The Balance between Carbohydrate and Fat Utilization at Rest and in Progressive Intensity Exercise in the Insulin Resistence

Pourpose: Analyze the influence of insulin resistance on the balance between carbohydrate and fat utilization at rest and in progressive intensity exercise. In many studies that measured the balance of substrate in subjects with insulin resistance, diabetes and obesity, it is a common feature the use of a fixed percentage of maximum VO2 for intensity-control.

Methods: Twelve sedentary male subjects were divided into two groups (>RI and <RI) according with their insulin resistance index (HOMA-IR). Using indirect calorimetry were analyzed: Carbohydrate and fat utilization at rest, the crossover point, the exercise intensity that elicits a maximal fat oxidation (Fatmax), carbohydrate and fat utilization at Fatmax. All variables were compared using the MANN-WHITNEY test.

Results: There were no significant differences between the group in Fatmax (37,35±7,99 vs. 39,81±3,84%VO2max) and the Crossover point (40,08±7,19 vs. 40,67±5,12%VO2máx). Also had not been observed any significant difference in the substrate balance at rest (0,095±0,009 vs. 0,069±0,028 g/min, 0,244±0,082 vs. 0,250±0,073 g/min, fat and carbohydrate, respectively) and at Fatmax (0,397±0,087 vs. 0,230±0,076 g/min, 0,689±0,229 vs. 0,867±0,222 g/min, fat and carbohydrate, respectively).

Conclusion: Insulin resistance did not influence the Crossover point and the Fatmax, as well as the substrate balance at rest and at Fatmax.