Assessing the impact of 24-hour activity behaviors on cardiorespiratory fitness in the older adult: a component analysis approach

Cardiorespiratory fitness (CRF) serves as a critical measure of the cardiovascular system's efficiency in delivering oxygenated blood to tissues and organs. Understanding the relationship between various activity behaviors and CRF is essential for devising effective health interventions for the older adult population. This study aimed to investigate the association between 24-h activity behaviors and CRF in older adult individuals, utilizing compositional data analysis. We utilized baseline data from the "Fifth National Physical Fitness Monitoring Cohort Study in Tianjin, China," which included 540 older adult participants. Physical activity and sedentary behavior were objectively measured using a three-dimensional accelerometer, and CRF was assessed via a gas metabolism analyzer. Compositional data analysis was employed to examine the relationships between 24-h activity behaviors-specifically, moderate-to-vigorous physical activity (MVPA), light physical activity (LPA), sedentary behavior (SB), and sleep (SLP)-and CRF. The analysis demonstrated that MVPA was significantly positively associated with CRF (βMVPA = 5.36,