Physical inactivity: prevalence and associated variables in Brazilian adults

Purpose: To measure the prevalence of physical inactivity, and variables associated with it, in an adult southern Brazilian population.

Methods: Population-based cross-sectional study covering a multiple-stage sample of 3182 subjects aged 20 yr or more. Physical activity was assessed through the short version of the International Physical Activity Questionnaire (IPAQ), using home interviews with last-week recall. The questionnaire covers leisure, occupation, transportation, and housework activities. Physical inactivity was defined as fewer than 150 min·wk−1 spent in moderate or vigorous physical activities. The time spent in vigorous activities was multiplied by two.

Results: The prevalence of physical inactivity was 41.1%. After multivariate analyses, inactivity was positively associated with age and socioeconomic status, and inversely associated with self-reported health status. Those with white skin color and women who live alone rather than with a partner were more likely to have physical inactivity. Body mass index showed a significant U-shaped relationship with inactivity among men.

Conclusion: The prevalence of physical inactivity in this Brazilian adult population is high, even though lower than reported in studies of leisure-time activity alone in other populations. Studies in developing countries may be seriously biased if activities during labor, transportation, and housework are not assessed.

In many countries, the profile of morbidity and mortality changed greatly during the 20th century, with a decrease in the frequency of infectious diseases and an increase in lifestyle-related diseases (21). This phenomenon, known as the epidemiological transition, has changed the focus of epidemiological research. The risk factors associated with chronic diseases have been investigated in numerous epidemiological studies, which have provided evidence of the importance of physical activity as a preventative factor (5,19,23,25). Even relatively minor modifications, such as encouragement of active forms of transportation, have potential benefits against obesity, for example (4). In addition to its preventative role, physical activity is also recommended as an intervention to treat various diseases (1,14).

Measurement of physical activity level is therefore increasingly important in the context of public health. However, the literature shows that more than 30 methods have already been used to assess this parameter (17), making it difficult to compare the results. Due to feasibility and cost constraints, most epidemiologists have opted to use questionnaires for this purpose, and many such questionnaires are available (16). Appreciation of these two factors, the increasing interest and the difficulty of measurement, stimulated the creation of a standardized questionnaire to evaluate physical activity in population studies worldwide.

The International Physical Activity Questionnaire (IPAQ; http://www.ipaq.ki.SE) was therefore developed by researchers from various countries, with the support of the World Health Organization (WHO) and the Centers for Disease Control (CDC). Several versions of the questionnaire were created, according to the number of questions (long or short), the recall period (usual week or last 7 d) and the method of application (self-administered, or telephone or face-to-face interview) used. The IPAQ working group recommended face-to-face interviews only for developing countries.

Whereas in developed countries population-based studies on physical inactivity and associated variables have already been conducted (7,8,20), in many developing countries such data are lacking. Some epidemiological analyses already undertaken in Brazil have addressed this issue (3,9,10). However, data from these studies are restricted to specific groups, such as industrial workers (3) or adolescents (9). Other investigations (10) addressed only leisure-time activities. To the authors’ knowledge, no population-based study of physical inactivity has been conducted in Brazil addressing the four significant components of an individual’s activity level (leisure, occupation, housework, and transportation).

This study was motivated by the availability of a standardized questionnaire to assess physical activity, which would provide comparable prevalences of inactivity worldwide, as well as by the paucity of studies addressing the four components of physical activity, specially in Brazil. The objective of this study was to determine the prevalence of physical inactivity, and the variables associated with it, in a representative sample of adults resident in Pelotas, Brazil.