Testing Self-Control as a Behavior Change Mechanism to Increase Physical Activity

Early Phase 1

Completed

Conditions: Self-control
Sedentary Lifestyle

Interventions: Behavioral: Self-control intervention
Behavioral: Control condition

Registration Number: NCT04522141

Lead Sponsor: Brandeis University

Brief Summary: The goal of this study is to test self-control as a behavior change mechanism for physical activity and to investigate whether a smartphone-based self-control intervention can increase physical activity among sedentary middle-aged adults.

Detailed Description: It is widely known that being physically active is beneficial for one's health and well-being, yet only a small percentage of adults engage in the recommended amounts of physical activity. Research has shown that health-damaging behaviors such as a sedentary lifestyle can be attributed in part to a lack of self-control. There is some evidence that self-control strategies can be improved with targeted interventions. The overall aim of the proposed study is to test self-control as a behavior change mechanism for physical activity and to investigate whether a smartphone-based self-control intervention can increase physical activity among sedentary middle-aged and older adults. To test the effect of this self-control intervention, participants will be randomized into two conditions: The self-control treatment group and the control group. Both groups will track their daily physical activity using a Fitbit step counter over eight weeks. Additionally, the self-control intervention group will receive a 7-week smartphone-based self-control intervention to learn strategies how to potentiate desirable impulses or weaken undesirable ones. It is expected that the self-control treatment group will show greater increases in physical activity and that changes will last longer compared to the control group. Self-control is expected to mediate the relationship between condition and physical activity. It is predicted that the self-control treatment group will show greater changes in self-control compared to the control group and that people who increase more in self-control also increase more in their physical activity. Two versions of the MindHike smartphone application will be used to communicate with all participants. The self-control treatment group will receive a version delivering a self-control intervention. The control group will receive a minimal version without the interventional components. Both groups are matched in terms of contact frequency.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 81

Inclusion Criteria

between 35-65 years of age
fluent in English
fit enough to walk for at least 20 min at a time
owns a smartphone

Exclusion Criteria

experienced a fall or heart problem/condition in the last 6 months
is currently participating in an exercise program to increase physical activity
is already physically active (physically active = exercise regularly 3 times per week, or more for at least 30min)
was advised by a doctor to not walk due to health conditions

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Self-control treatment group	Self-control intervention	The self-control treatment group will wear a Fitbit step counter across 8 weeks. In addition, they will use the MindHike smartphone application across 8 weeks. Each day, the app sends the a reminder to wear the Fitbit as well as a short interventional input targeting self-control.
Control group	Control condition	The control group will wear a Fitbit step counter across 8 weeks. In addition, they will use the MindHike smartphone application across 8 weeks. Each day, the app sends the a reminder to wear the Fitbit.

Primary Outcome Measures

Name	Time	Method
Self-Reported Physical Activity	Baseline (Pretest) T1, Week 8 (Posttest) T2, Week 12 (Follow-up) T3	International Physical Activity Questionnaire - short version. A continuous score will be calculated expressed as MET (Metabolic Equivalents) minutes per week: Total MET-min/week = (Walk METs\min\days) + (Mod METs\min\days) + Vig METs\min\days). A higher score means higher level of physical activity.
Objective Physical Activity	Average daily steps baseline week (week 1); average daily steps between pretest and posttest (week 2-8); average daily steps between posttest and followup (week 9-12)	Average daily steps baseline week, average daily steps between pretest and posttest, and average daily steps between posttest and followup. A higher score means more steps.
Self-Control	Baseline (Pretest) T1, Week 8 (Posttest) T2, Week 12 (Follow-up) T3	The Brief Self-Control Scale was used to measure self-control. Items are assessed from 1 (not at all) to 5 (very much). A mean across all items will be calculated. A higher score means a higher score in self-control.
Weekly Self-Control	Week 1, Week 2, Week 3, Week 4, Week 5, Week 6, Week 7	The Brief Self-Control Scale was used to measure weekly self-control. Items are assessed from 1 (not at all) to 5 (very much). A mean across all items will be calculated. A higher score means a higher score in self-control. Participants were asked to answer the items with respect to the last week.

Secondary Outcome Measures

Name	Time	Method
Satisfaction With Life	Baseline (Pretest) T1, Week 8 (Posttest) T2, Week 12 (Follow-up) T3	The Satisfaction with life scale was used to assess satisfaction with life. Items were assessed from 1 (disagree strongly) to 7 (agree strongly). A mean across all items will be calculated. A higher score means a higher satisfaction with life.
Stop & Go Switch Task	Baseline (Pretest) T1, Week 8 (Posttest) T2, Week 12 (Follow-up) T3	To measure attention switching and inhibitory control, we used the newly developed online app version of the Stop \& Go Switch Task (SGST). The SGST requires alternating between the "normal" condition (i.e., respond "Go" to the stimulus "Green" and "Stop" to the stimulus "Red") and the "reverse" condition (i.e., respond "Stop" to the stimulus "Green" and "Go" to the stimulus "Red"). For the SGST, the total number of correct responses across the mixed trials were calculated. Total range: 0 - 32. A higher score means a better outcome.
Backward Digit Span Test	Baseline (Pretest) T1, Week 8 (Posttest) T2, Week 12 (Follow-up) T3	To measure working memory capacity, we used the backward digit span test from the WAIS-III. The task includes increasingly longer series of digits, ranging from two to eight digits. Participants attempt to repeat them in the reverse order from which they were shown. The score is the longest string that is repeated exactly in reverse order. Digits are presented at a rate of one per second, beginning with a set size of two digits and progressing to eight digits. The accuracy score is the largest set size that was correctly reproduced. Possible range: 0 - 8. A higher score means a better outcome.
Sense of Control	Baseline (Pretest) T1, Week 8 (Posttest) T2, Week 12 (Follow-up) T3	12 items were used to assess sense of control. The scale consisted of two subscales: personal mastery (e.g., I can do just about anything I really set my mind to) and perceived constraints (e.g., What happens in my life is often beyond my control). All items were rated on a scale ranging from strongly agree (1) to strongly disagree (7). All items were coded so that a higher score reflected greater personal mastery and greater perceived constraints, respectively.
Big Five Personality Traits	Baseline (Pretest) T1, Week 8 (Posttest) T2, Week 12 (Follow-up) T3	The Big Five Inventory 2 was used to assess the Big Five personality traits. Items are assessed from 1 (disagree strongly) to 5 (agree strongly). A mean across all items per personality trait will be calculated. A higher score means a higher score on a personality trait.
Exercise Self-efficacy	Baseline (Pretest) T1, Week 8 (Posttest) T2, Week 12 (Follow-up) T3	Nine items were used to assess how sure participants are that they will exercise under certain circumstances (e.g., when you are feeling under pressure or when you are away from home). Items were assessed from 1 (very sure) to 4 (not at all sure). A mean across all items will be calculated. A higher score means lower exercise self-efficacy.
Immediate Word List Recall Task	Baseline (Pretest) T1, Week 8 (Posttest) T2, Week 12 (Follow-up) T3	Immediate episodic memory for verbal materials are tested using free recall of a word list drawn from the Rey Auditory-Verbal Learning Test. Participants are instructed to read carefully a list of 15 words which are presented at a rate of one second per word, and then to recall as many words as possible. In scoring the accuracy measure, one point is given for each correct response. Possible range: 0 - 15. A higher score means a better outcome.