Effects of High-Intensity Interval Training and Moderate-Intensity Continuous Training on Insulin Resistance Markers...

Previous studies have shown that physical activity (PA) can improve insulin sensitivity and reduce insulin resistance (IR), a key determinant of metabolic dysfunction. While the beneficial effects of PA are well-documented in adults, evidence regarding the relationship between PA intensity and insulin resistance in adolescents, particularly in North African populations, remains scarce. This study aimed to compare the effects of a 12-week school-based high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) intervention, versus usual physical education, on insulin resistance as assessed by the homeostasis model assessment of insulin resistance (HOMA-IR) in overweight and obese non-diabetic Moroccan adolescents. The study included 90 non-diabetic overweight and obese Moroccan adolescents aged 12 to 17 years. Participants were randomly assigned to three groups (HIIT, MICT, and control) within a 12-week school-based intervention. Insulin resistance was assessed using the HOMA-IR index. Linear regression models were used to examine the associations between exercise modality and HOMA-IR, adjusting for age, sex, baseline body mass index (BMI), and baseline HOMA-IR. Compared with the control group, both HIIT and MICT were associated with significant reductions in HOMA-IR. In the fully adjusted models, HIIT showed a greater decrease of -0.90 (95% CI: -1.07 to -0.72) (all p < 0.001) and MICT showed a decrease of -0.77 (95% CI: -0.94 to -0.61). Stratified analyses by BMI categories showed consistent improvements in insulin resistance for both overweight and obese adolescents. These findings suggest that school-based structured exercise interventions, particularly HIIT and MICT, independent of dietary modification, may contribute to improvements in insulin sensitivity and help reduce early metabolic risk in overweight and obese non-diabetic Moroccan adolescents. However, these results should be interpreted with caution given that dietary intake and other lifestyle factors were not strictly controlled.