Short-term HIIT and Fat(max) training increase aerobic and metabolic fitness in men with class II and III obesity

ObjectiveTo compare the effects of two different 2-week-long training modalities [continuous at the intensity eliciting the maximal fat oxidation (Fat(max)) versus high-intensity interval training (HIIT)] in men with class II and III obesity. MethodsNineteen men with obesity (BMI35 kg(.)m(-2)) were assigned to Fat(max) group (G(Fatmax)) or to HIIT group (G(HIIT)). Both groups performed eight cycling sessions matched for mechanical work. Aerobic fitness and fat oxidation rates (FORs) during exercise were assessed prior and following the training. Blood samples were drawn to determine hormones and plasma metabolites levels. Insulin resistance was assessed by the homeostasis model assessment of insulin resistance (HOMA2-IR). ResultsAerobic fitness and FORs during exercise were significantly increased in both groups after training (P0.001). HOMA2-IR was significantly reduced only for G(Fatmax) (P0.001). Resting non-esterified fatty acids (NEFA) and insulin decreased significantly only in G(Fatmax) (P0.002). ConclusionsTwo weeks of HIIT and Fat(max) training are effective for the improvement of aerobic fitness and FORs during exercise in these classes of obesity. The decreased levels of resting NEFA only in G(Fatmax) may be involved in the decreased insulin resistance only in this group.