Table 3.

Conceptual frameworks of interventions which included a psychological component

Approach/study	Approach or Theory/theories on which the modification has been based	Conceptual mechanisms of change	Details of intervention and depression specific elements (if any).
Motivational Interviewing (MI) [21]	The study employed Motivational Interviewing (MI) [37], and it used a goal-based approach in identifying patient readiness to change for diet and physical activity behaviours [38].	MI is a “client centred, directive method for enhancing intrinsic motivation to change by exploring and resolving ambivalence” [39] p. 25. MI comprises of two main components: (a) increasing an individual’s motivation to change behaviour; (b) increasing an individual’s commitment to change. MI draws explicitly and implicitly on a number of behaviour change conceptual frameworks [40]. Goal setting is based on self-regulation theory and control theory. Goal theory, focuses on mechanisms, which make it possible for intention to be translated into action. The mechanisms to enhance one’s ability to perform behaviour are, amongst others, self-monitoring or setting realistic goals [40].	Consultations s with exercise professionals were underpinned by a motivational interviewing (MI) approach and included goal setting. The short-term goals developed by participants included homework activities, which were reviewed at the beginning of the subsequent consultation [41]. The use of homework, including scheduling daily activities (‘therapeutic homework administration procedure’), was a depression-specific modification of the intervention. The use of homework has been recognised as effective in the treatment of mental illness [41] and planning daily activity can be as effective as Cognitive Behavioural Therapy (CBT) and other psychological treatments in alleviating depression symptoms. Treatment fidelity revealed, however, that these components of the interventions were not fully delivered.
Intervention based on the principles of SCT [23]	Social-Cognitive Theory (SCT)	SCT assumes that self-efficacy (confidence to perform a particular behaviour; perceptions about one’s own capabilities) is the key determinant of behaviour [42]. Self-efficacy expectations are beliefs about one’s ability to perform behaviour irrespective of the external circumstances [42]. Social influences and expectation of the outcomes of behaviour are other determinants of whether or not one will attempt to change [42]. According to SCT self-efficacy can be enhanced by: (i) mastery experience - taking small steps which lead to mastering a skill; (ii) vicarious learning – learning occurs through observing others; (iii) verbal persuasion and believing that one’s have what is required to succeed; (iv) affective states – dealing with negative emotions through various techniques [42].	It was a 10-week internet-based physical activity intervention and it included 4 modules with components addressing barriers to the initiation and maintenance of physical activity. Specifically, Module 1 Getting Started included information about the benefits of exercise; Module 2 Planning for Success introduced self-efficacy, outcome expectations and goal setting; Module 3 Beating the Odds looked at barriers to physical activity and looked at the ways of overcoming them; Module 4 Sticking with It provided guidance on maintenance.
Behavioural activation (BA) [20]	Behavioural Activation (BA) [43] is grounded in learning theory and contextual functionalism. The study used two modifications: behavioural activation (BA) and behavioural activation plus physical activity promotion (BAcPAc).	BA [43] is a development of activity scheduling, which is a CBT component. Two mechanisms of affecting change: 1. Using avoided activities as a guide for activity scheduling (PA can be one of those activities). That is, scheduling daily activities consistently with avoided activities but consistent with one’s valued direction. 2. Functional analysis of cognitive processes, which lead to activity avoidance. The therapy focuses on the entire event and factors that may affect the occurrence of negative responses. Contextualisation explores what factors predict and maintain negative responses [44]. A developmental formulation is established which explores how social context has affected a depressed individuals copying behaviour. Alternative approaches to creating one’s responses is developed [44].	BA activation has been proposed as a treatment for depression and as the basis for interventions to increase physical activity levels.
Intervention based on the CBT principles [19]	Cognitive Behavioural Therapy (CBT) CBT combines Cognitive Therapy (CT) [46] and Behaviour Therapy (BT) [48]. The CBT programme comprised 12-weekly sessions followed by 9 monthly booster sessions.	One could tackle a health-related behaviour by examining processes (hidden motivation and otherwise), which lie at the root of the problem. Changing self-referent negative thinking, which promotes low mood, may improve motivational and behavioural features. CBT enables individuals to develop better coping skills for dealing with negative self-referent thought, believes and attitudes, which, in turn, affect their feelings and behaviours (e.g. including PA). It comprises activity scheduling and cognitive challenges to negative thoughts, core beliefs and assumptions [44].	At the outset, the aim of the CBT sessions was to address patients’ depressive symptoms; after five sessions, the nurses delivering the interventions initiated discussions about a walking programmes and links between depression and PA. A manual was used to provide step-by-step visual instructions to facilitate sessions; it included elements common in depression CBT manuals plus additional concepts related to diabetes self-care and PA.
Intervention based on the principles of SDT [15, 16] Intervention based on the principles of SDT plus an MI element [27]	Self-Determination Theory (SDT) Exercise Referral Schemes are based on multiple theories. The studies included in this review explored such concepts as Self-Efficacy and Self-Determination Theories, and their effects on PA behaviour.	SDT focuses on both, the determinants and consequences of autonomous (e.g. personal values) and controls motives; it may promote more autonomous motivation, which has been found important in interventions for individuals with depression. It highlights the importance of feeling competent, in control and connected with others [27]. It assumes that high levels of autonomous motivation are link to finding PA intrinsically enjoyable or, at least, connected to desired outcomes [27].	Interventions based on SDT were not modified for individuals with depression. The researchers found that the intervention was effective in increasing physical activity levels in the cardiac group but not in the depression group. This suggests that unmodified interventions may be ineffective or less effective in depressed patients.
Intervention based on the Energy and Strength Model [24]	The study used the Strength and Energy Model [49, 50]; implementation intention and planning, self-efficacy and action control [51, 52].	The strength and energy model assumes that self-regulation is a global energy that is utilised on self-regulated activities in different areas of action. As a self-regulation is represented as a limited source, self-regulation in one area may lead to ego depletion, and a failure to self-regulate in the other areas. The regulation of depression symptoms may lead to reduction of self-regulation energy and difficulties in using self-regulation in the other areas, such as physically activity.	The intervention itself was designed for orthopaedic patients. The researchers were interested in whether depression limits usefulness of this programme. They concluded that depression did modify the effectiveness of the programme. They concluded: “a self-regulation intervention, which is not tailored to the needs of the individuals suffering from depressive symptoms, might not be effective…” [24] p. 7.