Mediators of change in physical activity following an intervention in primary care: PACE

Psychosocial mediators of physical activity behavior among adults and children

BACKGROUND

Researchers examining theory-based, physical activity (PA) interventions postulate that interventions are effective by changing theoretical constructs hypothesized to mediate the relationship between the intervention and PA behavior. Research indicates that PA interventions are effective for increasing PA behavior. However, whether effective interventions are due to predicted changes in theoretical constructs remains poorly understood.

METHODS

Studies that examined theoretical constructs (i.e., mediators) in PA interventions of adults or children, which used experimental designs and met other criteria for evaluating mediation, were collected via literature searches, personal searches of files, and personal communications. Only studies examining the direct effect of the intervention on the hypothesized mediator were considered relevant for this study.

RESULTS

Based on our criteria, the adult literature search yielded ten studies and the child literature search yielded two studies. The most common mediators examined included behavioral processes of change, cognitive processes of change, self-efficacy, decisional balance, social support, and enjoyment. Research indicates that behavioral processes are likely mediators. There was some support for the importance of self-efficacy as a mediator.

CONCLUSIONS

Few studies have used statistically recommended methods to examine mediators in PA intervention studies. Therefore, definitive conclusions about the importance of the mediators reviewed are not possible at this time. Additional PA mediator-intervention studies using recommended statistical methods are necessary to truly test if theory-based PA interventions are effective due to predicted changes in theoretical constructs.

Physical activity among older Filipino-American women

Filipino women (N = 530, mean age 63 years, predominantly low income) were recruited through various community based organizations and churches in Los Angeles County. All women were randomly invited to attend a single group session with a Filipino health educator to discuss breast and cervical cancer screening or the health benefits of exercise. At 3 months after the group session, the exercise assessment tool used in the National Health and Nutrition Examination Survey III was completed by 487 women (92 percent retention rate). This paper describes the pattern of physical activity among older Filipino-American women and a physical activity intervention specifically designed for this group.

Exercise and the transtheoretical model: a longitudinal test of a population sample

BACKGROUND

The purpose of this study was to test the ability of the Transtheoretical Model (TTM) to predict exercise stage transition of individuals in a large, untreated-population-based, random sample of Canadian adults (18-65 years of age) over two consecutive time periods.

METHODS

Assessments of TTM's stage of exercise behavior change, self-efficacy, pros, cons, experiential processes, and behavioral processes were made at baseline (time 1), 6 months (time 2), and 1 year (time 3). Six hundred eighty-three men and women, identified through random-digit telephone dialing, completed all measures across the three time points. Within each time period (time 1-2; time 2-3) participants were categorized as having regressed (moved back at least on stage), remained (no stage change), or progressed (moved forward at least one stage). Baseline TTM constructs were analyzed for their ability to predict change transition across the two time periods.

RESULTS

Of 40 possible predictions (20 for each time period) 18 (45%) were supported.

CONCLUSIONS

Overall, the findings demonstrate partial support for the internal validation of TTM in the exercise domain. Implications of the findings are discussed and future directions for researchers, practitioners, and program planners are provided.

Interventions to promote physical activity by older adults

Physical inactivity has been established to be an independent risk factor for a range of chronic diseases and conditions that threaten the health of the nation. However, only a minority of the population is currently meeting the recommended levels of regular physical activity, which have been linked with important health and quality-of-life benefits. Older adults are at particular risk for leading sedentary lifestyles. This article provides an overview of factors associated with physical activity for older adults and also describes potentially promising interventions for promoting regular physical activity in this growing population segment. Examples of interventions undertaken at personal and interpersonal as well as broader levels of analysis (e.g., environmental) are provided. Major issues currently facing the field are discussed, including the ongoing challenge of developing assessment tools that are sensitive to the more moderate-intensity physical activities favored by older adults and the formidable task of combining clinical approaches with environmental and policy strategies aimed at combating this public health problem.

Physician-based activity counseling: intervention effects on mediators of motivational readiness for physical activity

In theory-based interventions for behavior change, there is a need to examine the effects of interventions on the underlying theoretical constructs and the mediating role of such constructs. These two questions are addressed in the Physically Active for Life study, a randomized trial of physician-based exercise counseling for older adults. Three hundred fifty-five patients participated (intervention n = 181, control n = 174; mean age = 65.6 years). The underlying theories used were the Transtheoretical Model, Social Cognitive Theory and the constructs of decisional balance (benefits and barriers), self-efficacy, and behavioral and cognitive processes of change. Motivational readiness for physical activity and related constructs were assessed at baseline, 6 weeks, and 8 months. Linear or logistic mixed effects models were used to examine intervention effects on the constructs, and logistic mixed effects models were used for mediator analyses. At 6 weeks, the intervention had significant effects on decisional balance, self-efficacy, and behavioral processes, but these effects were not maintained at 8 months. At 6 weeks, only decisional balance and behavioral processes were identified as mediators of motivational readiness outcomes. Results suggest that interventions of greater intensity and duration may be needed for sustained changes in mediators and motivational readiness for physical activity among older adults.

Psychosocial predictors of changes in physical activity in overweight sedentary adults following counseling in primary care

BACKGROUND

Increasing regular physical activity in adults at elevated risk of cardiovascular disease is an important target for preventive medicine. This study evaluated demographic, social and cognitive predictors of self-reported changes in physical activity after 4 and 12 months in a randomized trial of behavioral counseling in primary care.

METHOD

Data were analyzed from 234 male and 271 female sedentary patients with a body mass index of 25-35 (age 49.1 years, SD 11.2 years), who had been counseled by nurses in general practice using stage-matched behavioral methods or standard health promotion and who were reassessed after 4 months. A total of 187 men and 231 women were reassessed after 12 months.

RESULTS

Physical activity at baseline was associated with educational status, having a partner who exercised, perceived barriers, and self-efficacy. Changes over 4 months were greater with behavioral counseling, in non-smokers and in patients with higher ratings of motivation to change and self-efficacy at baseline. Changes over 12 months were greater with behavioral counseling and were predicted in the behavioral group by social support variables, perceived benefits, and barriers. Stage of readiness to change predicted increased activity at 4 but not 12 months.

CONCLUSIONS

Social support and cognitive variables predict increased physical activity following counseling in primary care of sedentary overweight adults. Different factors are relevant to short- and long-term modifications in behavior.

Project GRAD: two-year outcomes of a randomized controlled physical activity intervention among young adults. Graduate Ready for Activity Daily

INTRODUCTION

Project Graduate Ready for Activity Daily evaluated a program to promote physical activity through the transition of university graduation in a randomized controlled trial.

METHODS

Three hundred thirty-eight university seniors participated in either a cognitive-behavioral intervention course or a knowledge-oriented general health course during the semester before graduation. Behaviorally oriented phone and mail follow-up was delivered to the intervention group for 18 months. Physical activity outcomes and mediating variables were assessed at baseline, 1 and 2 years (93% retention rate).

RESULTS

There were no significant intervention effects on physical activity outcomes at 2 years for either men or women. Experiential and behavioral processes of change were significantly improved for intervention women over 2 years.

CONCLUSIONS

Despite excellent participation in a theoretically based, well-attended intervention, few long-term effects on physical activity or its mediators were found. Additional research is needed to determine optimal interventions for physical activity and to validate or alter current behavior change theory.

Potential mediators of change in a physical activity promotion course for university students: Project GRAD

The purpose of the study is to evaluate the performance of theoretically-derived mediators of health behavior change. Participants were university seniors (184 females; 154 males) randomly assigned to an intervention course designed to promote physical activity or to a control course. Five physical activity outcomes and nine psychosocial mediating variables were assessed at baseline and the end of the 16-week course. For women, the intervention had significant effects on five of the mediators, including self-efficacy for making time, self-efficacy for resisting relapse, social support from friends, and experiential and behavioral processes of change. Among men, the intervention improved use of behavioral processes of change but also had the unintended effect of increasing perceived barriers to activity. For women, significant contributors to regressions explaining physical activity change were social support from friends (for total activity) and change in self-efficacy for resisting relapse (for vigorous exercise). For men, significant explanatory variables included change in enjoyment (for total activity), change in self-efficacy for resisting relapse (for strength exercise), and change in benefits (for moderate intensity activity). For both sexes, there were significant findings in the unexpected direction. Across the five physical activity outcomes, hypothesized mediators were inconsistent and weak contributors to the models. Investigating mediators of behavior change has the potential to stimulate improvements in theories and interventions.

Self-efficacy and participation in vigorous physical activity by high school students

The relationship between physical activity self-efficacy and participation in vigorous physical activity by high school students is examined in this article. Self-efficacy is hypothesized to be positively related to participation in three settings (physical education class, other school-related activities, and outside of school). The effects of age, gender, perceived barriers, and actual barriers are also examined. The sample consists of 1,041 grade 9 and 11 students from a large Metropolitan Toronto school board. Factors derived from a previous (factor) analysis were used to examine the effects of self-efficacy, perceived barriers, and life strain (an actual barrier). The results of multiple regression analysis indicate that physical activity self-efficacy, despite external barriers (but not internal barriers), is predictive of physical activity participation in the hypothesized direction. Other results show consistent age and gender effects on physical activity participation and some support for the hypothesized relationship between perceived barriers and participation.

Exploring self-efficacy as a predictor of disease management

Self-efficacy is posited in social cognitive theory as fundamental to behavior change. Few health behavior studies have examined self-efficacy prospectively, viewed it as part of a reciprocal behavioral process, or compared self-efficacy beliefs in the same population across different behaviors. This article first discusses self-efficacy in its theoretical context and reviews the available prospective studies. Second, it explores self-efficacy as a predictor of disease management behaviors in 570 older women with heart disease. Although the R2 statistics in each case were modest, the construct is shown to be a statistically significant (p<.05) predictor at both 4 and 12 months postbaseline of several disease management behaviors: using medicine as prescribed, getting adequate exercise, managing stress, and following a recommended diet. Building self-efficacy is likely a reasonable starting point for interventions aiming to enhance heart disease management behaviors of mature female patients.

Mediating variable framework in physical activity interventions. How are we doing? How might we do better?

INTRODUCTION

Behavioral science provides the foundation for physical activity interventions. The mediating variable framework is used to assess the status of physical activity interventions and the roles that are, or could be played, by behavioral theory.

METHODS

Twenty-five physical activity intervention studies and 45 physical activity correlational studies were found in the literature, tabulated, and included in the analysis.

RESULTS

Behavioral interventions for promoting physical activity have worked primarily when participants were motivated enough to volunteer or when a school-based physical education program changed. In most cases, behavioral or psychosocial theory accounted for 30% or less of the variability in physical activity behaviors. Most intervention studies do not measure mediating variables, and when they do, they do not systematically effect changes in all the mediating variables on which they are predicated.

DISCUSSION

To increase the effectiveness of physical activity interventions, more physical activity research should focus on a better understanding of the predictors of physical activity and toward interventions demonstrated to effect change in these predictors of physical activity.

CONCLUSION

Changing the focus to basic behavioral and social science and mediator change research should provide a more systematic and cost-effective approach to increasing the effectiveness of physical activity interventions.

Advice on exercise from a family physician can help sedentary patients to become active

OBJECTIVES

To test the effectiveness, in the setting of primary health care, of verbal advice on exercise from a family physician (FP) combined with supporting written information.

DESIGN

A controlled trial with subjects allocated to a control group or one of two intervention groups using a balanced design based on day of the week.

SETTING

Ten general practices in Perth, Western Australia.

SUBJECTS

All sedentary patients consulting an FP.

INTERVENTION

Verbal advice on exercise from the FP and a pamphlet on exercise mailed to the patient's home address within 2 days of his/her visit to the doctor.

MAIN OUTCOME MEASURE

Level of physical activity at follow-up.

RESULTS

6,351 adult patients attending an FP practice completed a screening questionnaire, and 763 sedentary adults were recruited to the project. The response to follow-up, via a postal survey at 1, 6, and 12 months after the index consultation was 70%, 60%, and 57%, respectively. At 1 month a subsample of the control and intervention subjects were contacted for a telephone interview to verify self-reported levels of activity (n = 136). Treating all nonresponders as sedentary, at 1 month significantly more subjects in the combined intervention groups reported doing some physical activity (40%) compared with the control group (31%). Similarly, at 6 months, 30% of the control group and 38% of the combined intervention groups were "now active." There was very little change at follow-up at 12 months (31% control and 36% intervention groups, respectively).

CONCLUSION

A simple intervention aimed at the promotion of physical activity to sedentary patients in general practice can help reduce inactivity.