Physical activity is reported to play an important role in the prevention of some chronic diseases.1–3 Physical activity is a broad term that encompasses both leisure time activity and activities associated with daily life. Leisure time physical activity (LTPA) refers to recreational exercise or sports that are not related to regular work, housework, or transport activities, while work-related physical activity (WRPA) refers to activities and/or physical demands related to regular work.4 LTPA and WRPA appear to have distinct effects on health. For instance, high physical demands during WRPA are associated with a higher risk of cardiovascular diseases, whereas participating in LTPA is associated with lower risk.5,6 In view of these findings, LTPA and WRPA should be investigated together.

Several studies have analyzed the point prevalence of both LTPA and WRPA in various countries.7–9 While the level of LTPA may have increased in recent years, information on temporal trends at the population level is still sparse. A recent review identified only 25 articles on temporal trends in the adult population.10 Although this review did not identify any studies investigating temporal trends within the national Spanish population, some studies have been conducted in Catalonia, a region in the northeast of Spain.11–13 In addition, a study with data from Madrid has recently been published.14

One study found that WRPA in Catalonia decreased from 1992 to 200311 while another found that Catalonian adults became less inactive during their leisure time from 1993 to 2001;12 however, a third study found that this change was not clearly evident in Cornella, a city of Catalonia.13 Trends in LTPA and WRPA between 1995 and 2008 were recently investigated in the region of Madrid and LPTA was found to have declined, mainly in light and moderate activities, accompanied by greater occupational physical inactivity.14

Information on temporal trends in physical activity can help to identify population subgroups at risk for inactivity, evaluate public health interventions, and develop specific physical activity interventions adapted to each country.15 A national analysis of temporal trends in LTPA and WRPA within Spain is warranted to identify potential factors associated with physical activity in the working population. To the best of the authors’ knowledge, no published study has previously determined time trends in physical activity in the working population within the last 20 years in Spain.

The main objectives of this study were: (i) to describe time trends in the prevalence of LTPA and WRPA among Spanish working adults from 1987 to 2006; and (ii) to determine the association of socio-demographic factors, self-rated health status, comorbidity and lifestyle behaviors with LTPA and WRPA.

The total number of participants aged 18-64 years who reported working at the time of the surveys during the entire period was 57,016 (22,046 women and 34,970 men). The employment rate significantly increased for women from 25.9% in 1987 to 52.2% in 2006 (p <0.001) and only slightly for men (71.8% to 75.3%). The mean age significantly increased from 35.8 to 38.3 years for women (p <0.05) but remained unchanged for men. In all surveys, women were significantly younger than men (p <0.05). The distribution of sociodemographic factors and health-related variables of the participants included according to the SNHIS conducted between 1987 and 2006 is shown in Tables 1 and 2.

Time trends for LTPA and WRPA by age group and gender are summarized in Table 3. Overall, women showed a lower prevalence of LTPA and WRPA than men (p <0.05, fig. 1). For both genders, the prevalence of all dependent variables was consistently higher in the youngest age group. Crude time trends analysis by age group and gender showed that the prevalence of LTPA increased in all age groups in both genders (p <0.001). Women showed significant increases in LTPA, particularly in the subgroups aged 18-34 and 50-64 years (p <0.001), whereas the increases for men were greater in the youngest group (p <0.001). The highest prevalences of LTPA and WRPA were found in the 2006 SNHIS for both genders, with values of 54.2% and 17.1% for women, and 57.8% and 31.5% for men, respectively (fig. 1).

Figure 1.

Time trends for the prevalence of leisure time physical activity (LTPA) and work-related physical activity (WRPA). Values are from the Spanish National Health Interview Survey and are expressed as percentages.

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This study found an increase in LTPA and WRPA over the last two decades (1987-2006) among the Spanish working population. Younger age, higher educational level, and being a non-smoker were associated with a higher likelihood of reporting LTPA, whereas being married, having worse self-perceived health status, and sleeping ≥ 8hours/day were associated with an increased probability of reporting WRPA. In contrast, being married, worse self-perceived health, and obesity were associated with lower LTPA, while being an ex- or non-smoker was associated with a reduced probability of reporting WRPA.

This is the first study to include national data over a 20-year period from the Spanish working population, as previous studies have been conducted in Catalonia11–13 or Madrid.14 We found an increase in LTPA over the last two decades in the Spanish working population, which concurs with studies from Canada,18 Sweden,19 England,20 USA,21 Finland,22 and Denmark,23 where an increase in LTPA over the last 15 years has also been found.

Analyzing data from the Behavioral Risk Factor Surveillance System from 1994 to 2004, the Centers for Disease Control reported that the prevalence of LTPA increased from 1994 to 2007.24 A systematic review including 25 studies on temporal trends among adults found that 17 studies (68%) detected that physical activity levels increased over time, three (12%) concluded that physical activity decreased, and the remaining five (20%) reported unchanged physical activity levels.9 A recent study conducted in Madrid found decreased LTPA; however, the data were collected from an urban, not a national, population.14 Comparisons across studies is challenging as the definitions of LTPA vary considerably, ranging from physical activity data based on questionnaires to physical fitness data based on aerobic tests.10 In addition, our study focused on LTPA and WRPA in the working population, whereas most studies have been performed in the general population.

In their review, Knuth and Hallal10 found that although LTPA increased, WRPA seemed to decrease. A study conducted in Finland showed an increase in LTPA and a decrease in WRPA.22 Furthermore, two previous studies conducted in Catalonia also reported a decrease in WRPA11 and an increase in LTPA12 from 1993 to 2001. These results conflict with those of the present study, as we also found an increase in WRPA in Spanish adults. These differences may be explained by the inclusion of only working people in this study. In any country, historical, cultural, and social factors may influence the prevalence of physical activity.25 In addition, because a self-reported measure of LTPA was used in our surveys, social desirability may have affected the participants’ attitudes due to an increased focus on physical activity in society over time.In agreement with other studies,20,26 the present study also found that women had a lower prevalence of LTPA and WRPA than men. Similar to our findings, gender differences in LTPA have been reported by Cornelio et al.13 One reason why women might report less LTPA than men could be a lower adherence to exercise.27

We found that younger age, higher educational level, and being an ex- or non-smokers were associated with a higher likelihood of practicing LTPA, a finding that concurs with prior research.19,22,28–30 Younger, non-smoking people can be expected to participate more in LTPA. Additionally, being married, having worse self-perceived health, and obesity were associated with a lower likelihood of LTPA. Self-reported health status has been found to be a good predictor of physical activity,31 and poor self-rated health is associated with lower physical activity.32

Interestingly, we found that worse self-perceived health status was associated with lower participation in LTPA but with higher participation in WRPA. One explanation may be that both people with no time to participate in physical activity during their leisure time may and those with higher physical activity demands at work might perceive their health as worse. This finding was more evident in men, because not participating in LTPA increased the probability of reporting WRPA, and could be expected as individuals with higher levels of WRPA may have less time or may be too tired after work to participate in LTPA. Additionally, persons included in the surveys may have been a selected population with higher demands at work.

Finally, being married, worse self-rated health status, and sleep ≥ 8hours/day were associated with increased WRPA, whereas older age, higher educational level, and being an ex- or non-smoker were associated with a lower probability of reporting WRPA. Our results are in agreement with those of previous studies that found that education was the most important determinant of WRPA, with higher rates of WRPA among persons with less education.33–35 Artazcoz et al36 found that higher WRPA was associated with being married, poor health status and lack of participation in LTPA.

In a European study, Vaz de Almeida et al37 identified the following risk groups for physical inactivity: women, persons with lower education, older people, and the overweight or obese. Therefore, programs to promote physical activity should focus on and adapt to the different groups identified in each country in order to increase participation and to maintain participation in those already engaged in activities.

The strengths of this study include its large sample size, a randomly selected population, use of a standardized survey (SNHIS) spanning 20 years, and pre-training of data collectors. However, this study also presents some limitations. Firstly, we used a self-reported measure of LTPA and WRPA and there was potential for recall and respondent bias when answering the questions. In addition, the validity of the questions included in the surveys related to LTPA and WRPA has not been analyzed, which limits the results of the study. The use of objective measures of LTPA and WRPA can complement self-reported measurements to avoid bias (i.e., quantification of physical activity levels by calculating MET); however, this is not generally feasible in large-scale population-based surveys due to extensive costs. Additionally, objective measurements for assessing physical activity only began to used fairly recently and obtaining data covering a time span of 20 years is difficult. In this scenario, questionnaires remain the most cost-effective methods for assessing physical activity in large-scale population-based studies. Even though individuals tend to overestimate their possible participation in exercise and underestimate sedentary behaviors, questionnaires are extremely useful for assessing patterns, frequency and time trends.38 Indeed, the use of the same national population-based survey for 20 years supports the generalization of our results because this survey allows representative population-based sample sizes to be included. Nevertheless, the use of self-reported questions on physical activity in the current study remains a drawback.

Despite these limitations, our findings provide additional insight into demographic aspects of LTPA and WRTA in Spanish working adults, for which there is little information nationwide. Therefore the data found in the current study constitute a valuable tool for examining trends in the Spanish working population and the effectiveness of campaigns to promote physical activity among this population, although caution should be exercised at this stage. Future studies that investigate the possible reasons why people do not practice physical activity, whether LTPA or WRPA, are required. Indeed, analysis of preferred activities could aid the promotion of physical activity in the working and general populations. We suggest that future surveys should include these questions to improve the information on LTPA and WRPA with the aim of enhancing healthcare promotion services.

In conclusion, we found an increase in LTPA and WRPA over the last two decades among the Spanish working population. Distinct factors were associated with a higher or lower likelihood of practicing LTPA and/or WRPA in women and men. Identifying these factors may lead to improvements in targeting at-risk groups, which could in turn reduce the prevalence of inactivity in this population.

All the authors contributed equally to the conception and design of the study, analysis and interpretation of the data, and drafting and critical review of the manuscript. All the authors have approved the final version for publication.

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