Association between BMI and health-related physical fi tness in adolescents with hearing impairment in China: a cross-sectional study

Background: This cross-sectional study aimed to address a critical gap in the understanding of the association between body mass index (BMI) and physical fitness levels in adolescents with hearing impairment (HI) in China. This study investigated how different BMI levels impact the physical fitness index (PFI) of HI adolescents. Methods: This study employed a physical fitness test for HI adolescents attending special education schools. The test included eight components: height, weight, 50-m sprint, standing long jump, sit and reach, endurance run, bent-knee sit-up (for girls), and pull-up (for boys). Test scores for each student were standardized by age and gender. Individual Z-scores were then calculated, and the sum of these Z-scores constituted the PFI. Logistic regression was used to analyze the relationship between BMI and PFI across different gender and age groups. Statistical significance was set at P < 0.05. Results: The linear regression model showed an inverted U-shaped relationship between BMI and PFI. At the same BMI level, boys exhibited superior physical fitness compared to girls with the same BMI (P < 0.05). Statistically significant differences in PFI levels were observed between normal-weight and obese males, as well as between underweight and obese boys (P < 0.05). In the 13-15 and 16-18 age groups, the increase in BMI has a greater impact on boys PFI than on girls. Conclusions: Adolescents with HI generally demonstrated good physical fitness. Compared to individuals with normal weight, those who were underweight, overweight, or obese exhibited lower levels of physical fitness. Future interventions should focus on adolescents with HI with abnormal BMI.