Limitations of Canada s physical activity data: implications for monitoring trends 1

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1 S185 REVIEW / SYNTHÈSE Limitations of Canada s physical activity data: implications for monitoring trends 1 Peter T. Katzmarzyk and Mark S. Tremblay Abstract: The current low level of physical activity among Canadians is a dominant public health concern. Accordingly, a clear understanding of physical activity patterns and trends is of paramount importance. Irregularities in monitoring, analysis, and reporting procedures create potential confusion among researchers, policy-makers, and the public alike. The purpose of this paper is to consolidate reported findings and provide a critical assessment of the physical activity surveillance procedures, analytical practices, and reporting protocols currently employed in Canada to provide insights for accurate and consistent interpretation of data, as well as recommendations for future surveillance efforts. Key words: surveillance, lifestyle, Canada Fitness Survey, sedentary. Résumé : Le faible niveau de pratique de l activité physique chez les Canadiennes et les Canadiens constitue une préoccupation majeure de santé publique. Bien entendu, il est important de saisir les pratiques et les tendances actuelles. Des irrégularités concernant le monitorage, l analyse et l établissement du bilan créent de la confusion auprès des chercheurs, des décideurs et du public en général. Cette étude se propose de consolider les observations antérieures, de faire une évaluation critique des méthodes d observation et d analyse de la pratique de l activité physique et de présenter des résultats couramment utilisées au Canada. Nous proposons une approche afin d interpréter de façon juste et valable les observations et nous recommandons des stratégies de surveillance. Mots-clés :surveillance, mode de vie, enquête condition physique Canada, sédentarité. [Traduit par la Rédaction] Background to the problem The current low level of physical activity among Canadians is a dominant public health concern. There is convincing evidence that a sedentary lifestyle will accelerate the onset and development of chronic diseases, including cardiovascular disease, diabetes, and cancer (US Department of Health and Human Services 1996; World Health Organization 2002, 2003a, 2003b). In 2001, the annual economic Received 21 March Accepted 16 June Published on the NRC Research Press Web site at apnm.nrc.ca on 14 November P.T. Katzmarzyk. 2 School of Kinesiology and Health Studies and Department of Community Health and Epidemiology, Queen s University, Kingston, ON K7L 3N6; Pennington Biomedical Research Center, Baton Rouge, LA M.S. Tremblay. Children s Hospital of Eastern Ontario Research Institute, Ottawa, ON. 1 This article is part of a supplement entitled Advancing physical activity measurement and guidelines in Canada: a scientific review and evidence-based foundation for the future of Canadian physical activity guidelines co-published by Applied Physiology, Nutrition, and Metabolism and the Canadian Journal of Public Health. It may be cited as Appl. Physiol. Nutr. Metab. 32(Suppl. 2E) or as Can. J. Public Health 98(Suppl. 2). 2 Corresponding author ( peter.katzmarzyk@pbrc.edu). costs associated with physical inactivity in Canada were estimated at $5.3 billion (Katzmarzyk and Janssen 2004). Accordingly, a clear understanding of physical activity and inactivity patterns and trends is of paramount importance. Irregularities in monitoring, analysis, and reporting procedures create potential confusion among researchers, policy-makers, and the public alike. The importance of having regular, robust, populationbased assessments of key physical activity measures is not only important for public health surveillance in Canada, but is also required to effectively monitor the success of population interventions aimed at increasing physical activity levels of a population. The purposes of this paper are to consolidate reported findings and to make a critical assessment of the physical activity inactivity surveillance procedures, analytical practices, and reporting protocols currently employed in Canada, to provide insights for accurate and consistent interpretation of available data, and offer recommendations for future surveillance efforts. Definitions of physical activity Physical activity can be defined as any bodily movement produced by the skeletal muscles that results in a substantial increase of energy expenditure over resting levels (Bouchard et al. 2007). Physical activity should not be confused with total daily energy expenditure, or the energy that an individual expends over a period of 24 h, which is important in Appl. Physiol. Nutr. Metab. 32: S185 S194 (2007) doi: /h07-113

2 S186 Appl. Physiol. Nutr. Metab. 32(Suppl. 2E), 2007 / Can. J. Public Health 98(Suppl. 2), 2007 studies of energy balance, weight maintenance, and various health outcomes. Total daily energy expenditure includes contributions from the basal metabolic rate (BMR), the thermic effect of feeding, growth (in children), pregnancy and lactation (in women), and physical activity. At the individual level, physical activity represents the most modifiable component of total energy expenditure, and is thus an important target for intervention. It is the physical activity component of total energy expenditure that is the focus of this paper. Physical activity is a behaviour that is embedded within an individual s social and cultural context. As such, physical activity is a difficult construct to measure; by comparison, physical fitness is a trait with components that can be measured objectively in either the laboratory or a field setting (e.g., muscular strength, maximal aerobic power, etc.). Current surveillance procedures The population surveillance of physical activity in Canada among youth and adults is limited mainly to the Physical Activity Monitor (PAM) series of surveys conducted by the Canadian Fitness and Lifestyle Research Institute (CFLRI) and the National Population Health Survey (NPHS) Canadian Community Health Survey (CCHS) series of surveys conducted by Statistics Canada (Table 1). The NPHS was conducted in , , and ; although the NPHS was a series of cross-sectional surveys, a longitudinal component was also included. The cross-sectional NPHS has been replaced by the CCHS, a series of crosssectional surveys conducted very two years, in , 2003, and Among children, both the National Longitudinal Survey of Children and Youth (NLSCY) and the Health Behaviour in School-Aged Children (HBSC) surveys include information on physical activity participation. In addition, the PAM often reports on the physical activity levels of children. Nevertheless, the surveillance of physical activity levels among children is not well developed in Canada; thus, the focus of this paper is on the monitoring of physical activity among adults. The surveys listed in Table 1 generally rely on self-reported or parental-reported physical activity levels, and (with one exception) do not include objective indicators of physical activity. There have been limited attempts to quantify the physical activity levels of the population with objective measurements (Canadian Fitness and Lifestyle Research Institute 2007; Thompson et al. 2005; CDC and NCHS 2007). For example, the Canadian Fitness and Lifestyle Research Institute recently conducted The Canadian Physical Activity Levels Among Youth (CAN PLAY) study, in which they collected pedometer data on a sample of approximately 6000 children and youth aged 5 19 y (Canadian Fitness and Lifestyle Research Institute 2007). The US National Health and Nutrition Examination Survey also included objective accelerometer measurements of physical activity on over 6000 participants in the wave of data collection (CDC and NCHS 2007). These represent the first efforts at population surveillance of physical activity using objective measures. From a monitoring perspective, there are various ways to define or express physical activity behaviours. Traditionally, physical activity has been described in terms of mode, intensity, frequency, and duration. For the purpose of health promotional strategies, there is interest in understanding the most popular modes of physical activity. For example, the most commonly reported physical activities among adults in Canada are walking and gardening or yard work (Canadian Fitness and Lifestyle Research Institute 2004). Although from the standpoint of public health recommendations the mode of physical activity may not seem as important as frequency, intensity, and duration, information about the types of physical activities that Canadians engage in is important when designing physical activity interventions, to increase the likelihood that the interventions will be adopted by large segments of the population. Information on the frequency of physical activity participation (or presence absence) is sometimes presented by itself as a marker of population activity. For example, in the United States Behavioral Risk Factor Surveillance System (BRFSS), a single question indicating if the participant reports no participation in exercise (e.g., running, calisthenics, golf, gardening, or walking) other than their regular job during the preceding month is used to determine the prevalence of no leisure-time physical activity (Hughes et al. 2006). A single question is also used in Finland to identify the prevalence of inactive people with leisure-time physical exercise < twice per week (Helakorpi et al. 2002). These simple indices can be tracked over time to assess changes in the physical activity behaviour of a population; however, little information is thus obtained about the total volume of physical activity undertaken by the population. According to Canada s physical activity guide to healthy active living, different combinations of intensity, duration, and frequency of physical activity are presumed to result in health benefits, as long as an adequate overall volume of physical activity is attained (Health Canada and the Canadian Society for Exercise Physiology 1998). Existing Canadian monitoring systems commonly combine information on mode, intensity, frequency, and duration to produce estimates of an individual s leisure-time physical activity energy expenditure (for example, kj/week or kjkg -1 d 1 ), or to assess the percentage of people meeting a defined threshold level of leisure-time physical activity (for example 12.5 kjkg -1 d 1 ; 3.0 kcalkg -1 d 1 ). There are pros and cons with each approach. By estimating an overall level of energy expenditure, no information is obtained on the frequency, duration, or intensity of physical activity; the only figure obtained is the accumulation of a given volume. This results in an informative continuous variable; however, it does not describe the prevalence of physical activity or inactivity. On the other hand, the volume of physical activity can be converted to a categorical variable, using a particular threshold to define the active or inactive population. With this approach, little information is obtained about the average level of physical activity in the population; one determines only the number of people that are above or below some arbitrary value. Increases in the prevalence of physical activity may actually come about in the face of a decrease in the overall physical activity of the population, particularly if changes are captured only at the extremes of the physical activity distribution. Regardless of the approach used, it is important that information on intensity, duration, and frequency of physical activities be collected as part of population surveillance, so that estimates of physical activity volume can be obtained.

3 Katzmarzyk and Tremblay S187 Table 1. Population surveys of physical activity levels in Canada. Survey Age range (y) Sample size CFLRI Canada Fitness Survey Campbell s Survey on Well-being Physical Activity Monitor CANPLAY* Statistics Canada Survey of Fitness, Physical Education and Sport Canada Health Survey (with Health Canada) General Social Survey Health Cycle General Social Survey Time Use Survey National Population Health Survey Canadian Community Health Survey National Longitudinal Study of Children and Youth , , Health Promotion Survey Health Behaviour in School-aged Children Survey *Assessed physical activity objectively using pedometers. Defining the at-risk population The current public health recommendations for physical activity are based mainly on scientific evidence linking physical inactivity to a host of chronic diseases, particularly cardiovascular disease (Pate et al. 1995; US Department of Health and Human Services 1996; Health Canada and the Canadian Society for Exercise Physiology 1998; Warburton

4 S188 Appl. Physiol. Nutr. Metab. 32(Suppl. 2E), 2007 / Can. J. Public Health 98(Suppl. 2), 2007 et al. 2007). The US Surgeon General has called for at least 30 min/d of moderate-intensity physical activity on most, and preferably all, days of the week (US Department of Health and Human Services 1996). Canada s physical activity guide to healthy active living calls for either (i) 1hof any (light) physical activity every day, (ii) min of moderate or vigorous physical activity at least 4 d/week, or (iii) vigorous physical activity for 20 min on at least 4 days a week (Health Canada and the Canadian Society for Exercise Physiology 1998). Ideally, when designing surveillance systems for physical activity, the threshold used to define physical activity should be tied to a specific outcome or recommendation. The above recommendations are based on specific health benefits derived from physical activity, particularly the prevention of chronic disease. However, they may not be adequate to prevent obesity or weight gain in many people. Estimating physical activity levels in Canada The levels of leisure-time physical activity energy expenditure in the main Canadian surveys were obtained from a questionnaire modeled after the Minnesota Leisure Time Physical Activity Questionnaire (Taylor et al. 1978). The questionnaires have remained generally similar over time, but there are some important differences in both the questions asked and the tactics of data analysis across time and between the PAM series and NPHS CCHS series of surveys. Briefly, a list of physical activities is provided to respondents, who indicate the number of occasions they performed each activity and the average duration of activity bouts. The average daily leisure-time activity energy expenditure (AEE, measured in kjkg 1 d 1 or kcalkg 1 d 1 ) is then calculated as follows: AEE ¼ ðn i D i METS i Þ=d where N i is the number of times the activity was performed, D i is the average duration of the activity (in hours), METS i is the estimated energy cost of the activity (kjkg -1 h 1 or kcalkg -1 h 1 ), and d is the number of days in the recall period (365 d in PAM and 91 d in NPHS/CCHS). In all cases, a predefined list of physical activities is provided, as well as an open-ended question that allows for the identification of a certain number of other activities that are not on the list (see Appendices A and B). Since the individual METS and resulting AEE values are adjusted for body mass, the temporal trends reported using these data are likely relatively independent of reported temporal trends in obesity. The main definitions and thresholds of physical activity used in the surveillance of physical activity in Canada are outlined in Table 2. Since the 1988 Campbell s Survey on Well-being (CSWB) (Stephens and Craig 1990), physical activity and inactivity levels have been expressed as specific thresholds of energy expenditure (kjkg 1 d 1 or kcalkg 1 d 1 ); however, the labels and thresholds have changed. In the PAM series of surveys, physical inactivity is defined as <12.5 kjkg 1 d 1, <3.0 kcalkg 1 d 1, whereas the contemporary NPHS/CCHS series of surveys have defined physical inactivity as <6.3 kjkg 1 d 1, <1.5 kcalkg 1 d 1. According to the background documentation for the surveys, a threshold of 12.5 kjkg 1 d 1 is equivalent to walking at least 1 h every day, whereas a threshold of <6.3 kjkg 1 d 1 is equivalent to walking no more than 15 min every day (Canadian Fitness and Lifestyle Research Institute 2004). However, the way in which these values were computed is not stated. The public health recommendation from CDC ACSM is to walk at least 30 min/d at a moderate intensity (to cover 3.2 km briskly); this should have a gross cost of about 830 kj, 200 kcal (Pate et al. 1995). Indeed, an average Canadian man of 80 kg walking for 30 min at 5.6 km/h (5.0 METs) would expend approximately 830 kj, 200 kcal (Ainsworth et al. 2000). An 80 kg man meeting the threshold of 12.5 kjkg 1 d 1 would expend approximately 1000 kj/d. Thus, the threshold of 12.5 kjkg 1 d 1 is a logical surveillance target, approximating current public heath recommendations. The current inactive threshold of <6.3 kjkg 1 d 1 employed by the CCHS is below currently recommended levels, and is likely below the level associated with substantial health benefits. A single report has analyzed population-level data related to the prevalence of adults meeting the recommendations in Canada s physical activity guide to healthy active living (Canadian Fitness and Lifestyle Research Institute 1998). Based on an analysis of data from the 1997 Physical Activity Monitor, it was estimated that one third of Canadians years of age were meeting the guidelines; however, this type of analysis has not been repeated in subsequent surveys. Temporal trends in physical activity levels The choice of physical activity threshold has important implications for monitoring trends in physical activity and inactivity and documenting the public health burden associated with physical inactivity. Figure 1 compares temporal changes in self-reported leisure-time physical inactivity in the PAM and NPHS CCHS series of surveys. The trends observed in the two series of surveys are similar; however, absolute prevalences differ at the same threshold. For example, in 2000, the prevalence of people expending < kjkg 1 d 1 was 61% in the PAM and 80% in the CCHS. Differences in methodology and scoring of activity codes likely explain differences between the two sets of results, but the difficulty of interpretation remains, as the explanation of what a threshold of 12.5 kjkg 1 d 1 represents in terms of minutes per day of activity is the same for both surveys. The trends of physical inactivity depicted in Fig. 1 suggest that leisure-time physical inactivity is decreasing over time. This is the opposite of what might be expected, given our society s drive towards engineering physical activity out of our everyday lives through reliance on electronics and mechanical devices. Indeed, Canadian trends for use of household entertainment devices that contribute to sedentary behaviour, show an increasing prevalence over time (Fig. 2). Furthermore, the reported temporal trends in physical inactivity are in the opposite direction to trends for the major inactivity-related diseases (Fig. 3). The prevalence of selfreported high blood pressure, diabetes, and obesity has increased over time, whereas the reported prevalence of physical inactivity has decreased. This is troubling, especially when coupled with evidence that dietary energy intake has declined over the past generation (Garriguet 2006). It is

5 Katzmarzyk and Tremblay S189 Table 2. Definitions and thresholds of leisure-time physical activity used for surveillance among adults in Canada. Prevalence (%) Threshold Label Surveys 3 h/week for 9 months/y Physically active 1981 Canada Fitness Survey 12.5 kjkg 1 d 1, 3 kcalkg 1 d 1 Physically active 1988 Campbell s Survey of Well-being; 1994, , National Population Health Surveys; , 2003, 2004, 2005 Canadian Community Health Surveys 12.5 kjkg 1 d 1, 3 kcalkg 1 d 1 Physically inactive 1995, 1997, 1998, 1999, 2000 Physical Activity Monitors 6.3 kjkg 1 d 1, 1.5 kcalkg 1 d 1 Physically inactive 1994, , National Population Health Surveys; , 2003, 2004, 2005 Canadian Community Health Surveys kjkg 1 d 1, kcalkg 1 d 1 Moderately physically active Fig. 1. Trends in the prevalence of physical inactivity of adult Canadians, as inferred from the Physical Activity Monitor (PAM) and Statistics Canada series of surveys ( , , National Population Health Surveys (NPHS) / , 2003, and 2005 Canadian Community Health Surveys (CCHS)). Data were obtained from Statistics Canada (2006) Year PAM <3.0 KKD NPHS/CCHS <3.0 KKD NPHS/CCHS <1.5 KKD Fig. 2. Trends in the percentage of households with entertainment equipment that promotes sedentary behaviour (data from Statistics Canada 2001, 2007). Households (%) VCR 80 one TV 70 DVD cable TV 10 0 computer internet possible that overweight or obese individuals are more likely to under-report food intake and that these same individuals over-report physical activity. Since two-thirds of Canadian adults are overweight, this may help to explain the trends depicted in this figure. It is also possible that the temporal trends in physical activity may differ across different age groups in men and women, and that positive trends in one group may mask negative trends in another. This is an important area for future study. Finally, the ill-health effects of a sedentary lifestyle do not appear immediately; the lag time between a reduction in physical activity levels and the Change from Baseline (100%) , , National Population Health Surveys; , 2003, 2004, 2005 Canadian Community Health Surveys Fig. 3. Trends in the percentage of physical inactivity, obesity, high blood pressure, and diabetes in Canada, Data are from the , , and National Population Health Surveys and the , 2003, and 2005 Canadian Community Health Surveys. All prevalences are age-standardized to the 2004 Canadian population. Data were obtained from Statistics Canada (2006) Year High Blood Pressure Diabetes Obesity Physical Inactivity development of disease has not been incorporated into Fig. 3; however, if one assumes that recent changes in physical activity are a reflection of longer-term trends, there is a disconnect between the trends in physical inactivity and the trends in physical inactivity-related disorders. There are several potential explanations for apparent decreases in the proportion of the Canadian population meeting the threshold for physical inactivity. Firstly, the observed trend may be real and people are indeed becoming more active in their leisure time. Although this trend is in the opposite direction to that for the major hypokinetic diseases, the trend towards a decrease in leisure-time physical inactivity may have been countered by larger increases in physical inactivity in other aspects of life such as the activities of daily living, commuting, and occupational physical activity. Leisure-time physical activity (LTPA) accounts for a relatively small part of total daily physical activity levels. There is substantial variation in the energy expended in earning a living (occupational physical activity), domestic chores and active transportation, and physical activity levels at work often play a large role in explaining individual differences in health-related outcomes (Tremblay et al. 2007). If one is concerned with the monitoring of physical activity

6 S190 Appl. Physiol. Nutr. Metab. 32(Suppl. 2E), 2007 / Can. J. Public Health 98(Suppl. 2), 2007 as it relates to obesity, total daily energy expenditure is an important aspect of the energy balance equation one cannot make assumptions from leisure-time physical activity levels. Unfortunately, current Canadian procedures do not have appropriate surveillance systems to cover these other aspects of physical activity. As mentioned previously, one of the dangers of using a threshold approach is that changes in the total volume of physical activity are not considered. It is entirely conceivable that the total volume of physical activity in the population is decreasing, even though a greater proportion of individuals are meeting a pre-defined, albeit low, threshold of physical activity. Shortcomings of current surveillance approaches In addition to the discrepancies in physical activity thresholds described above, the observed prevalences of physical activity or inactivity can potentially be influenced by bias and differences in the modes of data collection. Both respondent and response bias may influence physical activity surveillance. Given that the current surveillance relies on self-reported questionnaire responses, there is a potential for respondent bias to affect estimates. For example, the social desirability of reporting healthy behaviours may have increased over the last two decades, as the benefits of physical activity have been publicized. In addition to the social desirability of an active lifestyle, the active living approach to the promotion of physical activity has emphasized that many activities such as walking, gardening, and yard work, which previously were not viewed as exercise, can now be counted as physical activity. The emphasis on active living may have increased questionnaire reporting of low levels of physical activity; if this was previously undertaken but not reported, then the proportion of adults classed as physically active would increase artificially over time. When conducting repeated cross-sectional surveys, it is important to standardize the instrument across time; however, a comparison of the surveys listed in Appendix B indicates that in the NPHS CCHS series of surveys, yoga and tai chi and cross-country skiing were discontinued after and , respectively. On the other hand, three high-intensity physical activities were added to the surveys: basketball in 1996, in-line skating in 1998, and snowboarding and soccer in The addition of several physical activity options to the questionnaire makes it difficult to discern true temporal trends; it is possible that reported increases in leisure-time physical activity could be due, in part, to people now reporting participation in these popular activities. Furthermore, all other activities not listed in Appendix B were assigned an average intensity value. Consequently, high-intensity activities such as basketball and soccer now yield higher calculated physical activity scores than when they were reported as other activities. Modifications to the NPHS CCHS list of activities are made periodically in response to low population responses (removal of an activity from the list) or emerging responses (addition of an activity based on frequent reporting as other ). Figure 4 provides an example to illustrate how respondent bias may have influenced the interpretation of changes in Fig. 4. Trends in proportion of the adult population meeting physical activity guidelines ( 3 MET h/day of self-reported leisure-time physical activity) and the corresponding survey response rate (Craig et al. 2004). Adult Population (%) Response Rate Prevalence physical activity levels. In the PAM series of surveys, physical activity appears to have increased since However, several spurious influences may be involved. First, one of the included activities was walking for exercise (Appendix A). It is possible that people did a fair amount of walking in 1981, but that they did not consider it exercise ; given the subsequent emphasis on active living, respondents may have become more apt to report a large proportion of their walking as exercise in more recent surveys. Second, gardening or yard work is the second most frequent activity (after walking) reported by Canadian adults (Cameron et al. 2000). However, gardening and yard work were only added to questionnaires subsequent to the 1981 Canada Fitness Survey (Appendix A). Third, the 1981 CFS questionnaire differed from the 1988 CSWB and more recent questionnaires in one important respect. The more recent surveys queried respondents regarding physical activities performed over the previous 12 months (PAM) or 3 months (NPHS CCHS) only. However, in 1981, respondents were first asked about activities they performed daily, weekly, monthly, and then those in the past year. When asked about activities performed in the last year, the respondents were asked not to include those activities they had previously indicated in the daily, weekly, and monthly sections. This qualitative difference was likely a factor contributing to an apparent decline of physical activity levels from the 1981 baseline. Response bias can be introduced into a series of surveys by differing response rates over time, if respondents are inherently different on variables of interest. Figure 4 presents the proportion of physically active adults in the PAM over time, along with the corresponding response rates. There was an increase in self-reported physical activity levels over the course of the surveys, mirrored by a decrease in response rates. We can speculate from this association that if the people who responded faithfully to the survey tended to be more health conscious and physically active than average, then the reduction in response rates could explain the apparent increase of self-reported physical activity within the population. The response rates in the NPHS CCHS series decreased from a high of 86.2% in 1998 to a low of 79% in This type of bias is difficult to address in survey design, and its effects are also difficult to determine.

7 Katzmarzyk and Tremblay S191 A more subtle influence arises when surveys change data collection modes (self-administered versus interviewer administered, telephone vs. in-person, proxy interview, etc.) or there is a change in the proportion of data collected through the different modalities. For example, the physical activity data in the 1981 Canada Fitness Survey and 1988 Campbell s Survey on Well-being were collected using face-toface interviews in the home, whereas data in subsequent PAM surveys were collected via telephone interviews. The proportion of respondents in the Canadian Community Health Survey who were interviewed by telephone increased from 53% in to 70% in 2003 (Béland and St- Pierre 2008). Significant mode effects were observed for several variables, including obesity and physical activity (Béland and St-Pierre 2008). The prevalence of obesity in 2003 was 17.9% from personal interviews and 13.2% from telephone interviews; the corresponding results for inactivity were 42.3% and 34.4%, respectively. Béland and St-Pierre (2008) suggest that the mode differences were attributed to social desirability, response bias, and interviewer-related sources of variability. The proportion of interviews that are completed by proxy rather than by the respondent themselves may also influence the reported prevalence of health behaviours. However, the proportion of interviews conducted by proxy has not changed over the NPHS CCHS surveys (proxy interview rates were : 4.2%; : 2.3%; : 2.4%, : 6.3%; 2003: 2.1%; 2005: 1.6%). As previously mentioned, surveillance of physical activity in Canada relies almost exclusively on reports concerning leisure-time physical activity, despite general agreement that there are four domains of physical activity; leisure-time (focusing primarily on sports), commuting or active transportation, chores or personal care, and occupation (Armstrong and Bull 2006; World Health Organization 2002). It is likely that the distribution of time among these four domains, and the volume of physical activity associated with each domain, may vary within and between people over time. The NPHS CCHS surveys collect superficial information on non-leisure-time physical activity through the following questions (PAM surveys include similar questions):. In a typical week in the past three months, how many hours did you usually spend walking to work or school or while doing errands? (categories from none to more than 20 h). In a typical week how much time did you usually spend bicycling to work or school or while doing errands? (categories from none to more than 20 h). Thinking back over the past three months, which of the following best describes your usual daily activities or work habits?: Usually sit during the day and don t walk around very much; Stand or walk quite a lot during the day but don t have to carry of lift things very often; Usually lift or carry light loads, or have to climb stairs or hills often; Do heavy work or carry very heavy loads. These questions are rarely used in the surveillance of physical activity in Canada and even if they were, careful attention would be required to avoid duplication of data (e.g., correct for double-reporting through leisure-time physical activity and active transportation). Implications The efforts to monitor physical activity levels in Canada have a long history and are laudable. However, the lack of rigour with which the surveillance of physical activity has been and is being conducted carries several implications. As described earlier, there is great confusion as to appropriate thresholds defining physical inactivity or physical activity, and questions remain regarding the meaning of self-reported data obtained from national surveys. Given the importance of physical activity as a modifiable risk factor for major chronic diseases, there are dangers in basing national strategies and targets on data collected using the current methods of surveillance. Canada currently has two major physical activity goals. In 2004, the Federal, Provincial, and Territorial Ministers responsible for sport, recreation, and fitness called for a 10 percentage point increase in physical activity levels across provinces and territories by the year 2010 (Health Canada 2004). Further, the Integrated Pan-Canadian Healthy Living Strategy outlined the goal of a 20% increase in the proportion of Canadians who participate in moderate and vigorous physical activity for at least 30 min/d by 2015 (Health Canada 2005). The success of public health interventions designed to increase physical activity levels will be judged relative to these goals. Given the current state of physical activity surveillance, it will be difficult to determine whether these goals have been met. True increases in the health of the Canadian population will come about only with a true increase in average energy expenditures; however, the current targets will be met if there is an increase in the proportion of the population who meet or exceed a low threshold of physical activity. Indeed, the goals could theoretically be met despite a decrease in population-level energy expenditures. Conclusions A recommendation from the National Roundtable on Physical Activity Research (2003) was to develop better measures and a more comprehensive understanding of the current levels of physical (in)activity and eating behaviours among free-living Canadians. Furthermore, the Coalition for Active Living (CAL) specifically recommends to build on existing surveillance and monitoring systems to track progress among various population groups (Coalition for Active Living 2004). The present paper provides substantive evidence supporting these recommendations. The combination of self-reported data, inconsistent analyses, and comparisons and irregular reporting practices creates significant opportunity for misinterpretation and misrepresentation of the data, which in turn can misinform policy and distort our understanding of physical activity health relationships. There has been a downward shift of the physical activity cut-point used for Canadian public health surveillance with time (from 12.5 kjkg 1 d 1 to 6.3 kjkg 1 d 1 ). The health outcome data strongly suggest that our current physical activity monitoring systems, and the trends they have produced, deviate from reality, perhaps progressively, masking more pervasive sedentarism that eludes our present surveillance systems. Canadian data on physical activity mode, intensity, and duration have been collected for over two

8 S192 Appl. Physiol. Nutr. Metab. 32(Suppl. 2E), 2007 / Can. J. Public Health 98(Suppl. 2), 2007 decades. More robust analyses of the existing data that align with current public health recommendations may be quite informative in modeling the population-attributable risks associated with physical inactivity. Robust re-analyses that compare temporal trends under different assumptions and limiting the data to specific modes of physical activity would be very informative. The possible inclusion (in retrospective analyses) of active transportation and occupational physical activity data already captured should be explored. Further, a more robust monitoring system that includes more direct measures of physical activity is required for an accurately informed policy and a correct understanding of relationships between physical activity and the risks of developing various chronic diseases. Physical activity and inactivity surveillance in Canada requires increased resources, standardized methods of analysis and transparent reporting processes if it is to be effective in informing future intervention strategies and guiding important policy developments. References Ainsworth, B.E., Haskell, W.L., Whitt, M.C., Irwin, M.L., Swartz, A.M., Strath, S.J., et al Compendium of physical activities: an update of activity codes and MET intensities. Med. Sci. Sports Exerc. 32: S498 S504. doi: / PMID: Armstrong, T., and Bull, F Development of the work health organization global physical activity questionnaire. J. Public Health, 14: doi: /s x. Béland, Y. and St-Pierre, M Mode effects in the Canadian Community Health Survey: a comparison of CATI and CAPI. In Advances in telephone survey methodology. Edited by J. Lepkowski, C. Tucker, J.M. Brick, E. de Leeuq, L. Japec, P.J. Lavrakas, M.W. Link, and R. Langster. 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9 Katzmarzyk and Tremblay ment of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Atlanta, Ga. Warburton, D.E.R., Katzmarzyk, P.T., Rhodes, R., and Shephard, R.J Evidence-informed physical activity guidelines for Canadian adults. Appl. Physiol. Nutr. Metab. 32(Suppl. 2E): this issue. World Health Organization The World Health Report 2002: reducing risks, promoting healthy life [online]. World Health Organization, Geneva, Switzerland. Available from who.int/whr/2002/en/index.html [accessed 9 March 2007]. S193 World Health Organization. 2003a. Health and development through physical activity and sport. WHO Document Production Services [online]. World Health Organization, Geneva, Switzerland. Available from WHO_NMH_NPH_PAH_03.2.pdf [accessed 9 March 2007]. World Health Organization. 2003b. Diet, nutrition, and the prevention of chronic diseases [online]. WHO Technical Report Series No World Health Organization, Geneva, Switzerland. Available from [accessed 9 March 2007]. Appendix A. Table A1. List of physical activities in the physical activity monitor series of surveys , Walking for exercise Walking for exercise Walking for exercise Weight training Weight training Weight training Ice skating Ice skating Ice skating Ice hockey Ice hockey Ice hockey Bicycling Bicycling Bicycling Swimming in a pool Swimming Swimming Golf Golf Golf Tennis Tennis Tennis Home exercises Home exercises Home exercises Cross-country skiing Cross-country skiing Cross-country skiing Exercise classes Exercise classes or Exercise classes or Downhill skiing Downhill skiing Downhill skiing Running, jogging Jogging or running Jogging or running Baseball, softball Baseball or softball Baseball or softball Yoga Yoga or tai chi Racquetball Racquetball Squash Squash Curling Gardening or yard work Gardening or yard work Popular or social dance Popular or social dance Ballet, modern or jazz dance Ballet or modern dance Bowling Bowling Square or folk dance Volleyball Basketball In-line skating Badminton Soccer Football Gymnastics Snowboarding 10 more activities from reference card 5 more activities from reference card 3 more activities

10 S194 Appl. Physiol. Nutr. Metab. 32(Suppl. 2E), 2007 / Can. J. Public Health 98(Suppl. 2), 2007 Appendix B. Table B1. List of physical activities in the NPHS CCHS series of surveys Walking for exercise Walking for exercise Walking for exercise Walking for exercise Walking for exercise Walking for exercise Gardening/yard work Gardening/yard work Gardening/yard work Gardening/yard work Gardening/yard work Gardening/yard work Swimming Swimming Swimming Swimming Swimming Swimming Bicycling Bicycling Bicycling Bicycling Bicycling Bicycling Popular/social dance Popular/social dance Popular/social dance Popular/social dance Popular/social dance Popular/social dance Home exercises Home exercises Home exercises Home exercises Home exercises Home exercises Ice hockey Ice hockey Ice hockey Ice hockey Ice hockey Ice hockey Skating Ice skating Ice skating Ice skating Ice skating Ice skating Jogging/running Jogging/running Jogging/running Jogging/running Jogging/running Jogging/running Golfing Golfing Golfing Golfing Golfing Golfing Bowling Bowling Bowling Bowling Bowling Bowling Baseball/softball Baseball/softball Baseball/softball Baseball/softball Baseball/softball Baseball/softball Tennis Tennis Tennis Tennis Tennis Tennis Weight training Weight training Weight training Weight training Weight training Weight training Fishing Fishing Fishing Fishing Fishing Fishing Volleyball Volleyball Volleyball Volleyball Volleyball Volleyball Downhill skiing Downhill skiing Downhill skiing Downhill ski/ snowboard Downhill ski/ snowboard Downhill ski/ snowboard Cross-country skiing Cross-country skiing Yoga or tai chi Basketball Basketball Basketball Basketball Basketball In-line skating In-line skating In-line skating In-line skating Soccer Soccer Soccer Soccer 3 more activities 3 more activities 3 more activities 3 more activities 3 more activities 3 more activities