High intensity functional training versus traditional resistance training effects on inflammatory, metabolic, and physical outcomes in overweight men a randomized controlled trial

Overweight and obesity are major global health concerns linked to chronic diseases. This study compared the effects of high-intensity functional training (HIFT) and resistance training (RT) on metabolic, inflammatory, and physical markers in overweight men. Thirty-four overweight men (31.91 ± 2.44 years, BMI 27.78 ± 1.47 kg/m²) were assigned to the HIFT (n = 13), RT (n = 10), and control (n = 11) groups. The HIFT included four sets of 30-second exercises at 30% 1RM, whereas the RT involved three sets of 12 repetitions at 70% 1RM. Both interventions were performed thrice weekly for eight weeks. Blood samples were collected before and after training to assess the levels of inflammatory markers (IL-4, γ-IFN, MMP-9 and TLR4) and metabolic markers (FBS, LDL, HDL, triglycerides and cholesterol). Body composition and performance were evaluated. No significant differences in inflammatory markers were detected between the groups. HIFT and RT significantly reduced fasting blood sugar (p < 0.05). RT lowered total cholesterol, whereas triglycerides decreased in both groups. Skeletal muscle mass increased significantly. Compared with RT, HIFT led to greater body fat reduction, although both improved from baseline. Both groups had increased 1RM bench press strength. Compared with RT and the control, HIFT significantly increased VO₂max, whereas RT improved VO2max compared with the control. HIFT is a promising approach for managing overweight and obesity, particularly for enhancing cardiovascular fitness and body composition.Trial registration IRCT.ir, IRCT20170724035269N2, registered on 27/05/2025. This study was retrospectively registered.