Using convenience sampling method, the study included the students of class 2021 of Jining No. 7 Middle School and student athletes from the Jining Sports Training Center. Univariate and multivariate linear regression analyses were used to investigate the correlation between tooth brushing frequency and blood indicators such as eosinophil percentage (EOS%), eosinophil count (EOS#), basophil percentage (BAS%), basophil count (BAS#), superoxide dismutase (SOD), insulin-like growth factor 1 (IGF-1) and uric acid (UA).

A total of 305 students were included (167 from Jining No. 7 Middle School, 138 from Jining Sports Training Centre), with 192 (62.95%) males and 113 (37.05%) females. They were divided into three groups based on daily teeth brushing frequency: ≤1 time (40.33%, 123/305), 2 times (53.77%, 164/305), and ≥3 times (5.90%, 18/305).Univariate linear regression analysis showed that brushing twice daily was negatively correlated with EOS%, EOS#, BAS%, and BAS#(all β > 0, all P < 0.05), and positively correlated with SOD and IGF-1(both β < 0, P=0.028, P=0.007). Brushing three or more times daily was negatively correlated with UA[β(95% CI): -0.16(-0.27~0.04), P=0.008]. Multivariate linear regression analysis showed that brushing twice daily was negatively correlated with BAS%(β < 0, P=0.042) and positively correlated with SOD and IGF-1(both β > 0, P=0.036, P=0.012), while brushing three or more times daily was negatively correlated with UA(β < 0, P=0.026). Subgroup analysis revealed that in male adolescents, brushing twice daily was positively correlated with IGF-1(β > 0, P=0.044), and in female adolescents, brushing three or more times daily was negatively correlated with UA(β < 0, P=0.014).

The adolescent tooth brushing frequency correlates with several blood indicators affecting general health, suggesting that there may be a potential association between oral health and general health.

This cross-sectional study used stratified sampling to select adolescents aged 11-15 years from a sports school and some ordinary middle schools in Shandong Province in June 2023. The participants were divided into two groups: competitive sports group (high exercise intensity), and general sports group (moderate exercise intensity), based on their exercise intensity. Ultrasound images of long bones from nine body regions (including 3 upper limb bones and 6 lower limb bones) were collected for both groups. Two sonographers interpreted the images and calculated the ultrasound OR values (the ratio of ossification center length to epiphyseal length on the standard ultrasound section). The intraclass correlation coefficient (ICC) was used to assess the consistency of image interpretation between the observers. Differences in ultrasound OR values between the two groups were compared, and multivariate Logistic regression analysis was performed to assess the correlation between ultrasound OR values and exercise intensity.

A total of 252 adolescents who met the inclusion and exclusion criteria were included, with 154 in the competitive sports group (97 males and 57 females) and 98 in the general sports group (52 males and 46 females). The median height and average daily exercise duration were significantly higher in the competitive sports group than in the general sports group (all P < 0.001). The overall ICC for the interpretation of ultrasound OR values of long bones at 9 sites in 50 adolescents by the two sonographers was 0.930 (range: 0.853-0.964), indicating excellent inter-observer consistency. The medial femoral ultrasound OR values were higher in the competitive sports group than in the general sports group for both males and females (males: 0.87±0.07 vs. 0.84±0.04, P=0.025; females: 0.90±0.06 vs.0.85±0.14, P=0.027). Additionally, the differences in ultrasound OR values between the groups were observed in the lateral femoral and fibular bones in males and the radial bone in females (all P < 0.05). Multivariate Logistic regression analysis showed that the reciprocal of the medial femoral ultrasound OR value was correlated with exercise intensity (OR=0.046, 95% CI: 0.012-0.145, P=0.043), indicating that a decrease of 0.1 in the reciprocal of the medial femoral ultrasound OR value (equivalent to an increase of approximately 0.05-0.10 in the ultrasound OR value) was associated with a 2.17-fold increase in the likelihood of high-intensity exercise.

The medial femoral ultrasound OR value was correlated with exercise intensity among adolescents. This indicator may serve as an objective imaging parameter for assessing whether adolescent exercise meets recommended standards.

This prospective longitudinal cohort study employed convenience sampling to recruit adolescents receiving structured athletic training at Jining Sports Training Center in June 2023. Baseline measurements included height, weight, body mass index (BMI), blood pressure, heart rate, waist circumference, and hip circumference. Questionnaires assessed sleep duration, screen time, and household income. Follow-up measurements in June 2024 repeated these assessments while adding bioelectrical impedance analysis for body composition (lean mass, skeletal muscle mass, fat mass, and body fat percentage). Linear regression models examined associations between training type (direct-contact vs. non-contact sports) and follow-up body fat percentage, BMI, and waist circumference as dependent variables, adjusting for covariates.

The study included 110 adolescents (39 female, 71 male) with median age 13.21 years (IQR: 12.46-14.33). Participants comprised 65 direct-contact and 45 non-contact athletes. Baseline prevalence rates were 27.27% for overweight/obesity, 24.55% for elevated waist circumference, and 16.36% for elevated blood pressure. At follow-up, corresponding rates were 24.55%, 26.36%, and 13.64% respectively. The elevated blood pressure subgroup showed significantly higher waist circumference (P=0.034), elevated waist circumference rate (P=0.011), and body composition weight (P=0.049) compared to normotensive peers. Longitudinal analysis revealed 56.36% of participants increased BMI and 63.64% increased waist circumference. Adjusted linear regression demonstrated significant inverse associations between direct-contact training and body fat percentage (β=-6.57, 95% CI: -9.37 to -3.78, P < 0.001), BMI(β=-1.30, 95% CI: -2.50 to -0.11, P=0.036), and waist circumference(β=-2.31, 95% CI: -4.40 to -0.22, P=0.034).

Despite regular athletic training, substantial proportions of adolescents exhibited overweight/obesity, abdominal obesity, and elevated blood pressure, warranting clinical attention. Training modality appears to influence body composition changes, with direct-contact sports associated with more favorable adiposity-related outcomes.

This cross-sectional observational study employed convenience sampling to recruit 2021-grade(8th grade) students from Jining No.7 Middle School in Shandong Province on June 5, 2023. Data collection included questionnaires, physical examinations, and imaging assessments to obtain general information, secondary sexual characteristics development, and bone age. Venous blood samples were collected to measure fasting blood glucose(FBG), fasting insulin(FINS), homeostasis model assessment of insulin resistance(HOMA-IR), and 25-hydroxyvitamin D[25(OH)D] levels. Spearman correlation analysis and multivariate linear regression models were used to examine the associations between serum vitamin D levels and FBG, FINS, and HOMA-IR.

The study included 168 pubertal adolescents[69 females(41.1%), 99 males(58.9%); mean age(13.27±0.46) years]. All participants had entered puberty based on sexual development assessment. Vitamin D deficiency was observed in 41 participants(24.4%), insufficiency in 109(64.9%), and sufficiency in 18(10.7%). The median HOMA-IR was 3.49(2.57, 5.14).Significant differences were found across vitamin D status groups for HOMA-IR [4.45(2.54, 6.62) vs. 3.58(2.74, 5.13) vs. 2.25(1.62, 3.40), P=0.003] and FINS[21.5(13.4, 30.1) mU/L vs. 16.5(13.0, 23.9) mU/L vs. 11.2(8.3, 17.8) mU/L, P=0.006], showing decreasing trends with improving vitamin D status. Spearman analysis revealed significant inverse correlations between serum 25(OH)D levels and FBG(r=-0.171, P=0.027), FINS(r=-0.234, P=0.002), and HOMA-IR(r=-0.250, P=0.001).After adjusting for age, sex, body mass index, and daily outdoor activity time, multivariate linear regression demonstrated that log-transformed 25(OH)D levels were independently and inversely associated with FBG(β=-0.324, P=0.022), lnFINS(β=-0.241, P=0.048), and lnHOMA-IR(β=-0.312, P=0.017).

Vitamin D deficiency/insufficiency is prevalent among pubertal adolescents, and serum vitamin D levels show a significant inverse association with insulin resistance. These findings suggest the potential importance of vitamin D status in metabolic health during puberty.