Physical exercise is a common strategy in overweight and obesity management. Exercise type, intensity, duration, energy expenditure and the rate of perceived exertion (RPE) are the essential determinants of exercise efficiency. The purpose of the present study was to compare continuous and intermittent exercises targeted at the maximal fat oxidation intensity (FAT max) in obese individuals. Ten obese males (BMI > 30 kg/m2; age: 19 to 35 years) who maintained a sedentary lifestyle were recruited for this study to perform three separate exhaustive exercises: a continuous exercise at FAT max (CON), an intermittent exercise that alternates two minutes at FAT max −10% with one minute at FAT max +20% (INT½), and a second intermittent exercise that alternates four minutes at FAT max −10% with one minute at FAT max +40% (INT¼). The duration of the INT¼ exercise (65.1 min ± 13.4) was significantly longer than that of the CON exercise (55.4 min ± 6.0). No significant difference in the total amount of energy expenditure was observed across the three types of exercise (CON: 372 Kcal ± 98.2, INT¼: 398 Kcal ± 145.5, INT½: 374.4 Kcal ± 116.1). The fat oxidation rate after 45 min during the INT exercises (INT¼: 93.0 ± 19.1 mg/min, INT½: 71.1 ± 15.6 mg/min) was significantly higher than that of the CON exercise (36.1 ± 12.2 mg/min). The CON exercise was less well tolerated. The rate of perceived exertion (RPE) at the end of the CON (15.8 ± 2) was significantly higher than that of the INT exercises (13.5 ± 2 for the INT¼ and 13.1 ± 1.8 for the INT½). The INT exercises were more efficient in terms of duration, fat oxidation and RPE.
Keywords: RPE; energy expenditure; exhaustive exercise sessions; fat max intensity; fat oxidation rate; obesity.