INTRODUCTION

The management of neurodegenerative diseases such as Parkinson disease (PD) requires consideration of changing needs and functional abilities at different disease stages. Traditional models of care place less emphasis on starting rehabilitative therapy soon after diagnosis, which is incongruent with current evidence that physical activity (PA) can delay neurodegeneration and potentially modify disease progression.1,2 A recent framework suggested incorporating consultative, proactive therapy for evaluation, education, and advice starting in early disease stage.3 In consultative roles at this stage, physical therapists promote PA, encourage disease self-management, and address secondary prevention in efforts to delay the onset of activity limitations.4 Early intervention for people with PD can empower them to harness long-term benefits of PA and self-management.5

The unique and powerful role of PA—especially exercise (structured PA for health benefits)—in improving function and health outcomes in people with PD is widely demonstrated. Studies have shown that exercise improves motor performance, physical and cognitive function, and quality of life in people with PD.6–9 Furthermore, there is promising evidence that aerobic exercise and PA have the potential to modify disease progression.8–11 Exercise may have neuroprotective effects via mechanisms within the central nervous system that facilitate synaptogenesis, neurogenesis, and neurotransmitter synthesis.12,13 Symptom improvements may result from increases in cortical excitability, substantia nigra, and prefrontal brain activity after exercise in PD.13,14

Despite the many benefits of PA, individuals with PD face general and disease-specific barriers to exercise. General barriers include low health literacy,15 lack of motivation,16 lack of time,16 and the associated costs and transportation challenges.17 Additionally, disease-specific barriers such as fatigue, balance impairments, and mood disorders may prevent people from participating in PA.18 These barriers may explain why people with PD exercise less than the general population,19 and only 27% meet recommended levels of 150 minutes of moderate PA or 75 minutes of vigorous PA per week.20–22 The COVID-19 pandemic and the stay-at-home restrictions further increased barriers to exercise.23–25

Coaching to promote PA is an integral part of the consultative therapy model of care, and it is also well-suited for telehealth delivery.26,27 Physical therapists are training in motivational interviewing-style techniques and have expertise in exercise and PD management. Therefore, they are well-positioned to deliver PA coaching and consultation starting in early disease stages. Growing research in this area has led to studies using mobile health technology, home-based exercises, and coaching or peer coaching to promote exercise uptake in neurodegenerative diseases.28–34 While these trials showed promising results, many studies introduce exercise in a prescriptive manner (prescribing exercise modality, duration, frequency, and intensity) and rely on extrinsic feedback (such as mobile apps). The lack of autonomy in goal-setting and exercise modality and the extrinsic nature of feedback may limit the facilitation of intrinsic motivation for long-term exercise adherence.

Engage-PD, a 3-month telehealth coaching intervention, was developed after a pilot study with similar design demonstrated the feasibility of PA coaching intervention in PD.35 The intervention was grounded in self-determination theory36 to facilitate intrinsic or highly autonomous motivation for long-term PA uptake in people with PD.26 The intervention is defined using a logic model26 and uses behavior change techniques to engage people with early-stage PD to participate in PA as a disease self-management strategy. Engage-PD is grounded in self-determination theory to satisfy 3 basic psychological needs—autonomy, relatedness, and competence—to increase exercise self-efficacy for long-term PA sustainability.37–40 Autonomy is supported through participant-centered goal-setting and choice of exercise modality; relatedness is supported through participant-interventionist interactions and encouragements; competence is supported through experiencing success in overcoming barriers and reaching goals. Through the coaching process, we aim to increase exercise self-efficacy—people's belief in their capacity to perform exercise and overcoming barriers to exercise—a significant factor related to initial exercise uptake and long-term exercise adherence.40 Harnessing the self-determination theory, the program addresses barriers to exercise and supports progress toward goals that are purposeful and meaningful to participants. In addition, a telehealth delivery may increase accessibility and reduce costs for neurological populations.41,42

The primary purpose of this single cohort study was to determine the feasibility and preliminary efficacy of Engage-PD, a PA coaching program for people with PD delivered via telehealth. The secondary purpose was to explore whether participant characteristics at baseline were associated with changes in exercise self-efficacy and PA uptake. We expected that younger age and lower baseline levels of PA would be associated with more improvements in outcome measures post-intervention for people with PD.

METHODS Participants

A single cohort of participants were recruited between March 2020 and March 2021 from Columbia University Irving Medical Center Parkinson's Foundation Center of Excellence in New York, New York. Potential participants were referred by movement disorder specialists and a phone screening session was used to assess eligibility and interest. Participants were included if they were between the ages of 18 and 85 years, had a neurologist-confirmed diagnosis of idiopathic PD between Hoehn and Yahr (H&Y) stages I and III, were ambulatory for indoor and outdoor mobility without assistance or use of assistive devices, and either successfully completed the Physical Activity Readiness Questionnaire (PAR-Q)43 or received medical clearance to exercise from a medical doctor. Participants were excluded if they had coexisting neurological or musculoskeletal conditions that would restrict exercise. They were also excluded if they already had more than 150 minutes of moderate to vigorous PA per week. All participants provided electronic informed consent approved by the institutional review boards at Teachers College, Columbia University, and Columbia University Irving Medical Center. This trial has been registered on ClinicalTrials.gov (NCT049222190).

Intervention

The Engage-PD intervention consists of up to 5 personal coaching sessions delivered via telehealth, over a 3-month period.26 The number and frequency of the coaching sessions were determined based on individuals' needs and progress, with the typical interval between sessions starting from 2 weeks and gradually increased to 4 to 6 weeks. The coaching intervention was led by licensed physical therapists using Zoom Video Communications, Inc (San Jose, California). Sessions were scheduled at participants' convenience and each session consisted of individualized coaching activities (Table 1). Engage-PD is grounded in the self-determination theory44 and focused on promoting individual autonomy, competence, and relatedness to improve PA and exercise uptake.26,33,45 Therapists worked with participants to build multimodal programs incorporating aerobic, strengthening, balance, and flexibility exercises, with an emphasis on moderate- to high-intensity aerobic exercise at a minimum of 3 times per week and a total of 150 minutes.21,22

Table 1. - Overview of Engage-PD Intervention Session Activities Session 1 (within 2 wk of baseline assessment)

Introduce the participant to the program, and the Engage-PD Physical Activity Workbook.

Engage-PD Physical Activity Workbook Sections 1-4.

Introduce to mCOPM and ask the participant to consider goals for next session.

Discuss means of tracking PA (ie, written log or PA monitor).

Summarize meeting and review upcoming plan.

Session 2

Review PA log/data since the last session.

Review Sections 5-8 of the Engage-PD workbook

Discuss and finalize goals.

Begin instruction in physical activity/exercise program as appropriate.

Summarize meeting and review upcoming plan.

Sessions 3-4

Review PA log/data and adjust goals as necessary.

Discuss barriers and strategies for physical activity uptake.

Review instruction in physical activity/exercise program as appropriate.

Summarize meeting and review upcoming plan.

Last session

Review PA log/data.

Review and score goals.

Review instruction in physical activity/exercise program as appropriate.

Discuss barriers and strategies for sustained physical activity uptake.

Summarize meeting and review upcoming plan.

Abbreviations: PA, physical activity; mCOPM, modified Canadian Occupational Performance Measure.

Engage-PD workbook chapters: 1. Exercise, who me? 2. Let's get moving! 3. Overcoming challenges. 4. Safety and monitoring. 5. Developing a physical activity plan. 6. Goals and targets. 7. Recording your activities and progress. 8. My physical activity plan.

Six physical therapists who were trained in PA coaching delivered the intervention. Therapists were provided a detailed coaching manual, and underwent training on motivational interviewing techniques, goal setting, and promotion of self-determination theory themes. Training consisted of a 2-hour video and at least 2 observational sessions with an experienced therapist. Therapists worked with participants to establish individualized goals, using the modified Canadian Occupational Performance Measure (mCOPM).46,47 Therapists provided guidance on overcoming motivational, social, physical, and environmental barriers to PA. Participants chose exercises and physical activities that were meaningful and enjoyable to them, and specific recommendations on exercise modifications and symptom management were provided by the therapists. Examples of exercise modality that participants chose included walking, running, stationary biking, yoga, and virtual fitness and dance programs available through community organizations online. Advice on exercise modifications was tailored based on participants' functional ability and fitness level. Moderate- to high-intensity exercise was determined as 55% to 85% maximum heart rate based on the 220 − age formula,48 although the usage of this formula may be adjusted based on individual conditions, such as taking β-blockers. Participants monitored their heart rate by taking their pulse or using available wearable devices. When heart rate monitoring was less feasible, they used the modified Borg rating of perceived exertion to achieve a general target in the moderate-/high-intensity range. We used a conservative range of 3 to 6 out of 10 (moderate intensity); however, the recommendation was individualized based on participant ability and if able participants were encouraged to achieve vigorous intensity of 7 to 8. Therapists guided individuals through exercise progressions based on existing guidelines,49 but the goals set for progressions were individualized and autonomous. Therapists used a standardized approach to help participants set goals—identify current state, identify end goal at 3 months, and determine the next achievable step in the short term. Additionally, therapists provided training on safety and monitoring during exercise, and engaged care partners when necessary.

Participants also received a disease-specific workbook that was reviewed and referenced by their therapist at the beginning of the sessions and throughout the intervention. The workbook was developed after piloting in a previous study,35 and included evidence-based recommendations for exercise pertaining to frequency, intensity, and duration for categories of aerobic, strengthening/resistance, flexibility, and neuromotor exercises.50,51 The workbook also provides education on PA monitoring by using high- or low-tech options such as wearable activity monitors, smartphones, or exercise diaries, which can help support autonomy.

Outcome Assessments

All baseline and postintervention outcome assessments were carried out over Zoom by the study coordinator and the therapists. Baseline assessments, including the Brunel Lifestyle Inventory,52 the Exercise Self-Efficacy Scale,53,54 and the mCOPM,46,47 were conducted within 2 weeks prior to the first coaching session. Postintervention assessments, including all measures from the baseline assessment and an additional exit questionnaire to assess feasibility and participant perspectives, were conducted by the study coordinator a week after the last coaching session had ended at 3 months. When administering the questionnaires, the therapist or study coordinator read each question and ensured that the participants fully understood them before recording their answers.

Feasibility

Recruitment. Recruitment rate was calculated as the percentage of referred participants from the neurologists who signed the consent form and enrolled in the study.

Retention. Retention rate was calculated as the percentage of enrolled participants who completed posttest assessments.

Adverse Events. Any new adverse events were documented by the therapists during the coaching sessions and reported to the research team.

Acceptability. A customized postintervention questionnaire was administered by the study coordinator to assess participants' acceptability of the intervention.55 The questionnaire consisted of 26 Likert scale questions (1 = strongly disagree to 5 = strongly agree, example question: “I felt satisfied with the visits from my therapist.”). Questions were categorized into 4 domains: overall intervention satisfaction, therapist interaction, workbook, and self-efficacy.

Participant Perspectives. Ten open-ended questions were asked to gain insight into participants' perspectives of the intervention (such as “what were some tools/benefits you gained from this experience that you did not expect?”).

Intervention Outcomes

Physical Activity. The Brunel Lifestyle Inventory (Brunel) is a 10-item questionnaire that measures both planned and unplanned PA.52 Planned PA is defined as any activity that is scheduled, which may enhance health, fitness, or well-being (eg, brisk walking, cycling and team games), thus is conceptually similar to exercise. Unplanned PA is any form of PA that is excluded from planned PA (eg, heavy housework, climbing stairs, walking or cycling to work, gardening, shopping, and playing with children). The questionnaire was determined to have reasonable concurrent validity (r = 0.11-0.64) in a sample of healthy young adults.52,56 The test-retest reliability in our cohort of 14 participants with PD was good: planned PA, intraclass correlation coefficient (ICC)(2,1) = 0.77 (95% confidence interval [CI] = 0.42, 0.92); unplanned PA, ICC(2,1) = 0.80 (95% CI = 0.49, 0.93) (L Quinn et al, unpublished data, 2021).

Exercise Self-Efficacy. The Exercise Self-Efficacy Scale (ESE) is an 18-item test that measures an individual's self-efficacy to participate in exercise when social and physical barriers are present.53,54 Participants were asked to rate a 5-point Likert scale for confidence to exercise regardless of barriers, with “1” meaning “not at all confident” and “5” meaning “completely confident.” The ESE has been used in previous PD research and was sensitive to change,57 and the test-retest reliability in a cohort of 14 participants with PD was good: ICC(2,1) = 0.80 (95% CI = 0.49, 0.93) (L Quinn et al, unpublished data, 2021).

Participant Goals. The mCOPM46,47 is a tool used to evaluate perceived performance, satisfaction, and importance of individualized goals. The mCOPM is also a tool for initiating conversation about challenges faced in everyday living, which provides the basis for setting PA intervention goals. As such, when participants mentioned symptoms (such as constipation) or general mobility issues that they would like to address, therapists guided participants to set PA goals that may help address these issues (such as improved gut motility). Each individualized goal on the mCOPM is ranked on a 10-point scale, where “1” indicates the lowest level of performance, satisfaction, or importance, and “10” indicates the highest. We only analyzed the performance and satisfaction subscores for the purpose of this study. The original COPM questionnaire has been validated in the general and neurological populations.58

Statistical Analysis

Descriptive statistics were performed on participants' characteristics. We calculated recruitment and retention as percentages and calculated average score in each domain from the postintervention questionnaire. Missing data were excluded from the preliminary efficacy analyses. We determined the effect estimates for the pre-post difference of Brunel planned and unplanned PA scores, ESE, and mCOPM performance and satisfaction scores. The distribution of these variables was plotted and inspected for normality. The 95% CI of mean difference, Cohen's d, and 95% CI of Cohen's d were calculated. We chose to use an estimation method for statistical inference instead of null hypothesis testing (using P values) to provide more information about the size of the effects and to avoid drawing misleading conclusions.59

We also explored relationships between participant baseline characteristics and pre-post changes in 2 important outcomes—Brunel planned PA and ESE. Pearson's r was used to determine the strength of the association between age, baseline Brunel planned PA, and baseline ESE in relation to the pre-post changes in Brunel planned PA and ESE after missing data were excluded (Figure 1). Cohen's d was used to determine the effect of sex on the pre-post changes in Brunel planned PA and ESE. Kendall's τ b was used to determine the association between H&Y levels and the pre-post changes in Brunel planned PA and ESE. We interpreted Cohen's |d| = 0.2, 0.5, and 0.8 as small, medium, and large effect sizes, respectively.60 Pearson's |r| = 0.3, 0.5, and 0.7 were interpreted as a small, moderate, and large effect, respectively.61 Cutoffs for interpreting Kendall's τ b have not been established; therefore, we will interpret the strength of the relationship without predetermined values.

Figure 1.: CONSORT diagram, modified to represent our single cohort. This figure is available in color online (www.jnpt.org).RESULTS Feasibility Recruitment and Retention

Participants were recruited between March 24, 2020, and March 16, 2021, and all posttest assessments were concluded by June 22, 2021 (Figure 1). A total of 92 patients were referred and 62 were enrolled, resulting in a 67% recruitment rate. A total of 53 participants completed the posttest assessment, resulting in a retention rate of 85%. The majority of the participants enrolled were White and had at least a college education (Table 2). There were no standardized number of sessions due to the individualized design of the intervention; however, participants completed an average (SD) of 3.94 (0.93) sessions, with an average (range) session length of 60 (30-80) minutes.

Table 2. - Participant Characteristics at Enrollment (n = 62): Mean ± SD or Counts (Percentage) Reported Age, y 65.4 ± 9.2 Sex Male 39 (62.9%) Female 23 (37.1%) Weight, kg 73.6 ± 14.2 Height, cm 172.0 ± 8.9 Race/ethnicity White 53 (85.5%) Black/African American 3 (4.8%) Hispanic 1 (1.6%) Asian 0 (0%) Other 2 (3.2%) Declined 3 (4.8%) Education High school 2 (3.2%) College 25 (40.3%) Associates 2 (3.2%) Masters 15 (24.2%) Doctorate 5 (8.1%) Other advanced degree 7 (11.3%) Unknown 6 (9.7%) Missing 6 (9.7%) H&Y Stage I 16 (25.8%) Stage II 25 (40%) Stage III 21 (34%) Time since diagnosis, y 4.7 ± 4.3 MDS-UPDRSa 25.9 ± 4.1 MoCAb 23.4 ± 12.9

Abbreviations: H&Y, Hoehn and Yahr; MDS-UPDRS, Movement Disorders Society-Unified Parkinson's Disease Rating Scale (maximum score 199 indicating worst disability from Parkinson disease); MoCA, Montreal Cognitive Assessment (maximum score 30 indicating intact cognition).

aData from only 42 participants due to availability of MDS-UPDRS on medical history.

bData from only 18 participants due to availability of MoCA on medical history.

Adverse Events

There were no adverse events reported throughout the intervention period. Around half of the participants had a care partner involved in their coaching process for general encouragement and safety monitoring.

Acceptability

The intervention was well accepted and perceived by the participants. The average score for overall intervention satisfaction was 4.85 (95% CI = 4.77, 4.93) out of 5; for therapist interaction was 4.97 (95% CI = 4.95, 4.99) out of 5; for the workbook was 3.54 (95% CI = 3.31, 3.77) out of 5; for self-efficacy was 4.85 (95% CI = 4.79, 4.91) out of 5.

Participant Perspectives

Responses to the open-ended questions revealed that motivation, mood, weather, and other commitments were the top barriers that kept participants from engaging in regular exercise. Common motivations to join the study included interest in learning alternative strategies to manage PD, referral from a specialist, and searching for alternative therapies during the COVID-19 pandemic. Fifty-four percent of participants indicated they would have not joined the intervention if virtual sessions were not an option. Participants appreciated the informative communication and support from the therapists. Therapists' knowledge on PD, exercise resources, and goal setting strategies were highly valued by participants. Participants' intended to continue working toward the goals set in the program and develop future exercise plans. There was a mixed response to using technology in the program. While most participants found the virtual sessions and online resources to be accessible, some participants had difficulties using Zoom and other exercise-related applications. To reduce technological barriers and increase the sense of connectedness, participants commonly suggested it would have been beneficial to have 1 or 2 in-person sessions to enhance program delivery.

Intervention Outcomes Physical Activity

There was an improvement in mean Brunel planned PA scores from pre- to postintervention with a small effect size (Table 3 and Figure 2). There was also an increased Brunel unplanned PA score with a medium effect size (Table 3 and Figure 2).

Figure 2.: Pre- and postintervention Brunel planned physical activity and exercise self-efficacy scores. PA, physical activity. This figure is available in color online (www.jnpt.org). Table 3. - Mean Difference and Effect Sizes Pre- and Post-intervention Variable n Pre (Mean ± SD) Post (Mean ± SD) Difference Post-Pre (Mean ± SD) 95% CI of Difference Effect Size Cohen's d 95% CI of Effect Size Brunel planned PA 52 3.86 ± 0.93 4.11 ± 0.55 0.25 ± 0.81 0.03, 0.49 0.33 −0.058, 0.73 Brunel unplanned PA 52 2.32 ± 0.76 2.70 ± 0.69 0.38 ± 0.77 0.16, 0.60 0.52 0.12, 0.91 Exercise self-efficacy 52 56.00 ± 18.04 74.60 ± 12.29 18.81 ± 16.06 14.34, 23.28 1.20 0.78, 1.63 mCOPM—performance 50 4.12 ± 2.00 7.06 ± 2.25 3.26 ± 2.68 2.49, 4.02 1.63 1.17, 2.09 mCOPM—satisfaction 50 3.97 ± 2.02 6.93 ± 2.16 3.29 ± 2.68 2.53, 4.05 1.70 1.23, 2.16

Abbreviations: Brunel, Brunel Lifestyle Inventory; CI, confidence interval; mCOPM, modified Canadian Occupational Performance Measure; PA, physical activity; SD, standard deviation.

Exercise Self-Efficacy

There was an improvement in mean ESE from pre- to postintervention with a large effect size (Table 3 and Figure 2).

Participant Goals

There was an increase in mean performance and satisfaction scores for individualized goals from pre- to postintervention with large effect sizes (Table 3).

Relationship Between Baseline Characteristics and Outcomes

After excluding missing data, we explored the relationship between baseline characteristics and the change in Brunel planned PA and ESE (Table 4). Contrary to our expectations, there was no relationship between age and the change in Brunel planned PA (Figure 3A), or change in ESE (Figure 3B). On the other hand, there was a strong relationship indicating participants with lower baseline Brunel planned PA experienced greater improvements in Brunel planned (Figure 3C), and that participants with lower baseline ESE experienced greater improvements in ESE (Figure 3D). This was consistent with our expectations that lower baseline PA levels would be associated with greater improvements in PA. Additionally, there were no apparent influences of sex, H&Y levels, or time since diagnosis on the changes in outcomes (Table 4).

Figure 3.: Relationships between baseline characteristics and outcomes. Blue dots indicate data points; black lines indicate the least square line to represent trends. PA, physical activity; ESE, exercise self-efficacy. This figure isavailable in color online (www.jnpt.org). Table 4. - Exploratory Relationships Between Baseline Characteristics and Outcomes (n = 55 Analyzed) Variables Effect Size Statistics vs Change in Brunel Planned PA 95% CI vs Change in Exercise Self-Efficacy 95% CI Age Pearson's r −0.076 −0.34, 0.20 0.22 −0.05, 0.46 Sex (male vs female) Cohen's d −0.07 −0.64, 0.50 −0.20 −0.77, 0.38 Hoehn and Yahr Kendall's τ b 0.0019 −0.23, 0.23 0.079 −0.14, 0.30 Time since diagnosis Pearson's r 0.14 −0.14, 0.40 0.071 −0.21, 0.34 Baseline Brunel planned PA Pearson's r −0.81 −0.80, −0.70 −0.26 −0.50, 0.010 Baseline exercise self-efficacy Pearson's r −0.12 −0.38, 0.16 −0.75 −0.85, −0.60

Abbreviations: Brunel, Brunel Lifestyle Inventory; CI, confidence interval; PA, physical activity.

DISCUSSIONS

We conducted a single cohort study to examine the feasibility and preliminary efficacy of Engage-PD, a telehealth PA coaching program for people with PD. Our findings showed that the Engage-PD program, conducted during the first year of the COVID-19 pandemic, had high recruitment and retention rates and was well accepted and perceived by a cohort of participants with early-to-mid stage PD. In addition, participants increased their planned and unplanned PA, ESE, and performance and satisfaction scores regarding personalized goals with small to large effect sizes. We also explored the relationship between participant characteristics at baseline with observed changes in ESE and PA uptake after the intervention. Lower baseline planned PA was strongly associated with greater improvements in planned PA, whereas lower baseline ESE was strongly associated with greater improvements in ESE.

The intervention was feasible and well-accepted by participants. Although intervention components differed, our high retention rate and no adverse events were similar to previous coaching studies with remote exercise programs.28,29,32 Among the feedback we received, participants were most satisfied with the positive interactions with the therapist. By providing individualized coaching sessions, the intervention addressed multiple barriers to engage in PA reported by people with PD in the literature.15,17,62,63 Participants acknowledged that the intervention provided useful insights on knowledge of appropriate exercise, addressing the social aspects of exercise and motivation to exercise regularly. The Engage-PD workbook provides education and guidance for therapists and participants to engage in discussions related to exercise especially during the first couple coaching sessions, and it may be most helpful for those who have lower health literacy. As participants become familiar with the workbook contents, emphasis is shifted to therapist-participant interactions and collaborative problem-solving—which may explain why the workbook was not as well-perceived by participants. This highlights the importance of motivational coaching: despite lack of knowledge being a common barrier for exercise engagement,63 addressing knowledge alone is not enough to promote PA.44 Our intervention used coaching grounded in self-determination theory to address multiple aspects of the behavior change process to promote long-term PA uptake beyond the completion of intervention. The emphasis on therapist-participant interaction and autonomous goal setting is in contrast with other studies that have used mobile health to prescribe and monitor remote exercise programs.28–32

Coaching is well-suited to be delivered via telehealth, and may decrease the barriers in transportation and time.26 Using telehealth to deliver the intervention was crucial for recruiting the majority of the participants, which highlights the potential of telehealth to increase the accessibility of care for people with chronic diseases. A recent study by Flynn and colleagues64 also demonstrated feasibility for telehealth-delivered exercise programs for people with PD. However, in our study, many participants noted they would prefer to have some in-person components integrated into the program, suggesting that a hybrid model may be beneficial to increase connectedness and incorporate hands-on instructions while maintaining the ease of access provided by a telehealth approach.

There were large effect sizes on the changes in mCOPM and ESE scores, and small to medium effects for PA uptake following the intervention. Results from the mCOPM, similar to other forms of goal setting, are subject to participant bias. However, participants in our study identified specific, measurable outcomes related to individualized PA uptake. Self-efficacy is thought to be an important mediator to lasting PA behavior change,39,40 and the large effect size seen in this study is encouraging. This finding may suggest that participants have a high chance of continuing PA after the study ends. It is also important to note that, even without a standardized exercise prescription in