CSs 4-6 are conceptually linked in order to facilitate later comparison, although specific operationalisations of the design will be sensitive to local conditions and co-developed with local stakeholders. Our hybrid approach will create three Level 2 CSs that can be meaningfully compared, while leaving enough flexibility to make each CS reflect locally applicable social innovation.

The three CSs will focus on testing nature-based mindfulness interventions. In terms of NBRT, the benefits may include greater exposure to immune-function promoting microbial-biodiversity, greater physical activity, and more positive social interactions. Our target ‘at-risk’ group will be sedentary, low nature-users (<30mins per week) with metabolic syndrome (a combination of at least 3 of 5 risk factors: large waistline, high blood pressure, abnormal blood lipid levels, low HDL cholesterol, and high blood sugar), a condition common across Europe associated with an increased risk of stress and allostatic load related conditions such as heart disease, stroke, and type 2 diabetes.

The trials will adopt a two-arm wait-list design, randomising one group to a nature-based mindfulness intervention and one to a waiting list control condition (no treatment). The control group will receive the same intervention after the active intervention group. The ~5-week interventions will extend existing mindfulness-in-nature practices and involve elements of movement, rest, and mindful contemplation through different sensory modalities. The interventions will be developed using experiences from previous studies by the teams and co-creation with local stakeholders. They are tentatively planned to involve approximately three semi-structured 40-minute walks per week, 15 sessions in total.

The initial sessions will be led by a guide, with later sessions supported through established mobile applications that help people navigate selected nature routes. Data will be collected pre-, during, and post-intervention, and at 3-month follow-up to assess longer-term health/well-being effects and maintenance of nature contact. In order to evaluate the impact of different nature types as well as contextual factors, such as climate and culture, the CSs will be set in urban nature (CS4, Padua, Italy), rural mountainous settings (CS5, Salzburg, Austria), and in urban coastal zones (CS6, Barcelona, Spain).