Meeting Physical Activity Recommendations for Colon Cancer Prevention Among Japanese Adults: Prevalence and Sociodemographic Correlates

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1 Journal of Physical Activity and Health, 2011, 8, Human Kinetics, Inc. Meeting Physical Activity Recommendations for Colon Cancer Prevention Among Japanese Adults: Prevalence and Sociodemographic Correlates Kaori Ishii, Ai Shibata, and Koichiro Oka Background: Although physical activity is associated with a lower risk of colon cancer, few studies have described the physical activity required for colon cancer prevention in various sociodemographic subgroups. The current study examined the prevalence and sociodemographic correlates of attaining the 2 recommended physical activity criteria for colon cancer prevention among Japanese adults. Methods: The sample included 5322 Japanese adults aged 20 to 79 years. Seven sociodemographic attributes (eg, gender, age, education level, employment status) and the International Physical Activity Questionnaire were assessed via an Internet-based survey. The odds of meeting each physical activity criterion by sociodemographic variables were calculated. Results: Overall, 23.8% of the study population met the criterion of 420 minutes of moderate-intensity activity, and 6.4% met the criterion of 210 minutes of vigorous activity. Being male, highly educated, employed, living with another person, being married and having a higher household income were significantly correlated with the attainment of recommendations. Conclusions: Participants who met the 2 activity recommendations differed in gender, education level, employment status, marital status, living conditions, and household income. The findings of the current study imply that strategies to promote more intense physical activity in all demographic groups may be necessary. Keywords: moderate-to-vigorous physical activity, Internet-based survey, public health Colon cancer is one of the most common cancers in developed countries. Since the 1980s, the age-adjusted incidences of colon cancer have increased and are currently high among both males and females in Japan. 1 Many studies have consistently confirmed that a healthy lifestyle that includes low alcohol consumption, a healthy diet, no tobacco use, and physical activity can prevent colon cancer. 2,3 Therefore, an improvement in the lifestyles of individuals is necessary for the prevention of colon cancer. Recent studies have suggested that an increase in daily physical activity may reduce the risk of cancer. 4 7 A meta-analysis also revealed an approximate 24% reduction in colon cancer risk for individuals who were physically active. 3 In fact, physically active individuals were reported to have half as much risk of developing colon cancer than individuals who live a relatively sedentary lifestyle. 7,8 Thus, increasing physical activity should be a priority for colon cancer prevention. Available evidence suggests that more intense physical activities are more effective than low-intensity activities in preventing colon cancer. 3,9,10 A review study suggested that either 420 minutes per week of at least moderate-intensity The authors are with the Faculty of Sport Sciences, Waseda University, Tokorozawa, Japan. activity or 210 minutes per week of vigorous activity can contribute significantly to colon cancer prevention. 11 Although physical activity is associated with a lower risk of colon cancer, a large proportion of the population in developed countries is not sufficiently physically active to obtain this health benefits The World Health Organization Guide for Population-based Approaches to Increase Levels of Physical Activity encourages national action plans, including interventions, to reach the whole population. 15 This guide also emphatically indicates that some interventions may need to be tailored to meet the requirements of specific population groups such as adults, children, older persons, employees, people with disabilities, women, men, and cultural groups. Hence, an understanding of the level of physical activity among specific population groups is important to design strategies that aim to promote physical activity for colon cancer prevention. To the best of our knowledge, only 1 study from Australia 16 has described the fulfillment of the physical activity criteria for colon cancer prevention across various demographic groups. However, previous studies have found that the relationship between physical activity and sociodemographic status varies among countries Therefore, it is essential to examine the sociodemographic factors associated with performing physical activity for colon cancer prevention in the Japanese population. The current 907

2 908 Ishii, Shibata, and Oka study examined the prevalence and sociodemographic correlates of attaining the 2 different physical activity recommendations for colon cancer prevention among Japanese adults. Methods Participants and Data Collection In the present cross-sectional study, data were collected from an Internet-based survey of registrants from a 2008 Japanese Internet research service organization. This organization owned approximately 290,000 voluntarily registered samples and had obtained detailed sociodemographic data for each sample. The current study examined 5322 Japanese adults aged 20 to 79 years and stratified these adults by gender and age bracket (20 29 years, years, years, and >50 years). A total of 9481 potential respondents were randomly selected, and registrants received a website address via an invitation from the Internet research service organization (response rate = 56.1%). To estimate the representativeness of this sample, the age-adjusted prevalence of married and employed individuals in the current study were compared with those in the national survey. In the current study, the prevalence of married participants was 58.6% for males and 70.5% for females, whereas in the Japanese Population Census Survey of 2005, the age-adjusted prevalence was 56.7% and 62.3%, respectively. 21 With regard to the employment status, 80.6% of males and 30.7% of females in the current study were employed, whereas 80.5% of males and 60.6% of females worked full-time or part-time in the national survey. 22 The participants in the current study may have included more unemployed individuals; this indicates that the current study sample was slightly different from the general population. The Internet-based questionnaire was provided as a link on a website, which was then accessed by the registrants. All participants signed an informed consent form before answering the questionnaire. The current study received prior approval from the Ethics Committee of the Faculty of Sports Sciences, Waseda University, Japan. Measures Sociodemographic Attributes. Gender, age, education level, employment status, marital status, living conditions, and household income level were assessed by the self-administered questionnaire. Participants chose the most suitable answer from the categories of education level (graduate school, university, 2-years university, career college, high school, junior high school), employment status (office worker, independent businessman, professional, public official, student, housewife, part-time worker, unemployed), marital status (married, unmarried), living conditions (number of people cohabitating with, living alone), and household income (<3,000,000 yen, <5,000,000 yen, <7,000,000 yen, <10,000,000 yen, 10,000,000 yen). Physical Activity. The level of physical activity was estimated from the Japanese version of the short form of the International Physical Activity Questionnaire (IPAQ). 23 This self-administered questionnaire assessed the frequency and duration of walking for all purposes such as work, transport and recreation, moderate physical activity and vigorous physical activity, and sedentary activity for a usual week. The reliability and criterion validity of the scale were confirmed in a previous study of the Japanese population by using an accelerometer. 23 The total number of weekly minutes of moderate and vigorous physical activity was computed according to the IPAQ scoring manual. 24 Statistical Analyses Multiple logistic regression analyses were conducted to examine the independent relationships between each sociodemographic variable and the 2 physical activity criteria adjusted for all sociodemographic variables. Responses to sociodemographic attributes were categorized as follows: gender (male, female), age (20 29 years, years, years, >50 years), education level (4 years of university education or greater, 2 years of university education or equivalent, high school, junior high school), employment status (gainfully employed, unemployed), marital status (married, unmarried), living conditions (living with another individual, living alone), household income level (<3,000,000 yen, <5,000,000 yen, <7,000,000 yen, <10,000,000 yen, 10,000,000 yen). On the basis of the estimated weekly total minutes of physical activity, the participants were assigned to either meeting or not meeting the requirements according to 2 criteria: 420 minutes per week of at least moderate-intensity activity (moderate activity criterion) and 210 minutes per week of vigorous activity (vigorous activity criterion). For these analyses, all sociodemographic variables were included in the model. The odds of meeting each physical activity criterion by sociodemographic variables were calculated overall and by gender. A P-value of < 0.05 was considered statistically significant. All statistical analyses were performed with SPSS 12.0J for Windows. 25 Results Participant Characteristics Table 1 shows the characteristics of the participants. For the overall study sample, the mean age (standard deviation; SD) was 40.2 (13.9) years. The percentage of higher educated individuals was 66.3% in males and 34.5% in females. The mean minutes of at least moderate physical activity per week (SD) was (682.0) in male and (617.7) in female. Only 23.9% of the population met the criterion of moderate activity, and 6.4% met the criterion of vigorous activity. The prevalence of participants who met both criteria and 5 sociodemographic variables (education level, employment status, marital

3 Table 1 Descriptive Characteristics (Numbers and Percentages) for All Subjects and Subsamples Overall Males Females n = 5322 n = 2662 n = 2660 Age group n (%) n (%) n (%) P* (25.0) 665 (25.0) 665 (25.0) (25.0) 664 (24.9) 666 (25.0) (25.0) 665 (25.0) 666 (25.0) (25.0) 668 (25.1) 663 (24.9) Mean ± SD 40.2 ± ± ± 11.8 Educational level 4-years university or greater 2682 (50.4) 1764 (66.3) 918 (34.5) 2-years university or equivalent 1302 (24.5) 325 (12.2) 977 (36.7) <.001 High school or junior high school 1312 (24.7) 560 (21.0) 752 (28.3) Employment status Employed 2962 (55.7) 2145 (80.6) 817 (30.7) <.001 Unemployed 2238 (42.1) 453 (17.0) 1785 (67.1) Marital status Married 3437 (64.6) 1560 (58.6) 1877 (70.5) <.001 Unmarried 1885 (35.4) 1102 (41.4) 783 (29.4) Living condition Living with others 4573 (85.9) 2167 (81.4) 2406 (90.5) <.001 Living alone 749 (14.1) 495 (18.6) 254 (9.5) Household income level <3,000,000 yen 848 (15.9) 396 (14.9) 452 (17.0) <5,000,000 yen 1474 (27.7) 718 (27.0) 756 (28.4) <7,000,000 yen 1225 (23.0) 641 (24.1) 584 (22.0) <10,000,000 yen 1071 (20.1) 533 (20.0) 538 (20.2) 10,000,000 yen 704 (13.2) 374 (14.0) 330 (12.4) Vigorous physical activity, min/week Mean ± SD 50.9 ± ± ± Moderate physycal activity, min/week Mean ± SD 86.6 ± ± ± Walking, min/week Mean ± SD 211 ± ± ± minutes per week of moderate-intensity activity Not meeting 4052 (76.1) 1964 (73.8) 2088 (78.5) <.001 Meeting 1270 (23.9) 698 (26.2) 572 (21.5) 210 minutes per week of vigorous activity Not meeting 4982 (93.6) 2437 (91.5) 2545 (95.7) <.001 Meeting 340 (6.4) 225 (8.5) 115 (4.3) Note. Total numbers of respondents are not always equal because of missing data. * Comparisons between men and women with the chi-square test. 909

4 910 Ishii, Shibata, and Oka status, living conditions, and household income level) were significantly different depending on their gender. Association Between the Sociodemographic Variables and the Physical Activity Criteria Tables 2 and 3 show the odds ratios (ORs) of participants who met the 2 physical activity criteria overall and by gender, respectively. Overall, males were significantly more likely to meet the 2 physical activity criteria than females. In gender stratified analyses, among the male participants, highly educated participants were significantly less likely to meet both physical activity recommendations. Among male participants, those who were employed (OR = 0.73; 95% confidence interval (CI) = ) and among female participants, those who were 40 to 49 years old (OR = 0.71; 95% CI = ) and living with another person (OR = 0.59; 95% CI = ) were significantly less likely to meet the moderate activity criterion. Among female participants, those who were married (OR = 1.68; 95% CI = ) and had a higher household income (OR = 1.56; 95% CI = ) were significantly more likely to meet the moderate activity criterion. Age, marital status, living conditions, and household income levels in male participants and the education level in female participants were not associated with attaining either physical activity criteria. Overall, a linear trend was observed in the association of the education level with meeting moderate physical activity criteria (P =.011). Among male participants, a linear trend was observed in the association of education level with (P <.001) with meeting the moderate physical activity criterion and the association of education (P =.024) and household income levels (P =.015) with meeting the vigorous physical activity criterion. Discussion The current study examined the prevalence and sociodemographic correlates of meeting 2 different physical activity recommendations for colon cancer prevention among Japanese adults. The prevalence of meeting these physical activity recommendations was low. It was estimated that 23.8% of adults in Japan met the criterion of performing moderately intense activity for at least 420 minutes per week, and 6.4% met the criterion of performing vigorous activity for at least 210 minutes per week, including walking for all purposes such as work, transportation, and recreation and moderate and vigorous physical activity. In a study on Australian adults, only leisure-time physical activities were examined, and it was determined that the percentage of the population achieving these criteria was 26.0% for 420 minutes of moderate-intensity activity, and 10.3% for 210 minutes of vigorous activity. 16 Previous studies suggested that individuals who engage in more intense physical activities have a lower risk of developing colon cancer. 3,9,10 These findings indicate that more intense physical activity should be promoted in the Japanese population for colon cancer prevention. The current study showed that sociodemographic characteristics were independently related to meeting the physical activity recommendations for colon cancer prevention. Participants who met each recommended physical activity criterion differed by gender, education level, employment status, marital status, living conditions, and household income from those who did not meet the criteria. Different sociodemographic characteristics were associated with meeting the 2 physical activity criteria. Only males and those with lower levels of education were likely to meet the vigorous physical activity criteria. These findings are important for designing better strategies to promote vigorous physical activity targeted at specific groups. For example, using the behavioral change theories and additional focus on the built environment 26,27 for aiming to increase vigorous physical activity may be effective. Moreover, in the current study, individuals with a high education level and employment status were less likely to meet the physical activity recommendations for colon cancer prevention. Previous studies suggested that highly educated and employed individuals have little discretionary time for exercise This suggests that time-saving interventions such as lifestyle intervention rather than structured exercise programs, internet programs rather than face-to-face programs, and individual programs rather than group programs may be more effective for these individuals. These data are similar to those of previous studies that estimated the recommended levels of physical activity for colon cancer prevention. 16 Because these studies used different scales to measure physical activity, their findings should be compared and interpreted carefully. These previous studies 31,32 suggested that the relationship between physical activity and sociodemographic variables differed according to the domain of physical activity. The current study used a scale to measure moderate to vigorous physical activities, including activity for all purposes such as work, transportation, and recreation; however, the Australian study only examined moderate to vigorous leisure-time physical activities. Therefore, the comparison between the results of the current study and the Australian study by examining the association between the sociodemographic variables and the physical activity criteria must be undertaken carefully. A study conducted in Australia 16 showed that those who met 2 of the recommended physical activity criteria were more likely to be younger, male, and highly educated. In contrast, males and those with lower levels of education were more likely to meet the criterion of moderately intense activity for at least 420 minutes per week; in the current study, only males were more likely to meet the criterion of vigorous activity for at least 210 minutes per week. Males were consistently more likely to meet the recommended physical activity criteria than females; a similar tendency was observed in The National Health and Nutrition Survey 12 and in studies on the prevalence of physical activity. 19,20,33,34

5 Physical Activity for Colon Cancer Prevention 911 Table 2 Odds Ratios and 95% Confidence Intervals for Participants Who Were Engaged in a Physical Activity by Multiple Logistic Regression Analyses Gender 420 minutes per week of moderate-intensity activity 210 minutes per week of vigorous activity OR 95% CI P OR 95% CI P Males < <.001 Females Age group P for trend Educational level 4-years university or greater years university or equivalent High school or junior high school P for trend Employment status Employed Unemployed Marital status Married Unmarried Living condition Living with others Living alone Household income level 10,000,000 yen <10,000,000 yen <7,000,000 yen <5,000,000 yen <3,000,000 yen P for trend Abbreviations: OR, odds ratio; CI, confidence interval. Note. Odds ratios were calculated adjusted[auq1] for all variables listed in the table. Linear trends for ORs were tested using the logistic regression model with the exposure categories as ordinal variables. In previous studies, individuals with a high level of education were more likely to meet the recommendations; however, in the current study, males with lower levels of education were more likely to meet the recommendations. The Employment Status Survey 22 showed that in the Japanese population, highly educated individuals were engaged in sedentary work such as clerical jobs, whereas individuals with a low level of education were engaged in physically active work such as assembly line jobs. Therefore, the inclusion of occupational physical activity as a measure of physical activity may have influenced the results of the current study. However, only

6 Table 3 Odds Ratios and 95% Confidence Intervals for Participants Who Were Engaged in a Physical Activity by Multiple Logistic Regression Analyses According to Gender 420 minutes per week of moderate-intensity activity Males (n = 2662) Females (n = 2660) 210 minutes per week of vigorous activity 420 minutes per week of moderate-intensity activity 210 minutes per week of vigorous activity Age group OR 95% CI P OR 95% CI P OR 95% CI P OR 95% CI P P for trend Educational level 4-years university or greater < years university or equivalent High school or junior high school P for trend Employment status Employed Unemployed Marital status Married Unmarried Living condition Living with others Living alone Household income level 10,000,000 yen <10,000,000 yen <7,000,000 yen <5,000,000 yen <3,000,000 yen P for trend Abbreviations: OR, odds ratio; CI, confidence interval. Note. Odds ratios were calculated adjusted for all variables listed in the table. Linear trends for ORs were tested using the logistic regression model with the exposure categories as ordinal variables. 912

7 Physical Activity for Colon Cancer Prevention 913 a limited number of studies have investigated this issue; therefore, further studies are required to confirm the association between physical activity and sociodemographic characteristics. In the current study, females, individuals who were middle aged, highly educated, employed, living with another person, and with a low household income were less likely to meet the physical activity recommendations for colon cancer prevention. Previous studies have indicated that the characteristics of participants who met the general recommendations for health promotion differed by country Four previous studies have been conducted on large populations that comprised a wide range of age groups However, a comparison with and an interpretation of these studies should be performed carefully because they were conducted using different physical activity domains and recommendations. The current study, along with a study conducted in Canada, 18 used the 3 metabolic equivalents (METs) h -1 day -1 recommendation to estimate leisure-time physical activity, and a study in Australia 17 used the 150 min total physical activity recommendation, including all walking and moderate and vigorous physical activities; all these studies showed that males were more likely to meet the physical activity recommendations. A study performed in Japan 20 used a recommendation of 23 METs h -1 week -1 for all purposes such as work, transportation, and recreation, and studies in Canada, 18 Australia, 17 and the United States 19 used recommendations of at least 30 min of physical activity for 5 days per week or at least 20 minutes for 3 days per week to estimate leisure-time physical activity or physical activity for household chores and transportation; all these studies showed that younger age groups were more likely to meet these recommendations. However, the above-mentioned associations were not clearly observed in the current study. Thus, sociodemographic correlates of different physical activity recommendations may differ. Current physical activity recommendations promote lower intensity physical activities than those recommended for colon cancer prevention. 13 However, as suggested by the findings of the current study, it is necessary to effectively promote a more intense level of physical activity for colon cancer prevention targeted at specific populations, namely, females, highly educated individuals, employed individuals, unmarried individuals, individuals living with another person, and individuals with a low household income. This study has several strengths. First, few studies have examined the prevalence and sociodemographic correlates of meeting the physical activity recommendations for colon cancer prevention. Furthermore, no such study has been conducted in Japan, which has important cultural differences from other countries. For example, the prevalence of overweight participants (BMI 25.0 kg/m 2 ), which can be a risk factor for colon cancer, was 29.6% in males and 19.0% in females in Japan 12 compared with substantially higher prevalence rates observed in some Western countries (eg, the prevalence of overweight participants was 70.8% in males and 61.8% in females in United States adults 35 ). Therefore, the current study contributes to an understanding of the prevalence of meeting the physical activity recommendations for colon cancer prevention among specific groups of Japanese adults. Second, the current study examined multiple sociodemographic correlates. Previous studies focused on a small number of characteristics such as gender, age, educational level, and employment status, whereas the current study investigated a larger number of attributes to help promote meaningful physical activity for specific groups of Japanese adults.this study also has a few limitations. First, the current study was conducted in an Internet setting. A potential limitation of Internet surveys is that respondents tend to be young, educated, and with a higher income. 36 The participants in the current study may have included more unemployed individuals than those in the general Japanese population. Furthermore, previous studies 37,38 indicated that participants with high levels of leisure-time sedentary behavior (eg, Internet and computer use) reported low levels of physical activity. According to 2005 Census data, age-weighted prevalence estimates for the Japanese population indicated that 25.2% of the population met the criterion of moderate activity, and 6.5% met the criterion of vigorous activity. In the current study, the percentage of individuals who met the criteria was lower: 1.6% for moderate activity and a similar percentage for vigorous activity. Therefore, the current study sample may have underestimated the prevalence of individuals meeting the physical activity recommendations for colon cancer prevention compared with the general Japanese population. Therefore, we cannot exclude the possibility of a selection bias. Second, the current study used a self-administered questionnaire to examine physical activity; however, the reliability and validity of the scale were comprehensively examined and confirmed in a previous study. 23 Respondents of the current study were considered as a representative population because the Internet research service organization that conducted the current study used randomly selected people from a pool of 290,000 people so that an equal number of responses were obtained from each gender and age group between 30 to 79 years. Moreover, the respondents included those living in various regions with diverse occupations, and 94.7%, 91.7%, 81.2%, and 40.3% of the Japanese population in their 30s, 40s, 50s, and 60s 70s, respectively, use the Internet; 39 this may aid to guarantee the representativeness of the survey in any way. Since no other study has been conducted on this topic in the Japanese population, the findings of the current study will be important for the development of intervention strategies for population-based cancer prevention and will contribute to the promotion of physical activity for cancer prevention.

8 914 Ishii, Shibata, and Oka Conclusion The prevalence of individuals engaging in sufficient physical activity for colon cancer prevention was low. Male participants and individuals who were highly educated, employed, living with another person, married, and had a higher household income were significantly more likely to meet the physical activity criteria than female participants and individuals with a low level of education, unemployed, living alone, unmarried and with a low household income. The findings of the current study imply that strategies to promote more intense physical activities in all demographic groups may be necessary for colon cancer prevention. Acknowledgments This investigation was supported by the Health and Labour Sciences Research Grants for Clinical Cancer Research (No. 20 3) from the Japanese Ministry of Health, Labour, and Welfare, and the Grants-in-Aid for Scientific Research (No ) from the Japan Society for the Promotion of Science. References 1. 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