population is inactive. To address this, web-based physical activity interventions, which have the potential to reach large numbers of users at low costs, have received considerable attention. To fully...

Purpose: To investigate associations between aspects of time use and health-related quality of life (HRQoL) in youth. Methods: 239 obese and healthy-weight 10- to 13-year-old Australian children completed the Pediatric Quality of Life Inventory (PedsQL™) quantifying their health-related quality of life. Time use was evaluated over four days usin...

Nearly 70 years of sleep, sedentary behaviour, physical activity, and time-use research has led to the recent development of time-use epidemiology. To conceptualise the emerging research field and provide a framework for its further development, this paper defines its position among the established branches of science, explains its main concepts an...

The aim of this study was to investigate the phenomenon of activity (increased activity in response to monitor wear) and determine the minimum wear time of accelerometers when objectively measuring habitual physical activity levels of community dwelling stroke survivors. Exploratory, secondary analyses of cross-sectional data were carried out. Phys...

Objective: This study aimed to translate the physical activity (PA) questions in the WHO Health Behaviour in School-aged Children (HBSC) survey questionnaire into Japanese (HBSC-J) and to examine their validity. Methods: Participants were the 5th grade primary school students (70 students aged 11.3 ± 0.3 years: 10.6-11.9 years). The questionnaire w...

Sleep is important for the physical, social and mental well-being of both children and adults. Over the years, there has been a general presumption that sleep will inevitably decline with the increase in technology and a busy 24-hour modern lifestyle. This narrative review discusses the empirical evidence for secular trends in sleep duration and th...

The purpose of this study was to describe sources of variability in obesity-related variables in 6022 children aged 9–11 y from 12 countries. The study design involved recruitment of students, nested within schools, which were nested within study sites. Height, weight and waist circumference (WC) were measured and BMI was calculated; sleep duration...

Objectives: To examine whether meeting vs not meeting movement/non-movement guidelines (moderate-to-vigorous physical activity [MVPA], screen time, sleep duration), and combinations of these recommendations, are associated with health-related quality of life (HRQoL) in children from 12 countries in five major geographic regions of the world and ex...

Objectives Physical activity, sedentary and sleep behaviours have strong associations with health. This systematic review aimed to identify how clinical practice guidelines (CPGs) for the management of chronic obstructive pulmonary disease (COPD) report specific recommendations and strategies for these movement behaviours. Methods A systematic sea...

We investigated whether associations of neighborhood social environment attributes and physical activity differed among 12 countries and levels of economic development using World Bank classification (low/lower-middle-, upper-middle- and high- income countries) among 9–11 year old children (N=6161) from the International Study of Childhood Obesity,...

Background: The 3 "movement behaviours" of sleep, screen time, and physical activity are associated with a wide range of health outcomes in children. This study examined whether these behaviours cluster together within individuals in Australian primary school children. Methods: Three datasets including 4,449 9- to 11-year-old children were inter...

Objectives: To describe 24-hour time-use patterns and their association with health-related quality of life (HRQoL) in early adolescence. Methods: The Child Health CheckPoint was a cross-sectional study nested between Waves 6 and 7 of the Longitudinal Study of Australian Children. The participants were 1455 11- to 12-year-olds (39% of Wave 6; 51...

Objective: To examine the joint association of birth weight and physical activity/sedentary time with childhood obesity in 12 countries. Methods: A cross-sectional study of 5,088 children aged 9 to 11 years was conducted. Birth weight was recalled by parents or guardians. Moderate-to-vigorous physical activity (MVPA) and sedentary behavior were...

The health effects of daily activity behaviours (physical activity, sedentary time and sleep) are widely studied. While previous research has largely examined activity behaviours in isolation, recent studies have adjusted for multiple behaviours. However, the inclusion of all activity behaviours in traditional multivariate analyses has not been pos...

Time use could profoundly affect adolescents' health-related quality of life (HRQL). Ideally, overall time use patterns would be considered, because activities within a 24-hour day are inherently correlated (more in one activity means less in another). This review focused on the associations of (i) overall time use patterns and (ii) components of t...

Background Although ‘unhealthy’ diet is a well-known risk factor for non-communicable diseases, its relationship with socio-economic status (SES) has not been fully investigated. Moreover, the available research has largely been conducted in countries at high levels of human development. This is the first study to examine relationships among dietar...

Background Movement behaviours performed over a finite period such as a 24 h day are compositional data. Compositional data exist in a constrained simplex geometry that is incongruent with traditional multivariate analytical techniques. However, the expression of compositional data as log-ratio co-ordinate systems transfers them to the unconstraine...