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This study aimed to determine the effects of 12 weeks of isocaloric programs of high-intensity intermittent training (HIIT) or moderate-intensity continuous training (MICT) or a short-duration HIIT (1/2HIIT) inducing only half the energy deficit on a cycle ergometer, on body weight and composition, cardiovascular fitness, resting metabolism rate (RMR), respiratory exchange ratio (RER), nonexercise physical activity (PA) levels and fasting and postprandial insulin response in sedentary obese individuals. Forty-six sedentary obese individuals (30 women), with a mean BMI of 33.3 ± 2.9 kg/m2 and a mean age of 34.4 ± 8.8 years were randomly assigned to one of the three training groups: HIIT (n = 16), MICT (n = 14) or 1/2HIIT (n = 16) and exercise was performed 3 times/week for 12 weeks. Overall, there was a significant reduction in body weight, waist (p < .001) and hip (p < .01) circumference,, trunk and leg fat mass (FM; p < .01) and an increase in trunk and leg fat free mass (FFM; p < .01) and cardiovascular fitness (VO2max in ml/kg/min; p < .001) with exercise. However, no significant differences were observed between groups. There was no significant change in RMR, RER, nonexercise PA levels, fasting insulin or insulin sensitivity with exercise or between groups. There was a tendency for a reduction in AUC insulin with exercise (p = .069), but no differences between groups. These results indicate that isocaloric training protocols of HIIT or MICT (or 1/2HIIT inducing only half the energy deficit) exert similar metabolic and cardiovascular improvements in sedentary obese individuals.
Martins, Kazakova, and Kulseng are with the Obesity Research Group, Dept. of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway. Ludviksen is with the Center for Obesity, Dept. of Surgery, St. Olav Hospital—Trondheim University Hospital, Trondheim, Norway. Mehus is with the Dept. of Sociology and Political Science—Sport Science, Faculty of Social Sciences and Technology Management, Norwegian University of Science and Technology, Trondheim, Norway. Wisloff is with the K.G. Jebsen Center for Exercise in Medicine at Dept. of Circulation and Medical Imaging, Trondheim, Norway. Morgan is with the School of Biomedical and Molecular Sciences, University of Surrey, Guildford, UK. King is with the Institute of Health and Biomedical Innovation and School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Australia.