The Combined Effect OF Motivational Interviewing and Wearable Fitness Trackers on Motivation and Physical Activity In Inactive Adults: A Randomized Controlled Trial
Phase: NA
Conditions: Healthy
Sponsor: Colorado State University

 
Title: A Study to Test the Effectiveness of Different Interventions to Improve Physical Activity 
in Adults. 
NCT Number: NCT04902014 
Document Date: 9/8/2022 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Background 
Physical Activity (PA) and Health 
According to the Centers for Disease Control and Prevention (CDC), adults (≥ 18 years) 
should participate in at least 150 minutes (two hours and thirty minutes) moderate-intensity 
physical activity (MPA) per week, or 75 to 150 minutes of vigorous intensity physical activity 
(VPA) per week, or some combination of both.1 This level of PA is associated with substantial 
health benefits including improvements in cardiovascular health, muscular fitness, and cognitive 
function.1 More than two third of U.S. adults do not meet these guideline and have a 67% higher 
risk for all-cause mortality and contribute to the $117 billion dollars in health care costs 
associated with physical inactivity.14  
Self-Determination Theory and Physical Activity 
Behavior-change theory-driven interventions and in particular those based in Self-
Determination Theory (SDT) have been successful in improving PA participation in a variety of 
populations, in part due to a focus on intrinsic motivation.12,39-43 Behaviors that are intrinsically 
motivated are undertaken for the sake of the behavior itself; inherent satisfaction is the reward.10 
In contrast, extrinsic motivation is associated with motivation by external factors and at its 
extreme, motivation by coercion.10 More autonomous, or intrinsic motivation, is correlated to 
long-term PA engagement while extrinsic motivation has been shown to be effective in PA 
initiation, but not sustainability.9,17  
Wearable Fitness Trackers to Improve Physical Activity Engagement 
A promising tool to enhance PA participation is the use of a wearable fitness tracker 
(WFT) such as a Fitbit or Apple Watch. The small, relatively low-cost, and user friendly WFTs 
have been developed to support sedentary or under-active individuals in increasing their PA 

engagement.18  Short term studies have indicated that WFT use increases both self-reported PA 
and objectively measured PA in adults.44,45 However, this improvement is not sustained in a 
majority of individuals.46-51 Furthermore, it is known that most WFT consumers discontinue 
tracker use within six months of purchase.52 Therefore, it continues to be relatively unknown 
whether or not WFT impact motivation for PA or PA behavior in the long-term.50 
Multiple Behavior Change Techniques Are Better Than One  
One potential method to improve the effectiveness of WFTs is to combine them with 
other interventions. According to a review by Sullivan and Lachman,13 the most effective 
strategy to increase PA and sustain that increase is to employ multiple behavior change 
techniques.  Several studies have combined wearable tracker use with other interventions such as 
cash incentives for hitting goals,48 challenges sent to participants via email,47 and a mobile 
application loaded with an exercise program.44 Specifically, we propose combining WFT use 
with a Self-Determination theory driven Motivational Interviewing (MI) intervention to improve 
PA motivation and engagement.  
Motivational Interviewing and Physical Activity  
MI is a person-centered form of engagement that encourages people to assess their own 
position on the motivation continuum, explore the reasons behind their position, and determine 
how to best shift from amotivation or ambivalence to a more autonomous position. While MI 
was not developed with SDT in mind, Deci & Ryan53 point out that SDT and MI have 
historically been congruent, particularly with their emphases on autonomy support to make 
health-related decisions and changes. Specifically, both SDT and MI are focused on the central 
ideal of motivation and the development of internal motives, and the exposure and consideration 
of externally imposed goals or pressures to act which have no personal meaning to the 

individual.54 SDT constructs and MI, both on their own and combined, are effective in improving 
both motivation for PA and PA behavior in a range of age groups. A number of studies 
measuring changes in PA in response to an SDT-based intervention or MI, or a combination of 
the two saw statistically significant increases in PA.39,43,55-58 Research has also indicated that 
SDT-based MI is a powerful intervention to shift motivation for PA from mostly extrinsic to 
mostly intrinsic.39,59,60 
WFTs and MI: A Powerful Combination 
Two pilot studies61,62 found that combining SDT-based MI interventions with wearable 
tracker use significantly improved self-reported PA, body weight, and HDL cholesterol in 
African American men61 and increased the likelihood of meeting daily step goals in adolescent-
parent dyads.62 These results present an encouraging possibility for improving PA in sedentary 
adults: WFTs and SDT based MI. Given the popularity of wearable fitness trackers and the 
effectiveness of SDT based MI in increasing PA motivation and behavior, the combination of the 
two shows promise to improve the overall health of adults. Therefore, the purpose of this study is 
to assess the impact of a self-determination theory motivational interviewing intervention in 
combination with wearable fitness tracker use on motivation for PA and PA behavior. 
Methods 
Participant Recruitment and Health Screening 
Participants aged 18 and over will be recruited through a variety of means including 
flyers on the Colorado State University campus, flyers in local fitness centers, physician 
referrals, social media, and mass emails. In order to detect difference between groups with 95% 
confidence in repeated measures analyses, we will seek to recruit 40 total participants in order to 
allow for attrition. We aim to have 32 participants complete the study. To be included in this 

study, participants must be over the age of 18 and must not meet physical activity guidelines of 
at least 150 minutes of moderate physical activity per week. They must own an Android or 
iPhone smartphone device and be willing to download a mobile application onto that device for 
use during the intervention. They also must be willing to potentially wear a WFT and/or attend 
bi-weekly remote MI. Participants must not have a history of heart disease or diabetes, and must 
not have limiting conditions like concurrent cancer treatment, peripheral artery disease, 
orthopedic injury, or pain limiting arthritis. They must also not seek to participate in other 
structured PA programs for the duration of the study, must not be pregnant or seek to become 
pregnant, and must not have been diagnosed with alcohol or substance abuse during the previous 
twelve months. 
After having established the eligibility of a potential participant via a screening form, 
participants will be consented and will complete baseline assessments. This session will involve 
the administration of all self-reported measures, as well as instruction on accelerometer use 
Participants will wear the accelerometer for the subsequent7 days to provide baseline data on 
their baseline level of PA. Researchers will collect the ActiGraphs after the 7-day period.  
Participants who complete the baseline PA assessment invited to a remote session to 
general physical activity guidelines education and will take approximately 1 hour. Prior to this 
meeting, participants will have been randomly assigned to one of the four study groups (i.e., 
WFT, MI, WFT+MI, or PA Education Control) using a randomized number generator. To 
control for age and sex, participants will be age- and sex-matched in each group. During this 
remote meeting, participants will be inform as to which group they have been randomized into.  
Description of Intervention:  
 
The duration of the study will be twelve weeks. The four study conditions are as follows: 

 
WFT: Individuals assigned to this experimental condition will be given a wrist-worn 
WFT and will be instructed to wear it for the duration of the study. They will also be instructed 
to download the corresponding mobile application on their smartphones to be used for the 
duration of the study.  They will be trained by a member of our team on how to utilize the WFT 
and mobile application. The intended WFT tracks daily steps, miles traveled, kcals expended, 
and daily activity time. This device provides these data to the wearer via a small screen. 
Participants will be instructed to try and complete at least 150 minutes of PA per week. 
Researchers will have the capability to track participant daily PA via the WFT mobile 
application account created for each participant. These individuals will be asked to set biweekly 
PA goals, which will be emailed to the study coordinator. These participants will also receive 
general physical activity guidelines education and information on strategies to reach the 
recommended amount of activity per week during the initial baseline assessment meeting.  
Participants in this condition will be asked to ONLY wear the WFT provided to them by 
researchers.             
 
 
MI: The individuals will be scheduled for and participate in six biweekly remote SDT 
based MI sessions. These sessions will take place via video calling platforms like Microsoft 
Teams, Zoom, or Skype. The MI sessions will be conducted by a PhD student who has been 
trained by a MI practitioner. Participants will be provided a log book and will be asked to log 
their PA, with the goal of completing at least 150 minutes of PA per week. These participants 
will also receive general physical activity guidelines education and information on strategies to 
reach the recommended amount of activity per week during the initial baseline assessment 
meeting. Participants in this condition will be asked to NOT wear a WFT of their own over the 
course of the intervention.            

 
WFT+MI: These individuals will be given the wrist-worn WFT, be instructed to wear it 
for the duration of the study AND be scheduled for six SDT based remote MI sessions. These 
participants will also be trained by a member of our team on how to utilize the WFT and 
associated application. They will be instructed to try to complete 150 minutes of PA per week. 
Researchers will have the capability to track participant daily PA via the WFT and associated 
API. These participants will also receive general physical activity guidelines education and 
information on strategies to reach the recommended amount of activity per week during the 
initial baseline assessment meeting.  Participants in this condition will be asked to ONLY wear 
the WFT provided to them by researchers.               
 
 
PA Education Control: These participants will receive general physical activity 
guidelines education and information on strategies to reach the recommended amount of activity 
per week during the initial baseline assessment meeting. Participants will be asked to NOT wear 
a WFT of their own over the course of the intervention. At the conclusion of the study, these 
participants will be offered the chance to participate in one MI session.                  
Outcome measures: The following outcome measures will be collected at baseline, and at the 
completion of the twelve-week intervention. 
• Objectively measured PA engagement: PA will be objectively measured by one week 
of actigraphy using the ActiGraph wGT3-BT activity monitor. Participants will be given 
the ActiGraph and will be instructed to wear it on a provided elastic belt on their non-
dominant hip for one week. They will be given a log to record times that they removed 
the ActiGraph, which should only be when showering, bathing, or otherwise coming into 
contact with water. At the conclusion of the week, the ActiGraph data will be 
downloaded using ActivLife software. Daily PA will be assessed via the WFT 

application for individuals in the WFT+MI and WFT groups, and via self-report for the 
MI group.  
• Motivation for PA: Motivation for PA will be assessed using the Behavioral Regulation 
in Exercise Questionnaire (BREQ-3). This instrument is one of the most widely used in 
PA and exercise motivation research and has been validated in this population.21,22 This 
survey will be accessed via a secure online link.  
• Covariates: Each of the following covariates will be collected pre-intervention: age, 
race/ethnicity, education level, family affluence, and height/weight (BMI). All, except 
height and weight will be collected with self-report. Height and weight will be measured 
by lab personnel during the first visit to the lab. 
Data Analysis 
 
Means and standard deviations of the following variables will be calculated: baseline and 
follow-up MVPA, steps, and energy expenditure, baseline and follow-up scores for PA 
motivation subscales, and participant age and BMI. Paired t-tests will be used to compare within 
subjects pre-participation values from post-participation values for PA, and motivation variables 
by group. ANCOVA will be used to compare between subjects differences in outcome variables 
by group. Models will be developed based on covariate correlation with outcome variables and 
other covariates.