The YourMove Study: Optimizing Individualized and Adaptive mHealth Interventions Via Control Systems Engineering Methods (YourMove)

The purpose of this study is to determine the efficacy of a new digital health tool that uses a phone and smartwatch to encourage physical activity and increase weekly amounts of Moderate to Vigorous Physical Activity (MVPA) over 12 months among adults compared to a digital health intervention that mimics a standard of care corporate wellness program.

Study Overview

• Status: Completed
• Conditions: Sedentary Behavior; Inactivity, Physical
• Intervention / Treatment: Behavioral: COT-Based Intervention

Detailed Description

Strong evidence indicates physical activity (PA) reduces risk of bladder, breast, colon, endometrium, esophagus, gastric, and renal cancer, and there is moderate evidence for lung cancer. Individuals aged 25+ who are inactive are at high risk of developing a variety of cancers. Unfortunately, only 1/3 of adults meet guidelines for PA; thus, they are an important group to target. In response, the investigators developed JustWalk, a modular adaptive mobile health (mHealth) intervention that makes daily N-of-1 adjustments to support PA for each person. JustWalk can perform N-of-1 adaptation based on our innovative use of control engineering methods, which the investigators call a control optimization trial (COT).

The YourMove study is a 12-month 2-arm randomized control trial (RCT) designed to assess the efficacy of COT methods in 386 adults aged 25+ who are inactive. The investigators will evaluate the differences in minutes/week of moderate-to-vigorous intensity PA (MVPA), measured via accelerometers, among the COT-optimized (intervention) vs. non-COT intervention designed in accordance with standard of care digital corporate wellness to support physical activity (control) groups at 12 months.

The YourMove Study uses a fully integrated system of modalities that include: 1) a popular consumer-level wearable (e.g., Fitbit Versa) and corresponding app (e.g., the Fitbit app); 2) daily process-level analyses done using the Fitbit Versa and ecological momentary assessment (EMA) measures rooted in social cognitive theory (SCT) constructs to promote behavior change; 3) a highly tailored text messaging system encouraging participants to achieve recommended minutes of physical activity: >150 minutes per week of moderate-to-vigorous physical activity (MVPA); and 4) a self-study tool called "Reflect", which is meant to support individuals in self-experimentation to identify strategies that work for them to fit regular MVPA into their lives. The consumer-level devices and app will be used to self-monitor behavior, and their data will be passively acquired in real-time. A variety of self-reported measures asked daily via EMA enables the measurement of psychosocial factors important for the development of a dynamical SCT model and produces ambitious yet achievable step goals that are adaptive to each individual. Algorithms will be used to automatically deliver text messages to support individually tailored goal setting, performance feedback, and goal review in a highly dynamic style that reflects participants' behavioral progress towards achieving a minimum goal of 150 min/week of MVPA.

• Study Type: Interventional
• Enrollment (Actual): 386
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • California
    • San Diego, California, United States, 92093
      • University of California San Diego

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 25 years to 80 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Age 25-80 years old
• Intend to be available for a 12-month intervention
• Willing and able to attend 3 measurement visits over 12-months
• Willing and able to use a smartphone and text messaging
• Willing and able to use the wearable and corresponding app
• Willing and able to walk and engage in moderate-intensity physical activity
• Healthy enough to participate based on the Physical Activity Readiness Questionnaire
• BMI between 18-40 kg/m^2

Exclusion Criteria:

• Psychiatric or medical conditions that prohibit compliance with the study protocol
• Enrolled in or planning to enroll in a physical activity program during the study period
• Those with a mechanical medical implant, such as a pacemaker

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: COT-Based Intervention; The COT-based intervention will include the following to improve both steps/day (move more), and improving minutes/week of MVPA (exercise): adaptive daily steps/day goal-setting plus feedback; positive reinforcement (i.e., points, which translate to gift cards), self-monitoring of both steps/day and min/week MVPA; education about MVPA sent via text message in both conditions; planning support for scheduling bouts of MVPA via SMS in both conditions; and motivational messages sent via SMS in both conditions, and the use of a self-experimentation tool (REFLECT), developed based on prior successful pilot efforts, focused on fostering effective self-regulatory capacities of individuals.	Behavioral: COT-Based Intervention; The COT-based approach uses a controller that runs case-by-case dynamical systems simulations modeling based on answers to daily questions rooted in social cognitive theory to produce ambitious but achievable daily adaptive step goal recommendations. The process for the COT-based approach is as follows: Phase 1) 2-week measurement only; Phase 2) open-loop system identification experiment (meant to create individualized dynamical models for each participant); Phase 3) closed-loop experiment to optimize for PA initiation, and Phase 4) closed-loop experiment to optimize for PA maintenance.
No Intervention: Control; The non-COT approach was designed to be an equivalent to emerging standard of care options for digital health worksite wellness programs to increase PA (control) for a 12-month study period. Participants assigned to the non-COT-based (control) group will receive the latest Fitbit Versa smartwatch and will download the Fitbit smartphone app. Unlike the intervention group, the daily step goal and the accompanying number of points will be static (10,000 steps/day; 150 points/day, respectively). The goal will be delivered to participants via the standard Fitbit app features and points will be communicated via email. Participants will also receive a weekly PA goal (150 minutes of MVPA/per week) and the same accompanying motivational and informative texts that the intervention group receives. Control participants will not complete the physical activity and exercise reflection and planning exercise (Reflect).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in minutes of moderate-to-vigorous physical activity (MVPA)	Measured using a waist-worn tri-axial accelerometer for 7-days	Baseline, 12-months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in weight	Objectively measured weight in kilograms.	Baseline, 12-months
Change in Body Mass Index (BMI)	Weight and height will be combined to report BMI in kg/m^2.	Baseline, 12-months
Change in waist circumference	Weight and height will be combined to report BMI in kg/m^2.	Baseline, 12-months
Change in waist-to-hip ratio	Waist and hip circumference will be combined to report waist-to-hip ratio in cm/cm.	Baseline, 12 months
Change in body composition	Total body body composition (fat mass, including a rating of visceral adipose tissue, lean mass, and body water) measured with Bioelectric Impedance Analysis (BIA).	Baseline, 12 months
Change in basal metabolic rate	Measured with Bioelectric Impedance Analysis (BIA).	Baseline, 12 months
Change in systolic blood pressure	Systolic blood pressure in mmHg.	Baseline, 12 months
Change in diastolic blood pressure	Diastolic blood pressure in mmHg.	Baseline, 12 months
Change in flexibility	Sit and reach test.	Baseline, 12 months
Change in grip strength	Grip strength of the right and left hands in kilograms with a dynamometer.	Baseline, 12 months
Physical activity	Measured using Fitbit.	Through study completion, up to 12 months
Change in physical activity	Assessed through self-report using the Global Physical Activity Questionnaire. The questionnaire is comprised of 16 questions related to physical activity in three settings that include activity at work, travel to and from places, and recreational activities, in addition to sedentary behavior. Metabolic Equivalent (MET) values are assigned to time variables according to intensity of activity, moderate or vigorous, reported in each of the settings. MET values are then used to calculate total physical activity.	Baseline, 12 months
Sleep	Measured using Fitbit.	Through study completion, up to 12 months
Resting heart rate	Measured using Fitbit.	Through study completion, up to 12 months
Sedentary Behavior	Measured using Fitbit.	Through study completion, up to 12 months
Change in sleep	Assessed through self-report using a modified Pittsburg Sleep Quality Index questionnaire. Participants respond to questions related to sleep duration and how often they have difficulty falling asleep and staying awake, do not get enough rest. A higher score indicates more restful sleep.	Baseline, 12 months
Change in resting heart rate	Measured by research assistant.	Baseline, 12 months
Sedentary Behavior	Measured using a waist-worn tri-axial accelerometer.	Baseline, 12 months
Change in sedentary Behavior	Assessed using the Last 7 Day Sedentary Behavior Questionnaire (SIT-Q-7d), which assesses sitting or lying down in five domains (meals, transportation, occupation, non-occupational screen time, and other sedentary time), thus facilitating the calculation of domain-specific and total sedentary time. Frequency within the last 30 days is assessed on a 5-point response scale, ranging from "never or hardly ever" to "always or almost always".	Baseline, 12 months
Physical Activity: Change Strategies	Physical Activity: Change Strategies survey consists of 15-items that assess how often participants engage in strategies that help them change their physical activity in the past month using a 5-point response scale ranging from "Never" to "Many times".	Baseline, 12 months
Physical Activity Neighborhood Environment	Physical Activity Neighborhood Environment survey consists of 17-items that assess the environmental factors for walking and bicycling in various neighborhoods. Higher values from the scale indicate greater environmental support for physical activity.	Baseline, 12 months
Social Support for Physical Activity	Assessed using the Physical Activity and Social Support Scale which consists of 20-items scale based in five forms of social support - companionship, emotional, instrumental, informational, and validation for physical activity. Participants respond to items on a 7-point Likert scale ranging from "never" to "always", or "not applicable". A higher score indicates individuals who are seeking to change exercise behaviors feel a high level of support from friends and family.	Baseline, 12 months
Depression	Assessed using the Center for Epidemiologic Studies depression scale which consists of 10-items. Participants respond to items related to how they feel and behave on a 5-point response scale ranging from "Rarely or none of the time" to "All of the time". A score equal to or above 10 is considered depressed.	Baseline, 12 months
Anxiety	Assessed using the short-form of the state scale of the Spielberger State Trait Anxiety Inventory which consists of 6 items. Participants respond to items related to how they feel on a 4-point response scale ranging from "Not at all" to "Very much".	Baseline, 12 months
Self-esteem	Assessed using the Rosenberg Self-esteem Scale which consists of 10-items. Participants respond to items related to items related to global self-worth on a 4-point Likert scale ranging from "strongly agree" to "strongly disagree". Higher scores indicate higher self-esteem.	Baseline, 12 months
Quality of Well-being	Assessed using the Quality of Well-being survey, self-administered version which consists of 71 items. Participants respond to items related to health status and overall well-being over the previous 3 days. Scores are translated to quality-adjusted life years.	Baseline, 12 months
Change in Gait Speed	Measured using the 25-ft walk test	Baseline, 12 months
Change lower extremity functional strength	Measured using 5x sit-to-stand test which has participants stand up and sit down as quickly as possible 5 times from a straight-backed chair. Only assessed in participants 50 and older.	Baseline, 12 months
Change in balance	Assessed with feet in three different positions for 20 seconds each position (feet side by side, feet semi-tandem, and feet full-tandem). All balance testing will be measured using BtrackS balance tracking system, a computerized force plate that will provide a more objective and detailed assessment of balance than administrator observation alone, including total sway measured in centimeters. Only assessed in participants 50 and older.	Baseline, 12 months
Change in timed-up-and-go (TUG)	Participants will be instructed to stand up from a chair, walk around a cone set up 10 feet away, and return to sit in the chair. Only assessed in participants 50 and older.	Baseline, 12 months
Change in aerobic fitness	Assessed using a sub-maximal graded exercise test. A treadmill walking protocol at a participant-selected speed with elevation increases every 2 minutes will be employed until the participant reaches 85% of age predicted maximal heart rate (220 bpm - age) or volitional fatigue, whichever occurs first.	Baseline, 12 months

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Smoking & Marijuana Use	Assessed using modified items from the Customary Drinking and Drug Use Record. Participants will respond to 26 items related to their smoking and marijuana use over the past 6 months.	Baseline, 12 months
Alcohol Use	Assessed using modified items from the Customary Drinking and Drug Use Record. Participants will respond to 10 items related to their alcohol use over the past 6 months.	Baseline, 12 months

Collaborators and Investigators

• Sponsor: University of California, San Diego
• Collaborators: National Cancer Institute (NCI); University of Michigan; Arizona State University; Small Steps Labs, LLC
• Investigators: Principal Investigator: Daniel Rivera, PhD, Arizona State University; Principal Investigator: Eric Hekler, PhD, University of California, San Diego

Publications and helpful links

General Publications

• Kim M, Mansour-Assi S, El Mistiri M, Park J, Banerjee S, Khan O, De La Torre S, Higgins M, Godino J, Patrick K, Nebeker C, Jain S, Klasnja P, E Rivera D, Hekler E. Optimizing and Testing an Individualized and Adaptive Physical Activity Digital Health Intervention: Protocol for a Control Optimization Trial Embedded Within a Randomized Controlled Trial. JMIR Res Protoc. 2025 Aug 15;14:e70599. doi: 10.2196/70599.
• Mistiri ME, Khan O, Martin CA, Hekler E, Rivera DE. Data-Driven Mobile Health: System Identification and Hybrid Model Predictive Control to Deliver Personalized Physical Activity Interventions. IEEE Open J Control Syst. 2025;4:83-102. doi: 10.1109/ojcsys.2025.3538263. Epub 2025 Feb 4.

Study record dates

Study Major Dates

• Study Start (Actual): October 7, 2022
• Primary Completion (Actual): November 8, 2025
• Study Completion (Actual): November 8, 2025

Study Registration Dates

• First Submitted: October 21, 2022
• First Submitted That Met QC Criteria: October 26, 2022
• First Posted (Actual): October 31, 2022

Study Record Updates

• Last Update Posted (Actual): February 13, 2026
• Last Update Submitted That Met QC Criteria: February 11, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: physical activity; exercise; behavior; wearable; intervention; walking; sedentary; text message; technology; wellness; resilience; Fitbit; mobile application; ecological momentary assessment; EMA; smartwatch; reflection; inactivity; behavior mechanism; notifications
• Additional Relevant MeSH Terms: Motor Activity; Sedentary Behavior; Behavior
• Other Study ID Numbers: 20733 (DAIDS-ES Registry Number); 1R01CA244777-01A1 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No