Clustering of physical activity and diet
Activity assessment tools allow refinement of diet–physical activity clustering assessment. Corresponding data were summarised in a systemic review published in 2011, which included 56 studies, most dealing with children and adolescents (19 studies in children, 26 in adolescents and 11 in adults). Most studies used cross-sectional designs, and confirm the relationship between sedentariness (and, in parallel, screen time) and unhealthy dietary patterns, as illustrated by higher consumption of energy-dense snacks and less consumption of fruit and vegetables, consistent across age groups [41]. The strength of the relationship between diet and activity was small-to-moderate overall, and slightly less in adults than in younger age groups. Most studies of the relationships between diet and lung function/COPD adjust analyses for physical activity [17] but, again, residual confounding cannot be excluded, especially when measures are only questionnaire based.