Copyright 1992 by The Cerontological Society of America The Gerontologist Vol. 32, No. 4, 444-449
This health promotion trial included university faculty and staff aged 50 to 69 who had completed a health risk screening. Predictors of intention to exercise were education, gender, self-efficacy, outcome expectancy, perceived barriers, and baseline exercise frequency. Baseline exercise frequency was the only predictor of exercise behavior 1 year later. Key Words: Worksite health promotion, Health beliefs, Health behavior, Self-efficacy, Outcome expectancy
Exercise Beliefs and Behaviors Among Older Employees: A Health Promotion Trial1 Patricia A. Sharpe, PhD,2 and Cathleen M Connell, PhD3
efficacy, outcome expectancy, and perceived barriers. (See Janz & Becker, 1984, and Dzewaltowski, 1989b, for reviews of research based on the theoretical frameworks represented in this study.) Self-efficacy is defined as "the conviction that one can successfully execute the behavior required to produce the outcomes"; outcome expectation is defined as "a person's estimate that a given behavior will lead to certain outcomes" (Bandura, 1977, p. 193). An interaction term, self-efficacy by outcome expectancy, was also assessed because social cognitive theory states that the two constructs may interact in their influence on behavior. For example, selfefficacy regarding exercise may be high, but if the belief that exercise leads to desirable outcomes is weak, then behavior is less likely than if both selfefficacy and outcome expectancy were high. The barriers construct from the health belief model refers to the perceived negative aspects of taking a recommended action (Rosenstock, 1974). Two hypotheses to be tested in the present study were: a) beliefs about self-efficacy, outcome expectancy, barriers to exercise, self-rated health, and present exercise behavior are significant"predictors of intention to exercise, and b) intention to exercise is a significant predictor of follow-up exercise behavior, over and above the independent impact of being offered health promotion activities between baseline and follow-up. Method Sample
1 This research was supported by the Office of the Vice-President and Chief Financial Officer, University of Michigan, and by National Institute on Aging predoctoral and postdoctoral training grants (#T32-AG00134 and AGEA2T32AG00117-06) to the first author. The authors gratefully acknowledge the leadership of the late John P. Kirscht as principal investigator in the early phases of this research. The authors thank the program providers, Andrea Foote, John Erfurt, Max Heirich, Barbara Konopka, and Victoria Cameron, and Nadine Thomas for her assistance with manuscript preparation. 2 School of Social Work, 1065 Frieze Bldg., University of Michigan, Ann Arbor, Ml 48109-1285. 'School of Public Health, University of Michigan, Ann Arbor, M l .
444
The sample for the present study comprised 250 employees aged 50 to 69 who participated in a large university-supported health promotion trial (Connell, Sharpe, & Gallant, 1992). The total sample for the trial, of which the 250 older workers are a subset, represented all job categories at the university and did not differ from the campus as a whole in terms of age or gender distribution. (For a complete description of the entire sample, see Connell & Sharpe, 1990.) The Gerontologist
Downloaded from http://gerontologist.oxfordjournals.org/ at Purdue University Libraries ADMN on June 1, 2015
Regular physical activity imparts many health protective benefits to older adults, including desirable effects on body weight, blood pressure, glucose tolerance, blood lipids, and bone mineral content (Centers for Disease Control, 1989). Exercise improves aerobic capacity, muscle strength, and flexibility among older adults and may have positive psychological effects (Berger & Hecht, 1985; Hird & Williams, 1989). A portion of the physical decline that accompanies aging is related to physical disuse rather than disease processes and therefore may be prevented (Bortz, 1982; Bernadette et al., 1981). Despite the public's commonly held view of exercise as a positive behavior and its widely acknowledged benefits (Dishman et al., 1985), only about 8% of adults aged 65 and older engage in activity at a level known to have cardiorespiratory benefits (Caspersen, Christensen, & Pollard, 1986). The worksite offers a unique setting for facilitating exercise habits that could be maintained after retirement. Effective planning of worksite-based programs for both employees and retirees requires knowledge of factors that predict exercise intention and behavior, yet little theoretically based research includes older adults (Dzewaltowski, 1989a). To examine exercise intention and behavior among older participants in a controlled health promotion trial at the worksite, the present investigation employed key constructs from social cognitive theory (Bandura, 1986) and the health belief model (Rosenstock, 1974) that have been associated with exercise behaviors among various age groups. These constructs include self-
Table 1 . Demographic Characteristics of Older University Employees in a Health Promotion Trial (N = 198)
Characteristic Gender Male Female Race White Black Other Educational Level Less than high school Completed grade 12 Completed some college College graduate Job Category Instructional Office/clerical Professional/administrative Service/maintenance Skilled trades Nursing Research/library Other
Vol. 32, No. 4,1992
n
%
105 93
53.0 47.0
180 12 6
91.0 6.0 3.0
12 46 48 92
6.1 23.2 24.2 46.5
57 46 41 24 13 6 3 4
28.9 23.4 20.8 12.1 6.6 3.0 1.5 2.0
1990); 10% had high blood pressure (based on National Heart, Lung, and Blood Institute criteria); 65% had total cholesterol ^ 200 mg/dl, and 67% were exercising fewer than three times per week. Sixtyfive percent of the participants rated their health as excellent or very good. Procedure During the fall and winter of 1988-1989, all participants completed a health risk screening that included measurement of blood pressure, body weight, and total cholesterol, and a self-administered questionnaire that assessed health beliefs and behaviors. Immediate feedback and brief counseling about the screening results were provided by nurses who conducted the assessment. Prior to the initial screening, work units had been randomly assigned to an experimental or a control condition. Work units were defined by personnel office rosters and included employees engaging in related tasks, e.g., an academic department or a maintenance office. Units ranged in size from less than 20 to more than 100 employees and represented all major job categories on campus. Participants were blind to treatment group assignment but were told that the health screening would be provided again 1 year later. Participants in the experimental group were offered health promotion activities during the following year, including opportunities for one-toone meetings with health counselors, participation in walking groups at work, and/or exercise on their own at home or at university facilities. Participants in the control group were not offered health promotion activities during the year between the baseline and follow-up health risk screening. All study participants were rescreened in the spring of 1990. The following strategies were used to recruit employees to attend the follow-up screening: a) posting of information at work; b) direct contact with departmental representatives; c) telephone calls from the research staff; and d) provision of additional dates and sites to enhance the accessibility of screening. Measures Independent and dependent variables are presented in Appendix A. Gender, race, and education were nominal variables; age was a continuous variable. All health beliefs and exercise behavior were measured with 5-point ordinal response formats. Barriers to exercise was assessed by asking participants how difficult it would be to exercise vigorously for 20 minutes three times per week. Outcome expectancy was assessed by asking participants to rate how much they perceived regular exercise would benefit their health. The self-efficacy measure assessed participants' confidence that they could exercise at least three times a week. Behavioral intention is the immediate precursor of behavior (Fishbein & Ajzen, 1975) and was assessed by asking subjects if they intended to exercise vigorously three or more times per week during the next 6 months. Self-rated 445
Downloaded from http://gerontologist.oxfordjournals.org/ at Purdue University Libraries ADMN on June 1, 2015
Of the 250 participants who completed the baseline health risk screening, 213 (85%) responded to a questionnaire that assessed health beliefs. Fiftyseven percent (n = 121) of the employees who completed both the screening and the questionnaire participated in a second health risk screening 1 year later. Data were not available regarding specific reasons for dropout; however, work unit liaisons reported that some employees transferred to other work units or left the university. Because employees were assured confidentiality, complete personnel files were not linked to the health promotion data collected for the study and therefore tracking of employees was not feasible. Chi-square analyses revealed that neither the subset of participants who responded to the questionnaire (n = 213) nor the subset who participated in the reassessment 1 year later (n = 121) differed from the total baseline sample (n = 250) in terms of gender, race, job category, or age group distributions (50 to 60 and 61 to 69 years of age). Complete data on all of the variables used in the subsequent regression analysis were available for 198 of 213 persons who participated in both the initial health risk screening and the health beliefs questionnaire. Table 1 describes the demographic characteristics of these 198 participants. The sample was almost evenly divided between men and women (53% and 47%, respectively) and the majority were white (91%). The educational level was high, with 23% completing high school, 24% completing some college, and 46% completing a college degree (including some with graduate degrees). Job categories ranged from instructional faculty to office staff to service/maintenance staff. The mean age was 56.3 (SD = 4.4). The health risk screening revealed that 15% of the participants were smokers; 32% were overweight (body mass index equal to or exceeding the 85th percentile; see Kraemer, Berkowitz, & Hammer,
Results
Of the 198 participants at baseline, 95 were in the experimental group and 103 were in the control group. At follow-up, there were 60 experimental participants and 56 in the control group, resulting in attrition rates of 37% and 46%, respectively. Preliminary regression analysis revealed that attrition between baseline and follow-up was not differentially related to baseline exercise frequency for the experimental and control groups (F = .56, p = .76). Before proceeding with the multiple regression analysis to predict exercise intention at baseline and exercise behavior 1 year later, multicollinearity was assessed by regressing each predictor on all remain-
ing predictors (Lewis-Beck, 1980). Results indicated that multicollinearity did not pose a threat to parameter estimation (no multiple R2 exceeded .42). Demographic variables and health beliefs were entered in a hierarchical regression model to predict exercise intention at baseline (Time 1, referred to as T1). Next, exercise behavior 1 year later (Time 2, referred to as T2) was regressed hierarchically on demographic variables, exercise behavior at baseline (T1), treatment group, and exercise intention (T1). As shown in Table 2, gender, educational level, the health belief variables, and baseline exercise behavior were significant predictors of exercise intention (F = 23.99, p < .00001). (Educational level was used as a predictor instead of job category because some job categories, such as office personnel, were not exclusively blue or white collar.) The multiplicative interaction term, self-efficacy x outcome expectancy, was not a significant predictor, nor was selfrated health. The adjusted multiple R2 was .58. As shown in Table 3, baseline (T1) exercise behavior was the only significant predictor of exercise behavior at follow-up (T2). Neither demographic variables nor being offered health promotion activities were statistically significant predictors of exercise behavior at follow-up. In fact, the negative coefficient for group assignment was unexpected (i.e., being in the experimental condition was associated with less frequent exercise). The adjusted multiple R2 was .20. Because being offered health promotion activities did not significantly affect reported exercise frequency, self-reported attempts to improve physical fitness for the rescreened participants were examined for evidence of the potential impact of the worksite activities. Table 4 shows actions taken by those employees who reported that they had attempted to improve their fitness during the previous year. Forty-eight percent of the control group (n = 32) and 52% of the experimental group (n = 36) said
Table 2. Results of Hierarchical Multiple Regression Analyses Predicting Exercise Intention Among Older University Employees
Block/variables entered
Dependent Exercise intention at Timel (n = 198)
b
SEb
Beta
Block 1/
Education3 < High school Grade 12 Some college Age Race" Gender0
-.27 -.36 -.11 .02 -.45 -.44
.30 .18 .18 .01 .24 .15
-.05 -.11* -.03 .06 -.09 -.16**
-.19 .52 .11 .14 .69 -.07
.06 .14 .09 .05 .16 .04
-.19** .43*** .06 .16** .69*** -.35
Block 2/
Barriers Outcome expectancy Self-rated health Exercise (Timel) Self-efficacy Self-efficacy x outcome expectancy
Significance of change in F statistic
Multiple R2
Adjusted R2
.07
.04
p
This health promotion trial included university faculty and staff aged 50 to 69 who had completed a health risk screening. Predictors of intention to exercise were education, gender, self-efficacy, outcome expectancy, perceived barriers, and baseline exercise frequency. Baseline exercise frequency was the only predictor of exercise behavior 1 year later. Key Words: Worksite health promotion, Health beliefs, Health behavior, Self-efficacy, Outcome expectancy
Exercise Beliefs and Behaviors Among Older Employees: A Health Promotion Trial1 Patricia A. Sharpe, PhD,2 and Cathleen M Connell, PhD3
efficacy, outcome expectancy, and perceived barriers. (See Janz & Becker, 1984, and Dzewaltowski, 1989b, for reviews of research based on the theoretical frameworks represented in this study.) Self-efficacy is defined as "the conviction that one can successfully execute the behavior required to produce the outcomes"; outcome expectation is defined as "a person's estimate that a given behavior will lead to certain outcomes" (Bandura, 1977, p. 193). An interaction term, self-efficacy by outcome expectancy, was also assessed because social cognitive theory states that the two constructs may interact in their influence on behavior. For example, selfefficacy regarding exercise may be high, but if the belief that exercise leads to desirable outcomes is weak, then behavior is less likely than if both selfefficacy and outcome expectancy were high. The barriers construct from the health belief model refers to the perceived negative aspects of taking a recommended action (Rosenstock, 1974). Two hypotheses to be tested in the present study were: a) beliefs about self-efficacy, outcome expectancy, barriers to exercise, self-rated health, and present exercise behavior are significant"predictors of intention to exercise, and b) intention to exercise is a significant predictor of follow-up exercise behavior, over and above the independent impact of being offered health promotion activities between baseline and follow-up. Method Sample
1 This research was supported by the Office of the Vice-President and Chief Financial Officer, University of Michigan, and by National Institute on Aging predoctoral and postdoctoral training grants (#T32-AG00134 and AGEA2T32AG00117-06) to the first author. The authors gratefully acknowledge the leadership of the late John P. Kirscht as principal investigator in the early phases of this research. The authors thank the program providers, Andrea Foote, John Erfurt, Max Heirich, Barbara Konopka, and Victoria Cameron, and Nadine Thomas for her assistance with manuscript preparation. 2 School of Social Work, 1065 Frieze Bldg., University of Michigan, Ann Arbor, Ml 48109-1285. 'School of Public Health, University of Michigan, Ann Arbor, M l .
444
The sample for the present study comprised 250 employees aged 50 to 69 who participated in a large university-supported health promotion trial (Connell, Sharpe, & Gallant, 1992). The total sample for the trial, of which the 250 older workers are a subset, represented all job categories at the university and did not differ from the campus as a whole in terms of age or gender distribution. (For a complete description of the entire sample, see Connell & Sharpe, 1990.) The Gerontologist
Downloaded from http://gerontologist.oxfordjournals.org/ at Purdue University Libraries ADMN on June 1, 2015
Regular physical activity imparts many health protective benefits to older adults, including desirable effects on body weight, blood pressure, glucose tolerance, blood lipids, and bone mineral content (Centers for Disease Control, 1989). Exercise improves aerobic capacity, muscle strength, and flexibility among older adults and may have positive psychological effects (Berger & Hecht, 1985; Hird & Williams, 1989). A portion of the physical decline that accompanies aging is related to physical disuse rather than disease processes and therefore may be prevented (Bortz, 1982; Bernadette et al., 1981). Despite the public's commonly held view of exercise as a positive behavior and its widely acknowledged benefits (Dishman et al., 1985), only about 8% of adults aged 65 and older engage in activity at a level known to have cardiorespiratory benefits (Caspersen, Christensen, & Pollard, 1986). The worksite offers a unique setting for facilitating exercise habits that could be maintained after retirement. Effective planning of worksite-based programs for both employees and retirees requires knowledge of factors that predict exercise intention and behavior, yet little theoretically based research includes older adults (Dzewaltowski, 1989a). To examine exercise intention and behavior among older participants in a controlled health promotion trial at the worksite, the present investigation employed key constructs from social cognitive theory (Bandura, 1986) and the health belief model (Rosenstock, 1974) that have been associated with exercise behaviors among various age groups. These constructs include self-
Table 1 . Demographic Characteristics of Older University Employees in a Health Promotion Trial (N = 198)
Characteristic Gender Male Female Race White Black Other Educational Level Less than high school Completed grade 12 Completed some college College graduate Job Category Instructional Office/clerical Professional/administrative Service/maintenance Skilled trades Nursing Research/library Other
Vol. 32, No. 4,1992
n
%
105 93
53.0 47.0
180 12 6
91.0 6.0 3.0
12 46 48 92
6.1 23.2 24.2 46.5
57 46 41 24 13 6 3 4
28.9 23.4 20.8 12.1 6.6 3.0 1.5 2.0
1990); 10% had high blood pressure (based on National Heart, Lung, and Blood Institute criteria); 65% had total cholesterol ^ 200 mg/dl, and 67% were exercising fewer than three times per week. Sixtyfive percent of the participants rated their health as excellent or very good. Procedure During the fall and winter of 1988-1989, all participants completed a health risk screening that included measurement of blood pressure, body weight, and total cholesterol, and a self-administered questionnaire that assessed health beliefs and behaviors. Immediate feedback and brief counseling about the screening results were provided by nurses who conducted the assessment. Prior to the initial screening, work units had been randomly assigned to an experimental or a control condition. Work units were defined by personnel office rosters and included employees engaging in related tasks, e.g., an academic department or a maintenance office. Units ranged in size from less than 20 to more than 100 employees and represented all major job categories on campus. Participants were blind to treatment group assignment but were told that the health screening would be provided again 1 year later. Participants in the experimental group were offered health promotion activities during the following year, including opportunities for one-toone meetings with health counselors, participation in walking groups at work, and/or exercise on their own at home or at university facilities. Participants in the control group were not offered health promotion activities during the year between the baseline and follow-up health risk screening. All study participants were rescreened in the spring of 1990. The following strategies were used to recruit employees to attend the follow-up screening: a) posting of information at work; b) direct contact with departmental representatives; c) telephone calls from the research staff; and d) provision of additional dates and sites to enhance the accessibility of screening. Measures Independent and dependent variables are presented in Appendix A. Gender, race, and education were nominal variables; age was a continuous variable. All health beliefs and exercise behavior were measured with 5-point ordinal response formats. Barriers to exercise was assessed by asking participants how difficult it would be to exercise vigorously for 20 minutes three times per week. Outcome expectancy was assessed by asking participants to rate how much they perceived regular exercise would benefit their health. The self-efficacy measure assessed participants' confidence that they could exercise at least three times a week. Behavioral intention is the immediate precursor of behavior (Fishbein & Ajzen, 1975) and was assessed by asking subjects if they intended to exercise vigorously three or more times per week during the next 6 months. Self-rated 445
Downloaded from http://gerontologist.oxfordjournals.org/ at Purdue University Libraries ADMN on June 1, 2015
Of the 250 participants who completed the baseline health risk screening, 213 (85%) responded to a questionnaire that assessed health beliefs. Fiftyseven percent (n = 121) of the employees who completed both the screening and the questionnaire participated in a second health risk screening 1 year later. Data were not available regarding specific reasons for dropout; however, work unit liaisons reported that some employees transferred to other work units or left the university. Because employees were assured confidentiality, complete personnel files were not linked to the health promotion data collected for the study and therefore tracking of employees was not feasible. Chi-square analyses revealed that neither the subset of participants who responded to the questionnaire (n = 213) nor the subset who participated in the reassessment 1 year later (n = 121) differed from the total baseline sample (n = 250) in terms of gender, race, job category, or age group distributions (50 to 60 and 61 to 69 years of age). Complete data on all of the variables used in the subsequent regression analysis were available for 198 of 213 persons who participated in both the initial health risk screening and the health beliefs questionnaire. Table 1 describes the demographic characteristics of these 198 participants. The sample was almost evenly divided between men and women (53% and 47%, respectively) and the majority were white (91%). The educational level was high, with 23% completing high school, 24% completing some college, and 46% completing a college degree (including some with graduate degrees). Job categories ranged from instructional faculty to office staff to service/maintenance staff. The mean age was 56.3 (SD = 4.4). The health risk screening revealed that 15% of the participants were smokers; 32% were overweight (body mass index equal to or exceeding the 85th percentile; see Kraemer, Berkowitz, & Hammer,
Results
Of the 198 participants at baseline, 95 were in the experimental group and 103 were in the control group. At follow-up, there were 60 experimental participants and 56 in the control group, resulting in attrition rates of 37% and 46%, respectively. Preliminary regression analysis revealed that attrition between baseline and follow-up was not differentially related to baseline exercise frequency for the experimental and control groups (F = .56, p = .76). Before proceeding with the multiple regression analysis to predict exercise intention at baseline and exercise behavior 1 year later, multicollinearity was assessed by regressing each predictor on all remain-
ing predictors (Lewis-Beck, 1980). Results indicated that multicollinearity did not pose a threat to parameter estimation (no multiple R2 exceeded .42). Demographic variables and health beliefs were entered in a hierarchical regression model to predict exercise intention at baseline (Time 1, referred to as T1). Next, exercise behavior 1 year later (Time 2, referred to as T2) was regressed hierarchically on demographic variables, exercise behavior at baseline (T1), treatment group, and exercise intention (T1). As shown in Table 2, gender, educational level, the health belief variables, and baseline exercise behavior were significant predictors of exercise intention (F = 23.99, p < .00001). (Educational level was used as a predictor instead of job category because some job categories, such as office personnel, were not exclusively blue or white collar.) The multiplicative interaction term, self-efficacy x outcome expectancy, was not a significant predictor, nor was selfrated health. The adjusted multiple R2 was .58. As shown in Table 3, baseline (T1) exercise behavior was the only significant predictor of exercise behavior at follow-up (T2). Neither demographic variables nor being offered health promotion activities were statistically significant predictors of exercise behavior at follow-up. In fact, the negative coefficient for group assignment was unexpected (i.e., being in the experimental condition was associated with less frequent exercise). The adjusted multiple R2 was .20. Because being offered health promotion activities did not significantly affect reported exercise frequency, self-reported attempts to improve physical fitness for the rescreened participants were examined for evidence of the potential impact of the worksite activities. Table 4 shows actions taken by those employees who reported that they had attempted to improve their fitness during the previous year. Forty-eight percent of the control group (n = 32) and 52% of the experimental group (n = 36) said
Table 2. Results of Hierarchical Multiple Regression Analyses Predicting Exercise Intention Among Older University Employees
Block/variables entered
Dependent Exercise intention at Timel (n = 198)
b
SEb
Beta
Block 1/
Education3 < High school Grade 12 Some college Age Race" Gender0
-.27 -.36 -.11 .02 -.45 -.44
.30 .18 .18 .01 .24 .15
-.05 -.11* -.03 .06 -.09 -.16**
-.19 .52 .11 .14 .69 -.07
.06 .14 .09 .05 .16 .04
-.19** .43*** .06 .16** .69*** -.35
Block 2/
Barriers Outcome expectancy Self-rated health Exercise (Timel) Self-efficacy Self-efficacy x outcome expectancy
Significance of change in F statistic
Multiple R2
Adjusted R2
.07
.04
p
