Effectiveness of interventions to promote physical activity and/or decrease sedentary behaviour among rural adults: a systematic review and meta-analysis.

Physical inactivity and overweight and obesity are more prevalent among rural than urban populations. This study aimed to review published evidence of the effectiveness of interventions to increase physical activity (PA) and/or decrease sedentary behaviour (SB) among rural adults and to identify factors associated with effectiveness. Seven electronic databases were searched for controlled trials of a PA or SB intervention. Meta-analysis was conducted using random effects models and meta-regression. Thirteen studies were included in the qualitative synthesis (n = 4,848 participants) and 12 in the meta-analysis (n = 4,820). All studies were interventions to increase PA. Overall, there was no effect on PA (standardized mean difference [SMD] 0.11; 95% confidence interval [CI] -0.04, 0.25) or SB (SMD 0.07; 95% CI -0.33, 0.20). In PA subgroup analyses, studies employing objective outcome measures demonstrated effects in favour of the intervention (SMD 0.65, 95% CI 0.30, 1.00), while those using self-reported measures did not (SMD 0.00; 95% CI -0.11, 0.10). This review highlights significant gaps in our understanding of how best to promote PA and reduce SB among rural adults. Future studies should use objective measures of PA as study outcomes. The absence of interventions to decrease SB is of concern, with immediate action required to address this large knowledge gap.

Self-reported sleepwalking in Australian senior secondary school students.

BACKGROUND: Few studies have examined self-reported sleepwalking in older adolescents. The aim of this study was to examine the prevalence rates of sleepwalking in a one-month self-report period in Australian adolescents. METHODS: Participants were 532 Australian adolescents in their final two years of secondary school. RESULTS: The prevalence of sleepwalking in the one-month self-report period was 2.9% (95% confidence interval (CI) 1.47-4.33) in this sample-1% reported sleepwalking at least once a week in the previous month. A significant proportion (17.5%) of the participants was unsure if they had sleepwalked. CONCLUSION: The results provide data on the self-reported prevalence rate of sleepwalking in older adolescents. Compared with the population data, this rate falls within the confidence intervals of child and adult prevalence rates of sleepwalking and is consistent with a decline in sleepwalking from childhood and adulthood. Further research is needed to explore how adolescents know they sleepwalk to understand the reliability of self-report measures.

Testing the activitystat hypothesis: a randomised controlled trial.

BACKGROUND: It has been hypothesised that an 'activitystat' may biologically regulate energy expenditure or physical activity levels, thereby limiting the effectiveness of physical activity interventions. Using a randomised controlled trial design, the aim of this study was to investigate the effect of a six-week exercise stimulus on energy expenditure and physical activity, in order to empirically test this hypothesis. METHODS: Previously inactive adults (n = 129) [age (mean ± SD) 41 ± 11 year; body mass index 26.1 ± 5.2 kg/m(2)] were randomly allocated to a Control group (n = 43) or a 6-week Moderate (150 min/week) (n = 43) or Extensive (300 min/week) (n = 43) exercise intervention group. Energy expenditure and physical activity were measured using a combination of accelerometry (total counts, minutes spent in moderate to vigorous physical activity) and detailed time use recalls using the Multimedia Activity Recall for Children and Adults (total daily energy expenditure, minutes spent in moderate to vigorous physical activity) at baseline, mid- and end-intervention and 3- and 6-month follow up. Resting metabolic rate was measured at baseline and end-intervention using indirect calorimetry. Analysis was conducted using random effects mixed modeling. RESULTS: At end-intervention, there were statistically significant increases in all energy expenditure and physical activity variables according to both accelerometry and time use recalls (p < 0.001) in the Moderate and Extensive groups, relative to Controls. There was no significant change in resting metabolic rate (p = 0.78). CONCLUSION: Taken together, these results show no evidence of an "activitystat" effect. In the current study, imposed exercise stimuli of 150-300 min/week resulted in commensurate increases in overall energy expenditure and physical activity, with no sign of compensation in either of these constructs. TRIAL REGISTRATION NUMBER: ACTRN12610000248066  (registered prospectively 24 March 2010).

Associations between predictors of children's dietary intake and socioeconomic position: a systematic review of the literature.

Socioeconomically disadvantaged children are at higher risk of consuming poor diets, in particular less fruits and vegetables and more non-core foods and sweetened beverages. Currently the drivers of socioeconomically related differences in children's dietary intake are not well understood. This systematic review explored whether dietary predictors vary for children of different socioeconomic circumstances. Seven databases and reference lists of included material were searched for studies investigating predictors of 9-13-year-old children's diet in relation to socioeconomic position. Individual- and population-based cross-sectional, cohort and epidemiological studies published in English and conducted in developed countries were included. Twenty-eight studies were included in this review; most were conducted in Europe (n = 12) or North America (n = 10). The most frequently used indicators of socioeconomic position were parent education and occupation. Predictors of children's dietary intake varied among children of different socioeconomic circumstances. Socioeconomic position was consistently associated with children's nutrition knowledge, parent modelling, home food availability and accessibility. Indeterminate associations with socioeconomic position were observed for parent feeding practices and food environment near school. Differences in the determinants of eating between socioeconomic groups provide a better understanding of the drivers of socioeconomic disparities in dietary intake, and how to develop targeted intervention strategies.

A systematic review of the validity and reliability of sedentary behaviour measures used with children and adolescents.

The aim of this review was to evaluate the reliability and validity of methods used to assess the multiple components of sedentary behaviour (i.e. screen time, sitting, not moving and existing at low energy expenditure) in children and adolescents. Twenty-six studies met our inclusion criteria and were reviewed. Thirteen studies reported the reliability of self- and proxy-report measures of sedentary behaviour and seven of these were found to have acceptable test-retest reliability. Evidence for the criterion validity of self- and proxy-report measures was examined in three studies with mixed results. Seven studies examined the reliability and/or validity of direct observation and the findings were generally positive. Five studies demonstrated the utility of accelerometers to accurately classify sedentary behaviour. Self-report measures provide reliable estimates of screen time, yet their validity remains largely untested. While accelerometers can accurately classify participants' behaviour as sedentary, they do not provide information about type of sedentary behaviour or context. Studies utilizing measures of sedentary behaviour need to more adequately report on the validity and reliability of the measures used. We recommend the use of objective measures of sedentary behaviour such as accelerometers, in conjunction with subjective measures (e.g. self-report), to assess type and context of behaviour.

Trends in the duration of school-day sleep among 10- to 15-year-old South Australians between 1985 and 2004.

AIM: To compare self-reported school-day sleep duration in 10- to 15-year-old South Australians between 1985 and 2004. METHODS: Data were collected from 10- to 15-year-old participants in the 1985 Australian Schools Health and Fitness Survey (n = 390) and the 2004 South Australian Physical Activity Survey (n = 510). Identical self-report questionnaires were administered in both surveys, providing data on school-day bed-time, wake-time and sleep duration; as well as age, gender and socioeconomic status (SES). Analysis of co-variance (ANCOVA), controlling for age and SES, was used to compare all sleep variables between surveys. RESULTS: Declines in sleep duration were found for both girls (28 min) and boys (33 min) between surveys. The reduction was more pronounced in 'lower SES' boys (44 min) than 'higher SES' boys (23 min). Boys reported later bed-time than girls in the 2004 survey, while no gender differences were apparent in the 1985 survey. CONCLUSION: Our findings suggest reductions in school-day sleep duration have occurred in Australian children and adolescents over the last 20 years, due largely to later bed-times. The physiological significance of these declines and mediating influences, such as SES, are yet to be explicated.

Dietary intake, physical activity and TV viewing as mediators of the association of socioeconomic status with body composition: a cross-sectional analysis of Australian youth.

BACKGROUND: There is emerging evidence of socioeconomic gradients in adiposity among Australian youth. Behavioral mechanisms for these trends are unexplained. METHODS: In total, 194 South Australian children (97 boys, 11.48+/-0.43 years; 97 girls, 11.60+/-0.38 years) were assessed for pubertal status, stature, weight, skinfolds and waist girth. Socioeconomic status (SES) was represented by postcode of residence (Socioeconomic Index for Areas) and parent education. Children reported moderate-to-vigorous physical activity (MVPA), TV viewing (TV) and dietary intake (daily energy intake as a ratio of predicted basal metabolic rate (DEI/BMR); and fat intake), using three x 24 h recall. Path analysis (partial least-squared method) was used to analyze the independence and interdependence of pathways linking SES, anthropometric variables and measured behaviors. RESULTS: SES was negatively associated with waist girth and skinfolds in girls, and waist girth in boys. In models including behavioral variables, these SES gradients in girls were largely unattenuated; accordingly, physical activity and dietary intake were not confirmed as mediators of the association of SES and girls' adiposity. In boys there was evidence that the negative relationship between SES and waist girth was mediated by fat intake. CONCLUSIONS: The inverse relationships between SES and girls' adiposity were unexplained by the behavioral attributes measured in this study. Mediators of SES gradients in youth adiposity remain elusive, and may require intensive methodologies to explicate.

Evidence for secular trends in children's physical activity behaviour.

It is not clear whether the global increase in weight problems in children is the result of excessive energy intake or decreasing energy expenditure. Methodological limitations have made it difficult to analyse. There is evidence that at least part of the problem may lie with increasing energy consumption, but it is important to examine the other side of the energy equation also. However, it is not possible to conclusively describe physical activity trends because of the absence of suitable baseline data. One solution is to summate all available evidence in as many areas of daily activities as possible and then draw tentative conclusions. This review summarises available trend data on direct representations of physical activity in a range of contexts, together with indirect measures such as sedentariness, fitness, and attitudes. The conclusions drawn are: physical activity in clearly defined contexts such as active transport, school physical education, and organised sports is declining in many countries; young people would like to be active but are often constrained by external factors such as school policy or curricula, parental rules in relation to safety and convenience, and physical environmental factors.

A decrease in the association between the physical activity patterns of Australian parents and their children; 1985-1997.

The present study investigated the interactions between parents' and children's physical activity levels by examining whether or not parents who exercise have children who participate in sport. Of primary interest was an investigation of trends in these interactions over time. Information was collected from 10-13 y old children in 1985 (n = 2463) and then again in 1997-99 (n = 1469), about their sports participation and their perceptions of parents' exercise habits. Boys' participation in at least one sport declined from 87% in 1985 to 76% in 1997/1999 while, among girls, participation fell from 80% to 71%. According to their children's perceptions, mothers exercising regularly fell from 36% to 31% between surveys, while fathers exercising regularly fell from 39% to 32%. Interactions between parents' and children's exercise and sports behaviours were examined employing chi-square analysis techniques. Results showed gender-specific relationships for the 1985 sample, such that active fathers were associated with increased participation in sports by boys, and inactive mothers were associated with less participation in sports by girls. These interactions seemed to diminish over time. It is possible that changes in social structures during this time may be affecting familial behaviour relationships, such as the role modelling of active behaviours.

Body composition changes in female bodybuilders during preparation for competition.

OBJECTIVE: To determine anthropometric and body composition changes in female bodybuilders during preparation for competition. DESIGN: There was an attempt to match subjects in the control and experimental groups for height and percentage body fat (%BF) for the initial test of this longitudinal study. SUBJECTS: Five competitive bodybuilders (-X +/- s.d.: 35.3 +/- 5.7 y; 167.3 +/- 3.7 cm; 66.38 +/- 6.30 kg; 18.3 +/- 3.5 %BF) and five athletic females (-X +/- s.d.: 30.9 +/- 13.0 y; 166.9 +/- 3.9 cm; 55.94 +/- 3.59 kg; 19.1 +/- 3.3 %BF) were recruited from advertisements in a bodybuilding newsletter and placed on sports centre noticeboards. INTERVENTIONS: The following measurements were conducted 12 weeks, 6 weeks and 3-5 d before the bodybuilders' competitions: anthropometric profile, body density by underwater weighing, total body water via deuterium dilution and bone mineral mass from a dual-energy X-ray absorptiometry scan. A combination of the last three measurements enabled the %BF to the determined by a four compartment model. RESULTS: A significant (P < or = 0.001) 5.80 kg body mass loss by the bodybuilders as they prepared for competition was primarily due to a reduction in fat mass (FM; -4.42 kg; 76.2%) as opposed to fat-free mass (FFM; -1.38 kg; 23.8%). The decreases in body mass and FM over the final 6 weeks were greater than those over the first 6 weeks. Their %BF decreased (P < 0.001) from 18.3 to 12.7, whereas the values for the control group remained essentially unchanged at 19.1-19.6 %BF. These body composition changes by the bodybuilders were accompanied by a significant decline (P < 0.001) of 25.5 mm (76.3-50.8 mm) in the sum of eight skinfold thicknesses (triceps + subscapular + biceps + iliac crest + supraspinale + abdominal + front thigh + medial calf). CONCLUSIONS: Although the bodybuilders presented with low %BFs at the start of the experiment, they still significantly decreased their body mass during the 12 week preparation for competition and most of this loss was due to a reduction in FM as opposed to FFM.

Relationship between maximum aerobic power and resting metabolic rate in young adult women.

The literature is inconclusive as to the chronic effect of aerobic exercise on resting metabolic rate (RMR), and furthermore there is a scarcity of data on young women. Thirty-four young women exhibiting a wide range of aerobic fitness [maximum aerobic power (VO2max) = 32.3-64.8 ml.kg-1.min-1] were accordingly measured for RMR by the Douglas bag method, treadmill VO2max, and fat-free mass (FFM) by using Siri's three-compartment model. The interclass correlation (n = 34) between RMR (kJ/h) and VO2max (ml.kg-1.min-1) was significant (r = 0.39, P < 0.05). However, this relationship lost statistical significance when RMR was indexed to FFM and when partial correlation analysis was used to control for FFM differences. Furthermore, multiple linear-regression analysis indicated that only FFM emerged as a significant predictor of RMR (kJ/h). When high- (n = 12) and low-fitness (n = 12) groups were extracted from the cohort on the basis of VO2max scores, independent t-tests revealed significant between-group differences (P < 0.05) for RMR (kJ.kg-1.h-1) and VO2max (ml.kg-1.min-1) but not for RMR (kJ/h), RMR (kJ.kg FFM-1.h-1), and FFM. Analysis of covariance of RMR (kJ/h) with FFM as the covariate also showed no significant difference (P = 0.56) between high- and low-fitness groups. Thus the results suggest that 1) FFM accounts for most of the differences in RMR between subjects of varying VO2max values and 2) the RMR per unit of FFM in young healthy women is unrelated to VO2max.