Physical Activity-Sedentary Behaviour Profiles and Associated Lifestyle Characteristics in Adolescents: A...

Background/Objectives: Physical activity and sedentary behaviour are related but distinct components of adolescent movement behaviour and may combine into heterogeneous lifestyle profiles. This study aimed to identify empirically derived physical activity-sedentary behaviour profiles and to examine sociodemographic and lifestyle factors associated with profile membership. Methods: This cross-sectional, school-based study included 3307 Polish adolescents aged 15-17 years (52.22% girls; mean age, 15.89 ± 0.71 years). Weekly sedentary time and walking, moderate-intensity, and vigorous-intensity physical activity were assessed using the IPAQ-LF, reprocessed using predefined truncation procedures, standardised using z-scores, and entered into k-means clustering. Two- and three-cluster solutions were evaluated. Separate binary logistic regression models examined crude and sex- and school-type-adjusted associations between candidate lifestyle correlates and profile membership. Results: Although the two-cluster solution had a higher average silhouette coefficient (0.36 vs. 0.28), the three-cluster solution was retained because it provided a more differentiated and substantively interpretable representation of movement-behaviour patterns. The profiles comprised a walking-dominant activity profile (C1; n = 645; 19.50%), a high moderate-to-vigorous activity/lower sedentary profile (C2; n = 354; 10.71%), and a lower physical activity profile (C3; n = 2308; 69.80%). C3 had substantially lower walking, moderate-intensity, and vigorous-intensity activity than C1, while sedentary time was similar in magnitude between these profiles. After adjustment for sex and school type, C2 membership was associated with irregular eating patterns (OR = 1.73, 95% CI: 1.05-2.84), school-day sleep ≥ 9 h/day (OR = 1.98, 95% CI: 1.11-3.54), weekend sleep < 7 h/day (OR = 1.70, 95% CI: 1.02-2.82), and weekend sleep ≥ 9 h/day (OR = 1.59, 95% CI: 1.16-2.16). No lifestyle candidate correlate reached statistical significance in the adjusted C3-versus-C1 analyses. Conclusions: The identified profiles support viewing physical activity and sedentary behaviour as related but non-equivalent dimensions of adolescent movement behaviour. Lower physical activity did not necessarily coincide with higher sedentary time, while selected sleep-duration and eating-regularity characteristics were associated with the high moderate-to-vigorous activity/lower sedentary profile. These findings are exploratory and warrant confirmation in longitudinal studies using objective measures.