The association of perceived and objectively measured crime with physical activity: a cross-sectional analysis

BACKGROUND

Crime is one aspect of the environment that can act as a barrier to physical activity. The goals of this study were to (1) compare measures of perceived crime with observed crime and (2) examine the association between the independent and combined effects of objective and perceived crime on physical activity.

METHODS

Perceived crime and physical activity were assessed in 1659 persons via telephone survey. Crime was objectively measured in a subset of 303 survey participants.

RESULTS

For all types of crime, there was low agreement between objective and perceived measures. Both perceived and objectively measured crime were independently associated with leisure activities.

CONCLUSIONS

This study suggests that perceptions and objective measures of crime are both important correlates of leisure physical activity. Evaluating both measures is necessary when examining the relationship between crime and physical activity to develop interventions that will most influence leisure physical activity levels.

Reducing sedentary behavior in minority girls via a theory-based, tailored classroom media intervention

OBJECTIVE

To develop, implement and test an innovative, theory-based classroom media intervention known as Get Moving! to increase physical activity and decrease sedentary behaviors in predominantly Latina middle school girls.

RESEARCH METHODS AND PROCEDURES

School-based intervention on five to seven consecutive school days in seven schools (four intervention and three control) with high Latino populations (above 60%). Intervention schools were matched to control schools by ethnic makeup and socioeconomic status (SES). Measures conducted 3 months before and 3 months after intervention included height, weight, percentage body fat (bioimpedance analysis), physical activity and psychosocial aspects of activity by questionnaire. Subjects were middle school girls, mean age 12.5 years old, 73% Latina (N=459 girls).

RESULTS

Get Moving! significantly reduced time spent on sedentary behavior (beta+/- standard error, SE=-0.27+/-0.14, p<0.05) and significantly increased intrinsic motivation (beta+/-SE=0.11+/-0.05, p<0.05). There was a trend for mediation effects of intrinsic motivation, but this did not reach significance.

DISCUSSION

Get Moving! is a promising school-based approach that specifically targets physical activity and sedentary behavior in Latina girls, a population at high risk for obesity and related diseases.

An overview of "The Active by Choice Today" (ACT) trial for increasing physical activity

BACKGROUND

Although school-based behavioral interventions for increasing physical activity (PA) in children and adolescents have been conducted, little evidence suggests that these curriculum-based approaches lead to increases in overall activity outside of program days. The overall goal of the "Active by Choice Today" (ACT) trial is to expand the body of knowledge concerning the factors that influence long-term increases in PA in underserved adolescents (low socioeconomic status, minorities) during their middle school years.

DESIGN AND SETTING

An overview of the ACT study design, theoretical framework, process evaluation, and primary hypotheses is presented. The trial involves twenty-four middle schools (1560 6th graders) in South Carolina that are randomly assigned to one of two after-school programs (motivational and life skills intervention, or general health education).

INTERVENTION

The intervention integrates constructs from Self-Determination and Social Cognitive Theories to enhance intrinsic motivation and behavioral skills for PA. The intervention targets skill development for PA outside of program days and the after-school program social environment (autonomy, choice, participation, belongingness, fun, enjoyment, support) is designed to positively impact cognitive mediators (self-efficacy, perceived competence), and motivational orientation (intrinsic motivation, commitment, positive self-concept). MAIN HYPOTHESES/OUTCOMES: It is hypothesized that the 17-week motivational and life skills intervention will lead to greater increases in moderate-to-vigorous PA (based on 7-day accelerometry estimates) at post-intervention as compared to the general health education program.

CONCLUSIONS

Implications of this innovative school-based trial are discussed.

Physical Activity Inventory for Patients with Spinal Cord Injury

OBJECTIVES

To test the reliability and validity of a physical activity instrument adapted for individuals with spinal cord injuries (SCI), the Physical Activity Instrument-SCI (PAI-SCI).

METHODS

Eligible participants completed the adapted PAI-SCI questionnaire at baseline and 1 week later. At baseline, they were also given an Actical accelerometer to wear on their wrist for 1 week.

RESULTS

Forty-three male subjects completed the study. There was a moderate relationship between total score on the PAI-SCI and total activity count determined by accelerometry (r = 0.42, P = 0.036). The PAI-SCI was able to differentiate between people with upper and lower level injuries (P = 0.05). Test-retest reliability was supported for the exercise and the general activity/self care subscales and not supported for the light household or the outdoor/gardening subscales.

CONCLUSION

The PAI-SCI was able to distinguish between physical activity amongst those with upper level and lower level injuries. More research is needed before the PAI-SCI can be recommended for use in clinical trials.

A meta-analysis of pedometer-based walking interventions and weight loss

PURPOSE

Cross-sectional studies show that individuals who walk more tend to be thinner than those who walk less. This does not mean, however, that the association between higher step counts and lower weight is causal or that encouraging sedentary individuals to increase step counts helps them lose weight.

METHODS

In this meta-analysis, we searched 6 electronic databases and contacted pedometer experts to identify pedometer-based walking studies without a dietary intervention that reported weight change as an outcome. We included randomized controlled trials and prospective cohort studies published after January 1, 1995, in either English or Japanese, with 5 or more adult participants and at least 1 cohort enrolled in a pedometer-based walking intervention lasting at least 4 weeks.

RESULTS

Nine studies met the study inclusion criteria. Cohort sample size ranged from 15 to 106, for a total of 307 participants, 73% of whom were women and 27% of whom were men. The duration of the intervention ranged from 4 weeks to 1 year, with a median duration of 16 weeks. The pooled estimate of mean weight change from baseline using a fixed-effects model and combining data from all 9 cohorts was -1.27 kg (95% confidence interval, -1.85 to -0.70 kg). Longer intervention duration was associated with greater weight change. On average, participants lost 0.05 kg per week during the interventions.

CONCLUSION

Pedometer-based walking programs result in a modest amount of weight loss. Longer programs lead to more weight loss than shorter programs.

Exercise, energy balance and the shift worker

Shift work is now common in society and is not restricted to heavy industry or emergency services, but is increasingly found amongst 'white collar' occupations and the growing number of service industries. Participation in shift work is associated with increased body mass index, prevalence of obesity and other health problems. We review the behavioural and biological disturbances that occur during shift work and discuss their impact on leisure-time physical activity and energy balance. Shift work generally decreases opportunities for physical activity and participation in sports. For those shift workers who are able to exercise, subjective and biological responses can be altered if the exercise is taken at unusual times of day and/or if the shift worker is sleep deprived. These altered responses may in turn impact on the longer-term adherence to an exercise programme. The favourable effects of exercise on body mass control and sleep quality in shift workers have not been confirmed. Similarly, recent reports of relationships between sleep duration and obesity have not been examined in a shift work context. There is no evidence that exercise can mediate certain circadian rhythm characteristics (e.g. amplitude or timing) for improved tolerance to shift work. Total energy intake and meal composition do not seem to be affected by participation in shift work. Meal frequency is generally reduced but snacking is increased on the night shift. Unavailability of preferred foods in the workplace, a lack of time, and a reduced desire to eat at night explain these findings. 'Normal' eating habits with the family are also disrupted. The metabolic responses to food are also altered by shift work-mediated disruptions to sleep and circadian rhythms. Whether any interactions on human metabolism exist between timing or content of food intake and physical activity during shift work is not known at present. There are very few randomized controlled studies on the efficacy of physical activity or dietary interventions during shift work. Some favourable effects of such interventions on fatigue levels at work have been reported, but biological and behavioural outcomes relevant to long-term health and energy balance have not been studied adequately. In addition, recruitment and retention of research participants for randomized controlled trials of physical activity or dietary interventions have been very difficult. We present a model of the various behavioural and biological factors relevant to exercise and energy balance during shift work as a framework for future research.

Walking for transportation or leisure: what difference does the neighborhood make?

BACKGROUND

Patients are often advised to initiate a physical activity program by walking for transportation or leisure. This study explored whether neighborhood factors beyond the individual might affect compliance.

OBJECTIVE

We examined the associations between total walking and neighborhood factors in a multi-ethnic population-based sample in California and the roles race/ethnicity plays in these associations.

DESIGN

Cross-sectional study

PARTICIPANTS

Individual-level data were obtained from the 2003 California Health Interview Survey. Participants' census tracts were linked to Census 2000 data to capture neighborhood SES.

MEASUREMENTS AND MAIN RESULTS

The dependent variable was self-reported walking at recommended levels. Neighborhood SES was measured by a scale of 4 Census-based variables (alpha = 0.83). Social cohesion was measured by a scale tapping the extent of perceived social connectedness, trust, and solidarity among neighbors (alpha = 0.70). Neighborhood access to a park, playground, or open space was measured by a single item. Safety was measured by a scale of three items (alpha = 0.66). We performed a series of multiple logit models with robust variance estimates while taking complex survey design into account. Neighborhood social cohesion (odds ratio [OR] = 1.09, 95% CI = 1.04, 1.14) and access to a park, playground, or open space (OR = 1.26, 95% CI = 1.16, 1.36) were significant environmental correlates of walking at recommended levels, independent of individual socio-demographics. Subgroup analysis showed that neighborhood effects were different by race/ethnicity.

CONCLUSIONS

Neighborhood physical and social environmental factors are significantly associated with walking at recommended levels. Being aware of the ways that the environment could affect a patient's compliance with PA recommendations may help physicians tailor recommendations to circumstances.

Physical activity is inversely associated with total homocysteine levels, independent of C677T MTHFR genotype and plasma B vitamins

The homocysteine level is considered to be a product of genetic and lifestyle interactions, mainly mutated methylenetetrahydrofolate reductase (MTHFR) and the intake of folate, vitamin B12 and pyridoxine, and their blood levels. Physical activity has been associated with lower homocysteine levels in some population studies, especially among elderly subjects. To further elucidate the observed association between homocysteine and physical activity, while accounting for the effect of the MTHFR C677T genotype, and of plasma levels of folate and B12 vitamins, a cross-sectional study of 620 males and females, aged 70.5 +/- 6.8 years, was carried out. Information on lifestyle habits was collected and laboratory examinations of 12-h fasting total plasma homocysteine, folate, and vitamin B12, as well as DNA analysis for MTHFR C677T variant, were performed. Median total homocysteine values were 11.4 micromol/l for males and 9.4 for females; p < 0.001. Smoking and ethnic origin were not found to be associated with homocysteine levels. Physically active subjects had significantly lower total homocysteine levels when adjusted for sex (p = 0.01). Significant inverse correlations were found between body mass index, plasma folate, B12 and homocysteine levels. Homocysteine levels of the CC, CT and TT genotypes were 9.7, 10.6 and 10.2 mumol/l, respectively (p = 0.002, controlling for sex). In a multiple linear regression model, a sedentary lifestyle increased homocysteine levels by 7% as compared to an active one (p = 0.03) controlling for sex, age, body mass index, folate, vitamin B12, and C677T genotype, all of which were also found to be significantly associated with homocysteine levels. Any level of physical activity was found to be independently associated with lower homocysteine levels in an elderly population, controlling for MTHFR genotype, plasma B-vitamins, age, sex, smoking and BMI. This study emphasizes the importance of maintaining a physically active lifestyle in the elderly.

Effects of aerobic exercise on overweight children's cognitive functioning: a randomized controlled trial

The study tested the effect of aerobic exercise training on executive function in overweight children. Ninety-four sedentary, overweight but otherwise healthy children (mean age = 9.2 years, body mass index 85th percentile) were randomized to a low-dose (20 min/day exercise), high-dose (40 min/day exercise), or control condition. Exercise sessions met 5 days/week for 15 weeks. The Cognitive Assessment System (CAS), a standardized test of cognitive processes, was administered individually before and following intervention. Analysis of covariance on posttest scores revealed effects on executive function. Group differences emerged for the CAS Planning scale (p = .03). Planning scores for the high-dose group were significantly greater than those of the control group. Exercise may prove to be a simple, yet important, method of enhancing aspects of children's mental functioning that are central to cognitive and social development.

Early rising children are more active than late risers

BACKGROUND

A low level of physical activity impacts mental as well as physical health. This study investigated the daily lifestyle habits that affect physical activity in young children.

METHODS

The relationship between physical activity, assessed by means of a Mini-Mitter Actiwatch device, and observed daily lifestyle habits was analyzed for 204 children, aged 12 to 40 months (average: 22.6 months), for whom 6-consecutive-day data from both the Actiwatch and sleep log were obtained.

RESULTS

An older age, male gender, and early waking time showed significant positive correlations with physical activity level. Multiple regression analysis revealed that these three variables were significant predictors of physical activity.

CONCLUSION

Promoting an early rising time is suggested to be an important element of cultivating good health in young children.

Dietary fat subgroups, zinc, and vegetable components are related to urine F2a-isoprostane concentration, a measure of oxidative stress, in midlife women

Smoking, diet, and physical activity may impact chronic diseases in part by promoting or attenuating oxidative stress. We evaluated associations between lifestyle factors and urine F(2a)-isoprostanes, a marker of oxidative stress in 1610 participants of the Study of Women's Health Across the Nation (SWAN). Dietary intake and physical activity were assessed at baseline and the 5th year 05 (Y05). These data were related to Y05 urinary F(2a)-isoprostane concentration with regression analyses. Median urine F(2a)-isoprostane concentration was 433 ng/L overall, 917 ng/L in smokers [inter-quartile range (IQR): 467, 1832 ng/L], and 403 ng/L in nonsmokers (IQR: 228, 709 ng/L; P < 0.0001 for difference). Higher trans fat intake was associated with higher urine F(2a)-isoprostane concentration; partial Spearman correlations (rho(x|y)) between Y05 urine F(2a)-isoprostane concentration and trans fatty acids was 0.19 (P = 0.03) in smokers and 0.13 (P < 0.0001) in nonsmokers. Increased log trans fat intake from baseline to Y05 was associated with higher concentration of log urine F(2a)-isoprostanes in nonsmokers (beta = 0.131, SE = 0.04, P = 0.0003). In nonsmokers, the partial correlation (rho(x|y)) between lutein and urine F(2a)-isoprostane concentration was -0.13 (P < 0.0001). Increased intake of log lutein from baseline to Y05 was also associated with lower log urine F(2a)-isoprostane concentration (beta = -0.096, SE = 0.03, P = 0.0005) in nonsmokers. Increased zinc intake from baseline to Y05 was associated with lower log urine F(2a)-isoprostane concentration in smokers and nonsmokers (beta = -0.346, SE = 0.14, P = 0.01), and -0.117, 0.04 (P = 0.001), respectively]. In conclusion, diet (fat subtypes, zinc, and vegetable components) and smoking were associated with urine F(2a)-isoprostanes, a marker of oxidative stress.

Neighborhood factors associated with physical activity and adequacy of weight gain during pregnancy

Healthy diet, physical activity, smoking, and adequate weight gain are all associated with maternal health and fetal growth during pregnancy. Neighborhood characteristics have been associated with poor maternal and child health outcomes, yet conceptualization of potential mechanisms are still needed. Unique information captured by neighborhood inventories, mostly conducted in northern US and Canadian urban areas, has been shown to reveal important aspects of the community environment that are not captured by the demographic quantities in census data. This study used data from the Pregnancy, Nutrition, and Infection (PIN) prospective cohort study to estimate the influences of individual-level and neighborhood-level characteristics on health behaviors and adequacy of weight gain during pregnancy. Women who participated in the PIN study and who resided in Raleigh, North Carolina and its surrounding suburbs were included (n = 703). Results from a neighborhood data collection inventory identified three social constructs, physical incivilities, territoriality, and social spaces, which were hypothesized to influence maternal health behaviors. The physical incivility scale was associated with decreased odds (adjusted OR = 0.74, 95%CI = 0.57, 0.98) in participating in vigorous leisure activity before pregnancy after controlling for several individual confounders, and a crude association for decreased odds of excessive weight gain (OR = 0.79, 95%CI = 0.64, 0.98). The social spaces scale was associated with decreased odds for inadequate (adjusted OR = 0.74, 95%CI = 0.56, 0.98) and excessive (adjusted OR = 0.69, 95%CI = 0.54, 0.98) gestational weight gain. The social spaces scale was also associated with decreased odds of living greater than 3 miles from a supermarket (adjusted OR = 0.03, 95%CI = 0.00, 0.27). Territoriality was not associated with any pregnancy-related health behavior. None of the neighborhood constructs were associated with smoking or diet quality. Physical incivilities and social spaces neighborhood characteristics may be important to measure to improve our understanding of the potential mechanisms through which neighborhood environments influence health.

Determinants of incident hyperglycemia 6 years after delivery in young rural Indian mothers: the Pune Maternal Nutrition Study (PMNS)

OBJECTIVE

To study determinants of incident hyperglycemia in rural Indian mothers 6 years after delivery.

RESEARCH DESIGN AND METHODS

The Pune Maternal Nutrition Study collected information in six villages near Pune on prepregnant characteristics and nutrition, physical activity, and glucose tolerance during pregnancy. An oral glucose tolerance test (OGTT) was repeated 6 years after delivery.

RESULTS

A total of 597 mothers had an OGTT at 28 weeks' gestation; 3 had gestational diabetes (by World Health Organization 1999 criteria). Six years later, 42 of 509 originally normal glucose-tolerant mothers were hyperglycemic (8 diabetic, 20 with impaired glucose tolerance, and 14 with impaired fasting glucose). The hyperglycemic women had shorter legs and thicker skinfolds before pregnancy (P < 0.01, both), were less active and more hyperglycemic (2-h plasma glucose 4.8 vs. 4.4 mmol/l, P < 0.001) during pregnancy, and gained more weight during follow-up (6.0 vs. 2.7 kg, P < 0.001). Multivariate analysis revealed that total leukocyte count and blood pressure during pregnancy were additional independent predictors of 2-h glucose concentration at follow-up.

CONCLUSIONS

Our results suggest that compromised linear growth, adiposity, inflammation, and less physical activity predispose to hyperglycemia in young rural Indian women. International cut points of diabetes risk factors are largely irrelevant in these women.

Obesity and its association with diets and sedentary life style among school children in Seoul, Korea: Compliance with Dietary References Intakes for Koreans food guides

This study compared obese children's food group intakes with the new Dietary References Intakes for Koreans (KDRIs) food guides for 5th-6th grade school children. This study also determined the extent of sedentary life styles related with obesity in this area of children. This is a cross-sectional study of 799 school children. The dietitian sent a survey form describing the project and a questionnaire to the subject's family. The questionnaire included child demographics, family history of chronic diseases, the daily servings of five food groups, such as grains, meat and beans, dairy products, fruits, and vegetables. The daily or weekly hours of physical activity, television viewing, and computer usage were also surveyed. Obesity index (%) of the subjects was calculated, and children with an obesity index (%) equal to or greater than 20 were classified as the obese. Among the 799 participants, 50.7% were female. The percentages of the normal and the obese were 691 (86.5%) and 108 (13.5%) respectively. Obese children reported eating less vegetables (p<0.05), more high sugar snacks (p<0.05), and high fat snacks (p<0.05) than normal children. No significant differences in food servings of grains, meats and beans, and fruits, and dairy products between the normal and the obese were shown. Obese children reported fewer hours of physical activities (p<0.05) and more hours of computer usage (p<0.05) than normal children. Girls showed less likelihood of being obese (odds ratio, 0.575, CI (0.38, 0.87), p<0.05). More hours of physical activity significantly decreased the likelihood of being obese (odds ratio, 0.572, CI (0.35, 0.92), p<0.05). Family history of obesity almost doubled the likelihood of obesity in children (odds ratio, 2.653, CI (1.660, 4.241), p<0.05). In conclusion, frequent snacking, inadequate vegetable consumption, and sedentary lifestyle increased significantly the likelihood of obesity in children, which suggest that obesity intervention in this age group should focuse more on those variables.

Sensitivity of the hypothalamic paraventricular nucleus to the locomotor-activating effects of neuromedin U in obesity

Obesity is associated with a decrease in energy expenditure relative to energy intake. The decrease in physical activity associated with obesity in several species, including humans, contributes to decreased energy expenditure. Several hormones and neuropeptides that affect appetite also modulate physical activity, including neuromedin U (NMU), a peptide found in the gut and brain. We have demonstrated that NMU microinjected into the hypothalamic paraventricular nucleus (PVN) in rats increases the energy expenditure associated with physical activity, called non-exercise activity thermogenesis (NEAT). Here we examined whether obesity in rats is related to decreased sensitivity of the PVN to the locomotor-activating effect of NMU. Diet-induced obese (DIO) rats and lean, diet-resistant (DR) rats were given PVN microinjections of increasing doses of NMU both before and after 1 month on a high-fat diet. We found that NMU increases physical activity, energy expenditure, and NEAT in a dose-dependent manner in both DR and DIO rats, both before and after 1 month on the high-fat diet. Before high-fat feeding, the obesity-prone and lean rats showed similar levels of physical activity after intra-PVN microinjections of NMU. After 1 month of the high-fat diet, however, the obesity-resistant rats showed significantly more NMU-induced physical activity compared to the obese DIO rats. Taken together with previous studies, these results suggest that obesity may represent a state associated with decreased central sensitivity to neuropeptides such as NMU that increase physical activity and therefore energy expenditure.

PRIDE for PLAY: Personal Responsibility in Daily Effort for Participation in Lifelong Activity for Youths. A Singaporean Context

Singapore, a developed city state of four million people is experiencing the pitfalls that come with rapid modernisation and economic progress- elevated disease risk factors among adults and young people. Weekly compulsory physical education classes of 70 minutes in schools and the associated sports activities after classes are inadequate to meet emergent physical activity guidelines of a daily accumulation of at least 90 minutes of physical activity of at least moderate intensity. Daily play sessions that are exclusive of an active daily recess, physical education classes taught by trained specialists and after-school sport sessions, can provide many developmental and holistic health benefits that may carry over into adulthood. A school environment that is play-encouraging, play-enabling and play-inviting can be a useful, innovative and natural way of inculcating a love for movement and help redress a serious trend of physical activity insufficiency while youngsters engage electronic gaming activities. Pilot initiatives for the PRIDE (personal responsibility in daily effort) for PLAY (participation in lifelong activity for youths) programme is a radicalised approach in a number of primary schools in Singapore to infuse daily physical play of between 20 to 45 minutes during curriculum hours. The hope is that PRIDE for PLAY will reap benefits of improved holistic health of youngsters- better physical, social, emotional and mental attributes. While PRIDE for PLAY is no panacea to all of the ills of modernisation, it will go some way in helping the students of tomorrow to be physically healthy, socially more engaged and tolerant of others, mentally more apt to problem-solve and emotionally more proficient to embrace working life in adulthood. Key pointsPhysical play is natural among young people and a daily dose of play can help young people meet daily requirements for accumulated physical activity of at least 90 minutes and at least of a moderate intensity.Play is critical for child development and provides a healthy balance for many sedentary lifestyle activities.Parents, care-givers and teachers should emphasise and partake in daily play with young people.

Perceived risk of osteoporosis: restricted physical activities? Qualitative interview study with women in their sixties

OBJECTIVE

To explore elderly women's physical activity in relation to their perception of the risk of osteoporosis.

DESIGN

Qualitative study using in-depth interviews.

SETTING

Informants were purposely selected from a Danish population-based, age-specific cohort study conducted in the county of Copenhagen with people born in 1936.

SUBJECTS

Women in their sixties.

RESULTS

Women who perceived a current risk of osteoporosis tended to reduce their physical activity in an attempt to reduce the risk of bone damage. This behaviour was related to the imagined fragility of the bones (the risk inside the body), and the actual situations (the risk outside the body), including places and activities. Knowledge of a reduced bone mass reinforced the women's uncertainty about what their bones could endure. Experiences managing physical activity without injury resulted in reinterpretations of their risk of bone fractures and increased physical activity.

CONCLUSIONS

Perceived risk of osteoporosis may lead to decreased physical activity and hence actually increase the risk. When informing individuals about health risk people's images and imaginations of the actual risk have to be acknowledged. When a bone scan is being considered, explicit advice encouraging physical activity - especially the weight-bearing kind - should be stressed.

The ecology of childhood overweight: a 12-year longitudinal analysis

OBJECTIVE

To investigate ecological correlates of the development of overweight in a multisite study sample of children followed from age 2 to 12.

DESIGN

Longitudinal examination of covariates of overweight status throughout childhood, with covariates drawn from three ecological levels: sociocultural or demographic, quality of the child's home environment, and proximal child experience that could directly affect the balance between energy intake and energy expenditure.

SUBJECTS

A total of 960 children participating in a long-term longitudinal study provided growth data at least once; 653 of the children had complete data on covariates.

MEASUREMENTS

Height and weight measured seven times between ages 2 and 12 were converted to a body mass index (BMI) and entered into a latent transition analysis to identify patterns of overweight across childhood. Ecological correlates measured longitudinally included demographic characteristics obtained by maternal report, home environment quality obtained by observation and maternal report, and proximal child experience factors obtained by observation, maternal report and child report.

RESULTS

Four patterns of overweight were found: never overweight, overweight beginning at preschool age, overweight beginning in elementary school, and return to normal weight after being overweight at preschool age. The weight status groups differed on home environment quality and proximal child experience factors but not on demographics. Children overweight at preschool had less sensitive mothers than never overweight children. Children overweight at school age had fewer opportunities for productive activity at home than did never overweight children. School-age overweight children also watched the most TV after school. Multivariate logistic regression analyses further indicated the significance to children's weight status of proximal child experience variables. Less physically active children and those who watched more television after school were more likely to become overweight. Results did not vary by child sex.

CONCLUSION

The results support the idea that childhood overweight is multiply determined. The one potentially important and changeable factor identified as a target for intervention centers on how children spend their time, especially their after-school time. Children who are more physically active and spend less time watching TV after school are less likely to become overweight by age 12.

Traditional physical activity indexes derived from the Harvard alumni activity survey have low construct validity in a lower income, urban population

The purpose of this study is to investigate the construct validity of the Harvard Alumni Activity Survey (HAAS) in an urban, lower income population. Data were collected from 192 smokers enrolled in an antioxidant micronutrient trial. Activity data were compared to body mass index (BMI), diastolic, and systolic blood pressure. The traditional physical activity index (PAI), using data on stair climbing, walking, and sports, was calculated including and excluding body mass. A new scale, the total weekly activity (TWA) scale, was derived from other questions on the HAAS. The PAI scale calculated with body mass was unassociated with BMI and blood pressure. The PAI scale calculated without body mass was unassociated with BMI and systolic blood pressure but was associated with diastolic blood pressure (Beta = -0.001, p = 0.03). The TWA scale was associated with BMI (Beta = -0.01, p = 0.01), diastolic (Beta = -0.03, p = 0.01), and systolic blood pressure (Beta = -0.04, p = 0.01). A one standard deviation change in the TWA scale is predicted to be equivalent to a change of 0.99 BMI units, 2.97 mmHg of diastolic blood pressure, and 3.96 mmHg of systolic blood pressure. This work suggests that the TWA scale has greater construct validity than the traditional PAI scale in this population.

Effects of age and gender on physical performance

Our purpose was to examine the effects of age and gender on physical performance. We assessed a one-hour swimming performance and participation of 4,271 presumably healthy men and women, aged 19-91 years, from the 2001-2003 United States Masters Swimming long-distance (1 h) national competition. The decline in performance with increasing age was found to be quadratic rather than linear. The equation which best fit variation in 1 h swimming distance in meters (m) according to variations in age in years (y) in men was: distance (m) = 4058 + 2.18 age-0.29 age (http://www.acsmmsse.org/pt/re/msse/positionstandards.htm;jsessionid=DiRVACC7YS3mq27s5kV3vwpEVSokmmD1ZJLC7pdnol3KcfoSu0t!1096311956!-949856145!9001!-1), with the same equation for women except that 380 m needed to be subtracted from the calculated value at all ages (about a 10% difference). There was a large overlap in performance between men and women. The overall mean decline in performance with age was about 50% and was parallel in men and women. The mean difference in distance for a 1-year increment in age was -9.7 m at 21 y of age, -21.3 m at 40 y, and -44.5 m at 80 y. Far greater declines of about 96% in numbers participating with advanced age (80 y and over, 4% of peak numbers) were observed than in the 40-49 y age group. In conclusion, the declines in performance were parallel in men and women at all ages, and the 1-year age-related declines in performance were about twice as great at 40 y and more than four-times as great at 80 y than at 20 y of age, with even greater age-related declines in participation being noted for both men and women.

Exercise testing and training with the young cystic fibrosis patient

The purpose of the article is to review the literature related to exercise and Cystic fibrosis (CF), with particular focus on the young CF patient. Exercise intolerance is a characteristic of CF, however, recent studies in adults have advanced our understanding of how exercise can be used effectively as a prognostic marker and for rehabilitation purposes. New analyses from exercise testing have shown to have prognostic value, and different methods of exercise training have been reported to improve the functional capacity and quality of life of the young CF patient. There is a growing awareness and belief among clinicians of the benefits of exercise testing and training, however, recent work suggests that exercise is being underused in the healthcare management of the CF patient. More research is needed to identity which exercise tests and training programmes would be most feasible to incorporate into CF centres routine clinical procedures. Key pointsNew methods of health assessment from exercise testing in the young CF patient have shown to have prognostic value.The introduction of new training methods into exercise programmes can improve the functional capacity and quality of life of young patients with CF.Exercise is still being underused in the healthcare management of the CF patient.

Recent advances in free-living physical activity monitoring: a review

It has become clear recently that the epidemic of type 2 diabetes sweeping the globe is associated with decreased levels of physical activity and an increase in obesity. Incorporating appropriate and sufficient physical activity into one's life is an essential component of achieving and maintaining a healthy weight and overall health, especially for those with type II diabetes mellitus. Regular physical activity can have a positive impact by lowering blood glucose, helping the body to be more efficient at using insulin. There are other substantial benefits for patients with diabetes, including prevention of cardiovascular disease, hyperlipidemia, hypertension, and obesity. Several complications of utilizing a self-care treatment methodology involving exercise include (1) patients may not know how much activity that they engage in and (2) health-care providers do not have objective measurements of how much activity their patients perform. However, several technological advances have brought a variety of activity monitoring devices to the market that can address these concerns. Ranging from simple pedometers to multisensor devices, the different technologies offer varying levels of accuracy, comfort, and reliability. The key notion is that by providing feedback to the patient, motivation can be increased and targets can be set and aimed toward. Although these devices are not specific to the treatment of diabetes, the importance of physical activity in treating the disease makes an understanding of these devices important. This article reviews these physical activity monitors and describes the advantages and disadvantages of each.

Predictors of adherence to physical activity in the Lifestyle Interventions and Independence for Elders pilot study (LIFE-P)

OBJECTIVES

A prospective design was used to examine predictors of adherence to a physical activity intervention in older adults with compromised function.

METHODS

The sample included 213 men (31.1%) and women (68.9%) with an average age of 76.53 years.

RESULTS

The predictor variables accounted for 10% of the variance in percent attendance during adoption and transition, respectively. Adding percent attendance during adoption to the prediction of percent attendance during transition increased the explained variance in this phase to 21%. During maintenance, the predictors accounted for 13% of the variance in frequency of physical activity; this estimate increased to 46% when adding in percent attendance from the transition phase.

DISCUSSION

These results are encouraging in that the physical activity intervention appears to have been well tolerated by diverse subgroups of older adults. The role of prior behavior in predicting downstream adherence underscores the importance of developing proactive interventions for treating nonadherence in older adult populations.

Impact of diet, physical activity, lipid status and glycoregulation in estimation of score (systematic coronary risk evaluation) for ten years in postmenopausal women

The incidence of cardiovascular diseases (CVD) in women, although lower than in men, increases dramatically after the menopause. Diabetes mellitus is a more powerful predictor of CHD risk and prognosis in women than in men. The aim of this study was to promote diet and physical activity (PA) regimen in order to decrease coronary risk in next years in postmenopausal women with impaired glucose tolerance. Methodological approach of this research is to compare data gathered trough prospective and retrospective analysis of anamnestic data, clinical research, diagnostic tests and biochemical parameters of 100 examinees, regarding the glycoregulation, lipid status, body mass indexes, incidence of hypertension, uric acid and fibrinogen level. The SCORE (Systematic Coronary Risk Evaluation) assessment system is derived from a large dataset of prospective European studies and predicts any kind of fatal CVD events over a ten-year period. It was documented that the then year risk of fatal CVD exerted a shift toward the lower percent value in postmenopausal women after proposed diet/PA regimen. In pre-menopausal women the estimated ten year risk of fatal CVD by SCORE was shifted toward the level below 1%. The risk of 15% and above was not documented after diet/physical activity regimen. The prevalence of the atherogenic lipid markers at the beginning and the end of the assay decreased for all investigated lipid parameters in the group of pre-menopausal women what was more than in postmenopausal ones. Presented data indicate that dietary regimen and physical activity are crucial factors in CVD prevention throughout menopause and beyond. Behavioral changes aimed at decreasing food intake and increasing energy expenditure, should be implemented in pre-menopausal period of life.

Commercial venues as supports for physical activity in adolescent girls

OBJECTIVE

The purposes of this study were to describe the types and availability of commercial facilities for physical activity (PA) in six diverse geographic areas (Washington DC and Maryland; South Carolina; Minnesota; Louisiana; Arizona; and California) and to assess the relationship between those facilities and the non-school PA of adolescent girls.

METHODS

A total of 1556 6th grade girls participating in the Trial of Activity for Adolescent Girls (TAAG) wore accelerometers for 7 days providing 6 days of complete data, completed questionnaires in 2003 and had their residential addresses geocoded. Nearby commercial facilities available to provide PA (i.e. dance studios, youth organizations) within a 1-mile radius of participants' residences were identified and geocoded. The association between the presence of any commercial PA facility and girls' PA was determined using a multi-level design and controlling for demographic characteristics and other potential confounders. Analyses were conducted in 2005-2006.

RESULTS

Sixty-eight percent of the girls had at least one commercial PA facility near their homes. Availability and types of commercial PA facilities differed by where participants lived. Girls who lived near one or more commercial PA facilities had higher non-school MET-weighted moderate-to-vigorous PA than girls who had none near their homes.

CONCLUSIONS

The findings suggest that commercial PA facilities are important contributors to the accumulation of PA among adolescent girls.

Physical activity in adolescence and smoking in young adulthood: a prospective twin cohort study

AIMS

To control for familial confounds, we studied the association between adolescent physical activity and later smoking in twin siblings discordant for their baseline physical activity.

DESIGN AND MEASUREMENTS

In this prospective population-based twin study, we asked whether persistent physical activity/inactivity in adolescence (assessed at 16, 17 and 18.5 years) predicted questionnaire-reported daily smoking at ages 22-27. Twins who, on the three baseline questionnaires, consistently reported frequent leisure physical activity (more than three times weekly) were classified as persistent exercisers, those who exercised less than three times monthly were called persistently inactive, others were occasional exercisers.

SETTING

Finland.

PARTICIPANTS

A total of 4240 individuals, including 1870 twin pairs. Findings In analyses of individual twins, compared to persistent activity, persistent physical inactivity predicted increased risk of daily smoking (age- and sex-adjusted odds ratio 5.53, 95% confidence interval 3.88-7.88, P < 0.001). The risk remained elevated even after excluding all those who had smoked 50 cigarettes or more life-time at baseline and adjusted for educational level in adolescence. In within-pair analyses compared to the active members of discordant twin pairs, the physically inactive co-twins had increased risk of future daily smoking (sex-adjusted odds ratio 3.39, 95% confidence interval 1.56-7.39, P = 0.002).

CONCLUSIONS

Persistent physical inactivity in adolescence relates to adult smoking, even after familial factors are taken into account.

By your own two feet: factors associated with active transportation in Canada

OBJECTIVE

The purpose of this study is to examine socio-demographic, geographic and physical activity correlates of walking and cycling for non-leisure purposes, i.e., to work, school, or errands, in Canada.

METHODS

Cross-sectional data from the Canadian Community Health Survey (CCHS) 2003 (n = 127,610) were analyzed using logistic regression to identify factors associated with active transportation. The dependent variables were walking 6+ hours per week and any cycling per week. Independent variables were based on age; marital, education, working and immigrant status; income; geographic location; smoking; and other physical activity.

RESULTS

Age and income were associated with both walking and cycling, as was geographic location and other physical activity. The results demonstrated that, while similar, walking and cycling are associated with different factors, and that socio-demographic, geographic and health behaviour variables must be taken into consideration when modelling these transportation modes.

CONCLUSIONS

Although walking and cycling are relatively easy means to incorporate physical activity in daily life, these results suggest that it is the young and the physically active who engage in them. This research points to a need to address barriers among those who could benefit the most from increased use of both modes of travel.

Are students in public high schools in South Africa physically active? Outcome of the 1st South African National Youth Risk Behaviour Survey

BACKGROUND

The first Youth Risk Behaviour Survey in South Africa was carried out to establish the prevalence of key health risk behaviours among high school students. Though physical inactivity is a commonly reported contributory factor to chronic diseases of lifestyle in South Africa, there is no reliable national database on the participation of children and adolescents in physical activity.

METHODS

This cross-sectional national prevalence study among students attending government schools in the nine provinces in South Africa utilized a two-stage cluster sample design. Statistical analysis allowed for clustered sampling, and data collected through self-administered questionnaire were weighted to reflect the underlying student population.

RESULTS

Data of 10,699 participants were analyzed. More than one third (37.5%) of the students engaged in insufficient physical activity. By population group, a significantly lower proportion of white students (29.4%) than black (37.5%) and coloured students (45.6%) engaged in insufficient physical activity. Among those who abstained from participation, 25.9% were unwilling to participate, with significantly fewer white (26.8%) and black (25.1%) students feeling unsafe in their surroundings compared with coloured students (35.3%). Significantly fewer white students (5.6%) had no access to facilities compared to black students (17.0%). White students and students in higher grades reported lower rates of physical education classes at school.

INTERPRETATION

Though the promotion of physical activity and healthy lifestyle is a national priority in South Africa, the survey indicates the need to pay attention to an appreciable proportion of high school students who do not participate sufficiently in physical activity.

Walking age does not explain term versus preterm difference in bone geometry

OBJECTIVE

To elucidate the relationship between bone geometry and onset of walking in former term and preterm children.

STUDY DESIGN

We conducted a cross-sectional study of 128 preschool children aged 3 to 5 years who underwent peripheral quantitative computerized tomography measures of bone size at the distal tibia. Linear models were developed, stratifying by sex, to determine whether bone differences between children born term and preterm were caused by differences in walking age.

RESULTS

Children with a history of preterm birth walked later than children born at term (12.4 +/- 0.5 versus 10.9 +/- 0.2 months; P = .004); however, gestation-corrected walking age (11.4 +/- 0.5 for children born preterm) did not differ. In multiple regression analysis, boys born preterm had larger periosteal and endosteal circumferences and smaller cortical thickness and area than boys born term (least square means, 49.7 +/- 1.3 mm, 43.0 +/- 1.8 mm, 1.1 +/- 0.11 mm, and 49.3 +/- 3.2 mm2 versus 47.0 +/- 0.5 mm, 38.5 +/- 0.7 mm, 1.4 +/- 0.04 mm, and 56.9 +/- 1.2 mm2, respectively; all P < .05). Preterm birth remained statistically significant after adding the age of walking to the models, but no longer significant when current activity levels were included.

CONCLUSION

Greater periosteal and endosteal circumferences, with smaller cortical bone thickness and area, were found in former preterm boys, but not girls, and were explained by differences in current activity levels, not age of walking.

Cancer control through principles of systems science, complexity, and chaos theory: a model

Cancer is a significant medical and societal problem. This reality arises from the fact that an exponential and an unrestricted cellular growth destabilizes human body as a system. From this perspective, cancer is a manifestation of a system-in-failing.A model of normal and abnormal cell cycle oscillations has been developed incorporating systems science, complexity, and chaos theories. Using this model, cancer expresses a failing subsystem and is characterized by a positive exponential growth taking place in the outer edge of chaos. The overall survival of human body as a system is threatened. This model suggests, however, that cancer's exponential cellular growth and disorganized complexity could be controlled through the process of induction of differentiation of cancer stem cells into cells of low and basic functionality. This concept would imply reorientation of current treatment principles from cellular killing (cyto-toxic therapies) to cellular retraining (cyto-education).

Prevalence of cardiovascular disease risk in Ontario adolescents

We assessed traditional cardiovascular disease (CVD) risk factors in 3293 Canadian adolescents (age: 14.1 (SD 0.6) years; body mass index (BMI): 23.0 (SD 6.3)). Prevalence for obesity, borderline hypertension and hyperlipaemia was 23.7% (95% CI 1.5%), 9.1% (95% CI 1.0%) and 9.7% (95% CI 1.0%), respectively, with increased estimates in children with low cardiorespiratory fitness (p<0.05). Participants demonstrated increased CVD risk, highlighting the necessity of placing adolescents in the forefront of preventive CVD programs.

The role of physical activity in the management of impaired glucose tolerance: a systematic review

Although physical activity is widely reported to reduce the risk of type 2 diabetes in individuals with prediabetes, few studies have examined this issue independently of other lifestyle modifications. The aim of this review is to conduct a systematic review of controlled trials to determine the independent effect of exercise on glucose levels and risk of type 2 diabetes in people with prediabetes (IGT and/or IFG). A detailed search of MEDLINE (1966-2006) and EMBASE (1980-2006) found 279 potentially relevant studies, eight of which met the inclusion criteria for this review. All eight studies were controlled trials in individuals with impaired glucose tolerance. Seven studies used a multi-component lifestyle intervention that included exercise, diet and weight loss goals and one used a structured exercise training intervention. Four studies used the incidence of diabetes over the course of the study as an outcome variable and four relied on 2-h plasma glucose as an outcome measure. In the four studies that measured the incidence of diabetes as an outcome, the risk of diabetes was reduced by approximately 50% (range 42-63%); as these studies reported only small changes in physical activity levels, the reduced risk of diabetes is likely to be attributable to factors other than physical activity. In the remaining four studies, only one reported significant improvements in 2-h plasma glucose even though all but one reported small to moderate increases in maximal oxygen uptake. These results indicate that the contribution of physical activity independent of dietary or weight loss changes to the prevention of type 2 diabetes in people with prediabetes is equivocal.

Obesity prevention and the primary care pediatrician's office

PURPOSE OF REVIEW

The obesity epidemic confronts the pediatrician every day in the office. Pediatricians should help curb the epidemic through prevention and the usual pediatric primary care tasks of screening, communication and anticipatory counseling. This review highlights findings from recent literature to guide office-based prevention of obesity in children.

RECENT FINDINGS

More and more, children and society feel the effects of the obesity epidemic; prevention efforts need to begin earlier. Pediatricians' efforts to screen help identify at-risk children who may benefit from early lifestyle changes. The identification of overweight children also helps foster the appropriate work up of comorbidities. Pediatricians' communication of weight trajectories, which includes techniques like motivational interviewing, may help parents to adopt behavioral prescriptions. Pediatricians should focus on promoting breastfeeding, limiting television, increasing physical activity and reducing sugar-sweetened beverages. New tools used in the training setting show promising results.

SUMMARY

Pediatricians must focus efforts on preventing childhood overweight, while awaiting effective treatment options for this chronic illness with its many associated morbidities. Such prevention involves sensitively communicating early body mass index screening results to parents and helping them to adopt key behavioral changes in diet and physical activity.

Impact of hepatitis C virus infection on lifestyle

AIM

To evaluate the impact of the diagnosis of hepatitis C infection on lifestyle habits such as smoking, drinking, sports activity and diet.

METHODS

A self-administered, anonymous questionnaire was offered to out-patients with HCV infection consecutively attending three clinical centres in Italy.

RESULTS

Of the 275 respondents, 62.2% (171) were male. Mean age was 51 (range 20-80) years. Overall, after the diagnosis of hepatitis C, 74.5% of drinkers had modified (giving up or reducing) alcohol consumption, 21.3% of smokers had modified their habits and 32.3% of subjects who reported sports activity had either stopped or reduced frequency of activity or chose a less fatiguing sport. Sixty-four percent of the respondents reported having modified their diet, most of them on physician's advice.

CONCLUSION

After the diagnosis of hepatitis C many patients correctly modified their alcohol consumption and a minority their smoking habits. The reason for reported changes in diet and physical activity needs further investigations.

Comparing perceived and objectively measured access to recreational facilities as predictors of physical activity in adolescent girls

A number of studies in recent years have identified both self-report and objectively measured accessibility of recreational facilities as important predictors of physical activity in youth. Yet, few studies have: (1) examined the relationship between the number and proximity of objectively measured neighborhood physical activity facilities and respondents' perceptions and (2) compared objective and self-report measures as predictors of physical activity. This study uses data on 1,367 6th-grade girls who participated in the Trial of Activity for Adolescent Girls (TAAG) to explore these issues. Girls reported whether nine different types of recreational facilities were easily accessible. These facilities included basketball courts, golf courses, martial arts studios, playing fields, tracks, skating rinks, swimming pools, tennis courts, and dance/gymnastic clubs. Next, geographic information systems (GIS) were used to identify all the parks, schools, and commercial sites for physical activity located within a mile of each girl's home. These sites were then visited to inventory the types of facilities available. Girls wore accelerometers to measure their weekly minutes of non-school metabolic equivalent weighted moderate-to-vigorous physical activity (MW-MVPA). The number of facilities within a half-mile of girls' homes strongly predicted the perception of easy access to seven out of nine facility types. Both individual facility perceptions and the total number of facilities perceived were associated with increased physical activity. For each additional facility perceived, girls clocked 3% more metabolic equivalent weighted moderate-to-vigorous physical activity (p < 0.001). Although girls tended to record 3% more of this kind of physical activity (p < 0.05) per basketball court within a mile of their homes, objective facility measures were otherwise unrelated to physical activity. The results from this study suggest that raising the profile of existing facilities may help increase physical activity among adolescent girls.

Physical activity and breast cancer risk among women in the southwestern United States

Physical activity may influence breast cancer risk through multiple mechanisms and at different periods in life. In this study we evaluate breast cancer risk associated with total and vigorous physical activity at ages 15, 30, and 50 years and the referent year prior to diagnosis/selection. Participants were non-Hispanic white (NHW) (1527 cases and 1601 control subjects) and Hispanic/American Indian (HAI) (798 cases and 924 controls) women. Both total and vigorous activity reduced risk of breast cancer in a dose-response manner. Among premenopausal women, only high total metabolic equivalent of the task (MET) hours of activity during the referent year was associated with reduced breast cancer risk in NHW women (odds ratio [OR] 0.62; 95% confidence interval [CI] 0.43, 0.91). Among postmenopausal women, physical activity had the greatest influence among women not recently exposed to hormones. Among these women, high total lifetime activity reduced risk of breast cancer for both NHW (OR 0.60; 95% CI 0.36, 1.02; p trend 0.01) and HAI women (OR 0.52; 95% CI 0.23, 1.16; p trend 0.07). Additionally, high total MET hours of activity at age 30 years (OR 0.56; 95% CI 0.37, 0.85) and at age 15 years (OR 0.57; 95% CI 0.38, 0.88) reduced breast cancer risk among postmenopausal NHW women not recently exposed to hormones. Among HAI women, more recent activity performed during the referent year and at age 50 appeared to have the greatest influence on breast cancer risk. Among postmenopausal NHW women. there was a significant interaction between physical activity and hormone replacement therapy (p value, 0.01), while among postmenopausal HAI women, physical activity interacted with body mass index (p value, 0.04). These data suggest that physical activity is important in reducing risk of breast cancer in both NHW and HAI women.

Associations of androgens with physical activity and fitness in young black and white men: the CARDIA Male Hormone Study

OBJECTIVE

The association between physical activity or cardiovascular fitness and chronic disease risk in men might be mediated, in part, through androgens. Limited data exists on the potential associations of activity or fitness with serum hormones. We examined the associations of serum testosterone and sex hormone binding globulin (SHBG) concentrations with physical activity and cardiorespiratory fitness in black and white young men.

METHOD

Data were collected from 391 black and 604 white male participants of the Coronary Artery Risk Development in (Young) Adults (CARDIA) Male Hormone Study aged 24-32 in 1992-1993. Cross-sectional associations of serum total testosterone (TT), bioavailable testosterone (BT) and SHBG levels with self-reported total physical activity score, and in a subset of men (n=617) with cardiorespiratory fitness measured via duration on a treadmill test were assessed. Five-year longitudinal associations of change in hormones with changes in physical activity also were examined.

RESULTS

There were no cross-sectional or longitudinal associations of physical activity with SHBG, TT or BT in either black or white men. Fitness was positively associated with SHBG only in white men, but was not associated with TT or BT in either group.

CONCLUSION

Overall the results do not support an association of self-reported physical activity with androgens, whereas they do suggest that fitness might be associated with SHBG in white men.

Weekend schoolyard accessibility, physical activity, and obesity: the Trial of Activity in Adolescent Girls (TAAG) study

OBJECTIVES

To assess the accessibility and suitability of schools as recreational sites and to determine whether they are associated with young adolescent girls' weekend metabolic equivalent-weighted moderate-to-vigorous physical activity and body mass index (BMI).

METHODS

We drew a half-mile (0.805 km) radius around the residences of participants in the Trial of Activity for Adolescent Girls (n=1556) in Maryland, South Carolina, Minnesota, Louisiana, California, and Arizona. We visited all schools and parks within the defined distance and documented their amenities and accessibility on Saturdays in Spring 2003. Staff gathered data on each girls' height and weight and used accelerometers to record weekend metabolic equivalent-weighted moderate-to-vigorous physical activity.

RESULTS

Schools represented 44% of potential neighborhood sites for physical activity. However, a third of schools were inaccessible on the Saturday we visited. Neighborhoods with locked schools were primarily non-white, older, more densely populated, and of lower socioeconomic status. Though there was no relationship between school accessibility on Saturdays and weekend metabolic equivalent-weighted moderate-to-vigorous physical activity, the number of locked schools was associated with significantly higher body mass index.

CONCLUSIONS

The lack of relationship between metabolic equivalent-weighted moderate-to-vigorous physical activity and school accessibility may imply that young adolescent girls do not identify schools as recreational resources. However, due to the association between body mass index and locked schools, efforts to stem the obesity epidemic should include making schools more accessible.

Seasonal variation in leisure-time physical activity among Canadians

BACKGROUND

Cardiovascular disease (CVD) mortality is higher in winter than summer, particularly in cold climates. Physical activity reduces CVD risk but climate impacts participation in physical activity. Canada has substantial climatic variation but its relation with physical activity is understudied. In this investigation, we evaluated the relation between seasonality and physical activity among Canadians.

METHODS

We used public domain data from the Canadian Community Health Survey, Cycle 2.2 (CCHS 2.2), a representative, cross-sectional sample of free-living Canadians in 2004. Leisure-time physical activity was measured using a modified version of the Physical Activity Monitor that was validated. Season was determined by the time of the interview, i.e., Winter: January 1 to March 31, Spring: April 1 to June 30, Summer: July 1 to September 30, and Fall: October 1 to December 31. In all multivariate models, we adjusted for age, sex, education, and income adequacy.

RESULTS

There were 20,197 persons aged 19 years and older in this analysis. In the winter, 64% of Canadians were inactive as compared with 49% in the summer. Total average daily energy expenditure was 31.0% higher in summer than winter after multivariate adjustment. Leisure-time physical activity was 86% more likely in the summer than winter (multivariate OR = 1.86, 95% CI 1.40, 2.45). The relation between seasonality and physical activity was weakest in Newfoundland and Labrador and stronger in Saskatchewan and British Columbia (p-value for interaction = 0.02).

INTERPRETATION

Seasonality impacts physical activity patterns in Canada and varies across the provinces. This needs to be considered in physical activity programming.

Exploring associations between physical activity and perceived and objective measures of the built environment

The built environment may be responsible for making nonmotorized transportation inconvenient, resulting in declines in physical activity. However, few studies have assessed both the perceived and objectively measured environment in association with physical activity outcomes. The purpose of this study was to describe the associations between perceptions and objective measures of the built environment and their associations with leisure, walking, and transportation activity. Perception of the environment was assessed from responses to 1,270 telephone surveys conducted in Forsyth County, NC and Jackson, MS from January to July 2003. Participants were asked if high-speed cars, heavy traffic, and lack of crosswalks or sidewalks were problems in their neighborhood or barriers to physical activity. They were also asked if there are places to walk to instead of driving in their neighborhood. Speed, volume, and street connectivity were assessed using Geographic Information Systems (GIS) for both study areas. Locations of crashes were measured using GIS for the NC study area as well. Objective and perceived measures of the built environment were in poor agreement as calculated by kappa coefficients. Few associations were found between any of the physical activity outcomes and perception of speed, volume, or presence of sidewalks as problems in the neighborhood or as barriers to physical activity in regression analyses. Associations between perceptions of having places to walk to and presence of crosswalks differed between study sites. Several associations were found between objective measures of traffic volume, traffic speed, and crashes with leisure, walking, and transportation activity in Forsyth County, NC; however, in Jackson, MS, only traffic volume was associated with any of the physical activity outcomes. When both objective and perceived measures of the built environment were combined into the same model, we observed independent associations with physical activity; thus, we feel that evaluating both objective and perceived measures of the built environment may be necessary when examining the relationship between the built environment and physical activity.

Determining cardiovascular disease risk in elementary school children: developing a healthy heart score

At least 50% of children have one or more cardiovascular disease (CVD) risk factor. We aimed to 1) determine the prevalence of CVD risk factors in a sample of Canadian children, and 2) create a Healthy Heart Score that could be used in a school setting, to identify children with a greater number and severity of CVD risk factors. Children (n = 242, 122M, 120F, aged 9-11 years) were assessed for cardiovascular fitness, physical activity, systolic/diastolic blood pressure, and body mass index (BMI). Biological values were converted to age and sex specific percentiles and allocated a score. Healthy Heart Scores could range between 5 and 18, with lower scores suggesting a healthier cardiovascular profile. Seventy-seven children volunteered for blood samples in order to assess the relationship between the Healthy Heart Score and (total cholesterol (TC), high and low-density lipoprotein cholesterol (HDL, LDL) and triglycerides (TG). Fifty eight percent of children had elevated scores for at least 1 risk factor. The group mean Healthy Heart Score was 8 (2.2). The mean score was significantly higher in boys (9 (2.2)) compared with girls (8 (2.1), p < 0.01). A high score was significantly associated with a low serum HDL, a high TC:HDL and a high TG concentration. Our results support other studies showing a high prevalence of CVD risk factors in children. Our method of allocation of risk score, according to percentile, allows for creation of an age and sex specific CVD risk profile in children, which takes into account the severity of the elevated risk factor. Key pointsThere was a high incidence of elevated risk factors for cardiovascular disease in Canadian elementary school children.Physical fitness and physical activity levels were particularly low.In this cohort, boys had increased levels of cardiovascular disease risk factors compared with age-matched girls.

The role of physician counseling in improving adherence to physical activity among the general population

The regular practice of physical activity at appropriate levels ensures various benefits for the individual over the short, medium and long terms. It is therefore important in health promotion. On the other hand, sedentary behavior has reached alarming levels among the general population, which qualifies it as a serious health problem of endemic proportions. The present review describes public health problems consequent to sedentary behavior and the importance of physician counseling for change their patients behavior and making them more physically active on a regular basis. Models and behavioral theories are presented to facilitate physicians understanding of how to approach patients during clinical practice. We also describe programs conducted in many countries based on physician counseling for reducing sedentary behavior, and we present many tools used to quantify and qualify patients attitudes towards becoming more physically active. Through understanding the barriers faced by patients, we suggest methodologies that will enable physicians to use physical activity promotion appropriately. We hope that this will provide support for physicians in conducting physical activity counseling, as a means for improving the health of the population.

Effect of nutrition and physical activity on bone health of children and young adults

The development and maturation of the skeletal system starts in utero. The bone-growth process starts with the addition of cells; these cells grow and incorporate materials that increase bone strength. During puberty, this process is accelerated to the degree that approximately 25% of the total bone mass is accumulated. Failure to meet the increased demand for bone-building materials during an accelerated growth period may increase fracture tendency. The greater is the bone mass at the start of puberty; the better is the final outcome at full maturity. This is in accordance with the tracking theory (keeping bone growth along a steady percentile). Nutrition and physical activity will facilitate bone accumulation from an early age. Therefore, a program for bone health that includes physical activity and nutrition should be introduced early in the prepubertal age. There are differences in the timing and rate of bone-mass accumulation of different parts of the skeleton so that measurement of one bone may not represent the whole skeleton. In addition, bone measurements using different devices cannot be compared. Therefore, until a universal standard is reached, repeated measurements of one individual should be done using the same apparatus. The choice of the apparatus should be made so that the relevant part of the skeleton is measured. Repeated measurements of bone may detect bone mass loss much earlier than the osteoporosis line is reached. This suggests that a dynamic measure of bone growth rate similar to height velocity should be adopted, since both parameters in an optimal setting follow a steady percentile and falling of the percentile in both parameters needs an etiological diagnosis.

Longitudinal relationship between television viewing and leisure-time physical activity during adolescence

OBJECTIVE

The goal was to examine the longitudinal associations of changes in television viewing and other sources of sedentary behavior with changes in leisure-time moderate/vigorous physical activity in adolescence.

METHODS

We studied a cohort of 6369 girls and 4487 boys who were 10 to 15 years of age in 1997. During each of 4 years of follow-up assessments, participants self-reported their weekly hours of television viewing. By using a seasonal questionnaire, we also obtained detailed information on physical activities over the previous year, from which we calculated total leisure-time moderate/vigorous physical activity. We performed linear regression analyses to assess the longitudinal associations between 1-year changes in television viewing and 1-year changes in leisure-time moderate/vigorous physical activity during the same year, using data from 1997 through 2001.

RESULTS

One-year changes (mean +/- SD) were -0.13 +/- 7.2 hours/week for leisure-time moderate/vigorous physical activity, -0.55 +/- 7.0 hours/week for television viewing, and -1.02 +/- 11.0 hours/week for total sedentary behaviors. In longitudinal models adjusted for age, age2, gender, race/ethnicity, Tanner stage, menarche (in girls), baseline physical activity, and baseline television viewing, we found no substantive relationship between year-to-year changes in television viewing and changes in leisure-time moderate/vigorous physical activity (0.03 hours/week, for each 1-hour/week change in television viewing). There were no material associations in age or gender subgroups.

CONCLUSIONS

In this longitudinal study, changes in television viewing were not associated with changes in leisure-time moderate/vigorous physical activity. Our findings suggest that television viewing and leisure-time physical activity are separate constructs, not functional opposites.

Family support for physical activity in girls from 8th to 12th grade in South Carolina

OBJECTIVE

To examine the relationship between perceived family support and other selected correlates of physical activity (PA) with changes in PA over time.

METHODS

A total of 421 girls in South Carolina completed questionnaires at 8th, 9th and 12th grades (1998-2003). Family support for PA, PA self-efficacy, perceived behavioral control, attitudes, availability of equipment, and PA were measured.

RESULTS

Growth curve analysis showed that family support, perceived behavioral control, and self-efficacy were independently related to age-related changes in PA as reflected by total METs. Girls who reported lower family support at the 8th grade measure had more rapid declines in PA, and a unit change in family support was related to approximately 1/3 of a standard deviation change in total METs.

CONCLUSIONS

Maintenance of support from family members may reduce the decline in PA independent of girls' self-efficacy and perceived behavioral control.

Policies and opportunities for physical activity in middle school environments

BACKGROUND

This study examined physical activity opportunities and barriers at 36 geographically diverse middle schools participating in the Trial of Activity for Adolescent Girls.

METHODS

Principals, physical education and health education department heads, and program leaders were interviewed to assess policies and instructional practices that support physical activity.

RESULTS

Schools provided approximately 110 hours per year in physical education instruction. Approximately 20% of students walked or bicycled to school. Eighty-three percent of schools offered interscholastic sports and 69% offered intramural sports. Most schools offered programs for girls, but on average, only 24 girls ( approximately 5%) in the schools attended any programs. Only 25% of schools allowed after school free play. An overall score created to assess school environmental support for physical activity indicated that, on average, schools met 6.7 items of 10 items. Free/reduced lunch program participation versus not (p = .04), perceived priority of physical education instruction over coaching (p = .02), and safety for walking/bicycling to school (p = .02) predicted environmental support score.

CONCLUSIONS

Schools have policies and practices that support physical activity, although unfavorable practices exist. Schools must work with community partners and officials to provide environments that optimally support physical activity, especially schools that serve low-income students.

Determining physical activity patterns of suburban British Columbia residents

BACKGROUND

Physical activity is well recognized for its role in disease prevention. Public health surveillance and action is warranted to combat the escalating economic and human costs associated with physical inactivity.

METHODS

This study examined the proportion of the population who were physically active at intensities, durations and frequencies specified as the minimum to accrue health benefit as per Canada's Physical Activity Guidelines. Data were collected from 769 suburban residents via a telephone survey, and analyzed using three methods: Individual Assessment (IA) where individuals met the required frequency, intensity and duration through a combination of activities; Categorical Assessment (CA) where individuals met the required frequency, intensity and duration in one or more categories leading to duplicated head-counts; and, Time-based Assessment (TA) where individuals met the required time per week (recommended frequency x duration) in a category through some combination of activity. Z-scores were used to test the null hypothesis that the proportion of people meeting the criteria in more than one category was zero.

RESULTS

The number of people meeting the guidelines in more than one category (CA) is significantly different (p < 0.01) from zero for adults and the combined population, but not for children. Enough people are meeting the guidelines in more than one category to significantly influence the percentage calculated if one is not careful to avoid counting duplicates. Furthermore, significant differences were found between IA and TA for children, adults and the combined population with the time-based assessment significantly over-predicting the IA results.

INTERPRETATION

While 75% of the respondents reported they had been physically active during the previous week, only 39% of respondents reported enough physical activity to meet the guidelines for health benefits. This number varies widely depending on the method of classification. Canadians should be reminded of the physical activity guidelines by their health care providers to insure that those who are active are active frequently enough to accrue health benefit.

Visceral abdominal fat is correlated with whole-body fat and physical activity among 8-y-old children at risk of obesity

BACKGROUND

Abdominal fat is more related to health risk than is whole-body fat. Determining the factors related to children's visceral fat could result in interventions to improve child health.

OBJECTIVE

Given the effects of physical activity on adults' visceral fat, it was hypothesized that, after accounting for whole-body fat, physical activity would be inversely related to children's visceral (VAT), but not to subcutaneous (SAT), abdominal adipose tissue.

DESIGN

In this cross-sectional observational study conducted in forty-two 8-y-old children (21 boys, 21 girls) at risk of obesity [>75th body mass index (BMI) percentile, with at least one overweight parent], familial factors (eg, maternal BMI), historic weight-related factors (eg, birth weight), and the children's current physical activity (self-reported and measured with accelerometry) and diet were examined as potential correlates of the children's whole-body composition (measured with BMI and dual-energy X-ray absorptiometry) and abdominal fat distribution (measured by magnetic resonance imaging).

RESULTS

Accelerometer-measured physical activity was related to whole-body fat (r = -0.32, P < 0.10), SAT (r = -0.29, P < 0.10), and VAT (r = -0.43, P < 0.05). In regression models, whole-body fat was positively associated with and the only significant correlate of SAT. Whole-body fat was positively related and accelerometer-measured physical activity was negatively and independently related to the children's VAT.

CONCLUSIONS

Both SAT and VAT in 8-y-old children at risk of obesity are most closely associated with whole-body fat. However, after control for whole-body fat, greater physical activity is only associated with lower VAT, not SAT, in these children.

Assessment of female participation in an employee 20-week walking incentive program at Marshfield Clinic: a large multispecialty group practice

OBJECTIVE

We evaluated the short-term effect of a worksite-based walking incentive program to promote physical activity and well-being in employees of a private healthcare clinic.

DESIGN

A prospective, observational follow-up study.

SETTING

The study was conducted at Marshfield Clinic, a large private multispecialty group practice healthcare institution in Marshfield,Wisconsin, USA.

PATIENTS

Subjects for this study were Marshfield Clinic physicians and staff.

METHODS

From March 31, 2005 to August 20, 2005, physical activity level, body mass index (BMI) and other well-being characteristics were observed pre- and post-program among 191 female participants from the Marshfield Clinic. A brief Web site-accessible, self-reported survey assessed the effectiveness of the exercise program.

RESULTS

Our data show a statistically significant (p <0.0001) increase in participants' physical activity level, while a significant (p = 0.021) decrease in mean BMI was observed. However, there was no evidence of our incentive program reducing participants' blood pressure.

CONCLUSION

Preliminary findings of our study suggest that the goal of worksite programs designed to support employees in their efforts to improve or maintain their level of wellness is potentially achievable. Continuing research is needed to further assess whether persistent health benefits can be induced by worksite wellness programs.

Epidemiology of exercise and sleep

Although exercise is widely believed to improve sleep, experimental evidence has found acute and chronic exercise to exert only modest effects on subsequent sleep. However, these studies are limited in that they have primarily used good sleepers (floor/ceiling effects). In contrast to experimental studies, epidemiologic studies have consistently reported significant positive associations between self-reported exercise habits and better self-reported sleep. This association has been confirmed across a wide range of demographics. Nonetheless, epidemiologic studies on this topic have also had limitations. They have often assessed exercise and sleep using instruments of dubious validity. Moreover, the studies have generally not included clinical diagnoses of sleep disorders. Thus, the clinical relevance of these findings is unclear. In addition, possible alternative explanations for the association of exercise and improved sleep have often not been controlled (e.g. bright light, other healthy behaviors). This review will focus on these epidemiologic studies. We will review and critique representative survey and epidemiologic studies of exercise and sleep and discuss directions for future research in this area.