Objectives: High-Intensity Interval Training (HIIT) and Moderate Intensity Training (MIT) can combat the obesity epidemic. However, studies comparing their effects on obesity show controversial findings regarding weight loss. Adenosine has emerged as a possible, novel therapeutic agent to treat obesity, but more preclinical studies on its efficacy are needed. Therefore, the objectives of this study were to compare the effects of HIIT and MIT on obesity, and further to determine the dose-dependent effects of adenosine on body weight.
Equipment and methods: We induced obesity in male Wistar rats with high-fat diet (HFD) and monitored development of obesity by comparing the weight to rats on normal diet (ND). After 13 weeks of feeding, exercise training and intraperitoneal adenosine or placebo injections started. The animals were divided into the intervention groups based on equal average weight: (1) ND-1, 2) ND-2, (3) HFD, (4) HFD + placebo, (5) HFD + adenosine, (6) HFD + adenosine + HIIT, (7) HFD + placebo + HIIT, (8) HFD + adenosine + MIT, and (9) HFD + placebo + MIT. During the first six weeks of interventions, adenosine was injected at a dose of 0.2 mg/ml/kg and the following six weeks at 0.4 mg/ml/kg. Weight and feed consumption were determined, and energy intake was calculated as kJ/day.
Results: The HFD started to cause obesity after 19 weeks of feeding. Both HIIT and MIT were equally effective in counteracting the HFD-induced weight gain, while no differences in the effects were found between the two exercise modes. Adenosine, independent of the dose, also prevented weight gain but did not enhance the effects of HIIT or MIT on weight. The obesity-counteracting effects of the treatments were not due to lower energy intake. In conclusion, our study shows that HIIT and MIT are equally effective to combat obesity, and further, provide preclinical evidence of that adenosine injections could be used to treat obesity.