Mediators Of Change In Physical Activity Research Articles

Psychosocial mediators of physical activity change in a web-based intervention for Latinas.

Objective: To determine whether psychosocial constructs targeted in an online physical activity intervention for Latinas mediated changes in moderate-to-vigorous physical activity (MVPA). Method: Data were taken from a randomized trial of a web-based MVPA intervention for Latina women age 18-65 (N = 205) based on social cognitive theory and the transtheoretical model. Baseline and 6-month measures included minutes/week of MVPA (ActiGraph GT3X + accelerometers and 7-Day Physical Activity Recall Interview) and theorized mediators (self-efficacy, behavioral processes, cognitive processes, social support, enjoyment). A multiple mediation model adjusting for baseline MVPA was fit using a products of coefficients method, simultaneously testing all hypothesized mediators. Results: MVPA increased more in the intervention group than controls by 50 min/week (self-report) and 31 min/week (accelerometers). For the self-reported MVPA model, there was an intervention effect (a-path coefficient) on self-efficacy (b = 0.43, p < .01), cognitive processes (b = 0.64, p < .01), behavioral processes (b = 0.54, p < .01), and enjoyment (b = 9.91, p = .01). Changes in self-efficacy (b = 24.54, p = .03), social support from friends (b = 2.36, p = .04), and enjoyment (a = 0.74, p = .08) were associated with changes in MVPA (b-path coefficient). However, only changes in self-efficacy (b = 10.49, 95% CI [2.46, 24.54]) and enjoyment (b = 7.30, 95% CI [0.92, 21.78]) mediated the intervention effect on MVPA (ab-path coefficient). For the accelerometer-measured MVPA model, intervention effects were significant for self-efficacy (b = 0.48, p < .01), cognitive processes (b = 0.62, p < .01), and behavioral processes (b = 0.61, p < .01), yet only self-efficacy was associated with changes in MVPA (b = 4.43, p = .03), and mediated intervention effects on MVPA (b = 12.15, 95% CI [11.25, 16.34]). Conclusions: Future MVPA interventions with Latinas should target self-efficacy and enjoyment to maximize efficacy. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Supplemental Material for Psychosocial Mediators of Physical Activity Change in a Web-Based Intervention for Latinas

Supplemental Material for Psychosocial Mediators of Physical Activity Change in a Web-Based Intervention for Latinas

Psychosocial mediators of physical activity and fruit and vegetable consumption in the Faith, Activity, and Nutrition programme.

Performing and publishing mediator analyses, whether significant or null, provides insight into where research efforts should focus and will assist in developing effective and powerful behaviour change interventions. The present study examined whether self-efficacy, social support and church support mediated changes in leisure-time physical activity (PA) and fruit and vegetable (F&V) consumption in a faith-based intervention. A 15-month PA and F&V intervention, guided by the structural ecological model, targeted the social, cultural and policy influences within the church. Outcomes and mediators were measured at baseline and follow-up. Data were collected from 2007 to 2011. MacKinnon's product of coefficients tested for mediation. Sixty-eight African Methodist Episcopal churches in South Carolina, USA. Five hundred and eighty-two (PA) and 588 (F&V) church members. Despite the significant increases in PA and F&V consumption, none of the hypothesized mediators were significant mediators of change in PA or F&V consumption. When examining each path of the mediation model, the intervention did not change any of the hypothesized mediators. However, changes in some mediators were associated with changes in outcomes. Although there was no significant mediation, the association between changes in mediators and changes in PA and/or F&V consumption suggest that these variables likely play some role in changing these behaviours. Future studies should consider mediation analyses a priori, putting careful thought into the types of measures used and the timing of those measures, while also being cognizant of participant and staff burden. Finding a balance will be fundamental in successfully understanding how interventions exert their effects.

Exploring mediators of accelerometer assessed physical activity in young adolescents in the HEalth In Adolescents study – a group randomized controlled trial

BackgroundThere is a shortage of information about the factors that mediate physical activity intervention effects which involve youth. The purpose of this study was to examine whether personal, social and physical-environmental factors mediated the intervention effect on physical activity and whether gender and weight status moderated mediated effects in the Health In Adolescents Study – a school-based intervention to promote healthy weight development among young adolescents.MethodsParticipating schools were randomized to Control (n = 25) and Intervention (n = 12). The intervention components to enhance physical activity targeted change through theoretically informed mediators embedded in a social-ecological framework. Accelerometer assessed physical activity (mean count per minute) and self-efficacy, enjoyment, perceived social support from parents, teachers and friends and perceived environmental opportunities were measured by questionnaires at baseline and post-intervention after 20 months among 700 11–13 year-old adolescents (Intervention = 485; Control = 215). The product-of-coefficient test was used to examine mediation.ResultsNo mediating effect of any of the hypothesized mediators was identified and gender and weight status did not moderate any mediated effects with the exception of weight status that moderated the mediated effect of enjoyment. Few intervention effects were seen on the mediators, except for a positive change in social support from teachers among girls and the normal weight, and a negative effect on enjoyment and self-efficacy among the overweight. However, change in enjoyment, self-efficacy, perceived social support from friends and environmental opportunities were associated with change in mean count per minute with some variation across the investigated subgroups, and thus show evidence of being potential mediators of physical activity change in adolescents.ConclusionsWhile no mediation effects were observed, change in both personal and social-environmental factors predicted change in physical activity behavior. Hence, a social- ecological approach targeting a wide range of determinants to promote change in physical activity holds promise. Overweight and normal weight adolescents may not respond in the same way to school-based physical activity interventions. Therefore, strategies to better reach the overweight seem needed. Future studies should continue to identify mediating and moderation mechanisms in physical activity change in adolescents.

More Active Mums in Stirling (MAMMiS): a physical activity intervention for postnatal women. Study protocol for a randomized controlled trial

BackgroundMany postnatal women are insufficiently physically active in the year after childbirth and could benefit from interventions to increase activity levels. However, there is limited information about the efficacy, feasibility and acceptability of motivational and behavioral interventions promoting postnatal physical activity in the UK.MethodsThe MAMMiS study is a randomized, controlled trial, conducted within a large National Health Service (NHS) region in Scotland. Up to 76 postnatal women will be recruited to test the impact of two physical activity consultations and a 10-week group pram-walking program on physical activity behavior change. The intervention uses evidence-based motivational and behavioral techniques and will be systematically evaluated using objective measures (accelerometers) at three months, with a maintenance measure taken at a six-month follow-up. Secondary health and well-being measures and psychological mediators of physical activity change are included.DiscussionThe (MAMMiS study will provide a test of a theoretical and evidence-based physical activity behavior change intervention for postnatal women and provide information to inform future intervention development and testing within this population.Trial registrationCurrent Controlled Trials ISRCTN79011784

Mediators of physical activity change in a behavioral modification program for type 2 diabetes patients.

BackgroundMany studies have reported significant behavioral impact of physical activity interventions. However, few have examined changes in potential mediators of change preceding behavioral changes, resulting in a lack of information concerning how the intervention worked. Our purpose was to examine mediation effects of changes in psychosocial variables on changes in physical activity in type 2 diabetes patients.MethodsNinety-two patients (62 ± 9 years, 30, 0 ± 2.5 kg/m2, 69% males) participated in a randomized controlled trial. The 24-week intervention was based on social-cognitive constructs and consisted of a face-to-face session, telephone follow-ups, and the use of a pedometer. Social-cognitive variables and physical activity (device-based and self-reported) were collected at baseline, after the 24-week intervention and at one year post-baseline. PA was measured by pedometer, accelerometer and questionnaire.ResultsPost-intervention physical activity changes were mediated by coping with relapse, changes in social norm, and social modeling from family members (p ≤ 0.05). One-year physical activity changes were mediated by coping with relapse, changes in social support from family and self-efficacy towards physical activity barriers (p ≤ 0.05)ConclusionsFor patients with type 2 diabetes, initiatives to increase their physical activity could usefully focus on strategies for resuming regular patterns of activity, on engaging family social support and on building confidence about dealing with actual and perceived barriers to activity.Trial RegistrationNCT00903500, ClinicalTrials.gov.

Impact of a physical activity intervention program on cognitive predictors of behaviour among adults at risk of Type 2 diabetes (ProActive randomised controlled trial)

BackgroundIn the ProActive Trial an intensive theory-based intervention program was no more effective than theory-based brief advice in increasing objectively measured physical activity among adults at risk of Type 2 diabetes. We aimed to illuminate these findings by assessing whether the intervention program changed cognitions about increasing activity, defined by the Theory of Planned Behaviour, in ways consistent with the theory.MethodsN = 365 sedentary participants aged 30–50 years with a parental history of Type 2 diabetes were randomised to brief advice alone or to brief advice plus the intervention program delivered face-to-face or by telephone. Questionnaires at baseline, 6 and 12 months assessed cognitions about becoming more physically active. Analysis of covariance was used to test intervention impact. Bootstrapping was used to test multiple mediation of intervention impact.ResultsAt 6 months, combined intervention groups (face-to-face and telephone) reported that they found increasing activity more enjoyable (affective attitude, d = .25), and they perceived more instrumental benefits (e.g., improving health) (d = .23) and more control (d = .32) over increasing activity than participants receiving brief advice alone. Stronger intentions (d = .50) in the intervention groups than the brief advice group at 6 months were partially explained by affective attitude and perceived control. At 12 months, intervention groups perceived more positive instrumental (d = .21) and affective benefits (d = .29) than brief advice participants. The intervention did not change perceived social pressure to increase activity.ConclusionLack of effect of the intervention program on physical activity over and above brief advice was consistent with limited and mostly small short-term effects on cognitions. Targeting affective benefits (e.g., enjoyment, social interaction) and addressing barriers to physical activity may strengthen intentions, but stronger intentions did not result in more behaviour change. More powerful interventions which induce large changes in TPB cognitions may be needed. Other interventions deserving further evaluation include theory-based brief advice, intensive measurement of physical and psychological factors, and monitoring of physical activity. Future research should consider a wider range of mediators of physical activity change, assess participants' use of self-regulatory strategies taught in the intervention, and conduct experimental studies or statistical modelling prior to trial evaluation. ISRCTN61323766.

A new approach to physical activity maintenance: Rationale, design, and baseline data from the Keep Active Minnesota trial

BackgroundSince many individuals who initiate physical activity programs are highly likely to return to a sedentary lifestyle, innovative strategies to efforts to increase the number of physically active older adults who successfully maintain beneficial levels of PA for a substantial length of time are needed.Methods/DesignThe Keep Active Minnesota Trial is a randomized controlled trial of an interactive phone- and mail-based intervention to help 50–70 year old adults who have recently increased their physical activity level, maintain that activity level over a 24-month period in comparison to usual care. Baseline, 6, 12, and 24 month measurement occurred via phone surveys with kilocalories expended per week in total and moderate-to-vigorous physical activity (CHAMPS Questionnaire) as the primary outcome measures. Secondary outcomes include hypothesized mediators of physical activity change (e.g., physical activity enjoyment, self-efficacy, physical activity self-concept), body mass index, and depression. Seven day accelerometry data were collected on a sub-sample of participants at baseline and 24-month follow-up.DiscussionThe Keep Active Minnesota study offers an innovative approach to the perennial problem of physical activity relapse; by focusing explicitly on physical activity maintenance, the intervention holds considerable promise for modifying the typical relapse curve. Moreover, if shown to be efficacious, the use of phone- and mail-based intervention delivery offers potential for widespread dissemination.Trial registrationClinicalTrials.gov Identifier: NCT00283452.

Are constructs of the transtheoretical model for physical activity measured equivalently between sexes, age groups, and ethnicities?

Identifying mediators of physical activity change requires measurement instruments that are reliable, valid, and generalizable to multiple populations. Despite continued application of the transtheoretical model (TTM) to the study of physical activity, the structural components of the TTM measurement instruments have been understudied in diverse populations. A multiethnic sample (N = 700, M (age) = 47, 63% women, 38% Caucasian) of participants living in Hawaii completed TTM measures. The factor validity and measurement equivalence/invariance (ME/I) of decisional balance, barrier self-efficacy, temptations, and processes of change instruments were explored between men, women, age groups, and ethnicities. Measurement models of barrier self-efficacy and revised models of temptations and processes of change demonstrated sufficient evidence for ME/I among all subgroups. A revised model of decisional balance demonstrated sufficient evidence for ME/I between genders and among ethnicities, but not among age groups. Future research should examine the stability of these constructs across time.

Mediators of Change in Physical Activity Following an Intervention in Primary Care: PACE

Background.The current study evaluated the construct validity of a physical activity intervention in primary care by testing whether the intervention changed hypothesized mediators and whether changes in the mediators were associated with behavior change.Methods.Matched physician offices were nonrandomly assigned to intervention or control. Apparently healthy, sedentary, adult patients (N= 255) were recruited from physician offices. The intervention was brief, behaviorally based counseling by physicians, plus a telephone follow-up 2 weeks later. Assessments of physical activity and mediators were collected at baseline and at 4- to 6-week follow-up. Hypothesized mediators were processes of change, self-efficacy, and social support for exercise.Results.Patients who were counseled improved significantly more than those in the control group on behavioral and cognitive processes of change. Other changes in mediators were nonsignificant. Behavioral processes of change and self-efficacy made significant contributions to the multiple regression model explaining self-report and objective measures of physical activity.Conclusions.The intervention affected some of the targeted mediators of physical activity change. Two of three mediator variables were associated with changes in physical activity regardless of experimental condition and other variables. The construct validity of the intervention was partially supported.