Systematic Development of a Training Intervention to Support General Practitioners' Very Brief Physical Activity Advice for Patients With Coronary Heart Disease: Formative Intervention Development Study From the OptiCor Project

Despite strong evidence supporting the benefits of regular physical activity (PA) for managing coronary heart disease (CHD), PA advice remains infrequent in general practice. Barriers include the limited familiarity of general practitioners (GPs) with current PA guidelines and their application to CHD patients, their insufficient skills for delivering very brief advice, and time constraints. To our knowledge, no structured, theory-informed training has been reported in Germany to support GPs in delivering very brief PA advice in routine CHD care.

This intervention development study aimed to systematically develop and specify a training intervention to strengthen GPs' delivery of very brief PA advice to patients with CHD in routine primary care.

Guided by the behavior change wheel (BCW), we conducted a formative intervention development study informed by preceding empirical studies from the OptiCor project, including a cross-sectional survey, interviews, and focus groups with GPs and patients, alongside guideline recommendations and behavior change theory. These sources identified needs, barriers, and preferences related to PA advice. Findings were mapped onto COM-B (capability, opportunity, motivation-behavior) components to identify determinants of GP behavior and were specified using the theoretical domains framework (TDF). The BCW intervention function matrix informed discussions of suitable intervention functions and training components. Intervention components were specified using the behavior change technique (BCT) taxonomy, and GPs were involved throughout to ensure relevance, feasibility, and acceptability.

The development process resulted in a fully specified intervention: a structured, 3.5-hour, small-group training for GPs focusing on the very brief 3As method (ask/assess, advise, and assist). The training comprises theoretical input on PA and CHD, guided self-reflection and group discussions, moderated role-plays with simulated patients, experiential learning using PA stimuli, practical consultation materials, and short on-demand good practice videos. Outputs included a refined behavioral specification of GP-delivered PA advice, a COM-B/TDF-based behavioral diagnosis, BCT-specified training components, minor refinements after a preimplementation training rehearsal, and fidelity procedures to support standardized delivery.

This study resulted in a fully specified GP training intervention to strengthen very brief PA advice in routine CHD care. By integrating empirical findings, guideline recommendations, behavior change theory, and GP and patient input, the intervention targets the determinants of GP advising behavior and is described transparently to support evaluation and replication. Following this development work, the training and evaluation procedures were examined in a pragmatic pilot cluster randomized controlled trial (cRCT), which has been reported separately, before proceeding to an ongoing full-scale pragmatic cRCT evaluating the effects on GP behavior.