Journal of Physical Activity and Health, 2014, 11, 790-800 http://dx.doi.org/10.1123/jpah.2012-0110 © 2014 Human Kinetics, Inc.

Official Journal of ISPAH www.JPAH-Journal.com ORIGINAL RESEARCH

Intrapersonal and Social Environment Correlates of Leisure-Time Physical Activity for Cancer Prevention: A Cross-Sectional Study Among Canadian Adults Fabiola E. Aparicio-Ting, Christine M. Friedenreich, Karen A. Kopciuk, Ronald C. Plotnikoff, and Heather E. Bryant Background: Little is known about the intrapersonal and social factors associated with sufficient physical activity (PA) for cancer prevention, which is greater than for cardiovascular health. Methods: 1087 and 1684 randomly selected men and women, age 35–64, completed self-administered questionnaires on PA behavior and psycho-social characteristics. Using gender-stratified logistic regression, we investigated correlates of compliance with Canadian Society for Exercise Physiology PA guidelines for general health (150 min/wk), and the American Cancer Society (ACS; 225 min/wk) and World Cancer Research Fund/American Institute for Cancer Research (WCRF/AIRC; 420 min/wk) guidelines for cancer prevention. Results: Only 39% and 19% of men and women met ACS and WCRF/AICR guidelines, respectively. Self-efficacy, scheduling PA and friend social support were positively correlated with recommended PA for cancer prevention. In men, poor self-rated health and perceived negative outcomes were negatively correlated and hypertension was positively correlated with meeting cancer prevention guidelines. For women, not being married and having a companion for PA were positively correlated with meeting cancer prevention guidelines. Conclusions: Few adults participate in sufficient PA for cancer risk reduction. Multidimensional public health strategies that incorporate intrapersonal and social factors and are tailored for each gender are needed to promote PA for cancer prevention. Keywords: gender differences, guidelines, cancer risk-reduction, psycho-social, Canada Cancer remains a leading health burden with nearly 12.7 million estimated incident cases and 7.6 million deaths worldwide.1 In Canada, an estimated 177,800 incident cases and 75,000 deaths in 2011 made cancer the second leading cause of mortality and morbidity.2 Physical activity (PA) has been identified as a modifiable lifestyle risk factor and a target for cancer prevention strategies.3 Strong epidemiological evidence suggest a 25%–30% reduction in the risk of colon, breast, and endometrial cancers in physically active adults.4 Given that colon and breast cancers account for an estimated 12% and 28% of all new cancer cases, preventing these 2 cancers alone could have a significant impact on population health. Several health-related organizations have proposed their own guidelines to encourage inactive populations to engage in PA.5 In Canada, the Canadian Society for Exercise Physiology (CSEP) has developed guidelines that recommend a minimum of 150 minutes of moderate to vigorous aerobic PA per week, emphasizing that more PA provides greater health benefits.6 These recommendations are consistent with the Global Recommendations on Physical Activity for Health developed by the World Health Organization.7 CSEP also recommends that adults incorporate strength training activities at least 2 days per week; however, this study will focus only on levels of aerobic activity achieved. Although the specific dose of PA necessary for cancer prevention is not yet clear,4 research to date suggests that the greatest gains Aparicio-Ting is with the Dept of Community Health Sciences, University of Calgary, Calgary, Alberta, Canada. Friedenreich and Kopciuk are with the Dept of Population Health Research, Alberta Health Services, Calgary, Alberta, Canada. Plotnikoff is with the School of Education, University of Newcastle, Newcastle, NSW, Australia. Bryant is with Canadian Partnership Against Cancer, Toronto, Ontario, Canada. 790

in cancer risk reduction are made when PA exceeds the minimum 150 minutes per week recommended for general health benefits. In 2006, the American Cancer Society (ACS) recommended at least 225 minutes per week of moderate and preferably vigorous PA for colon and breast cancer risk reduction.8 Most recently, the World Cancer Research Fund with the American Institute for Cancer Research (WCRF/AICR) has recommended that adults participate in at least 60 minutes of moderate daily PA or 420 minutes per week, for cancer risk reduction.9 Despite the health benefits of PA, 35%–71% of adults in the European Union10 and the United States11 are insufficiently active. In Canada, recent population estimates suggests that as few as 15% of adults engage in sufficient total daily PA for health maintenance.12 Very few studies have attempted to estimate the prevalence of sufficient PA for cancer prevention. An Australian study found that only 26% of adults participated in at least 420 minutes of moderate PA per week.13 Similar estimates were also found in a sample of Canadian adults based on self-reported leisure-time physical activity (LTPA).14 These findings suggest a need for understanding of the factors that influence PA behavior at levels sufficient for cancer prevention so that novel intervention strategies can be designed. More recently, research has focused on an ecological framework for understanding the influences of interrelated personal, psychological, social, and environmental factors on PA behavior.15,16 Personal characteristics most commonly associated with PA behavior are age, gender, body mass index, self-rated health status, and socioeconomic status.16,17 PA self-efficacy, the self-confidence that one can overcome barriers to be physically active, is the psychological factor most consistently linked to PA behavior.16 Other psychological correlates include outcome expectations, perceived barriers, attitudes, subjective norms, and the decisional balance

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Correlates of Physical Activity for Cancer Prevention  791

between the advantages and disadvantages of being active.16,18 Components of the social environment, such as social support and having a companion for PA, have also been positively associated with PA behavior.19 Importantly, different PA correlates have been observed for men and women. Women more commonly report body image, appearance and health concerns as important reasons for being physically active and time constraints as a barrier to being active.20–22 Similarly, social support from significant others has been associated with achieving 150 minutes of moderate LTPA in women but not men.23 This study was undertaken to identify and compare genderspecific correlates of participating in sufficient LTPA to meet PA guidelines from CSEP for general health and from ACS and WCRF/ AICR for cancer prevention. While occupational, household and transportation activities can also contribute to overall health, leisuretime physical activity is the most modifiable type of PA and has been the main target of PA promotion.9 LTPA is also more likely to be intentional and at moderate and vigorous intensity than the majority of daily household and occupational activities.8 Evidence suggests that PA at higher intensities may result in a greater shift in inflammation biomarkers, insulin resistance, and sex and metabolic hormone levels that favor cancer risk reduction than light intensity activities.24,25 Therefore, leisure activity is a logical target for population health interventions aimed at cancer prevention and was the focus of this study. Taking an ecological perspective,26 this study included personal, psychological, and social environment variables previously associated with PA behavior at minimum levels recommended for general health (150 min/wk).16,17,20,23 However, this is the first study to date to explore if these associations still hold at higher PA levels recommended for cancer prevention benefits.

Methods This was a cross-sectional study that collected self-report data regarding PA behavior and psycho-social variables considered to be potential correlates of PA behavior.

Study Sample Participants were randomly sampled from the Tomorrow Project (TTP), an ongoing cohort study in Alberta, Canada since 2000 focused on cancer risk factors.27 Sampling methods have been reported elsewhere.27 In brief, the Population Research Laboratory at the University of Alberta recruited a geographically representative sample of adults age 35–69, using random digit dialling.27 In total, 29,815 Albertans were recruited from 2001–2008 (49.4% response rate) of which 9000 were randomly selected for recruitment into this study. Of those recruited, 4040 individuals completed the DPAQ, corresponding to a 45% response rate. This response rate was slightly lower than the 56% response rate for Survey 2008 questionnaires from the same mail-out period. A total of 1253 participants were excluded based on established exclusion criteria: age over 65 (n = 595), pregnant (n = 4), prior cancer diagnosis (n = 245), being underweight (n = 17), and having limited mobility that restricted usual activities (n = 392). In addition, 16 participants were excluded because they reported more than 112 hours of weekly PA, leaving 2771 participants for the analyses.

Data Collection Methods Data collection for this study occurred in conjunction with a regularly scheduled TTP follow-up between May–October 2008.

A mailed self-administered questionnaire, Survey 2008, was used to collect data regarding employment, residential and anthropometric changes and other risk factor information including alcohol consumption and tobacco history, hormone use, chronic conditions, cancer screening practices, fruit and vegetable intake, and PA. In the August and September mailings, TTP participants received an invitation letter to participate in our study, an informed consent form and the Determinants of Physical Activity Questionnaire (DPAQ). Participants who consented to take part in our study returned the completed DPAQ along with Survey 2008 materials. Completed DPAQs received were identified by a TTP assigned identification number and did not contain any personal identifiable information. Reminder postcards to nonresponders 6 weeks after the initial mailing date were sent by TTP staff according to TTP protocols. This study was approved by the ethics reviews boards of the University of Calgary and the former Alberta Cancer Board. All data were entered into a SQL database using TELEform software (Sunnyvale, CA).

Leisure-Time Physical Activity Assessment The long form of the International Physical Activity Questionnaire (IPAQ) was included in Survey 2008 to measure PA.28 IPAQ has been shown to be valid and reliable across a number of populations and has been used by researchers worldwide.28 Respondents reported frequency and duration of moderate and vigorous intensity PA for occupational, transportation, household and leisure-time physical activities over the past 7 days. Participants who reported more than 112 hours per week of total PA were excluded from the analysis, consistent with the data processing guidelines for the IPAQ that assume adults spend an average of 8 hours of the day sleeping.29 Since the PA guidelines used in this study did not distinguish between time spent in moderate and vigorous intensity activities, moderate and vigorous activities were weighted equally in the sum of total LTPA minutes per week. Dichotomous variables for participating in sufficient LTPA to meet each of the guidelines were derived from as follows: at least 150 min/wk to meet CSEP guidelines; at least 225 min/wk to meet ACS guidelines; and at least 420 min/wk to meet WCRF/AICR guidelines.

Potential Correlates of Physical Activity Demographic variables from the Survey 2008 questionnaire included age, sex, annual household income, educational attainment, employment status, and marital status. Survey 2008 was also the source for self-reported height and weight data used for the BMI calculations. Classification of weight status was as follows: BMI between 18.5 less than 25 kg/m2 as normal weight; BMI between 25 and less than 30 kg/m2 as overweight; and BMI equal to 30 kg/ m2 or higher as obese. Current smoking status and postal codes to indicate urban or rural residence were also collected. Participants also reported a number of preexisting chronic conditions, of which hypertension, hypercholesterolemia and diabetes were of interest for this study. To assess self-rated health status, respondents were asked “In general, would you say your health is excellent, very good, good, fair, or poor?” Data regarding psychological variables were collected in the DPAQ, a. self-administered questionnaire designed to capture a number of demographic, psychological and social variables associated with adult PA behavior in the literature. Items and scales for the DPAQ were compiled from published tools identified through a literature review and consisted of mainly Likert-scaled items. The validity of the DPAQ was tested by mailing questionnaires to a random sample of 700 Calgary, Canada residents, 20–65 years of

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792  Aparicio-Ting et al

age, identified through a purchased mailing list (Bungay International). Completed DPAQs were returned by 124 individuals (20.4% response rate). The test-retest reliability was assessed by participants completing the DPAQ again 2 weeks later. Internal consistency of each scale within the DPAQ was assessed using Cronbach’s alpha (Table 1) and found to be comparable to published validity scores, where available. The DPAQ had a good overall reliability (Spearman rank correlation coefficient across all items = 0.63). Data for various psycho-social variables were collected in the DPAQ. Respondents provided responses on 5-point Likert-type scales and the average response for each set of items provided scale scores. Intent to do PA was assessed by asking respondents “Do you plan to be physically active for at least the next 6 months?” with responses ranging from “definitely not (1)” to “definitely yes (5)”. PA self-efficacy was the average response across 17 items where respondents rated how confident they were that they could be physically active given a number of situations, from not at all confident (1) to extremely confident (5).30 Outcome expectations scores came from responses to the 17 item Outcome Expectations for Exercise Scale listing a number of potential outcomes for PA (eg, being physically active will make me feel tired, will make my muscles stronger). Level of agreement with each statement ranged from strongly disagree (1) to strongly agree (5).31 Items corresponding to negative outcomes were reverse coded. PA attitudes were assessed by 5 items asking respondents to indicate how useless/useful, harmful/beneficial, unenjoyable/enjoyable, stressful/ relaxing, or boring/interesting being active would be regardless of success or failure.32 Decisional balance was assessed using the decisional balance pros (5 items) and decisional balance cons (5 items) subscales.33 Responses to how strongly each of a number of statements influenced their decision about whether to be physically active ranged from not at all (1) to very much (5). Five items asking respondents their level of agreement with statements about how others might perceive someone who is physically active (eg, being physically active, others will think I have good stamina, others will think that I am in good shape) assessed self-presentation.34 Scheduling and planning of physical activities was assessed using a 9-item scale where respondents indicated how well a number of statements regarding the ability to schedule time for PA described them with responses ranging from “does not describe me” (1) to “describes me

completely” (5).35 Lastly, subjective norm was measured by asking respondents to rate the statement “Most people who are important to me think I should be physically active,” with responses ranging from very unlikely (1) to very likely (5).36 Social support was assessed using 13 items about social support from family (a spouse/partner and any immediate or extended relative with frequent contact), 10 items about support from friends and 4 items about support from their physician (if visited in the last year).37 For each of type of social support respondents were asked how often the source of social support had said or done something to either support or discourage PA. Respondents were also asked how often, over the past month, they did PA with their spouse or partner, family member, friend, coworker, or someone from their neighborhood and were categorized as either having at least 1 companion or no companion for PA.38

Statistical Analysis Univariate analyses were used to describe the study sample and to estimate the percentage within subgroups that met each of the PA guidelines. The Cochran–Armitage test was used to assess trends across proportions that met each guideline. Bivariate correlation between all explanatory variables was then used to assess multicollinearity before modeling.39 Gender stratified logistic regression was used to identify correlates of participating in sufficient LTPA to meet each of the guidelines of interest. Hierarchical backward elimination was used for variable selection,40 beginning with all potential correlates: intent, self-efficacy, outcome expectations, attitudes, decisional balance pros and cons, self-presentation, scheduling and planning of physical activities, subjective norm, social support from family, friends and physician, having a companion for physical activities, self-rated health status, BMI, smoking status, urban or rural residence, and the presence of hypertension, hypercholesterolemia, and diabetes. All models were adjusted for age, educational attainment, annual household income and employment status. Cross-validation was used to avoid overfitting.41 Two 5-fold cross-validations were conducted to provide sufficient power for analyzing a large number of covariates while producing robust estimates by replicating the cross-validation.41 For each model, data were divided into 5 randomly selected subsets and

Table 1  Internal Consistency and Reliability of Psychosocial Scales Included in the Determinants of Physical Activity Questionnaire Variable Psychological factors   Physical activity self-efficacy38   Outcome expectations31  Attitudes32   Decisional balance33  Self-presentation34   Scheduling and planning35   Subjective norms36 Social support   Social support from family score37   Social support from friends score37   Social support from physician score37   Companions for physical activity46 a

Based on test-retest over a 2-week period.

Cronbach’s alpha

Spearman Rank Correlationa

.910 .727 .734 .796 .845 .783 .790

0.664 0.641 0.672 0.603 0.603 0.729 0.533

.878 .920 .901 .693

0.593 0.575 0.787 0.531

Correlates of Physical Activity for Cancer Prevention  793

variable selection was conducted using each of 4 training sets. The resulting model was fit to a test subset, repeating this procedure 5-fold until each subset was used as a test subset.41 This procedure was repeated twice to obtain 10 folds of coefficient estimates for each model. Variables selected in at least 3 folds were included in the final models. Estimated coefficients and standard errors were averaged across the folds to yield Odds Ratio (OR) estimates and 95% confidence intervals (95% CI). Final models were fit to the whole sample and tested for goodness-of-fit using the HosmerLemeshow test, predictive value using Receiver-Operator Characteristic curves, and for appropriateness of the logit link.42 Statistical procedures were performed using STATA10 software (College Station, TX). The level of statistical significance was set at P ≤ .05.

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Results Study Sample The study sample was 61% female and had an average age of 53 years (Table 2). Most participants reported an annual household income of $60,000 or higher and achieved technical school or college training; however, women were generally less educated, reported a lower annual household income, and were less likely to be employed full-time. Women were also less likely than men to be married or living with a common-law partner. While most participants reported high self-rated health status and were disease free, women were more likely than men to rate their health as very good or better (67% versus 57%) and men were more likely to report hypertension, hypercholesterolemia, and diabetes (Table 2). Women scored slightly higher on outcome expectations, attitudes, decisional balance pros and scheduling and planning scales and slightly lower on self-presentation (Table 3) although the differences in scores were small and not likely to be practically significant (between 0.1 and 0.2 differences in scores out of 5). However, women were significantly more likely to be planning to be active within the next 6 months (81% versus 74%, Table 2).

Correlates of Meeting Physical Activity Guidelines Through Leisure-Time Physical Activity Overall, 39% [95% Confidence Interval (CI): 37%–41%] of participants met ACS, and 19% (95% CI: 18%–21%) met WCRF/AICR guidelines, compared with 53% (95% CI: 51%–54%) that met CSEP guidelines with no statistically significant differences between men and women (Figure 1). A statistically significant decreasing trend in the percentage of men and women that met each guideline was found as the amount of PA recommended increased from CSEP to WCRF/AICR guidelines. Self-efficacy, scheduling and planning of PA and weight status were all correlated with sufficient LTPA to meet ACS and WCRF/ AICR cancer prevention guidelines. Self-efficacy was strongly positively correlated to compliance with PA guidelines, with a stronger association observed for women compared with men for all guidelines related to cancer prevention. Each increase in self-efficacy score was associated with 1.8 times the likelihood of meeting ACS and WCRF/AICR guidelines by for women, but only an increase in likelihood of 1.3 times for meeting ACS guidelines and 1.4 times for meeting WCRF/AICR guidelines for men. Individuals were also more likely to participate in sufficient LTPA for cancer risk reduction if they planned for these activities as part of their schedule. Lastly, overweight and obese adults were less

likely to meet WCRF/AICR guidelines than their normal weight counterparts. Obese women were 57% less likely to meet WCRF/ AICR guidelines (Table 4), while obese men were 21% less likely to meet these guidelines, compared with their normal weight counterparts (Table 5). The gender-stratified analysis found that divorced, separated, widowed and single women were 1.5–2.5 times more likely than married women to met ACS and WCRF/AICR guidelines (Table 4). Women smokers were less likely to meet ACS guidelines than nonsmokers, but smoking status was not correlated with meeting WCRF/AICR guidelines (Table 4). Social support variables were also important for women to meet cancer prevention guidelines. Women were approximately 30% more likely to meet cancer prevention guidelines with every increase in the social support from friends score, while social support from family was only correlated with meeting WCRF/AICR guidelines (Table 4). In addition, women who reported a companion for PA were 80% more likely to meet WCRF/AICR guidelines than those without a companion. For men, those with hypertension were approximately 60% more likely to meet WCRF/AICR guidelines. Men with fair or poor self-rated health were 44% less likely to meet ACS guidelines and 60% less likely to meet WCRF/AICR guidelines than men that perceived themselves as generally healthy and men were less likely to meet WCRF/AICR guidelines by 30% for every increase in decisional balance cons score. Only social support from friends was correlated with sufficient LTPA for cancer prevention in men, increasing the likelihood of meeting WCRF/AICR guidelines by approximately 30% (Table 5).

Discussion To date, estimates of PA among Canadians have used the CSEP guidelines as the benchmark for sufficient activity for health benefits. Estimates from a national survey during the time period of this study reported that 47% of Canadians and 49% of Albertans, 35–65 years old, participated in sufficient LTPA to meet CSEP guidelines.44 In comparison, 53% of the current study sample met CSEP guidelines through LTPA. Differences in these estimates may be due to the differences between how the Canadian Community Health Survey (CCHS) questionnaire, used for the national survey, and the IPAQ measure LTPA. The CCHS measured LTPA through a multi- part item that asked respondents to report the number of times they participated in a given list of moderate and vigorous leisure activities over the past 3 months and the duration of each session in each activity in 15 minute increments. In contrast, the IPAQ captures time spent in moderate and vigorous LTPA over the past week. Differences in time references may result in estimates that vary according to seasonal variation and are influenced differently by acute illness. In addition, adults in this study reported low levels of chronic illness, suggesting that this sample was healthier and, therefore, more likely to participate in LTPA than the general population. The unique focus of this study was on PA guidelines specific for cancer prevention. Most adults in our sample were insufficiently active to receive cancer risk reduction benefits. Less than 40% of participants performed weekly LTPA at levels recommended for cancer prevention by ACS and less than 20% at levels recommended by WCRF/AIRC. In contrast to previous reports that men are more likely to participate in LTPA than women,45,46 gender differences in compliance with PA guidelines were not observed. These findings may reflect a “healthy enrollee” effect common in long-term cohorts such as the Tomorrow Project.27

Table 2  Study Sample Demographic, Medical, Lifestyle, and Psychosocial Characteristics, Alberta, Canada, 2008 Variable

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Demographics  Age    38–48 years old    49–55 years old    56–65 years old   Marital status    Married     Divorced, separated, or widowed    Single   Employment status    Employed full-time    Employed part-time    Unemployed    Retired   Annual household income    < $30,000    $30,000–$59,999    $60,000–$99,999    $100,000–$149,999    ≥ $150,000   Educational attainment     Less than high school    High school diploma     Technical school/college training    Some university    University degree    Post-graduate university education   Urban or rural residence    Rural    Urban    Total Medical and lifestyle   Body mass index (kg/m2)     18.5 to < 25     25 to < 30    ≥ 30  Hypertension    No    Yes  Hypercholesterolemia    No    Yes  Diabetes    No    Yes   Current smoking status    Daily    Occasionally    Not at all Psychological   Self-rated health status    Excellent    Very Good    Good    Fair/poor   Intent to be physically active    Definitely/probably not    Unsure    Probably yes    Definitely yes   Subjective norms    Very unlikely    Unlikely     Neither unlikely nor likely    Likely    Very likely Social   Companion for physical activity    No    Yes a

794

Based on Chi-squared test.

Men (n = 1087) % (n)

Women (n = 1684) % (n)

33.3 (362) 31.9 (347) 34.8 (378)

32.1 (541) 34.4 (580) 33.4 (563)

0.390

83.7 (906) 9.3 (101) 6.9 (75)

78.4 (1,317) 16.0 (268) 5.6 (94)

< 0.001

81.9 (874) 6.2 (66) 2.5 (27) 9.4 (100)

54.5 (891) 19.4 (318) 15.0 (245) 11.1 (181)

< 0.001

3.4 (36) 13.5 (141) 27.2 (285) 30.0 (314) 25.9 (271)

6.3 (100) 20.7 (326) 28.0 (441) 25.2 (397) 19.8 (313)

< 0.001

5.2 (56) 13.6 (147) 40.1 (435) 6.7 (73) 20.0 (217) 14.4 (156)

5.5 (93) 19.0 (320) 39.7 (668) 8.7 (146) 15.8 (265) 11.3 (190)

< 0.001

18.0 (196) 82.0 (891) 100.0 (1,087)

19.7 (332) 80.3 (1,352) 100.0 (1,684)

0.271

24.9 (263) 47.5 (502) 27.6 (292)

46.6 (750) 31.6 (508) 21.8 (350)

< 0.001

97.8 (1063) 2.2 (24)

98.7 (1662) 1.3 (22)

< 0.001

91.9 (999) 8.1 (88)

94.5 (1592) 5.5 (92)

Intrapersonal and social environment correlates of leisure-time physical activity for cancer prevention: a cross-sectional study among Canadian adults.

Little is known about the intrapersonal and social factors associated with sufficient physical activity (PA) for cancer prevention, which is greater t...
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