Independent and combined effects of physical activity and body mass index on the development of Type 2 Diabetes - a meta-analysis of 9 prospective cohort studies.

BACKGROUND: The aim of this harmonized meta-analysis was to examine the independent and combined effects of physical activity and BMI on the incidence of type 2 diabetes. METHODS: Our systematic literature review in 2011 identified 127 potentially relevant prospective studies of which 9 fulfilled the inclusion criteria (total N = 117,878, 56.2 % female, mean age = 50.0 years, range = 25-65 years). Measures of baseline physical activity (low, intermediate, high), BMI-category [BMI < 18.4 (underweight), 18.5-24.9 (normal weight), 25.0-29.9 (overweight), 30+ (obese)] and incident type 2 diabetes were harmonized across studies. The associations between physical activity, BMI and incident type 2 diabetes were analyzed using Cox regression with a standardized analysis protocol including adjustments for age, gender, educational level, and smoking. Hazard ratios from individual studies were combined in a random-effects meta-analysis. RESULTS: Mean follow-up time was 9.1 years. A total of 11,237 incident type 2 diabetes cases were recorded. In mutually adjusted models, being overweight or obese (compared with normal weight) and having low physical activity (compared with high physical activity) were associated with an increased risk of incident type 2 diabetes (hazard ratios 2.33, 95 % CI 1.95-2.78; 6.10, 95 % CI: 4.63-8.04, and 1.23, 95 % CI: 1.09-1.39, respectively). Individuals who were both obese and had low physical activity had 7.4-fold (95 % CI 3.47-15.89) increased risk of type 2 diabetes compared with normal weight, high physically active participants. CONCLUSIONS: This harmonized meta-analysis shows the importance of maintaining a healthy weight and being physically active in diabetes prevention.

An Evaluation of the My ParticipACTION Campaign to Increase Self-Efficacy for Being More Physically Active.

The objective of the My ParticipACTION campaign was to inspire Canadian adults to increase their physical activity through messaging that was relevant, engaging, and designed to build self-efficacy to be more active. This research examined the communication effects of the campaign according to the a priori Hierarchy of Effects Model (saliency → cognitive engagement → self-efficacy to become more active → trial behavior) and investigated how these effects related to overall self-efficacy for physical activity, intention to be active, and current activity level. Participants (N = 1,110) were recruited from an existing panel of Canadian adults 18 years and older and completed a short online questionnaire about the potential communication effects. Logistic regression models were constructed to test the communication effects adjusting for age, gender, and education. The relations were consistent with those hypothesized in the model. In addition, some earlier outcomes in the sequence of effects were associated with other outcomes further down the progression. When intention to be active was included, the initial relation between ad-specific self-efficacy and current physical activity disappeared. This analysis suggested that the campaign was successful in increasing self-efficacy to be more active and that using the Hierarchy of Effects Model was useful in guiding the design of campaign messages and assessing communication effects. Given the limited amount of theoretical testing of the Hierarchy of Effects Model, future research employing longitudinal designs is required to further confirm the communication effects of such an intervention and further test the model.

The pandemic of physical inactivity: global action for public health.

Physical inactivity is the fourth leading cause of death worldwide. We summarise present global efforts to counteract this problem and point the way forward to address the pandemic of physical inactivity. Although evidence for the benefits of physical activity for health has been available since the 1950s, promotion to improve the health of populations has lagged in relation to the available evidence and has only recently developed an identifiable infrastructure, including efforts in planning, policy, leadership and advocacy, workforce training and development, and monitoring and surveillance. The reasons for this late start are myriad, multifactorial, and complex. This infrastructure should continue to be formed, intersectoral approaches are essential to advance, and advocacy remains a key pillar. Although there is a need to build global capacity based on the present foundations, a systems approach that focuses on populations and the complex interactions among the correlates of physical inactivity, rather than solely a behavioural science approach focusing on individuals, is the way forward to increase physical activity worldwide.

ParticipACTION: awareness of the participACTION campaign among Canadian adults--examining the knowledge gap hypothesis and a hierarchy-of-effects model.

BACKGROUND: ParticipACTION was a pervasive communication campaign that promoted physical activity in the Canadian population for three decades. According to McGuire's hierarchy-of-effects model (HOEM), this campaign should influence physical activity through intermediate mediators such as beliefs and intention. Also, when such media campaigns occur, knowledge gaps often develop within the population about the messages being conveyed. The purposes of this study were to (a) determine the current awareness of ParticipACTION campaigns among Canadians; (b) confirm if awareness of the ParticipACTION initiative varied as a function of levels of education and household income; and, (c) to examine whether awareness of ParticipACTION was associated with physical activity related beliefs, intentions, and leisure-time physical activity (LTPA) as suggested by the HOEM. Specifically, we tested a model including awareness of ParticipACTION (unprompted, prompted), outcome expectations, self-efficacy, intention, and physical activity status. METHODS: A population-based survey was conducted on 4,650 Canadians over a period of 6 months from August, 2007 to February, 2008 (response rate = 49%). The survey consisted of a set of additional questions on the 2007 Physical Activity Monitor (PAM). Our module on the PAM included questions related to awareness and knowledge of ParticipACTION. Weighted logistic models were constructed to test the knowledge gap hypotheses and to examine whether awareness was associated with physical activity related beliefs (i.e., outcome expectations, self-efficacy), intention, and LTPA. All analyses included those respondents who were 20 years of age and older in 2007/2008 (N = 4424). RESULTS: Approximately 8% of Canadians were still aware of ParticipACTION unprompted and 82% were aware when prompted. Both education and income were significant correlates of awareness among Canadians. The odds of people being aware of ParticipACTION were greater if they were more educated and reported higher income. Awareness of ParticipACTION was also associated with outcome expectations, self-efficacy, intention, and LTPA status. CONCLUSION: Awareness of ParticipACTION is associated with LTPA. Knowledge gaps in awareness are associated with level of education and household income. Thus, future promotion campaigns should include specific strategies to target different segments of the population, especially people who are living in deprived conditions with lower levels of education.

Individual, social, environmental, and physical environmental correlates with physical activity among Canadians: a cross-sectional study.

BACKGROUND: The identification of various individual, social and physical environmental factors affecting physical activity (PA) behavior in Canada can help in the development of more tailored intervention strategies for promoting higher PA levels in Canada. This study examined the influences of various individual, social and physical environmental factors on PA participation by gender, age and socioeconomic status, using data from the 2002 nationwide survey of the Physical Activity Monitor. METHODS: In 2002, 5,167 Canadians aged 15-79 years, selected by random-digit dialling from household-based telephone exchanges, completed a telephone survey. The short version of the International Physical Activity Questionnaire was used to collect information on total physical activity. The effects of socio-economical status, self-rated health, self-efficacy, intention, perceived barriers to PA, health benefits of PA, social support, and facility availability on PA level were examined by multiple logistic regression analyses. RESULTS: Self-efficacy and intention were the strongest correlates and had the greatest effect on PA. Family income, self-rated health and perceived barriers were also consistently associated with PA. The effects of the perceived health benefits, education and family income were more salient to older people, whereas the influence of education was more important to women and the influence of perceived barriers was more salient to women and younger people. Facility availability was more strongly associated with PA among people with a university degree than among people with a lower education level. However, social support was not significantly related to PA in any subgroup. CONCLUSION: This study suggests that PA promotion strategies should be tailored to enhance people's confidence to engage in PA, motivate people to be more active, educate people on PA's health benefits and reduce barriers, as well as target different factors for men and women and for differing socio-economic and demographic groups.

Association between neighborhood active living potential and walking.

This paper examines the association between neighborhood active living potential and walking among middle-aged and older adults. A sample of 2,614 (61.1% women) persons aged 45 years or older and living in one of 112 census tracts in Montreal, Canada, were recruited between February and May of 2005 to participate in a 20-minute telephone survey. Data were linked to observational data on neighborhood active living potential in the 112 census tracts and analyzed through multilevel modeling. Greater density of destinations in the census tract was associated with greater likelihoods of walking for any reason at least 5 days per week for at least 30 minutes (odds ratio = 1.53, 95% confidence interval: 1.21, 1.94). Associations were attenuated but remained statistically significant after controlling for socioeconomic, health, lifestyle, and other physical activity characteristics. Sensitivity analyses showed that associations were robust across smaller and larger volumes of walking. No associations were found between dimensions of neighborhood active living potential and walking for recreational reasons. The authors conclude that a larger number and variety of neighborhood destinations in one's residential environment are associated with more walking and possibly more utilitarian walking among middle-aged or older adults.

Physical activity guidelines and guides for Canadians: facts and future.

This article summarizes the main findings from the papers included in this journal supplement. It consolidates the evidence currently available to inform and advance the development of physical activity guidelines for Canadians, and it highlights the specific needs of various population subgroups. The challenges of translating guideline information into effective and persuasive physical activity messages, of campaigns to disseminate messages, and of related evaluations are underlined. Recommendations on how to proceed are based on the evidence base provided by this series of papers; the immediate next steps mandated by this initiative are outlined and priorities for future research are indicated.

From walkability to active living potential: an "ecometric" validation study.

BACKGROUND: The purpose of this paper is to establish the reliability and validity of a neighborhood-level measure of active living potential by applying principles of ecometrics. METHODS: Following a 3-day training session, observers (n =8) were provided with a map of a predetermined walking route constructed through the joining of ten randomly selected street blocks. Then, using an 18-item observation grid, pairs of observers performed ratings of 112 neighborhoods. Resulting observations produced a hierarchically structured data set including 4032 observations nested within observers, which in turn were nested within neighborhoods. Data from the 2001 Canadian census were linked to the neighborhood data. RESULTS: Application of ecometric multilevel modeling analyses showed that once interitem and interobserver variability were statistically controlled, about one third of the variability in observations were at the between-neighborhood level. Reliability estimates were 0.78 for items measuring activity-friendliness, 0.76 for safety, and 0.83 for density of destinations. Assessment of the convergent validity of the instrument identified that safety of the environment was positively associated with neighborhood affluence. Density of destinations was negatively associated with affluence and positively associated with higher proportions of persons in the neighborhood walking to work. CONCLUSIONS: The three dimensions of the neighborhood active-living potential measure have good reliability and convergent validity and are able to capture between neighborhood differences. Measurement characteristics would have been difficult to ascertain without the ecometrics methodology.

Reliability and validity of Canada's Physical Activity Monitor for assessing trends.

PURPOSE: This investigation assessed the reliability and criterion validity of the Physical Activity Monitor, a telephone-interview adaptation of the Minnesota Leisure Time Physical Activity Questionnaire (MLTPAQ), which is currently used to assess trends in the Canadian population. METHODS: A sample of 512 people aged 18 yr and older was selected by random-digit dialing for telephone interviewing in the reliability study. The Monitor questions were administered twice, 3 wk apart. For the criterion validity study, a sample of 148 people aged 18-69 yr was selected at random from households. Participants completed the Monitor questions by telephone and an in-home step test to estimate maximum oxygen uptake. Another random sample of individuals aged 18-69 yr participated in a comparison study of the Monitor against the 1988 Campbell's Survey of Well-Being (CSWB) instrument. All studies were conducted in the vicinity of Toronto, Ontario. Spearman correlations controlling for age and sex were calculated as a measure of association for the reliability, validity, and comparison studies. Validity estimates were further adjusted for body mass index and physical activity demands of work and chores. RESULTS: The Monitor instrument produced reliable estimates of total energy expenditure (P=0.90, P<0.0001) with criterion validity of 0.36 (P<0.0001). The association between estimates of total energy expenditure derived from the Monitor and CSWB instruments was 0.77 (P<0.0001). CONCLUSION: The Physical Activity Monitor has acceptable test-retest reliability and criterion validity. The research also demonstrated that for the purpose of population monitoring a change in data collection mode-telephone interview versus self-administration in households-can yield reasonably comparable estimates from two adaptations of the MLTPAQ.

Evolution and devolution of national physical activity policy in Canada.

BACKGROUND: Low levels of physical activity (PA) and fitness have long been a government concern in Canada; however, more than half of adults are inactive. This article examines factors influencing policy development and implementation using Canadian PA policy as a case study. METHODS: Current and historical PA policy documents were amassed from a literature review, audit of government and non government websites and from requests to government officials in each jurisdiction directly responsible for PA. These were analyzed to determine policy content, results, barriers, and success factors. RESULTS: The national focus for PA policy in Canada has devolved to a multilevel system that meets most established criteria for successful strategies. Earlier PA targets have been met; however, the prevalence of PA decreased from 2005 to 2007. Annual per capita savings in health care associated with achieving the earlier target is estimated at $6.15 per capita, yet a fraction of that is directed to promoting PA. CONCLUSION: Evidenced-based strategies that address multiple policy agendas using sector-specific approaches are needed. Sustained high-level commitment is required; advocacy grounded in metrics and science is needed to increase the profile of the issue and increase the commitments to PA policies in Canada and internationally.

Markers of sedentarism: the joint Canada/U.S. Survey of health.

BACKGROUND: The Joint Canada/United States Survey of Health (JCUSH) was a one-time collaborative survey undertaken by Statistics Canada and the National Center for Health Statistics. METHODS: This analysis provides country-, sex-, and age-specific comparative markers of adult obesity and sedentarism, defined as independent and collective groupings of self-reported leisure-time inactivity (<1.5 MET-hours/day), usual occupational sitting, and no/low active transportation (<1 hour/week). Logistic regression assessed the likelihood of sedentarism in U.S. vs. Canada, with and without adjusting for BMI-defined obesity categories: healthy weight (18.5 ≤ BMI <25 kg/m2; n = 3542), overweight (25 ≤ BMI < 30 kg/m2; n = 2,651), and obesity (BMI ≥ 30 kg/m2; n = 1470). RESULTS: Compared with Canadians, U.S. adults are 24% more likely to be overweight/ obese, 59% more likely to be inactive in leisure-time, 19% more likely to report no/low active transportation, and 39% more likely to collectively report all sedentarism markers, adjusting for sex and age. Focusing on obese individuals in both countries, obese U.S. residents were 90% more likely to be inactive during leisure-time, 41% more likely to report no/low active transportation, and 73% more likely to report all sedentarism markers. CONCLUSIONS: This ecological analysis sheds light on differential risks of obesity and sedentarism in these neighboring countries.

Process and treatment of pedometer data collection for youth: the Canadian Physical Activity Levels among Youth study.

BACKGROUND: Pedometry methods for collecting data in young populations are advancing, but it is unclear how many days of data are enough for population monitoring. METHODS: Using random-digit dialing, 11,669 5- to 19-yr-olds were recruited into the Canadian Physical Activity Levels among Youth study and mailed a data collection package. Pedometers were worn for 7 d, and steps counts were logged daily. Reactivity was assessed by examining estimates from the pattern of pedometer data across days (arranged from first day of collection to last) using a repeated-measures ANOVA. Intraclass correlations (ICC) were computed for the first day and consecutive additional days (compared with the criterion estimate based on the whole week) to determine the minimal number of days required to achieve a reliability ICC of 0.70, 0.80, and 0.90. RESULTS: Most children (990%) wore the pedometer for 7 d. Mean steps per day differed across consecutive days (F = 52.7, P = 0.000); however, no difference occurred between the first and the second day of monitoring. Furthermore, no difference was observed between the first and either the third or the fourth day when monitoring commenced on a Monday or a Tuesday. Therefore, there was no clear evidence of reactivity. The first day provided a good representation of steps per day relative to the whole week in terms of both reliability (ICC = 0.79) and validity (relative absolute percent error [APE] =2.5%), and these improved with additional days (2 d, ICC > 0.85; > or = 3 d, ICC > 0.90; and > or = 3 d, APE < 1%). CONCLUSIONS: The Canadian Physical Activity Levels among Youth demonstrates the feasibility of national surveillance of physical activity using pedometers.Two days are sufficient to determine steps per day, and a single day appears defensible in terms of population monitoring if minimal standards for reliability are acceptable.

[Guides and guidelines for physical activity for Canadians: facts and future]. / Lignes directrices et guides sur l'activité physique à l'intention des Canadiens : les faits et l'avenir.

This article summarizes the main findings from the papers included in this journal supplement. It consolidates the evidence currently available to inform and advance the development of physical activity guidelines for Canadians, and it highlights the specific needs of various population subgroups. The challenges of translating guideline information into effective and persuasive physical activity messages, of campaigns to disseminate messages and of related evaluations are underlined. Recommendations on how to proceed are based on the evidence base provided by this series of papers; the immediate next steps mandated by this initiative are outlined and priorities for future research are indicated.

Low levels of recall among adult Canadians of the CSEP/Health Canada physical activity guidelines.

In 1998, Canadian guidelines were released to encourage sedentary adults to become more active. Representative surveys of over 4,400 Canadian adults found that unprompted recall of these guidelines was low (7.4% in 1999 and 5.2% in 2002), but was higher among educated, affluent, middle-aged, and the physically active. Achieving a high level of activity was associated with demographic variables and other information sources, but not with guideline recall. Guideline promotion has not reached those most in need.