The Relationship between Cardiorespiratory Fitness and Body Mass Index (BMI) in Adolescents of Pirngadi Christian High School, Surabaya

Abstract

Background: Cardiorespiratory fitness (CRF) reflects the ability of the heart and lungs to supply oxygen during physical activity. Low CRF values ​​are often associated with an increased risk of metabolic disease, while body mass index (BMI) is an indicator of nutritional status and body composition. Both are closely related to fitness and health in adolescents. Objective: To analyze the relationship between cardiorespiratory fitness and body mass index in adolescents at Pirngadi Christian High School, Surabaya. Methods: This study used an observational analytical design with a cross-sectional approach. Subjects were 30 students (aged 15–18 years) selected using purposive sampling. CRF was measured using a beep test and the results were converted to VO₂Max (ml/kg/min). BMI was calculated from body weight (kg) divided by height squared (m²). Data analysis used the Pearson correlation test with a significance level of 0.05. Results: The results showed that the average BMI of respondents was 22.5 ± 3.1 kg/m² and the average VO₂Max was 38.2 ± 4.5 ml/kg/min. Correlation analysis showed an r value of -0.612 (p = 0.001), indicating a significant negative relationship between BMI and CRF. Conclusion: There is a significant negative relationship between body mass index and cardiorespiratory fitness in adolescents at Pirngadi Christian High School, Surabaya. The higher the BMI, the lower the level of cardiorespiratory fitness.