Physical Activity and Sedentary Behaviour in the MEDIET4ALL Study: Associations with Mediterranean Lifestyle, Sleep,...

Background/Objectives: Physical activity and sedentary behaviour represent related yet distinct movement behaviours with potentially different behavioural, psychosocial, and lifestyle correlates. However, multinational evidence examining these behaviours within the Mediterranean lifestyle framework remains limited. This study investigated correlates of physical activity and sedentary behaviour among adults from Mediterranean and neighbouring countries participating in the MEDIET4ALL survey. Methods: Data were collected from 4010 adults (37.2 ± 15.4 years; 59.5% female) across 10 Mediterranean and neighbouring countries using a standardized multilingual e-survey. Physical activity was assessed using the short International Physical Activity Questionnaire (IPAQ-SF; MET-min/week), and sedentary behaviour was assessed by daily sitting time. Hierarchical multiple linear regression analyses were conducted separately for physical activity and sedentary behaviour. Exploratory bootstrapped mediation analyses examined whether life satisfaction (SLSQ) or social participation (SSPQ) mediated associations between MEDLIFE dietary dimensions and sitting time. Results: Higher physical activity was associated with more rural living environments, lower body mass index, more favourable smoking status, higher alcohol consumption, stronger adherence to Mediterranean dietary habits, longer sleep latency, higher stress, and greater social participation (β ≈ 0.05-0.11), whereas female sex, longer sleep duration, and higher anxiety were associated with lower physical activity (β = -0.04 to -0.23); the positive association with alcohol consumption should be interpreted cautiously in light of potential residual confounding. By contrast, sedentary behaviour was positively associated with higher education, higher body mass index, and more favourable smoking-status (β ≈ 0.04-0.09) and inversely associated with better self-reported health status, Mediterranean dietary consumption patterns, life satisfaction, and social participation (β = -0.04 to -0.07). Mediation analyses showed significant but small-magnitude indirect effects for the pathways linking MEDLIFE dietary consumption patterns and MEDLIFE dietary habits with sitting time through social participation (indirect β = -0.0032 and -0.0045, respectively), which should be interpreted with caution, whereas no significant indirect effects were observed through life satisfaction. Conclusions: Physical activity and sedentary behaviour are associated with different, though partially overlapping, lifestyle and psychosocial correlates within the MEDIET4ALL framework. Social participation may represent a modest behavioural pathway linking Mediterranean dietary dimensions with lower sitting time. Given the cross-sectional design, these findings should be interpreted as associative rather than causal, but they nonetheless reinforce the importance of integrated and context-sensitive lifestyle promotion strategies.