Longitudinal Study On Trajectories Of Physical Activity And Its Associations With Physical Fitness And Cognitive Ability In Children

PurposeThe purpose of this study,based on a cross-sectional and a 3-year longitudinal study among healthy preschoolers aged 4-5 years in Shanghai,was to explore:(1)the cross-sectional associations between the level of objectively measured physical activity and physical fitness in preschool children;(2)during the transition from kindergarten to primary school,the trajectories of children’s physical activity level and its effects on physical fitness and cognitive ability at follow-up;(3)the longitudinal associations of the baseline,changes in physical activity with children’s physical fitness and cognitive ability at follow-up.MethodsAt baseline stage,a total of 346 healthy preschoolers aged 4-5 years(58.1%of boys)were recruited from 8 kindergartens in Shanghai.Daily physical activity was objectively measured by accelerometer Acti Graph GT3X~+and physical fitness tests were conducted,including height,weight,triceps skinfold thickness,grip strength,tennis throwing,sit and reach,stand long jump,balance beam,10m SRT and 20m SRT.A total of 127 children(62.2%of boys)and 123 children(60.9%of boys)participated in two follow-up studies respectively.Daily physical activity level was measured objectively by accelerometer Acti Graph GT3X~+,physical fitness tests were conducted according to the corresponding age in both two stages.The children’s verbal intelligence quotient(VIQ),performance intelligence quotient(PIQ)and full intelligence quotient(FIQ)were assessed by using the urban version of China-Wechsler Intelligence Scale for Children(C-WYCSI)to evaluate their cognitive ability.Multiple linear regression model was used to explore the cross-sectional associations of the levels of physical activity with physical fitness after adjusting for confounding factors.Independent sample t test,paired sample t test and correlation analysis were used to explore the trajectories of children’s physical activity level during the transition from kindergarten to primary school over 3 years.Multifactor analysis of covariance was used to explore the effects of different MVPA and BMI groups on children’s physical fitness,cognitive ability and their interactions.Mixed linear regression model was used to explore the longitudinal associations of the baseline MVPA,changes in MVPA with children’s physical fitness at follow-up and the longitudinal associations of baseline SB,LPA,MVPA,changes in SB,LPA,MVPA with children’s cognitive ability at follow-up.Results1.Average TPA time of children was 167.99±35.07min/d,LPA time was97.17±17.54min/d and MVPA time was 70.82±17.53min/d,LPA(P<0.05),MVPA(P<0.05)and TPA(P<0.01)were significantly higher in boys than for girls.Boys’handgrip strength(P<0.01)and tennis throwing(P<0.01)were significantly higher than girls,while sit and reach test was significantly lower than girls(P<0.01).There were no significant sex differences in triceps skinfold thickness,stand long jump,10m SRT,20m SRT,and balance beam test(P>0.05).After adjusting for confounders,the stand long jump(P<0.01),tennis throwing(P<0.01)and 20m SRT laps(P<0.01)were positively associated with MVPA,while triceps skinfold thickness(P<0.05),10m SRT(P<0.01)and balance beam(P<0.05)were negatively associated with MVPA.Also,20 m SRT(P<0.05)and tennis distance(P<0.05)were positively correlated with LPA(P<0.05)and 10m SRT(P<0.05),balance beam(P<0.05)were negatively correlated with LPA.Meanwhile,the stand long jump(P<0.01)and tennis throwing(P<0.01)were positively correlated with MVPA,and triceps skinfold thickness(P<0.05)was negatively associated with MVPA.Negative correlation was observed between balance beam(P<0.05)and MVPA in girls.No significant correlation between MVPA,LPA and grip strength,flexibility was found in the study(P>0.05).2.SB time in children at follow-up was significantly higher than at baseline(P<0.01),while LPA(P<0.01)and MVPA(P<0.01)time were significantly lower than at baseline.At follow-up,boys’MVPA time on workdays(P<0.01)and weekends(P<0.01)were both significantly higher than girls.There was no significant correlation(P>0.05)in SB time between baseline and follow-up,while there was significant correlation in LPA(P<0.05)and MVPA time(P<0.01)on workdays.The main effect of MVPA(P<0.05),BMI group(P<0.05)on boys’grip strength were significant,and no interaction was found.The main effect of MVPA(P<0.05)and BMI(P<0.05)groups and their interactions(P<0.01)on boys’upper limb muscular strength were significant.The main effect of BMI group on boys’lower limb explosive strength was significant(P<0.01).The main effect of MVPA group on boys’agility was significant(P<0.05).The main effect of BMI group on boys’aerobic fitness was significant(P<0.01)and interaction with MVPA group was found(P<0.05).The main effect of BMI group on girls’aerobic fitness was significant(P<0.05)and there was no interaction with MVPA group(P>0.05).There were no main effects and interaction of MVPA and BMI group on children’s flexibility.Simple effect test showed that,in normal weight boys,the upper limb muscluar strength(P<0.05)and aerobic fitness(P<0.05)were significantly higher in the MVPA increasing group.In overweight and obese boys(P<0.01),was higher in continuous-active MVPA group(P<0.05).In continuous-active MVPA and continuous-inactive MVPA group,overweight and obese boys’upper limb muscular strength were significantly higher than in normal weight boys(P<0.01).In MVPA insreasing group,normal weight boys’upper limb muscular strength(P<0.05)and aerobic fitness(P<0.01)were significantly higher than overweight and obese boys.After adjusting for confounders,baseline MVPA was significantly positively associated with upper limb musclualr strength and aerobic fitness in children at follow-up.For each 1min increase in MVPA at baseline,the tennis throwing increased by 0.2m(95%CI:0.02,0.4)and 0.4laps(95%CI:0.04,0.7)at follow-up respectively,and this longitudinal association was independent of the baseline physical fitness composite score.Meanwhile,there was no significant association of baseline MVPA with other physical components(grip strength,lower limb explosive strength,flexibility and agility)at follow-up.After adjusting for confounders,there was no significant association of changes in MVPA with the physical fitness in children at follow-up.3.The main effect of MVPA groups on boy’s PIQ was significant(P<0.05)and there was no interaction with BMI groups.Among boys,PIQ was significantly higher in continuous-active MVPA group than in continuous-inactive MVPA group.The main effects and interactions of MVPA group and BMI group were not significant for VIQ,PIQ and FIQ in girls.After adjusting for confounders,baseline MVPA time was significantly positive associated with PIQ.For each 1min increase in baseline MVPA time,PIQ at follow-up increased by 0.9 points(95%CI:0.1,1.7),and this longitudinal association existed independently on the baseline physical fitness and coginitive ability sores.Compared with T1,FIQ in T2 and T3 increased by 0.8(95%CI:0.2,1.4)and 1.3(95%CI:0.6,2.0)respectively,and this association existed independently from baseline physical fitness,but after further adjustment for the baseline cognitive ability scores,there was no significant association.There was no significant association of baseline SB,LPA with VIQ,PIQ and FIQ at follow-up.After adjusting for confounders,there was no significant associations of changes in SB,LPA,and MVPA with VIQ,PIQ,PIQ in children at follow-up.Conclusion1.MVPA(compared with LPA)were more closely associated with physical fitness in preschool children.There were gender differences in the association of different levels of physical activity with components of physical fitness.Boys’body composition,upper limb muscular strength,lower limb explosive strength,agility and aerobic fitness could improve if they get more MVPA.For girls,agility,aerobic fitness and balance could be enhanced if obtain more MVPA.2.During the transition from kindergarten to primary school,children’s SB increased significantly on workdays and weekends,while LPA and MVPA both decreased significantly.There is a significant correlation between children’s LPA,MVPA on workdays at baseline and follow-up,but not between sedentary behavior.Children who had higher MVPA in preschool stage,also had higher upper limb muscular strength and aerobic fitness after 3 years.Boys who maintained high MVPA from preschool to primary school had positive effect on grip strength and agility,but this effect was not found in girls.For normal weight boys,increasing MVPA from preschool to primary school had a positive effect on upper limb muscular strength and aerobic fitness.For overweight and obese boys,changes in MVPA had no significant effect on aerobic fitness.Therefore,during this important stage of the connection between young and young,it is necessary to pay much attention and take timely and active measures to improve the level of children’s physical activity.At the same time,more effective targeted physical activity promotion programs should be developed for girls and overweight and obese children.3.Children who had higher MVPA in preschool stage,also showed higher PIQ after 3years.Boys who maintained high MVPA from preschool to primary school had a positive effect on PIQ,but this effect was found in girls.It suggested that gender considerations should be differentiated in the development of action plans for physical activity promotion children’s cognitive ability.