Relações da atividade física e do comportamento sedentário com um fenótipo da saúde musculoesquelética em adolescentes: consórcio RPS, São Luís

Abstract

Adolescence is an essential stage for musculoskeletal development, characterized by the consolidation of bone mass, muscle mass, and muscle strength, which are fundamental components for functional capacity and the prevention of musculoskeletal diseases in adulthood. These processes are strongly influenced by human movement–related behaviors, such as physical activity at different levels, as well as sedentary behavior. Insufficient levels of physical activity and excessive sedentary time during adolescence may compromise the development of the musculoskeletal system, resulting in less favorable health profiles, with an increased risk of chronic non-communicable diseases (NCDS) and functional frailty throughout life. In this context, this dissertation aims to analyze the association between physical activity, sedentary behavior, and the Musculoskeletal Health Phenotype in adolescents at the end of the second decade of life. This is a cross-sectional analytical study nested within a birth cohort, using data from the 18–19-year follow-up of the 1997/98 birth cohort from São Luís, Brazil, with a sample of 2,515 participants. Physical activity was assessed using a validated questionnaire, the Self-Administered Physical Activity Checklist (SAPAC), and actigraphy. Sedentary behavior was measured by the daily time spent in low-energy-expenditure activities. The outcome corresponded to the Musculoskeletal Health Phenotype, a latent variable constructed from the shared variance among bone mineral density, handgrip strength (HGS), and muscle mass. Associations were estimated using Structural Equation Modeling, adjusted for socioeconomic status, sex, and nutritional status. The results indicated that physical activity showed a direct positive association, increasing the values of the Musculoskeletal Health Phenotype (standardized coefficient = 0.143; p < 0.001), whereas sedentary behavior exerted a direct negative effect (standardized coefficient = −0.040; p < 0.001). Lower socioeconomic status increased the values of the Musculoskeletal Health Phenotype (standardized coefficient = 0.291; p < 0.001) and reduced sedentary behavior (standardized coefficient = −0.041; p < 0.001). Female sex was associated with lower levels of physical activity and greater sedentary behavior, while overweight increased the values of the Musculoskeletal Health Phenotype (standardized coefficient = 0.263; p < 0.001). The findings highlight the importance of interventions to promote physical activity among adolescents, preventing future risks to musculoskeletal health and associated chronic non-communicable diseases.