Older women and exercise: explanatory concepts

Women’s Health Issues 13 (2003) 158 –166

OLDER WOMEN AND EXERCISE: EXPLANATORY CONCEPTS Vicki S. Conn, PhD, RNa*, Kathryn J. Burks, PhD, RNa, Sherry H. Pomeroy, MS, RNb, Sherri L. Ulbrich, PhD, RNa, and Jane E. Cochran, MS, RNc a

School of Nursing, University of Missouri-Columbia, Columbia, Missouri School of Nursing, State University of New York at Buffalo, Buffalo, New York c Division of Endocrinology, School of Medicine, University of Missouri-Columbia, Columbia, Missouri b

Received 16 December 2002; received in revised form 7 April 2003; accepted 5 May 2003

Background. Older women remain predominantly sedentary despite potential health benefits and reduced risks of cardiovascular disease associated with regular exercise. Primary care interventions to increase exercise need to focus on constructs amenable to intervention that predict exercise behavior. Purpose. The study tested an explanatory model of older women’s exercise behavior using concepts from social cognitive theory, the transtheoretical model, and the theory of planned behavior (self-efficacy, outcome expectancy, perceived exercise barriers, processes of change, perceived health, and age). Methods. Data were collected by interviews with 203 older community-dwelling women physically capable of some exercise. Ordinary least squares regression results were used to determine the direct and indirect effects in a path model. Findings. All concepts and 13 hypothesized paths were retained in the trimmed model. The constructs accounted for 46% of the variance in exercise behavior. Outcome expectancy had the largest total effect. Processes of change had the largest direct effect on exercise behavior. Exercise self-efficacy and perceived exercise barriers accounted for similar amounts of variance in exercise behavior, whereas age and health had only modest effects. Conclusion. Important constructs for future exercise model testing and intervention research should include outcome expectancy, processes of change, exercise self-efficacy, and perceived barriers to exercise. Primary care interventions designed to increase older women’s exercise should focus on these same constructs.

Introduction Physical and psychological benefits of increased physical activity have been widely documented among older adults.1–7 Even among persons aged 90 years and older, physical activity is associated with enhanced quality of life.8 Despite these benefits, few older adults exercise and women are particularly likely to be sedentary.9 –12 Primary care may be an ideal setting to change older women’s exercise behavior.13 Aging women receive primary care, and the presence of health problems

may coincide with a window of opportunity to change health behaviors.14,15 Primary care and communitybased intervention studies have not been consistently successful in increasing exercise among aging women and men.16 –22 Further understanding of explanatory variables is necessary to develop interventions that will effectively increase exercise among older women. The purpose of this study was to examine concepts that explain exercise among community-dwelling older women.

Background * Correspondence to: Vicki Conn, PhD, RN, S317 School of Nursing, University of Missouri-Columbia, Columbia, MO 65211. E-mail: [email protected]. Copyright © 2003 by the Jacobs Institute of Women’s Health. Published by Elsevier Inc.

The transtheoretical model, social cognitive theory, and the theory of planned behavior are commonly applied in exercise behavior studies. These theories 1049-3867/03 $-See front matter. doi:10.1016/S1049-3867(03)00037-9

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Figure 1. Hypothesized path model.

contain partially overlapping constructs that predict exercise in large numbers of studies with younger adults and in more limited studies with aging adults.23,24 Despite these overlapping constructs, few studies have predicted behavior with concepts from multiple theories. Concepts from these frameworks selected for study include self-efficacy (social cognitive theory, transtheoretical model, theory of planned behavior), processes of behavior change (transtheoretical model), perceived barriers to exercise (social cognitive theory, theory of planned behavior), outcome expectancy (social cognitive theory, transtheoretical model, theory of planned behavior), age (social cognitive theory), and health (social cognitive theory). The proposed model is presented in Figure 1. Self-efficacy expectation Self-efficacy expectation is a central, pervasive belief regarding one’s capacity to exert control over one’s own behavior.25 Self-efficacy expectation beliefs are formed from cognitive processing of efficacy information conveyed enactively (by actual performance), vicariously, socially, and physiologically.26 The evidence of the relationship between exercise self-efficacy expectations and exercise is both reliable and substantial, despite diverse samples, measurement instruments, and measurement timing.9,23,27–30 People with higher exercise self-efficacy expectations maintain a sense of energy during exercise, perceive less effort being expended during exercise, report more positive affect during and after exercise, and report feeling more revitalized.31–33 Previous research examining path models with older adults has reported that exercise self-efficacy mediates the relationship between other constructs and exercise behavior.23,24 Exercise self-efficacy is an attractive potential concept for primary care intervention because it can be rapidly assessed, and specific interventions have been proposed to influence exercise self-efficacy.

Processes of change Processes of change are the cognitive and behavioral activities that move people toward changed behavior.34,35 Positive self-talk about exercise capacity and rewarding oneself for exercising are common processes to increase exercise behavior. Most previous research has found processes of change related to both actual exercise behavior and movement toward adopting exercise.36 – 40 These change processes have also been related to exercise self-efficacy.40 Processes of change may not be identical across different health behaviors, especially among older adult populations.41,42 The behavioral and cognitive activities that stimulate change are a particularly exciting area for research because they provide specific strategies for primary care interventions.43 Perceived barriers to exercise Individuals’ perceptions of internal and external obstacles to exercise constitute perceived barriers. Perceived barriers are related to exercise self-efficacy because behavior is influenced by the interaction of internal factors with perceptions about the environment wherein the behavior will be performed.26 People who perceive more barriers to exercise have less confidence in their ability to exercise. Empirical evidence suggests that perceived barriers to exercise are important for all ages.30,44 – 47 Many of the health, discomfort, or potential injury barriers among older adults could be addressed in primary care settings. Other common barriers among older adults include limited disposable income, fewer available social participants, and general access and availability issues.45,46 Outcome expectancy Outcome expectancies are beliefs that benefits will follow particular behaviors. Exercise outcome expectations include physical and psychological effects,

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social consequences, and internal self-rewards.48 Considerable empirical evidence documents that those who exercise believe in its positive consequences.30,48,49 Primary care providers often emphasize the health benefits of exercise as a strategy to change patients’ behavior. Even so, research often reports that outcome expectancy makes more modest contributions toward exercise than do exercise self-efficacy beliefs.23,28,50,51 Although considerable research has examined the association between exercise behavior and exercise self-efficacy, few models incorporating both outcome and exercise self-efficacy expectancies have been tested with older adults.23,24 Age and health Age consistently predicts exercise behavior among diverse samples. Age affects self-efficacy judgments because age is a powerful factor in self-evaluation. The perception that physical decline is an unalterable part of aging may contribute to older adults’ lower selfefficacy expectations.52 Age has been found to exert an indirect, but substantial, influence on exercise behavior through both exercise self-efficacy and outcome expectations.23 Perceived health state may determine one’s estimated exercise capacity and thus limit self-direction of exercise behavior.25 Health has been found to predict exercise behavior and has also been empirically linked to exercise self-efficacy.44,53 Resnick et al. found that health indirectly affected exercise among older adults through both exercise self-efficacy and outcome expectancy.51 Conn found an indirect effect of health on exercise through perceived barriers to exercise.23 Both age and health should be considered in behavior studies with older adults. Summary Multiple concepts from social cognitive theory, the transtheoretical model, and the theory of planned behavior have been empirically associated with exercise behavior among adults. Most relationships have been confirmed with older samples as well. Few studies have examined concepts from multiple frameworks. Studies rarely focus on older women, despite their high potential for sedentary behavior and some evidence of gender differences in relationships among constructs.5 This project examined a model with key concepts from commonly applied theories in a study of community-dwelling older women.

Methods A descriptive correlational study was conducted to examine the relationships among constructs.

Sample The participants included 203 older women who met the following inclusion criteria: • age 65 years and over; • able to walk without assistance; • conversant in English; • independent status as evidenced by the absence of paid or unpaid assistance with personal care. Women were recruited without regard for their current exercise behavior. The nonprobability sample was recruited at community groups such as religious and volunteer organizations, at aggregate living environments such as senior housing, and through informal contacts. Exclusion criteria were assessed through potential participant self-report. Measures Exercise self-efficacy. Exercise-specific self-efficacy was measured by the Self-Efficacy Scale designed by McAuley.29 The instrument contains six items measuring subjects’ perceived capability to exercise. For each item, subjects are asked to estimate their percent confidence (0% to 100%) that they can exercise under difficult circumstances. For example, one item is “I believe that I could exercise . . . if the weather was bad”. Each of the circumstances is appropriate for older adults (bored, on vacation, in the presence of pain/discomfort, not interested in exercise, had to exercise alone). Reliability has been reported at .93.29 This instrument was selected because it measures the behavioral domain at the appropriate level. Greater scores indicate more exercise self-efficacy. Outcome expectancy. Exercise outcome expectancy was measured with the benefits subscale of the Exercise Benefits/Barriers Scale.54 This scale was selected because it measures a variety of perceived consequences of exercise and is therefore conceptually consistent with both social cognitive theory and the theory of planned behavior. The scale includes exercise benefits applicable to older women (e.g., social interaction). The scale contains 29 potential beneficial consequences of exercise scored on a 4-point forcedchoice Likert format. Although factor analysis has documented five dimensions, a total score was used for this study. The instrument has documented internal consistency (standaradized alpha ⫽ .95), 2-week stability (r ⫽ .89), and predictive validity.54,55 Higher scores reflect more positive exercise outcome expectancy. Perceived barriers. The barriers subscale of the Exercise Benefits/Barriers Scale was used to measure perceived barriers.54 This scale measures diverse barriers that are commonly reported by older adults and that could be important for different forms of exercise that

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older women might perform. The scale contains 14 potential exercise barriers scored on a 4-point forcedchoice Likert format. Internal consistency (standardized alpha ⫽ .87), 2-week test-retest reliability (r ⫽ .77), and construct validity (65% of variance explained) have been reported in previous studies.45,54 Higher scores indicate more perceived barriers to exercise. Processes of change. Processes of change were measured by respondent self-report. Items were generated from previous research with older women and literature-reported strategies to change exercise behavior.42,56 For example, respondents were asked if they planned exercise into their daily schedule, obtained information about how exercise would benefit them, or if they gave themselves rewards for exercising. Each of the eight items was scored as present or absent. The highest score indicated use of all processes of change on the instrument. Psychometric testing has not been performed on this instrument. Perceived health. Perceived health was measured by three items similar to those often reported.57 Subjects rated their health as poor, fair, good, or excellent. Subjects also compared their health to others their age, using ratings of worse than others, about the same as others, or better than others. Finally, subjects rated the extent to which their health interfered with desired activities as a great deal, somewhat, or not at all. A higher summed score suggests better health. This subjective assessment of health was selected instead of other measures (e.g., number of chronic illnesses), because the perception of health was the intended construct. Exercise. Exercise was defined for this study as structured, planned, and repetitive body movement performed for the purpose of increasing fitness.58 Interviewers explained the definition of exercise to subjects before administering the exercise measures. The interviewer distinguished between the physical activity required for routine activities such as grocery shopping and intentional continuous walking for exercise. Exercise was measured with the six-item exercise subscale of the Health-Promoting Lifestyle Profile.59 Respondents rated how often they performed exercise, with higher scores indicating more exercise. Test-retest stability (r ⫽ .93) and internal consistency (alpha ⫽ .81), as well as concept validity (documented by factor analysis), have been established for this instrument.59 This instrument has been used extensively with older adults.60,61 Procedure The project was approved by the Institutional Review Board for the Protection of Human Subjects before data collection. Trained research assistants collected all data in a private location, usually in respondents’ individual homes. All data were collected by face-toface interview to prevent vision or literacy problems

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from hampering participation. Interviewers asked demographic questions first. Next, the interviewer explained the difference between physical activity (any body movement) and exercise, and provided examples. The interviewers then administered the measures of exercise, exercise self-efficacy, outcome expectancy, barriers to exercise, and processes of change. All data were collected at single interviews. Data analysis Scores were summarized for variables. Path analysis was used to test for the hypothesized links in the model with successive multiple regression equations calculated to estimate path coefficients (Fig. 1). Exogenous independent variables were age, perceived health, and outcome expectancy. Intervening endogenous variables were perceived barriers, exercise selfefficacy, and processes of change. Paths significant at the p ⫽ .10 level were retained from the full model for estimating the reduced model.

Results Women from ages 65 to 93 years (mean ⫽ 74.61, SD ⫽ 6.61) participated in the study. Most women were not currently married (n ⫽ 130, 64%), with many participants being widowed. Modest incomes were common, with 89% of the women reporting household incomes less than $30,000/year. The subjects reported a mean of 3.41 chronic illnesses (SD ⫽ 1.79, range 0 to 10) and 2.43 medications (SD ⫽ 2.11, range 0 to 16). Health scores ranged from 4 to 10 (mean ⫽ 7.79, SD ⫽ 1.73). The mean exercise score was 1.84 (SD ⫽ .67, range 1– 4). Exercise self-efficacy scores ranged from 0 to 100 (mean ⫽ 57.58, SD ⫽ 29.61). The mean perceived barrier value was 2.20 (SD ⫽ .25, range 1–2.75). Subjects reported 0 to 8 processes of change (mean ⫽ 2.55, SD ⫽ 1.99). Outcome expectancy scores ranged from 1.97 to 4 (mean ⫽ 2.80, SD ⫽ .31). Path coefficients were estimated by simultaneous entry of predictors for each hypothesized dependent variable in the model using a series of ordinary least squares regressions. The results of each regression are summarized in Table 1. Standardized betas for hypothesized paths are given in Figure 2. The explanatory variables accounted for 46% of the variance in the outcome variable of exercise behavior. Outcome expectancy had a direct effect on exercise scores. As predicted, outcome expectancy had a significant negative effect on barriers. The positive effects on exercise self-efficacy, processes of change, and exercise behavior were consistent with the proposed model. Moderate associations were documented between outcome expectancy and other constructs. The relationship between outcome expectancy and perceived barriers was

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Table 1. Regression analyses calculated to determine path coefficients in the hypothesized model (n ⫽ 203) Outcome Variable

R2

Exercise behavior F ⫽ 28.99, p ⬍ .0001

.47

Exercise self-efficacy F ⫽ 32.92, p ⬍ .0001

.40

Processes of change F ⫽ 16.79, p ⬍ .0001

.30

Barriers F ⫽ 44.11, p ⬍ .0001

.40

Predictor Variables

Beta

p

Processes of change Outcome expectancy Barriers Exercise self-efficacy Health Age

.27 .25 ⫺.19 .17 ⫺.06 ⫺.06

⬍.0001 .002 .005 .02 .25 .30

Outcome expectancy Barriers Health Age

.48 ⫺.15 .14 .03

⬍.0001 .04 .02 .58

Exercise self-efficacy Outcome expectancy Age Health Barriers

.39 .36 ⫺.16 ⫺.12 .08

.0003 ⬍.0001 .009 .05 .32

Outcome expectancy Health Age

⫺.60 ⫺.12 ⫺.04

⬍.0001 .04 .44

the strongest association demonstrated for outcome expectancy. The hypothesized association between age and processes of change was supported by the data. Although predicted, age did not have a significant association with exercise behavior, exercise self-efficacy, or perceived barriers. Age only remained in the trimmed model due to its association with processes of change. Health predicted processes of change, barriers, and exercise self-efficacy scores. The data did not support the hypothesized direct relationship between health and exercise behavior. Barriers had direct significant negative effects on

exercise self-efficacy and exercise behavior consistent with the hypothesized relationship. Although predicted, barriers were not significantly associated with processes of change scores. Barriers did mediate the relationship between outcome expectancy and exercise behavior and between health and exercise behavior. The predictor variables accounted for 40% of the variance in barriers scores. As hypothesized, exercise self-efficacy expectations had a direct significant effect on exercise behavior and on processes of change. Exercise self-efficacy had an intervening effect between processes of change and health, barriers, and outcome expectancy. The explan-

Figure 2. Path diagram with obtained path coefficients for the hypothesized model (n ⫽ 203).

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Figure 3. Trimmed causal model.

atory variables accounted for 40% of the variance in exercise self-efficacy. Processes of change had the strongest direct relationship with exercise of any of the study variables. As hypothesized, processes of change mediated the relationship between exercise behavior and outcome expectancy, age, health, and exercise self-efficacy. The predictor variables accounted for 30% of the variance in processes of change scores. Figure 3 summarizes the reduced path model with nonsignificant paths deleted from the model. All variables from the hypothesized model remained in the trimmed model because all variables had at least one significant path. Thirteen hypothesized paths were

retained in the reduced model. The importance of outcome expectancy, processes of change, perceived barriers, and exercise self-efficacy on exercise behavior is clear from the reduced model. Direct and indirect path causal effects for each of the variables are documented in Table 2. Outcome expectancy, with the highest total causal effect, remains important both because of direct effects and indirect effects through exercise self-efficacy, barriers, and processes of change. Processes of change had the next largest total causal effect. Exercise self-efficacy and barriers had identical total causal effect magnitude, although in opposite directions as predicted. Age was retained in the model only because of the indirect

Table 2. Direct and indirect causal effects of variables in the hypothesized model (n ⫽ 203)a Causal Effect Outcome Variable

Predictor Variables

Direct

Indirect

Total

Exercise behavior

Outcome expectancy Processes of change Exercise self-efficacy Barriers Age Health

.25 .27 .17 ⫺.19 ⫺.06 ⫺.06

.36 — .08 ⫺.02 ⫺.02 .02

.61 .27 .25 ⫺.21 ⫺.08 ⫺.04

Exercise self-efficacy

Outcome expectancy Health Barriers Age

.48 .14 ⫺.15 .03

.09 .02 — .01

.57 .16 ⫺.15 .04

Processes of change

Outcome expectancy Exercise self-efficacy Age Health Barriers

.36 .29 ⫺.16 ⫺.12 .08

.12 — .01 .04 ⫺.04

.48 .29 ⫺.17 ⫺.08 .04

Barriers

Outcome expectancy Health Age

⫺.60 ⫺.12 ⫺.04

— — —

⫺.60 ⫺.12 ⫺.04

a

Calculated from obtained path model coefficients (Fig. 2).

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effect through processes of change. Health also had only indirect effects on exercise behavior, but through barriers, exercise self-efficacy, and processes of change. Both age and health contributed little total causal effect on exercise scores. Outcome expectancy made the largest total causal contribution to each of the mediating variables (exercise self-efficacy, processes of change, and barriers). Health and age made modest contributions to the mediating variables, with total causal effect of less than .20 in each case.

Discussion The model developed and tested in this study accounted for a moderate proportion of variance in exercise behavior (46%) among older women. Central concepts present in this study and recent studies of retirement residents and aged men and women were consistent predictors of exercise.23,24 Together, these findings suggest that future model construction and primary care intervention testing about exercise among elderly women should incorporate processes of change, outcome expectancy, perceived barriers, and exercise self-efficacy as important concepts. Outcome expectancy was found to be an influential construct in predicting exercise behavior among these subjects. The strong total effect of outcome expectancy was somewhat surprising because some previous research has found limited effects of outcome expectancy on exercise when exercise self-efficacy is also measured.23,28 These findings confirm that the inclusion of compelling information about the benefits of exercise and the hazards of inactivity are important components of primary care interventions designed to increase exercise. The findings of this study support the importance of the transtheoretical model’s central construct of processes of change. The most frequently reported processes of change by these older women were to self-affirm their exercise ability, make an exercise commitment, reward themselves for exercise, obtain more information about exercise, and think about others’ (family, health care providers, etc.) encouragement of exercise behavior. Process of change is an exciting concept because it appears amenable to intervention. For example, Calfas et al. found that among young women an intervention altered exercise-related processes of change 2 years after the intervention.36,43 Primary care interventions that emphasize the processes of change need to be tested among aging adults. Few studies have examined both processes of change and exercise self-efficacy in relationship to exercise. Plotnikoff et al. found exercise self-efficacy a stronger predictor of exercise than processes of change among adults with diabetes.39 In contrast, our study found that processes of change had a larger direct and

total effect than exercise self-efficacy on exercise among elderly women. The consistent and robust relationship between exercise self-efficacy and exercise in diverse other studies justifies continued examination of self-efficacy constructs while also including processes of change measures.9,28 Exercise self-efficacy is an exciting construct because Bandura outlined specific intervention strategies to enhance self-efficacy.25 Some of Bandura’s suggested strategies are consistent with recent meta-analysis findings regarding interventions (e.g. practice sessions, self-monitoring) that increase physical activity among older adults.15 Further research is needed to expand our understanding of the relationships among processes of change, exercise self-efficacy, and exercise behavior. These findings support the importance of the transtheoretical model, theory of planned behavior, and social cognitive theory variables studied (outcome expectancy, processes of change, exercise self-efficacy, and perceived barriers) for exercise behavior among older women. While replication and extension in longitudinal descriptive research is essential, the findings provide some information for intervention development. A stronger emphasis on enhancing beliefs of positive outcomes of exercise and negative consequences of inactivity, overcoming barriers, enhancing exercise self-efficacy, and increasing processes of change for older women could yield substantial public health gains even if interventions prompt modest exercise increases in this vulnerable population.62 The emphasis on health benefits of exercise is especially consistent with interventions delivered in primary care settings. Potential confounding between age, health, and other variables is a common problem in aging research. This study found that health affected the three mediating variables, independent of age. Both age and health exerted limited influence on mediating or outcome variables. The limited effects of age and health are consistent with previous research that has included psychological model predictors.23,24 These finding suggest the other constructs are more important factors in determining exercise behavior than age or perceived health. It is also plausible that the restricted age sample could account for the limited influence of age. Limitations The nonprobability sample was not necessarily representative of all older women. The number of chronic illnesses and medication suggest the women had typical problems with chronic ailments. The findings should be replicated with other samples of older women. This study did not examine stage of behavior change either as an inclusion criterion or as a study variable. The constellation of constructs predicting

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exercise behavior probably differs at different stages of exercise behavior change.62– 64 Further research should examine outcome expectancy, exercise selfefficacy, perceived barriers, and processes of change among older women at different stages of health behavior change. The exercise measure was not validated with objective measures such as research ergometers that measure movement. Development of reliable and valid objective exercise measures applicable to older women would enhance this area of research. This study used measures of exercise self-efficacy and exercise consistent with the exercise older women report. Future research could examine more specific forms of exercise, such as walking. The explanatory power of the model could be enhanced by focusing on specific forms of exercise, since self-efficacy expectations are behavior-specific.26 This study examined only endurance exercise. Evidence of the profound benefits of resistance, flexibility, and weight-bearing exercise is accumulating.3 Also, this study focused on episodic planned exercise. Recent work suggests that research should also examine the accumulated overall physical activity that older adults perform. The concepts examined in this study have not been applied in studies of other forms of physical activity and exercise among older women.

[5]

[6] [7]

[8]

[9]

[10]

[11]

[12]

[13]

[14]

[15]

Conclusion In summary, this study found that the most important predictor of exercise behavior among older women was outcome expectancy, followed by processes of change, exercise self-efficacy, and barriers to exercise. Future research with this vulnerable, predominantly sedentary population should examine these constructs in relation to stages of change with longitudinal studies using diverse measures of exercise and physical activity. In addition, these concepts can be used to develop primary care interventions for enhancing older women’s exercise behavior.

[16]

[17]

[18]

[19]

[20]

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