Compositional Analysis Of 24-hour Movement Behaviors And Cardiorespiratory Fitness

Research Background: Cardiorespiratory Fitness（CRF）is a good indicator of the heart’s ability to deliver oxygen-rich arterial blood to tissues and organs such as muscles.Low CRF increases the morbidity and mortality of many chronic diseases,including cardiovascular disease and metabolic syndrome.As the key period of transition from adolescent to youth,cardiovascular health in college students is of great significance to their future health and quality of life.However,the decrease of CRF is a major manifestation of the decline of college students’ physical fitness at present.Studies have shown that moderate-to-vigorous physical activity（MVPA）and sedentary behaviors（SB）are significantly correlated with CRF.However,most current studies only consider the association between single movement behavior and CRF,ignoring the fact that the sum of the time of day is a fixed constant and that each movement behavior is interrelated in nature.24-h movement behavior was composed of SB,light physical Activity（LPA）,MVPA and sleep.Based on the interdependence of movement behaviors,this study used compositional analysis to explore the relationship between 24-h movement behaviors and CRF of 19–24-year-old college students,providing key theoretical and practical support for the development of 24-h movement behavior guidelines for Chinese college students.Research methods: The data of this study are from " Shanghai University of Sport Alumni Health Study".A total of 1758 college students were recruited for the study.After data checking and screening,a total of 1039 college students（including 517 male students;522 female students,mean age 21.46 ± 0.91）were included in the final analysis.SB,LPA,MVPA was collected by Acti Graph GT3X+ triaxial accelerometer and sleep was measured by self-reporting.CRF is measured by the maximum oxygen uptake of a power bike.Body fat percentage（BF%）was assessed by dual-energy X-ray absorptiometry.According to the BF% cut-off point set for cardiovascular metabolic risk in Chinese,they were divided into high BF% group（male BF% ≥ 24.0%,female BF% ≥ 33.0%）and low BF% group（male BF% < 24.0%,female BF% < 33.0%）.the study also collected the subjects’ height,weight,self-reported department（stratified by physical education students）,eating habits,health behavior scale and other variables.With SB,MVPA,LPA and sleep as independent variables and CRF as dependent variables,the relationship between 24-hour movement behavior and CRF was explored by traditional multiple linear regression analysis and compositional analysis.In addition,gender（male vs.female）,BF% group（high BF% vs.low BF%）,and student category（sports student vs.non-sports students）for subgroup analysis.Finally,the compositional isochronous substitution model was used to explore the predicted changes of CRF after the substitution of each movement behavior time.Results: 1.After adjusting for confounding factors,compositional data showed that 24-hour movement behavior had significant statistical significance with CRF（P < 0.01）;In particular,compared with other activities,the time distribution of MVPA was significantly positively correlated with CRF（Y₁⁴ = 1.71,P < 0.001）,while the time distribution of SB was significantly negatively correlated with CRF（Y₁² =-2.38,P < 0.001）.No significant correlation was found between the time distribution of LPA（Y₁³ =-0.80,P = 0.35）and sleep（Y₁¹ = 1.38,P = 0.18）and CRF compared with other activities.2.In the subgroup analysis,after adjusting confounding factors,the findings of girls group,high BF% group and non-sports students’ group were consistent with the above results;In the male group,the low BF% group and the sports student’s group,only the relative distribution of 24-hour activity time was significantly correlated with CRF（P < 0.01）,but no correlation was found between each component of activities and CRF.3.In compositional isochronous substitution,the increase or decrease of CRF depends on the behavior of the substitution or substituted activity and that is asymmetric.When 15 minutes of MVPA was substituted for sleep,SB,or LPA,the CRF increased by 0.17,0.27,and 0.25 units,respectively,but CRF was significantly reduced by 0.2,0.3,and 0.28 units when substituted in reverse.Therefore,when MVPA and other activities are substituted for other activities,CRF increases.When SB is substituted for other activities,CRF decreases.Conclusion:There is a significant correlation between 24-hour movement behavior and cardiopulmonary fitness of college students.The results suggest that college students,especially those with high body fat percentage or non-physical activity,should engage in more moderate-to-vigorous physical activity physical activity.At the same time,the asymmetry of isochronous substitution results further emphasizes that sedentary behavior should be converted to light or moderate-to-vigorous physical activity physical activity as much as possible to reduce the adverse effects of sedentary behavior or physical inactivity.