A Study On The Current Status Of Sedentary Behavior,BMI;posture Characteristics Of Junior High School Students And Their Interrelationship

Objective:The physical posture of middle school students was investigated,and the detection rate and characteristics of abnormal posture,sedentary behavior and BMI index of middle school students were screened.To study the relationship between junior high school students ’ body posture and sedentary behavior and BMI index;the moderating effect of BMI index.To promote the physical health of middle school students put forward theoretical contribution and practical ideas.Methods: Relevant definitions of body posture were summarized by literature method.Students in the first and second grades of Qingtaishan Middle School and Huayang Middle School in Chengdu City were used to collect information on students’ sedentary behavior by questionnaire,and the indicators of high and low shoulders,lateral body tilt,lateral neck tilt,O-leg,anterior neck tilt and anterior pelvic tilt were measured by weight scale,video camera,body posture grid chart and Posture Check software;descriptive statistics,chi-square test,one-way variance,independent sample t-test,and Spearman’s correlation were used to analyze the data.Results :（1）Comparison of the current situation and differences of sedentary time:the average sedentary time of the tested group in a week was 214.92±74（min）,92% of the students were sedentary for more than 2h,of which 32% were sedentary for >4h;the average weekend sedentary time of girls was 379.04±124.44（min）overall higher than that of boys 341.10±143.26（min）,and there was Significantly different（P < 0.05）,the average sedentary time of girls in a week 226.43 ± 75.39（min）is higher than that of boys 205.44 ± 71.89（min）,and significantly different（P < 0.05）;the weekday sedentary time of junior grade 166.47 ± 68.15（min）is higher than that of junior grade 148.5 ±54.16,with a significant difference（P < 0.05）.There was a significant difference（P <0.05）;the sedentary time of different BMI classes was significantly different（P < 0.01）,the sedentary time of the BMI normal group was higher than that of the lean group,and the sedentary time of the BMI regroup was higher than that of the lean and normal groups.（2）Comparison of the current situation and differences of body posture: the number of people with all 6 body posture measurement indexes normal in this tested group of junior high school students was only 5%,and the percentage of abnormal body posture was 95%.The number of abnormal body posture in the group with abnormal body posture was mainly concentrated in those suffering from 1 to 3 abnormal body postures,accounting for 25%,34% and 28% respectively;the number of abnormal body postures such as high and low shoulder,O-leg and anterior neck tilt among all measurement indexes was detected as high as 50% and above.The abnormal rate of anterior pelvic tilt in the second year of junior high school was 14.7% lower than that of27.3% in the first year of junior high school,and there was a significant difference（P <0.05）.58% of abnormal high and low shoulders were detected in the normal BMI group,lower than 87.1% in the skewed BMI group（P < 0.05）and 64.6% in the skewed BMI group（P < 0.05）;5% of abnormal body lateral tilt were detected in the normal BMI group,lower than The detection of O-leg abnormality in the BMI normal group was45.4%,which was lower than that in the BMI lean group 70.8%（P < 0.01）;the detection of neck anterior tilt abnormality in the BMI normal group was 41.1%,which was lower than that in the BMI lean group 80.6%（P < 0.01）;The distribution of abnormal body posture was significantly higher among students who failed（2-4h）and seriously failed（>4h）in sedentary time than those who passed（≤2h）,and the abnormal detection rate of high and low shoulder and forward neck tilt was also significantly higher than those who passed（≤2h）in sedentary time.Correlation analysis among the three: sedentary time showed a weak positive correlation with high and low shoulder（r=0.3 P<0.01）and a weak positive correlation with neck anteversion（r=0.3 P<0.01）;sedentary time showed a positive correlation with BMI normal group（r=0.5 P<0.01）;BMI showed a weak negative correlation with O-leg（r=-0.19 P<0.05）and neck anteversion showed a weak positive correlation（r=0.2P<0.05）.（4）Regression analysis: the effect of sedentary time on high and low shoulder and neck anteversion was statistically significant（P < 0.01）,when the sedentary time increased by one unit（2h）,the abnormal detection rate of high and low shoulder and neck anteversion was 286.1% and 233.9% of the original one,respectively.the effect of BMI class on O-leg was statistically significant,when the BMI class increased by one unit,the abnormal detection rate of O-leg The detection rate was 46.7% of the previous one.Conclusion:（1）More than 90% of the sedentary behaviors showed a failure;the sedentary time of girls was higher than that of boys,and the sedentary time of weekdays was higher in the second year of junior high school,and the higher the BMI value of individuals whose sedentary time was longer.（2）Abnormal body posture is common among junior high school students;the abnormal group mainly focuses on one to three abnormal body postures such as high and low shoulders;the pelvic anterior tilt has improved in the second year of junior high school or due to the training of the sports midterm program;the greater the difference between individual BMI values and the normal BMI range,the higher the risk of abnormal body posture detection;the greater the number of abnormal body posture detection in the group with substandard sedentary time.（3）The longer the sedentary time,the higher the detection rate of abnormal upper limb posture such as high and low shoulder,and the higher the BMI measurement result;when the BMI deviates from the normal level,either too high or too low indicates the worse the abnormal detection status of neck anteversion and O-leg,which needs further attention.（4）Prolonged sedentary and individual’s physical condition have a certain relationship with abnormal body posture,the weaker the physical condition or obesity will lead to poorer detection of abnormal body posture.