Table 1 Constructs and Measures

Self-report using an adapted version of Godin and Shephard's 'Leisure Time Exercise Questionnaire' [32]

Resting heart rate, blood pressure, limb girth circumferences, 6 minute walk, sit to stand (30 seconds), 1 repetition maximum strength test, and Apley's shoulder test [43].

The Actigraph GT3X accelerometer is a small matchbox-sized unit worn on a belt on the hip that is a valid and reliable tool for measuring physical activity among adults [45, 46], and will be worn for eight consecutive days, before the intervention commences and during the final week of the intervention.

European Organization for Research and Treatment of Cancer core quality of life questionnaire (EORTC QLQ-C30, version 3 [35]) and the prostate tumour-specific module (EORTC QLQ-PR25 [36]).

Memorial Anxiety Scale for Prostate Cancer (MAX-PC) [37]

Centre for Epidemiological Studies Depression Inventory (CES-D) [40].

Participants rate the certainty with which they believe they can perform three physical tasks. For each task, they rate the certainty with which they believe they can perform these tasks for three time durations: 10, 20, and 30 minutes. Confidence will be measured on an 11-point Likert scale, from 0 (not at all confident) to 100 (extremely confident). Measure based on exercise and cancer research in which task self-efficacy was measured [48].

Participants rate the certainty with which they believe they can perform exercise when faced with specific barriers. Items (barriers) from Bandura's [47] self-efficacy to regulate exercise instrument, with supplementary items from research on barriers to physical activity for prostate cancer survivors [8] and research on barrier self efficacy and cancer survivors [48]. The 11-point Likert scale used in the measurement of task self-efficacy will also be used to assess barrier self-efficacy.

Multidimensional Outcome Expectations for Exercise Scale (MOEES) [49].

Participants indicate the number of days per week they intend to perform at least 30 minutes of exercise at a light, moderate or strenuous intensity now and in 12 weeks. Items adapted from previous research using social cognitive theory constructs [51].

Participants asked perceptions of frequency with which each facilitator and barrier occurs using a 5-point-Likert scale anchored by 0 (never) and 4 (always). Measure based on guidelines for the development of scales to assess barriers to physical activity for cancer patients [52] and content (i.e., facilitators and impediments) drawn from our prior work with prostate cancer survivors [8].