The Study On The Effect Of Physical Activity On Preschool Children’s Cognitive Abilities

PurposeBased on objective method of accelerometer to access daily physical activity level on Shanghai preschool children, and on the basis of recommendation for preschooler physical activity to evaluate the percentage of participants meet the need. In addition, identify the relation between daily physical activity level and cognitive abilities. Further study explore whether peripheral blood levels of growth factor play a mediator role in the impact of physical activity on cognitive abilities.MethodsStudy one(Chapter two)A total of 306 participants recruited(boys, 176; girls, 130) from 7 kindergartens on Yangpu and Baoshan District, Shanghai, according to the result of sample estimation. Participants’ physical activity were assessed using Acti Graph GT3 X accelerometer(GT3X, Acti Graph, Pensacola, FL, USA), which was worn for seven consecutive days, with 1-second epoch set for data collection. On the first monitoring day parents of children were instructed on how to wear and remove the accelerometer and where to position it(i.e., right hip, on the right midaxillary line at the level of the iliac crest). Participants were asked to wear the accelerometer during all waking hours except for showering, swimming or sleeping. The research staff collected the accelerometers at the end of seven days of monitoring and transferred the data to the computer using Actilife version 6.11.5 software. The accelerometer output was derived as counts per minute(cpm) for all children and thresholds for sedentary behavior, light, moderate and vigorous intensity were ≤100 cpm, 101-1679 cpm, 1680-3367 cpm and ≥3368 cpm, respectively, which were used to calculate time spent at each intensity activity for participants.Study two(Chapter three)Based on "China- Wechsler Abbreviated Intelligence Scale for children(C-WAISC)"(City version), two verbal and two performance quizzes represented verbal IQ and Performance IQ respectively. According to Handbook, give four tests weight coefficients to calculate the full IQ. Cardiorespiratory fitness and motor ability were measured using 20 meters multistage shuttle run and 10 meters × 2 shuttle run. Linear regression models explored the relation between physical activity and intelligence, after adjusted confounders.Study three(Chapter four)Peripheral blood growth factors of participants were accessed after signed informed consent from their parents. ELISA(Enzyme-linked Immunosorben Assay, ELISA) and R & D System(Human IGF-1 Quantikine ELISA Kit; Human BDNF Quantikine ELISA Kit, U.S.) kit were used to detect the concentrations of IGF-1 and BDNF. Using a linear regression model to test whether plasma IGF-1 and /or BDNF to play a mediator role in the impact of physical activity on cognitive abilities. If the hypothesis is true, it should meet the following three conditions: First, the level of physical activity must significantly associated with cognitive ability; Second, the level of physical activity must be significantly correlated with plasma growth factors; Finally, it must be shown that plasma growth factor levels was significantly associated with cognitive abilities after controlling the level of physical activity.ResultsStudy one(Chapter two)(1) According to the inclusion criterion of at least 2 week days + 1 weekend day valid data, there were a total of 271 participants(boys, 152; girls, 119) including the final statistics, which accounted 88.6 percentage of total sample size. Overall, the mean wear time was 750.1 minutes, 6.3 days, and the average time of physical activity in a day for SB, LPA, MPA and VPA time were 580.6, 98.6, 40.3 and 31.6 minutes, respectively. Except SB and MPA, the boy’s LPA, VPA, MVPA and TPA were significantly higher than girls.There was no significant difference was found in SB and any other intensify of physical activity among normal weight, overweight and obese preschoolers; but MPA and TPA of weekend days were significantly higher than week days, corresponding to the SB of weekend was significantly lower than week days.(2) On the basis of different physical activity recommendation for preschoolers that should accumulate at least 180 minutes at any intensity and at least 60 minutes MVPA spread throughout the day, there were 37.6% and 74.9% of the participants to meet or excess the need of recommendation in Shanghai preschoolers.Study two(Chapter three)There was a total of 291 participants completed Wechsler Abbreviated Intelligence Scale test(boys, 165; girls, 124), of which 5 participants excluded in the final statistical analysis because of significant mental retardation(boys, 4; girls, 1. Full IQ score from 54.2 to 73.8 points). Finally, there were a total of 260 valid data(boys, 144; girls, 116) to this analysis. In the regression analysis in boys, the significant positive association was found between LPA and full IQ, after adjusted potential confounders, the standardized regression coefficients was 0.260(P <0.05). Inversely, the relation between physical activity and intelligence performance was not found in girls.Study three(Chapter four)There were 189 participants(boys 109; girls, 80) volunteered to test peripheral growth factor level, and a total of 174 preschoolers(boys, 97; girls, 77) have the complete data of level of physical activity, cognitive ability tests and peripheral blood growth factors. Regardless of the results of the regression analysis of the boys or girls, the results did not support the hypothesis that peripheral blood levels of growth factor play a mediator role in the impact of physical activity on cognitive abilities.ConclusionsStudy one(Chapter two)This study built on the basis of objective measurement of physical activity, we found daily physical activity levels of preschool children in Shanghai at a medium level, compared with the report of similar studies. There was at least 25% of participants were not meet the need of current recommendation of physical activity for preschool children, especially in girls. In future studies, the researches should focus on intervention programs for physical activity of preschooler children and help them establish good physical activity habits to enhance physical fitness and health.Study two(Chapter three)This study found that the there was significant positive association between level of physical activity and cognitive abilities in preschool boys, especially the LPA. With every 10 minutes/day increment in LPA, the performance of full IQ scores was increased by 1.9 points. The results suggest that perhaps we do not over-emphasize the intensity of the physical activity, and we should be more concerned about the total amount of daily physical activity for preschool children.Study three(Chapter four)The results from our study did not find the mediator effect of peripheral growth factor on the association between physical activity and cognitive abilities. We need more powerful study design, such as the longitudinal study and intervention experiment to identify the potential mediator effect in the future.