Studying Movement-Related Behavioral Maintenance and Adoption in Real Time: Protocol for an Intensive Ecological Momentary Assessment Study Among Older Adults

Background Older adults struggle to maintain newly initiated levels of physical activity (PA) or sedentary behavior (SB) and often regress to baseline levels over time. This is partly because health behavior theories that inform interventions rarely address how the changing contexts of daily life influence the processes regulating PA and SB or how those processes differ across the behavior change continuum. Few studies have focused on motivational processes that regulate the dynamic nature of PA and SB adoption and maintenance on microtimescales (ie, across minutes, hours, or days). Objective The overarching goal of Project Studying Maintenance and Adoption in Real Time (SMART) is to determine the motivational processes that regulate behavioral adoption versus maintenance over microtimescales, using a dual process framework combined with ecological momentary assessment and sensor-based monitoring of behavior. This paper describes the recruitment, enrollment, data collection, and analytics protocols for Project SMART. Methods In Project SMART, older adults engaging in at least 30 minutes of moderate-to-vigorous intensity PA per week complete 3 data collection periods over 1 year, with each data collection period lasting 14 days. Across each data collection period, participants wear an ActiGraph GT3X accelerometer (ActiGraph, LLC) on their nondominant waist and an ActivPAL micro4 accelerometer (PAL Technologies, Ltd) on their anterior thigh to measure PA and SB, respectively. Ecological momentary assessment questionnaires are randomly delivered via smartphone 10 times per day on 4 selected days in each data collection period and assess reflective processes (eg, evaluating one’s efficacy and exerting self-control) and reactive processes (eg, contextual cues) within the dual process framework. At the beginning and end of each data collection period, participants complete a computer-based questionnaire to learn more about their typical motivation for PA and SB, physical and mental health, and life events over the course of the study. Results Recruitment and enrollment began in January 2021; enrollment in the first data collection period was completed by February 2022; and all participants completed their second and third data collection by July 2022 and December 2022, respectively. Data were collected from 202 older adults during the first data collection period, with approximate retention rates of 90.1% (n=182) during the second data collection period and 88.1% (n=178) during the third data collection period. Multilevel models and mixed-effects location scale modeling will be used to evaluate the study aims. Conclusions Project SMART seeks to predict and model the adoption and maintenance of optimal levels of PA and SB among older adults. In turn, this will inform the future delivery of personalized intervention content under conditions where the content will be most effective to promote sustained behavior change among older adults. International Registered Report Identifier (IRRID) DERR1-10.2196/47320

1 R15 AG066950-01 3 BMIO MAHER, J an essential first step towards a larger program of research aimed at integrating real-time data from smartphone-based questionnaires and activity monitors to deliver personalized intervention content when it will be most effective, to promote sustained behavior change among older adults.

CRITIQUE 1
Significance: 2 Investigator(s): 2 Innovation: 2 Approach: 3 Environment: 2 Overall Impact: The proposed prospective cohort study seeks to determine the microtemporal processes (unfolding over minutes, hours, and days) that drive adoption and maintenance of physical activity (PA) and sedentary behavior (SB) among older adults. The investigators propose to recruit two groups -100 PA adopters and 100 PA maintainers. Participants will complete 3 waves of data (baseline, 6 months, 12 months). Each wave will consist of 14 days of wrist actigraphy monitoring to assess PA and SB and 4 days of EMA (10x/day) to assess reflective (e.g., evaluating one's selfefficacy and exerting self-control) and reactive (e.g., contextual cues) microtemporal processes. The central hypothesis is that reflective processes will be more strongly linked to PA adoption, whereas reactive processes will be more strongly linked to PA maintenance. The significance of the proposed research is high. If successful, the proposed project (which is well supported by rigorous prior research) would advance knowledge of the microtemporal processes in daily life that predict PA and SBknowledge that could inform the development of future just-in-time interventions designed to promote long-term change in PA and SB. The proposed project is highly likely to generate multiple peerreviewed publications, will strengthen the research environment, and will expose two undergraduate students to an intensive research experience. The innovation of the proposed research is also high due to its focus on within-person, time-varying microtemporal processes (both reflective and reactive processes) as determinants of both PA adoption and maintenance, which is a potentially important departure from contemporary health behavior theories. Regarding approach, the strengths outweigh the weaknesses. Approach strengths include preliminary data that supports the feasibility of the approach, appropriate frequency and duration of EMA, a carefully described determination PA adoption and maintenance status, valid assessments of key variables, a well-conceived and carefully described analytic plan for each aim, and a thoughtful analysis of potential problems and alternative solutions. In addition, two undergraduate students will be extensively involved in appropriate research tasks and appropriate plans are in place to recruit students belonging to underrepresented groups. Approach weaknesses include potential difficulties in recruiting 100 PA maintainers, issues with obtaining usable accelerometry data during swimming, and a lack of justification for the short window for PA and SB assessment after each EMA prompt (which could exclude relevant data). The investigators are strongthe PI has impressive publication, funding, and undergraduate research mentoring records, and the team possesses the needed expertise and has a history of collaboration. The environment is also strong, providing the needed research resources, community recruitment sites, and pool of wellqualified undergraduate students. As the many strengths of this application far outweighed the identified weaknesses, the overall impact of this application is considered high.

Strengths
• The application addresses the significant and prevalent problem of poor sustainment of healthy changes in PA and SB in older adults. Existing interventions often fail to have lasting effects on PA and SB. • If successful, the proposed project would advance knowledge of the microtemporal processes (internal and contextual) in daily life that predict PA and SB. In turn, this knowledge could inform the development of just-in-time interventions to deliver the most appropriate content at the most appropriate time, which ultimately could promote long-term change in PA and SB. • Prior research that serves as key support appears to be extensive and rigorous, including key evidence from this team and others suggesting that momentary reflective and reactive processes vary within people and that these processes and their variability (instability) are associated with subsequent activity-related behaviors. The rationale for the proposed study is strongly supported by contemporary theories and the extant evidence. • The proposed project is highly likely to generate multiple peer-reviewed publications making important contributions to the field, will strengthen the research environment at UNC-Greensboro, and will expose two undergraduate students to an intensive research experience. Weaknesses • The focus on the two selected groups is appropriate, given the limited scope for the R15 mechanism; however, adding a third group (inactive) would considerably increase the knowledge to be gained (minor).

Strengths
• PI Maher is an Assistant Professor of Kinesiology with expertise in motivation, PA, SB, EMA, accelerometry, and intensive longitudinal data. She has very strong publication and funding records for her career stage and has a track record of successfully engaging and mentoring undergraduate students in research (including a high percentage of students from underrepresented groups). • The team of co-investigators and consultants provides complementary expertise in communitybased recruitment of older adults, motivation for PA and SB, EMA research, and advanced statistical methods for clustered, intensive longitudinal data and has a history of collaboration. Weaknesses

Strengths
• The focus on within-person, time-varying microtemporal processes as determinants of both PA adoption and maintenance is a potentially important departure from contemporary health behavior theories, which tend to emphasize between-person, time-invariant factors and behavioral adoption only. • The examination of both reflective and reactive processes is also novel in this context and has the potential to provide new insights into determinants of both PA adoption and maintenance. Weaknesses

Strengths
• Preliminary studies support the feasibility of the proposed EMA and actigraphy approach in the target population and this team's ability to recruit and retain participants in multi-wave EMA studies. • The frequency of EMA (10x random times/day) and duration (three 4-day periods) seems appropriate, balancing data capture and participant burden. EMA items were taken directly or modified from established measures.
• The determination of adoption and maintenance status is carefully described and appropriate, with maintainer status being confirmed by accelerometry data.
• Conducting the introductory sessions at UNCG campus, a community location, or the participants' homes should enhance recruitment.
• Other approach strengths include appropriate eligibility criteria, a carefully described data collection plan, valid assessments of key variables (including the use of separate activity monitors to measure PA and SB), a well-conceived and carefully described analytic plan for each aim, and a thoughtful analysis of potential problems and alternative solutions.
• Over three years (including summers), two undergraduate students will be extensively involved in the proposed project through the execution of tasks appropriate for their level, including recruitment, data collection, and preliminary data management/analysis. These undergraduate students will also have the opportunity to pursue their own independent projects using the collected data under the mentorship of the PI and to present their findings at local and/or national research conferences.
• Appropriate plans are in place to recruit students belonging to underrepresented groups.
• Such an intense and closely mentored research experience is likely to enhanced these students interest in a career in biomedical sciences. Weaknesses • Given the low levels of PA in the target population (older adults), recruiting 100 PA maintainers may prove difficult, raising a concern about the feasibility of recruitment for this group. Complicating this issue is the likely possibility that some participants initially classified as maintainers will be reclassified as adopters after examination of the accelerometry data. That said, the planned recruitment efforts at community fitness centers (and letters of support) somewhat allay this concern. • Given that older adults are likely to engage in low-impact MVPA like swimming (15% in one of their preliminary studies), it seems key for the proposed project to be able to capture PA during that activity. However, as the investigators point out, the Actigraph GT3x-BT is not waterproof and must be removed prior to swimming. The investigators state they will attempt to impute PA data during swimming from the ActivPAL3 (which is waterproof), but the feasibility and validity of such an approach is not clear in the application. • It is not clear why PA and SB will be operationalized as MVPA during only the 30 minutes after the EMA prompt. It seems that such an approach would exclude meaningful PA and SB data, such as that during 30-60 minutes after an EMA prompt.

Strengths
• UNC-Greensboro provides the needed research resources for the proposed project, and the partnerships with community fitness centers should facilitate recruitment. • A pool of well-qualified undergraduate students (who will likely pursue careers in the biomedical sciences) is available at UNC-Greensboro. Weaknesses

Study Timeline:
Protections for Human Subjects:

Budget and Period of Support:
Recommended budget modifications or possible overlap identified: • Budget for all three years combined is provided, not each year separately.

CRITIQUE 2
Significance: 3 Investigator(s): 3 Innovation: 4 Approach: 6 Environment: 2 Overall Impact: This R15 proposal examines predictors of physical activity patterns among older adults, with a specific focus on adopting and sustaining physical activity. The proposal uses a rich array of EMA and actigraphy assessments to delineate these associations. Overall the application examines an interesting and important topic, as well as providing a unique training opportunity for students and a strong environment. One approach-related concern is a lack of cohesion between the rich, multidomain data used to characterize predictors of behavior and the outcome metrics, which appear to rely on categorization of sustained activity patterns. With that relatively minor concern, overall enthusiasm for the application is strong.

Strengths
• Older adults are soon to be over-represented in the U.S. demographic make-up and reducing chronic disease risk through increased physical activity is an important goal • Understanding predictors of sustained PA at a more granular level could provide important insight to guide future intervention efforts • The examination of both reflective and reactive motivational processes and behavioral patterns is important and conceptually relevant • Provides important and clear integration for scientific opportunities among trainees Weaknesses • Although the overall study methodology and EMA focus is interesting, the potential knowledge gained does not seem to build substantially from the existing knowledge base examining individual differences in affective change following acute exercise (which may parallel some of the reactive conceptual processes). • The use of categorization for physical activity metrics is problematic in that this artificial categorization, while clinically meaningful, may inadvertently obscure interesting patterns in the data. This use of categorical analysis also seems to contradict the other strengths of the proposal, which are the granular collection of EMA data. In essence, whereas the explanatory data are captured in a fine-grained, microtemporal fashion, they are then mapped onto summary, artificial categories as the primary outcomes of interest.

Strengths
• The PI has been quite productive and is focused in this area of research • The team is well-balanced in terms of conceptual expertise, community outreach connections, and analytical skill sets. All of which increase confidence in the feasibility of the proposal • It is a particular strength to have expertise in longitudinal modeling approaches, given the focus of the proposal

Weaknesses
• None noted

Strengths
• The use of EMA is potentially innovative and informative • The collection of both reflective and reactive predictors of PA is novel • The longitudinal examination of PA, with both initiation and sustained components, has not been adequately delineated in prior studies Weaknesses • It is unclear whether the present proposal would provide novel inferences above and beyond trait level factors already known to associate with some of the proposed PA outcomes. While the use of microtemporal data collection is potentially interesting, the rationale for this methodology to substantially inform the literature on this topic seems weak as currently presented.
• Given that many individuals may initiate PA only to stop soon after and then initiate again, there seem to be other potential lost opportunities to uncover interesting predictors of PA behavior given the proposed assessment schedule.

Strengths
• The use of EMA, actigraphy, and other ecological assessments is a strength • The examination of dual-processes for PA outcomes at different time points of importance (initiation and maintenance) is interesting and a logical extension in this area of study • The use of microtemporal sampling for EMA data is potentially interesting and informative, although not adequately linked to the core elements of the proposal

Weaknesses
• The complex nature of the longitudinal data collected seems poorly integrated with the outcome metrics, which seem overly simplified given the rich predictor data being sampled.
• Implicit in the classification of individuals as adapter and/or maintainer is the degree of variability among individuals and whether these classifications are truly represented in the population at large. Clearly some individuals will maintain regular exercise and a subset of those will meet conventional guidelines thresholds (e.g. 150 mins), but the stringent use of such a cut-point may prove problematic without a better idea of whether these are true latent classes or putative empirical classes based on using a clinical cut point.

Strengths
• Strong environment to carry out the proposed study

Weaknesses
• None noted by reviewer

Budget and Period of Support:
Recommend as Requested:

CRITIQUE 3
Significance: 1 Investigator(s): 2 Innovation: 3 Approach: 4 Environment: 2 Overall Impact: This project aims to understand motivational cues for physical activity and sedentary behavior (such as affective states) which potentially rapidly change over time. They will use smartphone-based EMA in older adults intended to adopt physical activity, assessing various motivational processes (reflective, reactive). The goal is to generate foundational knowledge that would then provide the basis for just-in-time adaptive interventions to improve physical activity and sedentary behavior as captured by sensors. The work is novel and well thought-out and considered impactful. It is supported by strong preliminary data demonstrating feasibility and proof of concept. The PI is very experienced in this mode of data collection and analysis. Two concerns arise: the data will be correlational and therefore findings will be exploratory; and, there is perhaps a missed opportunity to use digital phenotyping. Given the more preliminary nature of this project (it is an R15, not an R01) these concerns are felt to be minor and outweighed by the many strengths of the proposal. Beyond the scientific merits, this study is exemplary as an opportunity for students to gain research experience.

Strengths
• Increasing physical activity and reducing sedentary behavior is very important. It may be the number one public health goal in the US.
• The study has the potential to generate fundamental, widely-applicable insights about motivation.

Weaknesses
• Correlational nature of data makes this less impactful.

Strengths
• PI has a very strong background and track record.
• Investigative team has all of the requisite expertise for this study.

Weaknesses
• None noted by reviewer

Strengths
• Highly innovative conceptually. • Although EMA cannot still be considered very innovative, this is an innovative use of the technique.

Weaknesses
• Perhaps a missed opportunity to look beyond self-reportable microtemporal processes and use digital phenotyping, and/or gather qualitative feedback.

Strengths
• Although an observation-only design has some weaknesses, one strength is the large sample size and feasibility of this approach: it should generate strong data in support of the long-term goal of creating just in time adaptive interventions.
• Combining EMA and sensor monitoring to study microtemporal motivational processes is a methodologically strong approach.
• Good attention to both gender and racial/ethnic diversity.

Weaknesses
• None noted by reviewer