Introduction: Metabolic syndrome has traditionally been associated with cardiovascular diseases and has recently been linked to increased susceptibility to COVID-19 infection, thus highlighting the need for multimodal interventions to optimize management of this condition. Aim: To assess the effects of high-intensity interval training (HIIT) alongside a low-fat diet and carboxytherapy on metabolic syndrome features. Material and methods: Sixty women (50–60 years old) diagnosed with metabolic syndrome were assigned to a 4-week intervention of either HIIT in combination with a low-fat diet and carboxytherapy (experimental group: n1 = 30, age = 54.17 ±2.82 years, body mass index (BMI) = 32.10 ±0.91), or a low-fat diet and carboxytherapy only (active control group: n2 = 30, age = 54.10 ±2.64 years, BMI = 32.12 ±1.19). Exclusion criteria were uncontrolled hypertension, diabetes mellitus, coronary artery disease, smoking, contraindications to carboxytherapy, and contraindications to exercise testing/training. Outcome measures were waist circumference (WC), BMI, serum triglycerides (TG), systolic blood pressure (SBP), diastolic blood pressure (DBP), high-density lipoproteins (HDL), and fasting blood glucose (FBG). Results: Both groups showed significant improvements in all outcome measures compared to baseline values (p < 0.05). The experimental group showed significantly greater improvements in mean values of WC, BMI, TG, SBP, DBP, and FBG (p < 0.05), as well as a tendency for a significant difference in HDL (p = 0.075) compared to the control group. Conclusions: The addition of HIIT to a low-fat diet and carboxytherapy could lead to greater improvements in metabolic cardiovascular risk factors in women with metabolic syndrome than a low-fat diet and carboxytherapy alone. This could suggest a good rationale for the inclusion of HIIT in the multimodal interventions rendered to women with metabolic syndrome.
