Objective: To assess the validity and repeatability of a simple index designed to rank participants according to their energy expenditure estimated by self-report, by comparison with objectively measured energy expenditure assessed by heart-rate monitoring with individual calibration. Design: Energy expenditure was assessed over one year by four separate episodes of 4-day heart-rate monitoring, a method previously validated against whole-body calorimetry and doubly labelled water. Cardio-respiratory fitness was assessed by four repeated measures of sub-maximum oxygen uptake. At the end of the 12-month period, participants completed a physical activity questionnaire that assessed pastyear activity. A simple four-level physical activity index was derived by combining occupational physical activity together with time participating in cycling and other physical exercise (such as keep fit, aerobics, swimming and jogging). Subjects: One hundred and seventy-three randomly selected men and women aged 40 to 65 years. Results: The repeatability of the physical activity index was high (weighted kappa ¼ 0.6, P , 0:0001). There were positive associations between the physical activity index from the questionnaire and the objective measures of the ratio of daytime energy expenditure to resting metabolic rate ðP ¼ 0:003Þ and cardiorespiratory fitness ðP ¼ 0:001Þ: As an indirect test of validity, there was a positive association between the physical activity index and the ratio of energy intake, assessed by 7-day food diaries, to predicted basal metabolic rate. Conclusions: The summary index of physical activity derived from the questions used in the European Prospective Investigation into Cancer and Nutrition (EPIC) study suggest it is useful for ranking participants in terms of their physical activity in large epidemiological studies. The index is simple and easy to comprehend, which may make it suitable for situations that require a concise, global index of activity.

The indices of physical activity derived from this questionnaire have levels of validity and repeatability comparable to other physical activity instruments that are used in large epidemiological studies and which have undergone such intense development and testing.

Variants in mitochondrial DNA (mtDNA) could be associated with type 2 diabetes because ATP plays a critical role in the production and release of insulin. Diabetes can be precipitated both by mtDNA mutations and by exposure to mitochondrial poisons. The risk of inheriting diabetes from an affected mother is greater than that from an affected father, but this is not explained by maternally inherited diabetes and/or deafness (MIDD) caused by the 3243G : C mtDNA point mutation, which accounts for less than 0.5% of cases of diabetes. A common mtDNA variant (the 16189 variant) is positively correlated with blood fasting insulin, but there are no definitive studies demonstrating that it is associated with diabetes. We demonstrated a significant association between the 16189 variant and type 2 diabetes in a population-based case-control study in Cambridgeshire, UK (n=932, odds ratio=1.61 (1.0-2.7, P=0.048), which was greatly magnified in individuals with a family history of diabetes from the father's side (odds ratio=infinity; P<0.001).

Standard theory of planned behavior (TPB) questions to elicit salient behavioral beliefs may elicit instrumental consequences of behavior, and overlook affective consequences. Two hundred thirteen English adults (35 to 75 years of age) completed a questionnaire that contained closed measures of TPB constructs, and open-ended questions that asked not only about advantages and disadvantages, but also what respondents would like or enjuy and disfike or hate about being more physically active. Beliefs elicited by affective questions were associated more strongly with a closed affective attitude scale. Beliefs elicited by instrumental questions were associated more strongly with a closed instrumental attitude scale. Closed measures of the standard TPB variables explained 48% of the variance in intention to increase physical activity, while affective attitude explained an additional 1 1% of the variance. Applications of the TPB should consider affective and not just instrumental determinants of behavior.The most active areas of attitude research over the past two decades have involved the theory of reasoned action (TRA;Ajzen & Fishbein, 1975;Fishbein & Ajzen, 1980) and its extension, the theory of planned behavior (TPB; Ajzen, 1988, 199 1). One reason for this is the parsimony of these theories. According to the TRA, behavior is predicted solely by intention to perform that behavior. In turn, intention is predicted by attitude toward the behavior and subjective norm. The TPB added the construct of perceived behavioral control to the TRA as a predictor of both intention and behavior itself. In a variety of settings, it has been shown repeatedly that the TPB is successful at predicting not only intention to

Background/Objective:To report 30-year (1985–2015) prevalence trends in overweight, obesity and abdominal obesity among children by school level and socioeconomic status (SES).Subjects/Methods:Five cross-sectional, population child surveys (age 4–18 years; n=27 808) conducted in 1985–1997–2004–2010–2015 in New South Wales, Australia. Outcomes were prevalence of measured overweight, obesity and waist-to-height ratio (WHtR⩾0.5) by sex, school level (children (primary) and adolescents (high)) and SES tertile.Results:In 2015, the prevalences of overweight, obesity and WHtR⩾0.5 in children were 16.4%, 7.0% and 14.6%, respectively, and in adolescents 21.9%, 17.2% and 4.6%, respectively. Obesity prevalence has not significantly changed in children or adolescents since 1997, nor since 2010 (children, P=0.681; adolescents, P=0.21). Overweight has not significantly changed in children since 1997, but has in adolescents since 1985, with a relative increase of 16 percentage points (P<0.001) between 2010 and 2015. WHtR⩾0.5 prevalence has significantly changed since 1985, except in adolescent girls between 2010 and 2015. Between 2010 and 2015 the relative increase in WHtR⩾0.5 was 17 and 40 percentage points in children and adolescent boys, respectively. Significant disparities in prevalence rates between children and adolescents from low and high SES backgrounds began in 2010 for overweight, since 1997 for obesity and since 2004 for WHtR⩾0.5. Differences between SES groups have become larger over the past 18 years.Conclusions:Since 1997, obesity has remained stable, and overweight has stabilized in children, not in adolescents. WHtR⩾0.5 significantly increased between 1985 and 2015, with prevalence rates at each survey around twice the obesity prevalence. Compared with high SES children and adolescents, the risk of overweight, obesity and WHtR⩾0.5 was significantly higher for low SES children and adolescents. The findings are highly relevant to policy makers involved in child obesity prevention interventions and highlight the need for better targeted interventions among children and adolescents from low SES backgrounds, and adolescents in particular.