“HIIT the Inflammation”: Comparative Effects of Low-Volume Interval Training and Resistance Exercises on Inflammatory Indices in Obese Metabolic Syndrome Patients Undergoing Caloric Restriction

Exercise is a cornerstone in metabolic syndrome (MetS) treatment. However, the effects of low-volume exercise modalities on MetS-associated low-grade inflammation are unclear. A total of 106 MetS patients (53.7 ± 11.4 years) were randomized to low-volume high-intensity interval training (LOW-HIIT, 14 min/session), single-set resistance training (1-RT, ~15 min/session), whole-body electromyostimulation (WB-EMS, 20 min/session), three-set resistance training (3-RT, ~50 min/session), each performed 2 ×/week for 12 weeks, or a control group (CON). All groups received nutritional counseling for weight loss. Inflammatory and cardiometabolic indices were analyzed pre- and post-intervention. All groups significantly reduced body weight by an average of 3.6%. Only LOW-HIIT reduced C-reactive protein (CRP) (−1.6 mg/L, p = 0.001) and interleukin-6 (−1.1 pg/mL, p = 0.020). High-sensitivity CRP and lipopolysaccharide-binding protein decreased following LOW-HIIT (−1.4 mg/L, p = 0.001 and −2.1 ng/mL, p = 0.004) and 3-RT (−0.6 mg/L, p = 0.044 and −2.0 ng/mL, p < 0.001). MetS severity score improved with LOW-HIIT (−1.8 units, p < 0.001), 1-RT (−1.6 units, p = 0.005), and 3-RT (−2.3 units, p < 0.001). Despite similar effects on body weight, low-volume exercise modalities have different impact on inflammatory and cardiometabolic outcomes in MetS patients. LOW-HIIT has superior efficacy for improving inflammation compared to 1-RT and WB-EMS. Resistance-based exercise appears to require a higher volume to promote beneficial impact on inflammation.