Abstract

Purpose: We examined the efficacy of an intervention tailored to the individual's stage of change for exercise adoption on exercise stage of change, physical activity, and physical function in community-dwelling older adults. Design and Methods: We randomized participants to a print and telephone intervention or a contact comparison group. Through the use of longitudinal analyses we examined the intervention's effectiveness in promoting stage progression, altering decisional balance and the processes of change, increasing self-efficacy and physical activity, and improving physical function among older adults who completed the 24-month study (N = 966). We conducted similar analyses that excluded individuals who were in maintenance at baseline and 24 months. Results:  At the end of the study, there were no differences in stage progression, self-efficacy, decisional balance, the processes of change, physical activity, or physical function by intervention assignment. When the analyses excluded those participants (n = 358) who were in the maintenance stage for exercise throughout the intervention, we found that, compared with the comparison group, a greater proportion of individuals who received the exercise intervention progressed in stage by 24 months. Conversely, more individuals in the comparison group remained stable or regressed in stage compared with the intervention group. Implications: Results indicate that a tailored intervention is effective in increasing motivational readiness for exercise in individuals who were in stages of change other than maintenance.

Regular physical activity is associated with a decreased risk of functional limitation among older adults, a delay or decrease in the incidence of chronic health problems, an improved quality of life, and a reduced risk of falling (Miller, Rejeski, Reboussin, Ten Have, & Ettinger, 2000). Despite the known physiological and psychological benefits of a physically active lifestyle, physical inactivity remains a major health problem among older adults in the United States, with a majority of older adults failing to reach the minimum recommended levels of physical activity (Kamimoto, Easton, Maurice, Husten, & Macera, 1999; Kruger, Carlson, & Buchner, 2007).

Physical activity interventions that include older adults and use an assortment of behavioral and educational strategies have been somewhat effective in increasing the adoption of physical activity (Hillsdon, Foster, & Thorogood, 2005; Marcus et al., 2006). Many intervention studies with older adults have provided organized, center-based exercise classes for a small number of participants (e.g., DiBrezzo, Shadden, Raybon, & Powers, 2005), but several studies of middle-aged and older adults have shown that most of these individuals prefer to do their physical activity outside a formal setting, and home-based exercise has higher adherence rates (Ashworth, Chad, Harrison, Reeder, & Marshall, 2005; Juneau et al., 1987; King et al., 2000; King, Haskell, Taylor, Kraemer, & DeBusk, 1991).

Several theories of behavior change have been used to develop interventions to promote physical activity, including the transtheoretical model of health behavior change (TTM). The TTM is an integrative theoretical model that uses individual decision-making processes to explain intentional health behavior change (Prochaska & Velicer, 1997). It has been used to tailor interventions to increase physical activity and exercise in diverse populations (Jones et al., 2001; Marcus et al., 1998), and it has been validated for use in community-dwelling older adults (Barké & Nicholas, 1990; Riebe et al., 2005).

Although it has been demonstrated that interventions based on the TTM are effective in increasing exercise under some circumstances, it has not been applied to a large-scale community-based intervention in older adults. Our purpose in this study was to determine whether an exercise intervention tailored to an individual's stage of change for exercise would be effective in progressing stage of change, increasing utilization of TTM constructs (self-efficacy, decisional balance, and the processes of change), increasing physical activity behavior, and improving physical function in community-dwelling older adults.

Methods

Participants

The study participants were volunteers for the Study of Exercise and Nutrition in Older Rhode Islanders (SENIOR) Project, a community-based health-promotion study designed to increase fruit and vegetable consumption and exercise among community-dwelling older adults (Clark et al., 2005). We recruited participants into the study over a period of 14 months by using a variety of methods, including direct mailings, advertisements, flyers, and presentations given at senior housing sites (Greaney, Lees, Nigg, Saunders, & Clark, in press).

Study entry criteria included being 60 years of age or older and residing in the greater East Providence, Rhode Island area. We excluded those individuals who were not living independently in the community. Participants completed the Physical Activity Readiness Questionnaire as modified for older adults, which identifies participants who should seek out medical consultation before engaging in a new program of exercise (Thomas, Reading, & Shephard, 1992). Participants who answered “yes” to any of the questions on the Physical Activity Readiness Questionnaire were strongly urged to check with their health care provider prior to entering the study, but medical clearance was not required. The University of Rhode Island's Institutional Review Board approved the study, and all participants provided informed consent.

Design

The SENIOR Project consisted of a 12-month intervention followed by a 12-month nonintervention observational period (Clark et al., 2005). We randomly assigned participants to one of four interventions: Group 1 increased fruit and vegetable consumption; Group 2 increased exercise; Group 3 increased both exercise and fruit and vegetable consumption; and Group 4 was a contact-comparison group. In this article we examine the effects of the intervention designed to increase exercise, so we combined the four groups to form two: an intervention group consisting of all participants who received the intervention for increasing exercise (Groups 2 and 3) and a comparison group consisting of participants who did not receive the intervention for increasing exercise (Groups 1 and 4). Data reported here were collected at baseline, 12 months, and 24 months.

Intervention

The SENIOR Project's intervention components have been discussed in detail elsewhere (Clark et al., 2005). Briefly, we developed the interventions on the basis of the TTM, and they included a series of written materials and counselor calls designed to encourage movement through the stages of change to increase exercise, fruit and vegetable consumption, or both. The tailored materials included behavior-specific manuals, newsletters, expert systems reports, and coaching calls. We contacted participants monthly by means of print or telephone contact throughout the 12-month intervention period.

For those participants who received the exercise intervention, we strongly encouraged them to adopt a habitual pattern of intentional physical activity (exercise) performed at home or in formal exercise settings consistent with the recommendations for apparently healthy adults by the American College of Sports Medicine (1998). This guideline recommends several sessions per week of aerobic (cardiorespiratory), flexibility, and muscle-strengthening exercises. We chose these criteria for physical activity because this level of activity has been demonstrated to improve physical fitness, physical function, and general health, which are particularly important in older adults (American College of Sports Medicine).

In the intervention's print materials and during the coaching calls, we encouraged participants to engage in aerobic exercise of moderate to vigorous intensity, such as brisk walking, cycling, swimming, and exercising in aerobic exercise classes or on exercise machines, for 3 to 5 days per week for a minimum of 20 minutes. We recommended flexibility exercises, such as stretching, yoga, Pilates, and tai chi, for at least 2 days per week, and we encouraged muscle-strengthening exercises such as weight lifting, calisthenics, and resistance equipment for 2 to 3 days per week. We gave participants information on how to do these exercises at home and we encouraged them to use exercise facilities and to join formal exercise programs available within the community. Details of the intervention components follow.

Manual

At the start of the intervention, each participant received an intervention-specific manual that was organized by stages of change and that incorporated stage-specific behavioral strategies commonly employed to advance to the next stage. The manual also included information about the benefits of physical activity, what types of exercise are recommended, how to safely engage in exercise, and a listing of community resources for exercise, including formal exercise programs. Individuals not receiving the exercise intervention received either a manual about fruit and vegetable consumption or a fall-prevention manual; neither of these manuals included any information about physical activity or exercise.

Newsletters

We sent intervention-specific newsletters to participants on a monthly basis, except for Months 4, 8, and 12, when they received an expert system report (subsequently described). Newsletters were stage specific, and participants received the newsletter designed for their stage of change as determined during the evaluations conducted at baseline and at 4 and 8 months. The newsletters included stories about older adults, practical tips about exercise, suggested physical activities, interactive sections, and local resources for exercise. The newsletters addressed stage-appropriate processes of change, and they included material to effect positive changes in self-efficacy and decisional balance.

Expert System Assessments and Reports

During the 12-month intervention, we collected data on TTM constructs and other behavioral and health information at baseline and at 4 and 8 months. On the basis of the participants' responses, a computer-based expert system generated a 4- to 5-page report that was mailed directly to each participant's home. Reports provided normative (compared with peers in the same stage of change, or SOC) and ipsative (based on current and previous responses from the individual) feedback on the individual's physical activity behavior to encourage continued positive behavior change.

Coaching Calls

Participants received three 15-minute coaching calls from trained counselors during the 12-month intervention period, approximately 4 to 6 weeks after they received their expert system reports, which the counselors used to guide calls. Counselors used a standardized protocol incorporating motivational interviewing strategies in a stage-matched manner (Rollnick, Heather, & Bell, 1992).

Demographics and Overall Health

Participants provided demographic information, including gender, age, race or ethnicity, and educational level. Participants also completed the Medical Outcomes Study 36-item Short Form, and the answer to the first question on this form; we used the General Health subscale (general health perception) to assess perceived health status (McHorney, Ware, and Raczek, 1993). The first measure is categorical and we used it for descriptive purposes; we used the latter measure as a covariate in the statistical analyses.

Outcome Measures

Participants completed a baseline assessment in person at their home or in the project office. We had the assessment administered by trained project staff members who were of similar age and ethnicity as the participants and from the intervention community. The project staff members administered the assessment before randomization (baseline), at the end of the 12-month intervention period, and 12 months after the completion of the intervention (24 months), during which no intervention was delivered. The present study includes measures obtained at baseline and at 12 and 24 months; they are described in the paragraphs that follow.

TTM constructs

Measuring SOC for exercise is ideal for gaining a better understanding of physical activity and exercise behavior, because it focuses on intention and perception of behavior rather than actual behavior (Nigg & Riebe, 2002). We measured all TTM constructs (SOC, self-efficacy, decisional balance, and processes of change) by using instruments validated in community-dwelling older adults, and details of these instruments follow here.

SOC for Exercise

We determined SOC for regular aerobic exercise by using a validated questionnaire and scoring algorithm (Nigg & Riebe, 2002). The criterion used for SOC for exercise was the volume of exercise recommended by the American College of Sports Medicine (1998), which recommends aerobic exercise of moderate to vigorous intensity, lasting at least 10 minutes, for a total of 20 to 60 minutes per day, 3 to 5 days per week. This criterion is consistent with the exercise message used in the intervention and with the U.S. Surgeon General's recommendations for physical activity (U.S. Department of Health and Human Services, 1996), which emphasizes moderate to vigorous physical activity on most days of the week.

On the basis of their responses to the questionnaire, we classified participants into one of five stages. Participants classified in the precontemplation stage had no intention to begin exercising in the next 6 months, whereas those in the contemplation stage intended to begin exercising within the next 6 months. Individuals in the preparation stage intended to change within the next month. Those in action had been exercising regularly over the past 6 months, and participants in the maintenance stage had been exercising regularly for 6 months or more (Nigg & Riebe, 2002).

Self-Efficacy

The six-item exercise self-efficacy scale measured a participant's confidence in his or her ability to exercise despite adverse or challenging situations (Benisovich, Rossi, Norman, & Nigg, 1998). Self-efficacy scores range from 1 to 5, with higher scores indicating greater self-efficacy.

Decisional Balance (Pros and Cons)

This two factor, ten-item Likert-format scale measures the pros (advantages) and cons (disadvantages) of adopting or maintaining exercise (Nigg, Rossi, Norman, & Benisovich, 1998). Scores range from 1 to 5, with higher scores demonstrating more exercise pros or exercise cons.

Processes of Change

This questionnaire includes 30 statements that participants are asked to rate in terms of frequency of occurrence over the past month on a 5-point Likert scale ranging from 1 = never to 5 = repeatedly (Nigg & Riebe, 2002). The questionnaire contains three items for each of the 10 processes of change and provides individual scores (ranging from 1 to 5) for each process. For analyses, we divided the processes into two groupings—experiential and behavioral processes. Scores range from 15 to 75, with higher scores indicating greater use.

Physical Activity Behavior

We measured physical activity by using the Yale Physical Activity Survey (YPAS). The YPAS is a validated survey for older adults that is designed to assess exercise, household, and recreational physical activity during a typical week in the previous month (DiPietro, 2001). We calculated five activity dimensions: vigorous activity, leisurely walking, moving on feet, standing, and sitting. We then summed the results to calculate the YPAS summary score. A higher score indicates higher levels of physical activity.

Physical Function

We measured physical function by using the Timed Up-and-Go (TUG) test. The TUG test is a practical, reliable measure of functional mobility in older adults (Podsiadlo & Richardson, 1991). The TUG test measures, in seconds, the time taken by an individual to stand up from a standard armchair, walk a distance of 3 m, turn, walk back to the chair, and sit down again. TUG scores have been able to distinguish between older adults who need assistance in activities of daily living, those who are independent, and those with somewhat impaired mobility (Van der Bij, Laurant, & Wensing, 2002). TUG scores of less than 12 seconds reflect normal physical function in community-dwelling adults (Bischoff et al., 2003).

Analysis

We conducted all analyses by using SPSS version 15.0 (SPSS, Chicago, IL). We calculated means, standard deviations, and frequencies for demographic characteristics, health status, SOC, physical activity, and physical function variables at baseline by using SPSS descriptives. We set significance a priori at p <.05.

The purpose of the analyses was to evaluate the intervention's effect on progressing SOC, promoting use of TTM constructs, increasing physical activity, and improving physical function. To examine SOC progression, we conducted chi-square analyses using three stage movement groups (progress, regress, stable) to test the hypothesis that stage progression differed by exercise intervention assignment at 12 and 24 months. We defined stage progression as an increase of one or more stages from baseline; we defined stage regression as a decrease of one or more stages from baseline. We categorized participants who remained in the same stage as being in the stable stage. Because there was a large proportion of participants who remained in a maintenance mode for exercise throughout the intervention who would not be expected to progress in stage, we also evaluated SOC progression while excluding participants who remained in maintenance at baseline and 24 months.

We used a series of repeated measures analysis of covariance to answer these research questions: First, do self-efficacy, decisional balance, and processes of change scores differ in participants who received the intervention? Second, did the intervention have an effect on physical activity and physical functioning? We included the following covariates in all models: gender, age at baseline, and perceived health status at baseline. Time was the within-subject factor and intervention assignment was the between-subject factor. We also evaluated these questions while excluding participants who remained in maintenance at both time points (baseline and 24 months).

Results

Participants

The results presented in this article include study participants who completed the 24-month evaluation (N = 966). This includes 21 people who completed the 24-month assessment but did not complete the 12-month assessment. Table 1 shows the characteristics of these people at baseline.

Baseline Equivalence of Intervention Groups

As shown in Table 1, there were no significant differences between individuals in the intervention and comparison groups based on age, education, gender, race, perceived health status, SOC, YPAS summary score, or TUG score. Overall, 58.2% (n = 562) of the total sample was in action or maintenance stages for exercise at baseline (56.4%, n = 265, of the intervention group and 59.9%, n = 297, of the comparison group).

Adherence

Of the 1,274 people enrolled in the study at baseline, 80.5% (n = 1,026) completed the 12-month follow-up, and 75.8% (n = 966) completed the 24-month evaluation. Analyses published elsewhere have examined differences between participants who withdrew and those who completed the study, and there were no differences in attrition by race–ethnicity or intervention assignment (Greaney et al., in press). Compared with participants who withdrew, participants completing the study were more likely to be female (77.8% vs 70.8%, p =.01), in the action or maintenance stages for exercise at baseline (80.1% vs 70.3%, p <.01), younger (76.2, SD = 6.8, vs 78.5, SD = 6.8; p <.001), and have more years of education (12.87 years, SD = 2.2, vs 12.11 years, SD = 3.4; p <.01; see Greaney et al.). Participants who dropped out of the study also had lower self-efficacy than did participants who completed the 24-month study (3.22, SD =.95, vs 3.37, SD =.90; p =.02).

Program Outcomes

With the exception of participants in the precontemplation stage who progressed in stage at 24 months, participants who received the intervention were no more likely to progress in stage, regress in stage, or remain stable in stage than were participants who did not receive the intervention. In addition, there were no differences in self-efficacy, decisional balance, and the processes of change by intervention assignment. Furthermore, there were no differences in physical activity behavior and physical function, as measured by the YPAS and TUG, respectively, by intervention assignment over the course of the study. Additional details about the program's outcomes are provided in the following paragraphs.

Progress in Stage of Change

Table 2 shows the proportion of participants in the intervention and comparison groups who progressed, regressed, or maintained SOC from baseline to 12 months and from baseline to 24 months. At 12 months, χ2(2, N = 941) = 2.02, p =.36, and 24 months, χ2(2, N = 966) = 5.61, p =.06, there were no differences between the intervention group and comparison group with respect to the proportion of individuals who progressed, regressed, or maintained stage. When we excluded participants who were in the maintenance stage at baseline and 12 months from the analysis (n = 378), the results remained unchanged, χ2(2, n = 563) = 2.01, p =.37. However, when we excluded participants (n = 358) who were in the maintenance stage throughout the 24-month period from this analysis, we found that a greater proportion of individuals who received the exercise intervention progressed in stage by 24 months compared with individuals in the comparison group. Consistent with this finding, more people in the comparison group than people in the intervention group remained stable or regressed in stage, χ2(2, N = 608) = 6.30, p =.04.

A description of stage progress according to the baseline SOC by intervention assignment is shown in Table 3. Although not significantly different, a greater percentage of participants in the intervention group who were in contemplation, preparation, and action stages at baseline had progressed in stage at 12 months, compared with the comparison group. Overall, 22.3% of the intervention group progressed in stage by 12 months compared with 19.4% of the comparison group (p =.36). We found similar results at 24 months (27.2% vs 20.7%, p =.06), and this time individuals receiving the intervention who were in the precontemplation stage at baseline were more likely to progress in stage than individuals in the comparison group who were in precontemplation stage at baseline, χ2(2, n = 177) = 4.11, p = 04.

TTM Constructs

The means of the TTM constructs are shown in Table 4. With the exception of exercise pros at 24 months, there was no difference in the use of these constructs by intervention assignment over the course of the study. When we excluded individuals who were in the maintenance stage at baseline and 24 months from the analysis (n = 358), the results remained unchanged (data not shown).

Behavioral Outcomes

The adjusted means of the YPAS summary score and the TUG score at 12 and 24 months by intervention assignment are shown in Table 5. There were no significant differences between the intervention and comparison groups with respect to physical activity (YPAS summary score) or physical function (TUG score) at 12 or 24 months. When we excluded the individuals who remained in the maintenance stage at baseline and 24 months from the analysis (n = 358), the results remained unchanged (data not shown).

Discussion

There were no significant differences between the intervention group and the comparison group in the percentage of individuals in each of the SOCs for exercise at 12 months, at the end of the intervention period, or a long-term effect at 24 months. There were limited differences in stage progression between the intervention and comparison groups (individuals in the precontemplation stage who received the intervention were more likely to progress in stage than were individuals in the comparison group). When we excluded the large number of participants who remained in the maintenance stage for the entire study period from the analysis, there was a long-term effect at 24 months, so that individuals who received the exercise intervention were more likely to progress in stage and individuals in the comparison group were more likely to regress in stage or remain stable in stage. Concurrently, with the exception of exercise pros at 24 months, there were no differences in use of the TTM constructs, or any changes in physical activity or physical function throughout the intervention.

It is intriguing that individuals in the precontemplation stage at baseline who received the intervention had significantly more stage progression than did similar individuals in the comparison group. This suggests that the intervention was more effective in individuals who were not considering becoming physically active at the start of the study. This could have important public health implications if confirmed in subsequent studies, as it suggests that the most sedentary older adults could benefit from a low cost, primarily print-based intervention.

Sedentary individuals (in the precontemplation, contemplation, or preparation stages) were more likely to drop out of the study, although the drop-out rate among sedentary individuals was similar between the intervention group and the comparison group. Participants who dropped out of the study had lower exercise self-efficacy than did those who completed the study. Some studies of exercise adherence have reported that low levels of self-efficacy and readiness to change are associated with drop out from the exercise program (Young, King, Sheehan, & Stefanick, 2002), whereas higher levels of self-efficacy predict adoption and maintenance of exercise (Oman & King, 1998). Overall, individuals completing the study were younger and had more education than those who dropped out of the study; each of these variables is associated with higher levels of physical activity and better health (Bish, et al., 2005; U.S. Department of Health and Human Services, 1996).

There were no differences between the intervention and comparison groups in YPAS summary score and TUG scores at 12 or 24 months, suggesting that the intervention was not effective in improving self-reported physical activity or physical function. The lack of effect of the intervention on these variables remained when individuals in maintenance at each time point were excluded from the analyses. The lack of effect on physical activity behavior and function is not surprising, because the primary outcome of this study was SOC, which reflects intentions for and perception of exercise behavior and does not necessarily reflect actual exercise behavior. For example, an individual who moved from precontemplation to contemplation or who remained in the maintenance stage, as a large portion of our participants did, would not be expected to change physical activity behavior and consequently physical function.

Advancing age is associated with declines in physical activity, physical fitness, and physical function (American College of Sports Medicine, 2004). Interestingly, neither physical activity nor physical function declined significantly in our sample, as evidenced by the stable YPAS summary scores and TUG scores over 24 months. The mean scores on the TUG test are well below the 12-second cutpoint for normal physical function in community-dwelling older adults, demonstrating that our participants were particularly vigorous. We do not know if those who dropped out of the study were more likely to experience declines in physical functions and physical activity or be institutionalized, but this is certainly a possibility.

The modest results found in our study of younger and older adults are consistent with the findings of previous studies in younger and older adults that used similar methodologies (Banks-Wallace & Conn, 2002; Conn, Valentine, & Cooper, 2002; Eakin, Glasgow, & Riley, 2000; Hillsdon et al., 2005; Kahn et al., 2002; Van der Bij, et al., 2002). A recent Cochrane review concluded that physical activity interventions have moderate to little effect (Hillsdon et al.). It is believed that physical activity interventions have had equivocal results in part as a result of methodological problems, including incomplete or inconsistent application of behavioral theory (Baranowski, Anderson, & Carmack, 1998; Epstein, 1998; Prochaska & Velicer, 1997). The SENIOR Project's intervention was designed with one theoretical model, the TTM, and it maintained theoretical integrity in both the development of the intervention and the outcome measurements. Nevertheless, the results were still modest, indicating the difficulty in understanding and altering this complex behavior.

The main focus of our intervention was at the intrapersonal (individual) level; the intervention did not incorporate interpersonal and environmental factors that are thought to mediate physical activity and exercise behavior (King, 2001). In a very small subsample of our participants, we have shown that a number of personal and physical environmental factors affected physical activity behavior (King et al., 2006), but we are unable to evaluate this possibility in the context of the intervention.

Print interventions have generally had a small effect on physical activity behavior (Marshall, Owen, & Bauman, 2004). The use of tailoring and adding other methods such as counseling in combination with print materials, similar to the methods used in the SENIOR Project, have improved the impact of print and other types of physical activity interventions (Kahn et al., 2002; Van der Bij et al., 2002). One difficulty with print interventions, such as the SENIOR project, is that it is difficult to assess the dose of the intervention that the particpants received; we were unable to assess the amount of time spent using the materials or ensure that people actually read and understood the materials. We did not screen for literacy or cognitive function, although it is known that cognitive decline is common in aging adults (Craik & Bialystok, 2006; Raz, Rodrigue, Kennedy, & Acker, 2007).

A high proportion of our sample was in action or maintenance stages at the start of the study, which may have affected our ability to assess the impact of our intervention, because the participants perceived that they were already engaging in adequate amounts of exercise. Over 70% of the individuals in maintenance for exercise at baseline remained in maintenance at 24 months. These results are not unexpected, as a recent study of long-term maintenance of regular exercise (McAuley et al., 2007) reported that regular exercise behavior was a strong predictor of maintaining exercise over the long term. The high proportion of people in the maintenance stage is consistent with other studies of adults of all ages obtained in statewide samples in Rhode Island (Garber, Allsworth, Hesser, & Marcus, 2006; Laforge et al., 1999).

When we excluded participants who were in the maintenance stage at both time points (baseline and 12 months, baseline and 24 months), we found that individuals in all SOCs in the exercise intervention group were more likely to advance in stage by 24 months. This was not an immediate effect of the intervention: At 12 months there were no differences between the intervention and comparison groups with respect to the proportion who progressed, regressed, or remained stable in stage. These results are similar to results found in studies of physical activity (McAuley et al., 1999) and smoking cessation (Prochaska et al., 2001) that have found that individuals who received behaviorally based interventions continued to improve their behavior after completion of the intervention, indicating that the effects of the treatment continued long after the end of the intervention. The consistency between the SOC and self-reported physical activity and independently assessed physical function provides further validation for the SOC for exercise, extending the results of previous studies (Schumann, Estabrooks, Nigg, & Hill, 2003; Schumann et al., 2002; Spencer, Adams, Malone, Roy, & Yost, 2006).

Use of TTM Constructs

There were no differences in the scores of the TTM constructs by intervention assignment. We were unable to detect differences between the intervention and comparison groups with respect to exercise self-efficacy, decisional balance, experiential processes, and behavioral processes at 12 and 24 months, even when we excluded the large number of participants who remained in maintenance throughout the intervention. These results are in contrast to other studies of exercise adoption and maintenance in older and younger adults, in which self-efficacy and the use of cognitive and behavioral strategies predict exercise behavior (Bock et al., 1997; Brassington, Atienza, Perczek, DiLorenzo, & King, 2002; Cheung et al., 2007; Kosma, Cardinal, & McCubbin, 2004; McAuley et al., 2007; Oman & King, 1998; Velicer, Norman, Fava, & Prochaska, 1999). However, it is possible that the number of participants who progressed or regressed in stage was inadequate for us to detect differences in the use of these behavioral processes.

Study Limitations

This study had several limitations, the greatest being the potential for sampling (volunteer) bias, whereby persons in the preaction stages may have been less likely to volunteer as participants in this study, whereas persons in maintenance were more likely to volunteer. There is also the possibility of drop-out bias because individuals who were sedentary and with lower levels of self-efficacy at baseline were more likely to withdraw than participants who were regular exercisers. The drop-out pattern was similar between the exercise intervention and the comparison groups, so there is no differential group effect of the dropouts.

Lastly, all of the measures, except physical function, were measured by self-report, which can reduce the sensitivity and specificity of the instruments as a result of report and response biases. However, TUG scores are an objective measure of physical function, and the TUG scores and self-report of physical activity mirrored each other, suggesting that the self-reported physical activity data were valid.

Conclusions

The SENIOR exercise intervention demonstrated that a community-based intervention to promote exercise that is grounded by behavioral theory can be modestly effective in promoting stage progression over the long term. Nevertheless, the intervention did not increase physical activity behavior or improve physical function. Future research evaluating the intrapersonal, interpersonal, and environmental mediator and moderators variables affecting the adoption and maintenance of exercise behavior is needed to provide important insights into factors that can be addressed in future behavior-based interventions to improve outcomes.

This research was supported by Grant 1R01AG16588 from the National Institute on Aging, National Institutes of Health. Preliminary results were presented in a symposium at the 57th Annual Scientific Meeting of the Gerontological Society of America, Washington, DC, November 19–23, 2004, and at the 26th Annual Meeting of the Society of Behavioral Medicine, Boston, MA, April 13–16, 2005.

We thank all participants of the Study of Exercise and Nutrition in Older Rhode Islanders (SENIOR) Project and acknowledge the contributions of all the members of the SENIOR Project Research Team, including the following individuals: Bryan Blissmer, PhD; Robert Dufresne, PhD; Catherine English, PhD, RD; Geoffrey W. Greene, PhD, RD, RN; Andrea Luisi, PharmD; Norma Owens, PharmD; Cynthia Padula, PhD, RN; James Prochaska, PhD; Susan Rossi, PhD, RN; Sandra Saunders, MS, MPH; Laurie Ruggiero, PhD; Kira Stillwell, MS; and Nancy Fey-Yensan, PhD, RD.

1

Public Health Nutrition, Harvard School of Public Health, Boston, MA.

2

Department of Kinesiology, University of Rhode Island, Kingston.

3

Department of Biobehavioral Sciences, Columbia University, New York, NY.

4

Department of Psychology, University of Rhode Island, Kingston.

5

Program in Gerontology and Rhode Island Geriatric Education Center, University of Rhode Island, Kingston.

6

School of Nursing, University of Rhode Island, Kingston.

7

Department of Public Health Sciences, University of Hawaii at Manoa, Honolulu.

8

Cancer Prevention Research Center, University of Rhode Island, Kingston.

Decision Editor: William J. McAuley, PhD

Table 1.

Characteristics of 966 Participants Completing the SENIOR Project by Intervention Assignment.

 Intervention Assignment<--CO?1-->
 
    
 Intervention Group
 
 Comparison Group
 
  
Characteristic n (M% (SDn (M% (SDp 
Baseline age: years (75.2) (6.7) (74.7) (6.6) .28 
Education: years (12.9) (2.7) (12.9) (3.1) .59 
YPAS summary score (44.9) (26.4) (45.7) (31.4) .66 
TUG: seconds (8.7) (4.1) (8.8) (5.7) .74 
Gender      
    Male 128 27.2 146 29.6  
    Female 342 72.8 348 70.4 .43 
Race or ethnicity      
    White 362 78.4 379 77.0  
    Black 10 2.2 12 2.4  
    Portuguese–Cape Verdean 60 13.0 71 14.4  
    Other 30 6.5 30 6.1 .91 
Perceived health status      
    Excellent–very good 221 47.4 244 49.3  
    Good 188 40.3 192 38.8  
    Fair–poor 57 12.2 59 11.9 .65 
SOC for exercise at baseline      
    Precontemplation 89 18.9 88 17.7  
    Contemplation 32 6.8 29 5.8  
    Preparation 84 17.9 82 16.5  
    Action 22 4.7 30 6.0  
    Maintenance 243 51.7 267 53.8 .77 
 Intervention Assignment<--CO?1-->
 
    
 Intervention Group
 
 Comparison Group
 
  
Characteristic n (M% (SDn (M% (SDp 
Baseline age: years (75.2) (6.7) (74.7) (6.6) .28 
Education: years (12.9) (2.7) (12.9) (3.1) .59 
YPAS summary score (44.9) (26.4) (45.7) (31.4) .66 
TUG: seconds (8.7) (4.1) (8.8) (5.7) .74 
Gender      
    Male 128 27.2 146 29.6  
    Female 342 72.8 348 70.4 .43 
Race or ethnicity      
    White 362 78.4 379 77.0  
    Black 10 2.2 12 2.4  
    Portuguese–Cape Verdean 60 13.0 71 14.4  
    Other 30 6.5 30 6.1 .91 
Perceived health status      
    Excellent–very good 221 47.4 244 49.3  
    Good 188 40.3 192 38.8  
    Fair–poor 57 12.2 59 11.9 .65 
SOC for exercise at baseline      
    Precontemplation 89 18.9 88 17.7  
    Contemplation 32 6.8 29 5.8  
    Preparation 84 17.9 82 16.5  
    Action 22 4.7 30 6.0  
    Maintenance 243 51.7 267 53.8 .77 

Note: The intervention and comparison groups are n = 470 and n = 496, respectively; some data are missing, so the sample size for all variables may not equal 966. Values given in parentheses refer to means or standard deviations, as shown. SENIOR = Study of Exercise and Nutrition in Older Rhode Islanders; YPAS = Yale Physical Activity Survey; TUG = Timed Up-and-Go test; SOC = state of change; SD = standard deviation.

Table 2.

SOC Movement from Baseline by Intervention Assignment.

 Intervention Assignment<--CO?2-->
 
   
 Intervention Group
 
 Comparison Group
 
 
Stage Movement n n 
12 months     
    Progress 102 22.3 94 19.4 
    Regress 102 22.3 124 25.6 
    Stable 253 55.4 266 55.0 
24 months     
    Progress 128 27.2 103 20.8 
    Regress 117 24.9 138 27.8 
    Stable 225 47.9 255 51.4 
 Intervention Assignment<--CO?2-->
 
   
 Intervention Group
 
 Comparison Group
 
 
Stage Movement n n 
12 months     
    Progress 102 22.3 94 19.4 
    Regress 102 22.3 124 25.6 
    Stable 253 55.4 266 55.0 
24 months     
    Progress 128 27.2 103 20.8 
    Regress 117 24.9 138 27.8 
    Stable 225 47.9 255 51.4 

Note: Intervention and comparison groups are n = 470 and n = 496, respectively; some data are missing, so the sample size for all variables may not equal 966. SOC = stage of change.

Table 3.

SOC Movement from Baseline by Stage and Intervention Assignment.

 Progress<--CO?3-->: %<--CO?4--> (n)
 
 Regress: % (n)
 
 Stable: % (n)
 
 
Baseline Stage Intervention Comparison Intervention Comparison Intervention Comparison 
12 Months       
    Precontemplation 37.1 (33) 37.6 (32)   62.9 (56) 62.4 (53) 
    Contemplation 59.4 (19) 48.3 (14) 37.5 (12) 44.8 (13) 3.1 (1) 6.9 (2) 
    Preparation 45.6 (36) 38.3 (31) 41.8 (33) 40.7 (33) 12.7 (10) 21.0 (17) 
    Action 77.8 (14) 58.6 (17) 16.7 (3) 37.9 (11) 5.6 (1) 3.4 (1) 
    Maintenance   22.6 (54) 25.8 (67) 77.4 (185) 74.2 (193) 
24 Months       
    Precontemplation* 58.4 (52) 43.2 (38)   41.6 (37) 6.8 (50) 
    Contemplation 62.5 (20) 51.7 (15) 31.3 (10) 31.0 (9) 6.3 (2) 17.2 (5) 
    Preparation 51.2 (43) 46.3 (38) 33.3 (28) 40.2 (33) 15.5 (13) 13.4 (11) 
    Action 59.1 (13) 40.0 (12) 36.4 (8) 50.0 (15) 4.5 (1) 10.0 (3) 
    Maintenance   29.2 (71) 30.3 (81) 70.8 (172) 69.7 (186) 
 Progress<--CO?3-->: %<--CO?4--> (n)
 
 Regress: % (n)
 
 Stable: % (n)
 
 
Baseline Stage Intervention Comparison Intervention Comparison Intervention Comparison 
12 Months       
    Precontemplation 37.1 (33) 37.6 (32)   62.9 (56) 62.4 (53) 
    Contemplation 59.4 (19) 48.3 (14) 37.5 (12) 44.8 (13) 3.1 (1) 6.9 (2) 
    Preparation 45.6 (36) 38.3 (31) 41.8 (33) 40.7 (33) 12.7 (10) 21.0 (17) 
    Action 77.8 (14) 58.6 (17) 16.7 (3) 37.9 (11) 5.6 (1) 3.4 (1) 
    Maintenance   22.6 (54) 25.8 (67) 77.4 (185) 74.2 (193) 
24 Months       
    Precontemplation* 58.4 (52) 43.2 (38)   41.6 (37) 6.8 (50) 
    Contemplation 62.5 (20) 51.7 (15) 31.3 (10) 31.0 (9) 6.3 (2) 17.2 (5) 
    Preparation 51.2 (43) 46.3 (38) 33.3 (28) 40.2 (33) 15.5 (13) 13.4 (11) 
    Action 59.1 (13) 40.0 (12) 36.4 (8) 50.0 (15) 4.5 (1) 10.0 (3) 
    Maintenance   29.2 (71) 30.3 (81) 70.8 (172) 69.7 (186) 

Notes: Intervention and comparison groups are n = 470 and n = 496, respectively; some data are missing, so the sample size for all variables may not equal 966. SOC = stage of change.

*Significant difference (p <.05) in stage progression by intervention assignment.

Table 4.

Adjusted Means of the TTM Constructs by Intervention Assignment.

 Intervention <--CO?5-->Group
 
 Comparison Group
 
  
Construct M SE M SE p 
Self-efficacy      
    Baseline 3.41 .04 3.37 .04 .57 
    12 months 3.50 .05 3.41 .04 .10 
    24 months 3.52 .05 3.41 .05 .11 
Pros      
    Baseline 3.51 .05 3.47 .05 .52 
    12 months 3.64 .05 3.65 .04 .98 
    24 months 3.81 .05 3.67 .05 .03 
Cons      
    Baseline 1.22 .02 1.24 .02 .31 
    12 months 1.16 .02 1.49 .02 .20 
    24 months 1.15 .02 1.16 .02 .80 
Experiential processes      
    Baseline 50.87 .57 50.52 .55 .63 
    12 months 53.32 .52 52.46 .51 .21 
    24 months 54.83 .58 52.83 .56 .10 
Behavioral processes      
    Baseline 45.04 .55 43.61 .53 .05 
    12 months 46.40 .53 45.51 .51 .20 
    24 months 46.13 .56 45.13 .54 .17 
 Intervention <--CO?5-->Group
 
 Comparison Group
 
  
Construct M SE M SE p 
Self-efficacy      
    Baseline 3.41 .04 3.37 .04 .57 
    12 months 3.50 .05 3.41 .04 .10 
    24 months 3.52 .05 3.41 .05 .11 
Pros      
    Baseline 3.51 .05 3.47 .05 .52 
    12 months 3.64 .05 3.65 .04 .98 
    24 months 3.81 .05 3.67 .05 .03 
Cons      
    Baseline 1.22 .02 1.24 .02 .31 
    12 months 1.16 .02 1.49 .02 .20 
    24 months 1.15 .02 1.16 .02 .80 
Experiential processes      
    Baseline 50.87 .57 50.52 .55 .63 
    12 months 53.32 .52 52.46 .51 .21 
    24 months 54.83 .58 52.83 .56 .10 
Behavioral processes      
    Baseline 45.04 .55 43.61 .53 .05 
    12 months 46.40 .53 45.51 .51 .20 
    24 months 46.13 .56 45.13 .54 .17 

Note: Intervention and comparison groups are n = 470 and n = 496, respectively; some data are missing, so the sample size for all variables may not equal 966. Adjusted means indicates that the analyses controlled for gender, age, and perceived health status at baseline. TTM = transtheoretical model of behavior change; SE = standard error.

Table 5.

Adjusted Means of the YPAS Summary Score and TUG Scores by Intervention Assignment.

 Intervention Group
 
 Comparison Group
 
  
Scores M SE M SE p 
YPAS summary score      
    Baseline 46 1.4 46 1.3 .96 
    12 months 46 1.2 47 1.1 .81 
    24 months 47 1.3 47 1.2 .92 
TUG score (seconds)      
    Baseline 8.4 0.2 8.6 .2 .51 
    12 months 8.6 0.2 8.7 .2 .50 
    24 months 8.9 0.3 8.9 .3 .93 
 Intervention Group
 
 Comparison Group
 
  
Scores M SE M SE p 
YPAS summary score      
    Baseline 46 1.4 46 1.3 .96 
    12 months 46 1.2 47 1.1 .81 
    24 months 47 1.3 47 1.2 .92 
TUG score (seconds)      
    Baseline 8.4 0.2 8.6 .2 .51 
    12 months 8.6 0.2 8.7 .2 .50 
    24 months 8.9 0.3 8.9 .3 .93 

Note: Intervention and comparison groups are n = 470 and n = 496, respectively; some data are missing, so the sample size for all variables may not equal 966. Adjusted means indicates that the analyses controlled for gender, age at baseline, and perceived health status at baseline. YPAS = Yale Physical Activity Survey; TUG = Timed Up-and-Go test; SE = standard error.

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