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The Three Cs - Increasing Physical Activity
Initial registration date
March 04, 2019
December 02, 2019 9:23 AM EST
University of Aberdeen
Other Primary Investigator(s)
Additional Trial Information
Physical inactivity is one of the four major risk factors for non-communicable diseases (WHO 2016). Decisions about engaging in physical activity involve making trade-offs between immediate costs and future benefits suggesting that time preference (how present or future oriented an individual is) and present bias (the enhanced significance an individual attaches to immediate outcomes) may play a part in how these decisions are made. Despite demonstrated correlational associations between physical activity and time preference and present bias, to date, time preference and present bias have not been taken into account when designing interventions to increase physical activity. Within economics the quasi-hyperbolic model (Laibson 1997) is currently used to model such intertemporal decision making. From examining the quasi-hyperbolic model it can be seen that the individual’s decision to engage in physical activity depends on the temporally proximal costs and the temporally distant benefits of that activity, how much they discount the temporally distant benefits and how present biased they are when the time to be active becomes immediate. This suggests that an effective intervention should aim to increase the salience of future benefits and counteract present bias. Increasing the salience of temporally distant benefits might be achieved by getting the individual to consider the future consequences of their actions and connect to their future-self. Present bias is often assumed to involve temptation and self-control. Commitment contracts (paying a forfeit for failing to follow through with plans) are often regarded as a method of overcoming temptation and therefore counteracting present bias. This leads to the conclusion that an effective intervention could aim to (a) increase the salience of temporally distant benefits of activity by considering future consequences of current inactivity and connecting to one’s future-self and (b) counteract the temptation component of present bias by applying commitment. This study seeks to develop, and then test the effectiveness of one such intervention which has the potential to be inexpensive and easy to administer and could therefore provide a valuable addition to measures being used to counteract the physical inactivity crisis.
Intervention One - Consideration & Connection. This is designed to increase the salience of an individual’s beliefs about the future benefits of physical activity and to improve their connection to their future-self.
Intervention Two - Consideration & Connection & Commitment Group (C&C&C). This intervention combines the Consideration and Connection intervention with the Commitment task.
Intervention Start Date
Intervention End Date
Primary Outcomes (end points)
The primary outcome is increase in step count over baseline at four and eight weeks.
Primary Outcomes (explanation)
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
A three (equal) arm randomised control trial comparing the effectiveness of Consideration & Connection (C&C) and Consideration, Connection & Commitment (C&C&C) compared to a control group.
Experimental Design Details
The trial will be run online through a Qualtrics interface. The recruitment literature will have a link to this interface and interested individuals will be able to access the website.
Information, Consent and Eligibility
Once participants have accessed the initial section of the Qualtrics interface they will be given more information on the study and then be asked to give consent. Following on from this eligibility will be ascertained by answering self-report questions. Activity levels will be derived from answering questions adapted from the short self-administered form of the International Physical Activity Questionnaire (IPAQ) (https://sites.google.com/site/theipaq/). Vigorous minutes will be multiplied by two to give moderate minutes. Participants will be ineligible if they are typically active for more than 70 minutes per week. Participants will also be asked how old they are, whether they are already taking part in a physical activity program, whether they are willing and able to undertake a walking plan and whether they are able to send and receive email messages. They will also be asked if they know of any other reason why they should not engage in physical activity.
The interface will terminate with a suitable thank you message at this point for ineligible participants and no data will be retained.
The Qualtrics interface will trigger a notification email for study administration purposes at this point for all eligible participants who complete the initial survey.
Randomisation and Blinding
Once consent has been given and eligibility has been established participants will be randomised to one of the three groups (Control, Consideration & Connection and Consideration & Connection & Commitment) through a Qualtrics computer generated sequence.
It will not be possible to carry out full blinding of the participants as those who receive the intervention will be aware of the contents of the intervention. As it is essentially a trial run by one person it will also be difficult to blind the researcher about the assignments to the various groups.
After randomisation participants will be issued with an activity pack that contains a pedometer, instructions on how to operate the pedometer, instructions about how to record baseline activity and a diary for recording baseline step counts (see appendix).
Baseline will be assessed by instructing the participant to wear the pedometer all day (not just when they go for a walk), every day for one week. The participant will record the step count from each of those days in the diary. They will then report these values as part of the main data collection.
Main Trial Period
Once participants have complete the procedure of taking baseline activity measures they will return to the interface to report their baseline activity. At this stage they will be asked to complete various questions relating to the outcome measures required. After that those randomised to the Consideration & Connection and Consideration & Connection & Commitment groups will perform various intervention tasks (see appendix).
The Qualtrics system will trigger an email to a study administration with details of the participant and their baseline step count. This will allow a personalised walking plan to be produced.
The personalised, progressive walking plan will then be posted to the participant (see appendix). Those in the Consideration & Connection & Commitment group will also receive instructions about accessing stickK.com (see appendix). The walking plan will consist of daily targets for each week. These targets will be based upon their baseline step count and aimed at increasing their weekly step count to at least 15000 steps per week by the end of the intervention period (4 weeks). (For the first week their daily target will be average daily baseline step count (adbs) + 750 steps; for week two adbs + 1500 steps and for week three and four adbs + 2250 steps.) The final four weeks of the plan will consist of a maintenance phase of attempting to achieve at least 15000 steps per week. (i.e. adbs + at least 2250 steps).
The rationale behind aiming for this increase over baseline is that walking at least 15000 steps per week would bring the participant into line with the recommended minimum guidelines of 150 minutes (on the assumption that 3000 steps equate to 30 minutes (Marshall, Levy et al. 2009)) of moderate exercise a week (UK Government 2011).
During the intervention period (four weeks) participants will report daily step counts on a weekly basis through Qualtrics. Those in the Consideration & Connection group and the Consideration & Connection & Commitment group will also review the effect on their future-selves of their current week’s activity levels.
At the end of the intervention period (four weeks) and again at the end of the maintenance phase (a further four weeks) participants will be administered physical activity report questions based on the short self-report IPAQ questionnaire (https://sites.google.com/site/theipaq/).
At the end of the study) participants will report step counts, complete follow up repeat measures and be asked follow up qualitative questions through the Qualtrics interface. The purpose of the responses in the free text boxes is to provide further information to inform the discussion of the results of the research. If step count reporting has been incomplete the follow up questionnaire will be distributed once the remaining duration of the walking plan has elapsed.
Participants will be sent one prompt and two reminder emails via the Qualtrics interface at each stage of the study. Confirmation of posting emails will be sent once the activity and diary packs have been posted. Participants will receive an Amazon voucher for £15 on completion of the final follow-up questionnaire. Participants will be allowed to retain the pedometers. These strategies are intended to maximise retention rates, data gathering and adherence to the intervention protocol.
Randomisation carried out by Qualtrics software.
Was the treatment clustered?
Sample size: planned number of clusters
Sample size: planned number of observations
Sample size (or number of clusters) by treatment arms
33 individuals per treatment arm
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
INSTITUTIONAL REVIEW BOARDS (IRBs)
University of Aberdeen College of Life Sciences and Medicine Ethics Review Board
IRB Approval Date
IRB Approval Number
Post Trial Information
Is the intervention completed?
Is data collection complete?