Validity and prognostic value of parental ratings of children's activity.

OBJECTIVE: To determine whether parental reports of children's physical activity are stable over time and correlate with objectively-measured physical activity. METHODS: Participants were 322 twin children from a large UK twin cohort. When the children were aged 4 (1999) and 11 (2006), mothers rated their activity levels using four different measures. These included children's enjoyment of active pastimes, their habitual activity level, their activity compared with others of the same age and sex and a standard scale for 'fidgetiness'. Children wore an Actigraph (model 7164) for 7 consecutive days at the 11 year follow up from which total physical activity was calculated. RESULTS: From age 4 to 11 amount and enjoyment of physical activity declined, but significant temporal correlations over the 7 year interval (range r=0.19 to 0.52) suggested that relative activity level was maintained. Habitual physical activity level, enjoyment of activity and fidgetiness at age 11 were all significantly associated with activity counts (all p values<0.05). CONCLUSIONS: These results indicate that parental ratings can be valid indicators of children's physical activity, and that children who are perceived to be more active at 4 years are still more active at 11 years.

Randomized controlled trial of the efficacy of aerobic exercise in reducing metabolic risk in healthy older people: The Hertfordshire Physical Activity Trial.

BACKGROUND: While there are compelling observational data confirming that individuals who exercise are healthier, the efficacy of aerobic exercise interventions to reduce metabolic risk and improve insulin sensitivity in older people has not been fully elucidated. Furthermore, while low birth weight has been shown to predict adverse health outcomes later in life, its influence on the response to aerobic exercise is unknown. Our primary objective is to assess the efficacy of a fully supervised twelve week aerobic exercise intervention in reducing clustered metabolic risk in healthy older adults. A secondary objective is to determine the influence of low birth weight on the response to exercise in this group. METHODS/DESIGN: We aim to recruit 100 participants born between 1931-1939, from the Hertfordshire Cohort Study and randomly assign them to no intervention or to 36 fully supervised one hour sessions on a cycle ergometer, over twelve weeks. Each participant will undergo detailed anthropometric and metabolic assessment pre- and post-intervention, including muscle biopsy, magnetic resonance imaging and spectroscopy, objective measurement of physical activity and sub-maximal fitness testing. DISCUSSION: Given the extensive phenotypic characterization, this study will provide valuable insights into the mechanisms underlying the beneficial effects of aerobic exercise as well as the efficacy, feasibility and safety of such interventions in this age group. TRIAL REGISTRATION: Current Controlled Trials: ISRCTN60986572.

Energy intake at breakfast and weight change: prospective study of 6,764 middle-aged men and women.

To investigate the association between percentage of total daily energy intake consumed at breakfast and weight change in middle-aged men and women, the authors analyzed data from a prospective population-based cohort study from Norfolk, United Kingdom. Participants were 6,764 men and women aged 40-75 years at baseline (1993-1997). Participants completed a 7-day food diary at baseline, and objective measurements of height and weight were carried out at baseline and follow-up (1998-2000). Mean baseline body mass index (weight (kg)/height (m)(2)) was lowest among persons in the highest quintile of percentage of daily energy consumed at breakfast (mean values were 26.0 in the highest quintile and 26.3 in the lowest quintile), despite higher daily total energy intake in this group. Although all participants gained weight, increased percentage of daily energy consumed at breakfast was associated with relatively lower weight gain (adjusted beta coefficient = -0.021, 95% confidence interval: -0.035, -0.007; p = 0.004). The association between percentage of daily energy intake consumed at breakfast and weight gain was independent of age, sex, smoking, total energy intake, macronutrient intake, social class, and physical activity. Redistribution of daily energy intake, so that more energy is consumed at breakfast and less energy is consumed later in the day, may help to reduce weight gain in middle-aged adults.

Differences in physical activity and sedentary time in relation to weight in 8-9 year old children.

BACKGROUND: The health benefits of physical activity for children are well established. Although objective measures of physical activity are increasingly used there is still a lack of adequate data on physical activity in children. Sex differences in physical activity have been consistently demonstrated and lower levels of physical activity in obese than non-obese children have been shown. However, differences across the whole weight spectrum have not been examined in detail. The aim of this study was to assess associations between physical activity and sedentary time across the weight spectrum in children, and to determine whether the associations differed by sex. METHODS: Participants in the current study were 176 boys and 169 girls aged 8-9 years old taking part in a longitudinal study of associations between eating behaviours, physical activity and weight gain during childhood. Height, weight and waist circumference were measured, and physical activity data were collected using an Actigraph model GT1M worn for 5 consecutive days. Associations between sex, weight and physical activity were analysed using linear regression models. RESULTS: Boys had higher total activity (mean difference = 119, p < 0.001) and more minutes of moderate and vigorous physical activity (MVPA) (mean difference = 25, p < 0.001) than girls. A higher percentage of boys (72%) than girls (30%) met current physical activity guidelines of 60 minutes MVPA per day. In boys, weight status significantly predicted total activity (p = 0.001) and MVPA (p = 0.001) but there were no significant associations in girls. There was no significant difference in time spent sedentary between boys and girls, and weight status did not predict sedentary time. CONCLUSION: In boys, physical activity was progressively lower across the weight spectrum, but in girls physical activity was consistently low across all weight categories. Intervention is required prior to 8 years old to prevent weight-related declines in physical activity in boys and further research is required to determine at what age, if ever, weight related differences in physical activity are apparent in girls.

Socioeconomic position and risk of short-term weight gain: prospective study of 14,619 middle-aged men and women.

BACKGROUND: The association between socioeconomic position in middle age and risk of subsequent, short-term weight gain is unknown. We therefore assessed this association in a prospective population based cohort study in Norfolk, UK. METHODS: We analysed data on 14,619 middle-aged men and women (aged between 40-75 at baseline) with repeated objective measures of weight and height at baseline (1993-1997) and follow up (1998-2000). RESULTS: During follow up 5,064 people gained more than 2.5 kg. Compared with the highest social class, individuals in the lowest social class had around a 30% greater risk of gaining more than 2.5 kg (OR 1.29; 95% CI 1.11-1.51; p for trend = 0.002). This association remained statistically significant following adjustment for sex, age, baseline BMI, smoking, and follow up time (OR 1.25; CI 1.07-1.46; p for trend <0.001). We also found no material difference between unadjusted models and those including all confounders and potential mediators. CONCLUSION: Individuals of low socioeconomic position are at greatest risk of gaining weight during middle age, which is not explained by classical correlates of socioeconomic position and risk factors for obesity.