Table 5 Theoretic construct and item(s) used for assessing processes at baseline and 4 months

PERCEIVED IMPORTANCE

Measure was generated specifically for this study to be sensitive to the concept that someone might not see the importance about the specific recommended guidelines (5 days of at least 30 min) for PA until after exposure to e-coachER

Question used:

Using an 11 point Likert scale (0 = Strongly Disagree, 10 = Strongly Agree)

Doing at least 30 min of moderate intensity physical activity (e.g. brisk walk) on at least 5 days a week is important to me

PERCEIVED CONFIDENCE

Measure was generated specifically for this study to be sensitive to the concept that someone might not be confident about achieving the specific recommended guidelines (5 days of at least 30 min) for PA until after exposure to e-coachER

Question used:

Using an 11 point Likert scale (0 = Strongly Disagree, 10 = Strongly Agree)

I am confident that I can do at least 30 min of moderate intensity physical activity (e.g. brisk walk) on at least 5 days a week

COMPETENCE

Perceived competence scale (PCE) used in Williams, Freedman, and Deci (1998) [43]

4 item measure perceived competence for specific activity assuming one is intending to start or maintain said activity. Amended to reflect ‘physical activity’ as opposed to ‘exercise’. Can be taken at any time point as does not assume one is already active at baseline

Questions used:

Using a 5 point scale (1 = strongly disagree; 2 = disagree; 3 = neither agree nor disagree; 4 = agree; 5 = strongly agree). NB. 1 item to recode

I feel confident in my ability to be physically active regularly

I do not feel capable of being physically active regularly. (NB. reverse code (5 = strongly disagree; 4 = disagree; 3 = neither agree nor disagree; 2 = agree; 1 = strongly agree)

I am able to be physically active regularly

I am able to meet the challenge of being physically active regularly

Scoring instructions: reverse code the one item then sum all 4 items

AUTONOMY

Perceived Autonomy (Taken from the Psychological need satisfaction in exercise scale (PNSE) [44]. 4 item (reduced from 5 items) subscale measure for perceived autonomy. Amended to say ‘physical activity’ as opposed to ‘exercise’. Factor loadings available to reduce items based on strongest correlations

Questions used:

Using a 5 point scale (1 = strongly disagree; 2 = disagree; 3 = neither agree nor disagree; 4 = agree; 5 = strongly agree). NB. 1 item to recode

I feel free to be physically active in my own way

I feel free to make my own decisions about physical activity

I feel like I am in charge of how often I do physical activity

I do not feel free to choose which physical activities I participate in

(NB. reverse code (5 = strongly disagree; 4 = disagree; 3 = neither agree nor disagree; 2 = agree; 1 = strongly agree)

Scoring instructions: reverse code the one item then sum all 4 items

RELATEDNESS (AVAILABILTY OF SUPPORT)

Items asking if there are people in your life who you can be physically active with. Measure developed specifically for this study as many existing measures of relatedness assumed that participants were already exercising at baseline (e.g.” I feel attached to my exercise companions because they accept me for who I am”)

Questions used:

Using a 5 point scale (1 = strongly disagree; 2 = disagree; 3 = neither agree nor disagree; 4 = agree; 5 = strongly agree)

There are others in my life with whom I can be physically active

There are people in my life I can enjoy being physically active with

There are people in my life who can encourage me to be physically active

Scoring instructions: Sum all 3 items

RELATEDNESS (FREQUENCY OF SUPPORT)

3 items taken and amended from a previous 5 item 5 point Likert scale showing reliability and validity from a previous study by [47], (alpha = 0.76 at baseline). Only items that did not assume baseline physical activity levels were included

Questions used:

Using a 5 point scale (1 = almost never; 2 = once in a while; 3 = sometimes; 4 = often; 5 = very often)

‘In the last 30 days how often did others…..’

Discuss physical activity with me?

Encourage me to do physical activity?

Share ideas with me on how to get enough physical activity?

Scoring instructions: Sum all 3 items

ACTION PLANNING

Action/Coping planning scale [48]. 5 items using 5 point scale on action planning with all references to ‘exercise’ changed to ‘physical activity’

Questions used:

Using a 5 point scale (1 = strongly disagree; 2 = disagree; 3 = neither agree nor disagree; 4 = agree; 5 = strongly agree)

‘In the last 30 days I have regularly made weekly plans for…’

When to be physically active

Where to be physically active

How often to be physically active

What to do if something interferes with my plans

How to cope with possible setbacks

Scoring instructions: Sum all 5 items

SELF MONITORING

Self-monitoring for physical activity with 2 items taken from [49] and 3 new items taken from NDPS. Any references to ‘exercise’ amended to ‘physical activity’

Questions used:

Using a 5 point scale (1 = strongly disagree; 2 = disagree; 3 = neither agree nor disagree; 4 = agree; 5 = strongly agree)

‘In the last 30 days I have…

Consistently monitored the amount of physical activity I do

Regularly thought about how much physical activity I am doing

Scoring instructions: Sum both items