Composición corporal y nivel de experiencia en mujeres adultas jóvenes que realizan HIIT

Introduction: The clinical validity of the body mass index (BMI) is currently questioned due to its inability to distinguish actual adiposity in physically active populations. High-intensity interval training (HIIT) is positioned as an efficient strategy to optimize body composition and metabolic health. Objective: To analyze the relationship between BMI, body fat percentage according to the American Council on Exercise (ACE) classification, and experience level in young adult women performing HIIT. Methodology: A cross-sectional observational design was implemented with 50 women stratified into three experience levels, evaluating body weight and body fat percentage using multi-frequency bioelectrical impedance analysis under strict standardization protocols. Results: No significant differences were found in body mass index (p = 0.268); however, body fat percentage showed a drastic reduction in the expert group (16.7 ± 1.5%) compared to the beginner (30.0 ± 2.5%) and intermediate (30.1 ± 2.9%) levels, demonstrating a statistically significant difference (p < 0.001; η² = 0.419). Discussion: The findings suggest a diagnostic disconnect in which body weight does not adequately reflect differences in adiposity, showing that a profile compatible with the “Athlete” category was observed exclusively in participants with a higher level of experience in HIIT training. Conclusions: Experience level is associated with differences in body adiposity as measured by body fat percentage, whereas BMI shows limited ability to capture these variations. The profile consistent with the “Athlete” category was observed exclusively in the expert level.