The academic value of the "Hu Line" has been extended to other related disciplines. Considering China's large population and obvious differences in distribution, this study draws on the research results of population geography to explore the population density and distribution criteria of the "Hu Line".

To investigate and analyze the current situation of health literacy and sedentary time among urban and rural high school students in the southeast and northwest halves of the "Hu Line", and to provide a basis for improving the physical and mental health of high school students in China.

A stratified cluster random sampling method was used to study the health literacy and sedentary time of freshmen and sophomores in 62 schools in 31 provinces (municipalities directly under the central government and autonomous regions) of China from January to March 2019 (12 400 questionnaires on health literacy and 12 400 questionnaires on sedentary time each were uniformly mailed and distributed in advance). Multiple linear regression models were used to analyze the coefficient of variance expansion, and after correcting for confounding factors, we analyzed the factors affecting the length of meditation time of high school students in the southeastern and northwestern halves of both sides of the "Hu Line".

Finally, 9 057 health literacy questionnaires were included, of which 7 489 (82.7%) were from the southeast half of China and 1 568 (17.3%) from the northwest half of China, and 8 031 questionnaires on sedentary time were included, of which 6 614 (82.4%) were from the southeast half of China and 1 417 (17.6%) from the northwest half of China. Health literacy scores and sedentary time of high school students in the southeast half of China were higher than those in the northwest half of China (Z=-4.009, -9.198; P<0.001). The health literacy scores of high school students in the southeastern half of China aged 17 and 18, female, urban and rural, with father's education of less than college and college, mother's education of college and bachelor's degree, annual family income of 10 000-, 50 000-, 80 000-, and >100 000 yuan, and family size of 1, 3, 7, 9, and ≥10 were higher than those of the northwestern half of China (P<0.05) ; Those high school students in the southeastern half of China aged 15, 16, 18, and male and female, urban and rural, father's education less than college, college, mother's education less than college, annual family income <10 000, 25 000-, 50 000-, 80 000-, and >100 000 yuan, and the number of people in the family of 3, 4, 5, and 6 people were higher than those in the northwestern half of China in terms of the number of hours spent in meditation (P<0.05). The results of the multiple linear regression model analysis showed that after correcting for confounders, the length of time high school students in the southeastern half of China spent sedentary still was positively correlated with annual family income (β=0.324) and mother's educational attainment (β=0.644) but negatively correlated (P<0.05) with both the health literacy scores (β=-0.015) and the father's educational attainment (β=-0.212) were negatively correlated (P<0.05) ; standardized regression coefficients β were compared with annual family income (0.164) > mother's educational attainment (0.131) > father's educational attainment (-0.056) > health literacy score (-0.050). The length of sedentary time of high school students in the northwestern half of China was positively correlated with health literacy score (β=0.017), father's education (β=0.789), and mother's education (β=0.540) (P<0.05) ; standardized regression coefficients β were compared with father's education (0.163) > mother's education (0.111) > health literacy score (0.056) .

Health literacy scores and meditation hours of high school students in the southeastern half of China were higher than those in the northwestern half of China. Meditation duration of high school students in the southeastern half of China was positively correlated with annual family income and mother's education, but negatively correlated with health literacy scores and father's education, while meditation duration of high school students in the northwestern half of China was positively correlated with health literacy scores parent's education. Annual family income had the highest weight on the effect of meditation duration for high school students in the southeast half of China, and father's education had the highest weight on the effect of meditation duration for high school students in the northwest half of China.