Andrew J. Atkin

Methods of Measurement in epidemiology: Sedentary Behaviour

BACKGROUND Research examining sedentary behaviour as a potentially independent risk factor for chronic disease morbidity and mortality has expanded rapidly in recent years. METHODS We present a narrative overview of the sedentary behaviour measurement literature. Subjective and objective methods of measuring sedentary behaviour suitable for use in population-based research with children and adults are examined. The validity and reliability of each method is considered, gaps in the literature specific to each method identified and potential future directions discussed. RESULTS To date, subjective approaches to sedentary behaviour measurement, e.g. questionnaires, have focused predominantly on TV viewing or other screen-based behaviours. Typically, such measures demonstrate moderate reliability but slight to moderate validity. Accelerometry is increasingly being used for sedentary behaviour assessments; this approach overcomes some of the limitations of subjective methods, but detection of specific postures and postural changes by this method is somewhat limited. Instruments developed specifically for the assessment of body posture have demonstrated good reliability and validity in the limited research conducted to date. Miniaturization of monitoring devices, interoperability between measurement and communication technologies and advanced analytical approaches are potential avenues for future developments in this field. CONCLUSIONS High-quality measurement is essential in all elements of sedentary behaviour epidemiology, from determining associations with health outcomes to the development and evaluation of behaviour change interventions. Sedentary behaviour measurement remains relatively under-developed, although new instruments, both objective and subjective, show considerable promise and warrant further testing.

Correlates of physical activity in youth: a review of quantitative systematic reviews

To increase young peoples physical activity (PA) levels it is important to understand the correlates of PA in children and adolescents. We sought to identify factors associated with childrens and adolescents’ PA by reviewing systematic quantitative reviews of non-intervention research. Systematic reviews examining associations between quantitatively measured variables and PA in young people (< 19 years) from 2000–2010 were identified using electronic and manual searches. Nine systematic reviews were identified. Demographic/biological correlates of PA were age and gender. Psychological correlates of PA were positive motivation, positive body image and the existence of barriers to PA. Behavioural correlates of PA were previous PA, sport participation, smoking, and sedentary behaviour. Social/cultural correlates of PA were parental influence and social support, and environmental correlates of PA were access to facilities, distance from home to school, time spent outside, and local crime. The evidence is suggestive of a number of different types of correlates of PA for children and adolescents. Beyond age and gender, though, most are likely to have only small or small-to-moderate effects in isolation and may work best in interaction with other influences. Psychologists must look to social, organisational and community-level correlates in addition to individual correlates.

Associations between sedentary behaviour and physical activity in children and adolescents: a meta-analysis

Physical activity and sedentary behaviour are associated with metabolic and mental health during childhood and adolescence. Understanding the inter‐relationships between these behaviours will help to inform intervention design. This systematic review and meta‐analysis synthesized evidence from observational studies describing the association between sedentary behaviour and physical activity in young people (<18 years). English‐language publications up to August 2013 were located through electronic and manual searches. Included studies presented statistical associations between at least one measure of sedentary behaviour and one measure of physical activity. One hundred sixty‐three papers were included in the meta‐analysis, from which data on 254 independent samples was extracted. In the summary meta‐analytic model (k = 230), a small, but significant, negative association between sedentary behaviour and physical activity was observed (r = −0.108, 95% confidence interval [CI] = −0.128, −0.087). In moderator analyses, studies that recruited smaller samples (n < 100, r = −0.193, 95% CI = −0.276, −0.109) employed objective methods of measurement (objectively measured physical activity; r = −0.233, 95% CI = −0.330, −0.137) or were assessed to be of higher methodological quality (r = −0.176, 95% CI = −0.215, −0.138) reported stronger associations, although effect sizes remained small. The association between sedentary behaviour and physical activity in young people is negative, but small, suggesting that these behaviours do not directly displace one another.

Seasonal variation in children’s physical activity and sedentary time

ABSTRACT Purpose Understanding seasonal variation in physical activity is important for informing public health surveillance and intervention design. The aim of the current study was to describe seasonal variation in children’s objectively measured physical activity and sedentary time. Methods Data are from the UK Millennium Cohort Study. Participants were invited to wear an accelerometer for 7 d on five occasions between November 2008 and January 2010. Outcome variables were sedentary time (<100 counts per minute, min·d−1) and moderate to vigorous physical activity (MVPA) (>2241 counts per minute, min·d−1). The season was characterized using a categorical variable (spring, summer, autumn, or winter) and a continuous function of day of the year. Cross-classified linear regression models were used to estimate the association of each of these constructs with the outcome variables. Modification of the seasonal variation by sex, weight status, urban/rural location, parental income, and day of the week (weekday/weekend) was examined using interaction terms in regression models. Results At least one wave of valid accelerometer data was obtained from 704 participants (47% male; baseline age, 7.6 (0.3) yr). MVPA was lower in autumn and winter relative to spring, with the magnitude of this difference varying by weekday/weekend, sex, weight status, urban/rural location, and family income (P for interaction <0.05 in all cases). Total sedentary time was greater in autumn and winter compared with spring; the seasonal effect was stronger during the weekend than during the weekday (P for interaction <0.01). Conclusions Lower levels of MVPA and elevated sedentary time support the implementation of intervention programs during autumn and winter. Evidence of greater seasonal variation in weekend behavior and among certain sociodemographic subgroups highlights targets for tailored intervention programs.

Parenting styles, family structure and adolescent dietary behaviour

OBJECTIVE To examine associations between parenting styles, family structure and aspects of adolescent dietary behaviour. DESIGN Cross-sectional study. SETTING Secondary schools in the East Midlands, UK. SUBJECTS Adolescents aged 12-16 years (n 328, 57 % boys) completed an FFQ assessing their consumption of fruit, vegetables, unhealthy snacks and breakfast. Adolescents provided information on parental and sibling status and completed a seventeen-item instrument measuring the general parenting style dimensions of involvement and strictness, from which four styles were derived: indulgent, neglectful, authoritarian, authoritative. RESULTS After controlling for adolescent gender and age, analysis of covariance revealed no significant interactions between parenting style and family structure variables for any of the dietary behaviours assessed. Significant main effects for family structure were observed only for breakfast consumption, with adolescents from dual-parent families (P < 0.01) and those with no brothers (P < 0.05) eating breakfast on more days per week than those from single-parent families and those with one or more brother, respectively. Significant main effects for parenting style were observed for all dietary behaviours apart from vegetable consumption. Adolescents who described their parents as authoritative ate more fruit per day, fewer unhealthy snacks per day, and ate breakfast on more days per week than those who described their parents as neglectful. CONCLUSIONS The positive associations between authoritative parenting style and adolescent dietary behaviour transcend family structure. Future research should be food-specific and assess the efficacy of strategies promoting the central attributes of an authoritative parenting style on the dietary behaviours of adolescents from a variety of family structures.

Patterns of adolescent physical activity and dietary behaviours.

BackgroundThe potential synergistic effects of multiple dietary and physical activity behaviours on the risk of chronic conditions and health outcomes is a key issue for public health. This study examined the prevalence and clustering patterns of multiple health behaviours among a sample of adolescents in the UK.MethodsCross-sectional survey of 176 adolescents aged 12–16 years (49% boys). Adolescents wore accelerometers for seven days and completed a questionnaire assessing fruit, vegetable, and breakfast consumption. The prevalence of adolescents meeting the physical activity (≥ 60 minutes moderate-to-vigorous physical activity/day), fruit and vegetable (≥ 5 portions of FV per day) and breakfast recommendations (eating breakfast on ≥ 5 days per week), and clustering patterns of these health behaviours are described.ResultsBoys were more active than girls (p < 0.001) and younger adolescents were more active than older adolescents (p < 0.01). Boys ate breakfast on more days per week than girls (p < 0.01) and older adolescents ate more fruit and vegetables than younger adolescents (p < 0.01). Almost 54% of adolescents had multiple risk behaviours and only 6% achieved all three of the recommendations. Girls had significantly more risk factors than boys (p < 0.01). For adolescents with two risk behaviours, the most prevalent cluster was formed by not meeting the physical activity and fruit and vegetable recommendations.ConclusionMany adolescents fail to meet multiple diet and physical activity recommendations, highlighting that physical activity and dietary behaviours do not occur in isolation. Future research should investigate how best to achieve multiple health behaviour change in adolescent boys and girls.

Change in objectively measured physical activity during the transition to adolescence

Background Physical activity (PA) declines during adolescence but change in different PA intensities across population subgroups is rarely explored. We describe change in sedentary (SED) time, light (LPA), moderate (MPA) and vigorous PA (VPA) assessed at three time points over 4 years. Methods Accelerometer-assessed PA (min) was obtained at baseline (N=2064), 1 and 4 years later among British children (baseline mean±SD 10.2±0.3-year-old; 42.5% male). Change in SED (<100 counts/min (cpm)), LPA (101–1999 cpm), MPA (2000–3999 cpm) and VPA (≥4000 cpm) was studied using three-level (age, individual and school) mixed-effects linear regression including participants with data at ≥2 time points (N=990). Differences in change by sex, home location and weight status were explored with interactions for SED, LPA and moderate and vigorous PA (MVPA). Results SED increased by 10.6 (95% CI 9.1 to 12.2) min/day/year. MPA and VPA decreased by 1.4 (1.0 to 1.8) and 1.5 (1.1 to 1.8) min/day/year, respectively. VPA decreased more than MPA as a percentage of the baseline value. MVPA declined more steeply among boys (3.9 (3.0 to 4.8)) versus girls (2.0 (1.2 to 2.7) min/day/year) despite lower MVPA among girls at all ages; rural (4.4 (3.5 to 5.2)) versus urban individuals (1.3 (0.4 to 2.3) min/day/year) and on weekends (6.7 (5.2 to 8.1)) versus weekdays (2.8 (1.9 to 3.7) min/day/year). MVPA was consistently lower among overweight/obese individuals (−17.5 (−3.9 to −2.5) min/day/year). Conclusions PA decreases and is replaced by SED during early adolescence in British youth. Results indicate the urgency of PA promotion among all adolescents but especially girls and in rural areas. Increasing VPA and targeting PA promotion during weekends appear important.

Interventions to Promote Physical Activity in Young People Conducted in the Hours Immediately After School: A Systematic Review

BackgroundAfter school is a critical period in the physical activity and sedentary behaviour patterns of young people. Interventions to promote physical activity during these hours should be informed by existing evidence.PurposeThe present study provides a systematic review of interventions to promote physical activity in young people conducted in the hours immediately after school.MethodsThe review was conducted in accordance with guidelines from the National Institute for Health and Clinical Excellence. Studies were located through searches of electronic databases, including MEDLINE, EMBASE, PsychINFO and ERIC. For included studies, data were extracted and methodological quality assessed using standardised forms.ResultsTen papers, reporting nine studies, met inclusion criteria. Three studies reported positive changes in physical activity and six indicated no change. Evidence suggests that single-behaviour interventions may be most effective during these hours.ConclusionLimitations in study design, lack of statistical power and problems with implementation have likely hindered the effectiveness of interventions in the after-school setting to date. Further work is required to develop interventions during this critical period of the day.

Family circumstance, sedentary behaviour and physical activity in adolescents living in England: Project STIL

BackgroundIdentification of non-modifiable correlates of physical activity and sedentary behaviour in youth contributes to the development of effective targeted intervention strategies. The purpose of this research was to examine the relationships between family circumstances (e.g. socio-economic status, single vs. dual parent household, presence/absence of siblings) and leisure-time physical activity and sedentary behaviours in adolescents.MethodsA total of 1171 adolescents (40% male; mean age 14.8 years) completed ecological momentary assessment diaries every 15 minutes for 3 weekdays outside of school hours and 1 weekend day. Analysed behaviours were sports/exercise, active travel, TV viewing, computer use, sedentary socialising (hanging-out, using the telephone, sitting and talking) and total sedentary behaviour. Linear regression was employed to estimate levels of association between individual family circumstance variables and each behaviour.ResultsCompared to girls from higher socioeconomic status (SES) groups, girls from low SES groups reported higher weekend TV viewing and higher weekday total sedentary behaviour. For boys, single parent status was associated with greater total sedentary behaviour compared to those from dual parent households. Boys and girls from low socio-economic neighbourhoods reported lower participation in sports/exercise compared to those living in higher socio-economic neighbourhoods.ConclusionAssociations were not consistent across behaviours or between genders. Overall, findings indicate that boys from single parent households and girls from low socio-economic families may be at increased risk of high sedentary behaviour. Those living in low socioeconomic neighbourhoods may be at increased risk of reduced participation in sports and exercise.

Family-based interventions to increase physical activity in children: a systematic review, meta-analysis and realist synthesis.

Family‐based interventions represent a potentially valuable route to increasing child physical activity (PA) in children. A dual meta‐analysis and realist synthesis approach examined existing interventions to assist those developing programmes to encourage uptake and maintenance of PA in children.