© 2004 American Public Health Association
Sandrine Bertrais, Paul Preziosi, Louise Mennen, Pilar Galan, and Serge Hercberg, are with the Unité Mixte de Recherche, Institut National de la Santé et de la Recherche Médicale (INSERM U557), Institut National de la Recherche Agronomique (INRA U1125), Conservatoire National des Arts et Métiers (CNAM EA3200-MR), Paris Prance. Louise Mennen and Serge Hercberg are also with the Unité de Surveillance et dEpidémiologie Nutritionnelle (USEN), Institut de Veille Sanitaire (InVS)-CNAM, Paris, France. Jean-Michel Oppert is with the Service de Nutrition, Hôtel-Dieu, Assistance Publique-Hôpitaux de Paris (AP-HP), EA 3502 Université Pierre-et-Marie Curie (Paris VI), Paris, France. Correspondence: Requests for reprints should be sent to Serge Hercberg, MD, PhD, Nutritional Epidemiology Research Unit, UMR INSERM U557, INRA U1125, CNAM EA 3200-MR, 5 rue du Vertbois, F-75003 Paris, France (e-mail: hercberg{at}cnam.fr).
Objective. We evaluated the characteristics of French subjects meeting current public health recommendations for physical activity. Methods. We assessed leisure-time physical activity cross-sectionally in 7404 adults aged 45 to 68 years with applied logistic regression models. Results. Meeting the recommended physical activity levels was more likely in subjects aged 60 years and older and in women with higher education levels or living in rural areas and was less likely in smokers. No association was found with time spent watching television. The contribution of vigorous activity to total time spent being active was approximately 2 times higher in subjects meeting recommendations. Conclusions. Participation in some vigorous activity may be viewed as a "facilitator" to attain physical activity recommendations. Relationships with physical environment variables in Europe need further investigation.
A low level of physical activity is recognized as a major risk factor for the development of several chronic diseases, including coronary heart disease, hypertension, obesity, type 2 diabetes, osteoporosis, and certain forms of cancer, as well as some mental health problems.1,2 Given the numerous benefits for health and well-being of regular physical activity, specific recommendations for the general population have been issued by US13 and European4,5 public health authorities and scientific expert panels. The 1990 American College of Sports Medicine (ACSM) guidelines, which focused on cardiorespiratory and muscular fitness, recommended vigorous exercise for at least 20 minutes performed 3 or more days per week.3 Recognition that moderate amounts of physical activity also confer substantial health benefits, especially for inactive or irregularly active subjects, led the Centers for Disease Control and Prevention (CDC) and the ACSM,2 as well as the US Surgeon General,1 to publish new recommendations focused on health-related physical activity. According to the 1995 CDC/ACSM guidelines, all adults should accumulate 30 minutes or more of moderate physical activity on most, and preferably all, days of the week.2 At present, a limited number of studies from the United States,68 Australia,9 and England10 have assessed the proportion of adults meeting these new guidelines, with observed rates varying from 25% to 50%. To our knowledge, no such studies have been conducted in populations from other European countries. Identifying the correlates (personal, social, and environmental) of participation in physical activity is a first step that may help to target at-risk populations and guide the development of preventive programs. Among the many factors related to overall physical activity levels, associations with sociodemographic variablessuch as age, gender, education, and income levelsare well documented.1,11,12 The most recent studies have focused on environmental factors, taking a broader "ecological" approach to understand the correlates of physical activity.12 The influence of the physical environment, which provides cues and opportunities for physical activity, is in particular a subject of growing interest.12,13 Urban/rural status is 1 of the physical environment variables that can be easily obtained. Some studies have shown that rural US adults are less likely to meet the recommended levels of physical activity than their urban counterparts.14,15 However, other studies from the United States16,17 and England10 do not support these findings. Compared with the United States and other European countries, there are very few data regarding the habitual level of physical activity/inactivity in France.5 Therefore, the aims of the present study were to investigate individual and environmental factors, including the degree of urbanization of the place of residence, in relation to leisure-time physical activity (LTPA) in a national sample of middle-aged French adults and to compare physical activity patterns between the subjects who did and the subjects who did not meet the current public health recommendations (PHR).
Study Population Subjects were participants of the Supplémentation en Vitamines et Minéraux Antioxydants (SUVIMAX) study, an ongoing, randomized, double-blind, placebo-controlled, primary prevention trial designed to evaluate the impact of a daily antioxidant supplementation at nutritional doses on the incidence of ischemic heart disease and cancer.18 A total of 12 735 subjects (men, aged 4560 years; women, aged 3560 years), from all over France, were included in 19941995, with a planned follow-up of 8 years. All subjects gave their informed written consent to the study, which was approved by the ad hoc ethical committees (i.e., The Comité Consultatif de Protection des Personnes dans la Recherche Biomédicale and the Commission Nationale de lInformatique et des Libertés). Details on recruitment, study design, and baseline characteristics of the subjects have been reported previously.18 For the present study, only those subjects with available data on LTPA in 1998, the year during which a detailed physical activity questionnaire was sent to the entire cohort, were included. So that a similar age range would be considered in both genders, the sample was further restricted to subjects aged 45 years or older in 1998. We also excluded subjects who had been confined to bed for more than 1 month during the period covered by the physical activity questionnaire. Analyses in the present report were thus based on data from 3404 men and 4000 women.
Assessment of Leisure-Time Physical Activity and Television Watching The questionnaire has been described in detail elsewhere.19,21 Briefly, for LTPA, subjects were asked to report all activities performed at least 10 times for 10 minutes per session during leisure time over the past 12 months. Then, detailed information was collected about the frequency and duration of each activity reported. Hours per week for all activities performed during the past year were summed to obtain an indicator expressed in hours per week of leisure activity. An energy expenditure indicator also was calculated by multiplying the number of hours per week of each leisure activity by its estimated metabolic cost. This score was expressed in metabolic equivalent task (MET)-hours per week of leisure activity. A MET is the ratio of the working metabolic rate of an activity divided by the resting metabolic rate.22 One MET represents the metabolic rate of an individual at rest (sitting quietly) and is set at 3.5 mL of oxygen consumed per kilogram body mass per minute, or approximately 1 kcal/kg/h. A 10-MET activity would require 10 times the resting metabolic rate. METs for each activity were drawn from compendiums published by Ainsworth et al.22,23 Television watching was measured using a single question: "In general, how many hours per day do you spend watching television?" (hours/day). Based on the 1990 ACSM3 and the 1995 CDC/ACSM2 PHR for physical activity, we defined 4 groups of LTPA:
Subjects in groups 3 and 4 were considered to meet the current PHR. Four groups of television watching also were defined on the basis of the distribution of the time spent watching television in our sample (median, 2 h/d): less than 1 h/d, 1 to 2 h/d, 2 to 3 h/d, and
Sociodemographic Variables, Smoking Status, and Geographic Data
Data Analyses
The mean age was 55.4 ±4.7 years in men and 53.2 ±5.3 years in women. In men and women, respectively, the mean LTPA duration was 4.8 ±5.6 h/wk and 3.8 ±4.4 h/wk, and the median LTPA score was 15.5 MET-h/wk (Q1 = 5.9 and Q3 = 31.4) and 11.0 MET-h/wk (Q1 = 3.7 and Q3 = 23.3). Recommended levels of physical activity were achieved by 62% of men and 52% of women, whereas 10% of men and 12% of women reported no physical activity at all in their leisure time during the previous year (gender differences in distribution of the 4 groups, P < .001) (Table 1 2 test, .11 in men and .12 in women).
In both genders, subjects who were 60 years of age and older were approximately twice as likely to achieve recommended levels compared with subjects who were 45 to 49 years old (Table 2
One hundred fifty different recreational activities, practiced on a regular basis, were observed. In subjects who reported at least 1 activity, the mean number of activities was 3.2 ±1.5 in men who met the PHR and 1.9 ±1.0 in men who did not meet the PHR (P < .0001). The corresponding figures were, respectively, 3.2 ±1.4 and 1.9 ±1.0 in women (P < .0001). The 2 most common physical activities performed, whether or not subjects met the PHR, were walking for pleasure (i.e., walking slowly, as opposed to brisk walking) and gardening in both men and women (Table 3
Figure 1
In this study, meeting the recommended physical activity levels was more likely in subjects 60 years of age and older and in women with higher education or living in rural areas and was less likely in current smokers. No association was found with time spent watching television. As there are few data regarding the physical activity levels and patterns in France, our findings with a detailed questionnaire may give a first insight for comparison of the French situation with other countries where surveillance of physical activity is well established.7 In our sample, approximately two thirds of the men and half of the women achieved recommended levels of physical activity. These rates appear quite different from those that have been reported to date in US adults. Using the 1990 National Health Interview Survey, Jones et al.6 estimated that 32% of adults engaged in moderate LTPA at least 10 times over a 2-week period for a total duration of 30 minutes or more. Similar figures were reported in 2 more recent US studies.7,8 However, our data appear to be in line with recent results from a pan-European survey on physical activity involving representative samples of approximately 1000 subjects older than 15 years of age in all 15 member states of the European Union.26 Although the proportion of subjects meeting recommended levels was not specifically assessed in that study, on average, nearly three quarters of the population participated in some kind of LTPA.26 In accordance with our data, in the French subsample of that study, 54% of subjects engaged in more than 3.5 h/wk of LTPA, and women were found to participate in daily physical activity less and for shorter periods of time. Our results showing healthier physical activity patterns in subjects older than 60 years of age can be interpreted as increased LTPA participation with retirement, as recently confirmed by longitudinal data from the Atherosclerosis Risk in Communities Study cohort.27 Numerous studies have shown that performing some LTPA in comparison with being completely inactive is positively related to educational level.1,7,28 The relationship of education to compliance with current physical activity recommendations is less clear. Positive associations were documented in a national US cross-sectional study by Jones et al.,6 in the Behavioral Risk Factor Surveillance System,7 and in the National Physical Activity Surveys in Australia,9 whereas nonsignificant findings were found in a US study by Martin et al.8 In our sample, compliance with the PHR for physical activity was related to educational level, although this relationship was statistically significant after multivariate adjustment only in women. It is known that health risk behaviors such as smoking and inadequate levels of physical activity tend to cluster,11 as we indeed observed in the present study. In contrast, we did not find that LTPA levels or compliance with physical activity guidelines was related to time spent watching television in either gender. Our results are in agreement with the notion that sedentary behavior is not just the opposite of activity; that is, physical activity and television watching represent 2 distinct dimensions of lifestyle.29 Several studies have shown independent associations of LTPA and television watching with health outcomes such as obesity and other cardiovascular risk markers.3033 These findings suggest that public health policies should encourage both an increase in physical activity and a decrease in sedentary occupations, specifically, time spent watching television. Concerning obesity prevention, there is evidence from intervention studies that a reduction in television and videotape viewing and video game use can be effective, in children, to limit body weight gain over time.34 Along the same lines and according to the recent report of the Task Force on Preventive Services,35 the use of prompts to encourage using stairs instead of elevators or escalators has been recognized as an effective intervention. So far, few studies have addressed the relationships of physical activity behavior with physical environment, especially in Europe. The Health Survey for England, when considering only sports and exercise activities, showed that women living in more urban areas (inner London, mining areas, and industrial or urban areas) were less likely to be active than those in less urban areas (categorized as mature, prosperous, or rural).10 Findings from the Québec Heart Health Demonstration Project also showed higher physical activity levels in rural settings compared with suburban and inner city communities.36 Using postal code areas to categorize subjects as "coastal" or "inland" residents, Bauman et al.37 found that Australian adults who lived in close proximity to the coast were 27% more likely to report adequate activity levels. The authors hypothesized that environmental attributes of the coastal setting, such as proximity to recreational spaces and attractive, free-of-charge facilities, may positively influence physical activity participation. Such physical environment factors favoring access to outdoor recreational facilities could explain the higher levels of physical activity in rural women observed in our study. From a public health perspective, interventions that attempt to change the local environment to create opportunities for physical activity were shown to be effective.35 Access to places for physical activity can be created or enhanced by building walking trails or facilities or by providing training in use of equipment if necessary.35 In contrast, 2 recent US studies showed that rural adults were less likely than their urban counterparts to achieve the recommended levels of physical activity,14,15 and another study showed that the prevalence of leisure-time inactivity was inversely related to the degree of urbanization,38 a finding consistent with other US national surveys.12,39 The discrepancy with the European and Australian results may be partially attributable to differences in methodologies. First, the urbanization degrees used in these US studies are based on population size, whereas both the density of the population and the economic activity of the area were taken into account in our study.24 Moreover, whereas participation (yes/no) in physical activity during leisure time is 1 of the easiest measures to define in population surveys, the proportion of subjects meeting physical activity guidelines may vary according to the methods used to measure and score the levels of physical activity.40 Finally, urban/rural status is a proxy measure that is probably too global to measure for all environmental aspects effectively. To better characterize the environment in relation to physical activity patterns, variables describing transportation systems (transit availability, street characteristics) and land development patterns (density, land use) would be needed.12,13 An interesting finding of our study is that subjects who met the PHR reported, on average, more activities and spent more time practicing vigorous activity. For the same duration of activity, vigorous activity induces a higher energy expenditure than moderate activity. Thus, practicing some vigorous activity is a more efficient way to achieve the recommended level, considering that time constraints are frequently reported as barriers to exercise.11 Although the benefits of moderate-intensity activity cannot be overlooked and moderate-intensity activity can be adopted more easily by inactive subjects, some data indicate that regular vigorous activity has a higher protective effect for outcomes such as total and cardiovascular mortality.41 The present study has a cross-sectional design; thus, it is not possible to draw conclusions regarding causality. Another limitation is that it was limited to middle-aged subjects only, with an age range between 45 and 68 years. US data such as those from the Behavioral Risk Factor Surveillance System7,17 have shown that the percentages of subjects meeting the recommended physical activity levels were higher in younger age groups (1829 y) compared with other age groups (3064 y). In addition, all data were self-reported, and some misclassifications may have occurred, especially because of overreporting for physical activity. Another concern is that subjects were enrolled in a nutritional intervention study. Although characteristics of the participants of the SUVIMAX. study were found close to the national population with regard to geographic density and socioeconomic status,18 these subjects may have had a healthier lifestyle. Finally, because occupational and household-related physical activity was not taken into account, the proportion of persons who reach the recommended levels of physical activity may be underestimated, especially in men with lower levels of education, because they probably have more physically demanding jobs.6,42,43 The absence of household-related physical activity assessment may be another source of misclassification, particularly in women. In summary, in this study of middle-aged French subjects, factors positively associated with meeting recommended physical activity levels were age in both genders and education and a rural place of residence in women, whereas a negative association was found with smoking both in men and in women. To develop effective interventions and policies, there is a need for further investigation in European populations of the relationships of habitual physical activity levels to physical environment variables, such as urban/rural status. Comparing physical activity patterns between the subjects who did and did not meet current public health recommendations, we showed that the contribution of vigorous activity to total time spent being active was approximately 2 times higher in subjects meeting recommendations. This suggests that participation in some vigorous activity, when feasible and safe, may be a valuable strategy for increasing the proportion of subjects who attain the recommended levels, especially in population subgroups perceiving time constraints as an important barrier to exercise. Additionally, the data indicate that preventive programs should encourage both an increase in physical activity and a reduction of time spent in sedentary occupations.
The SUVIMAX. project received support from public and private sectors. Special acknowledgments are addressed to Fruit dOr Recherche, Lipton, Cereal, Candia, Kelloggs, CERIN, LU/Danone, Sodexho, LOréal, Estée Lauder, Peugeot, Jet Service, RP Scherer, France Telecom, Becton Dickinson, Fould Springer, Boehringer Diagnostic, Seppic Givaudan Lavirotte, Le Grand Canal, Air Liquide, Carboxyque, Klocke, Trophy Radio, Jouan, and Perkin Elmer.
Human Participant Protection
Contributors S. Bertrais designed the study, planned and performed the analyses, and drafted the article. S. Hercberg conceived and is the national coordinator of the SUVIMAX. study. P. Preziosi and P. Galan contributed to the study design and supervised data collection. L. Mennen assisted with the writing. J.-M. Oppert supervised and assisted with the study design and analyses, interpretation of the findings, and writing of the article. All authors reviewed drafts of the article. Accepted for publication July 18, 2003.
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