High Intensity Interval Training Improves Endurance Performance and Increases Brown Adipose Mass in Diet-Induced Obese Mice

Abstract

Inadequate diet and inactivity are associated with several metabolic diseases, mainly obesity. High intensity Interval Training (HIIT) is a promising exercise strategy for obese but its effects deserve further investigation. PURPOSE: To evaluate the effects of HIIT training on endurance and fat mass in diet-induced obese mice. METHODS: Fifteen C57BL/6 mice were randomly assigned to Control group (CC, n=5), Hipercaloric diet group (HC, n=5) and HIIT training plus Hipercaloric diet group (IH, n=5). Food and water were administered ad libitum. Hipercaloric diet was composed of 60%fat, 30%carbs and 10%protein. Control diet was composed of 30%fat, 60%carbs and 10%protein. Every group underwent a ramp test (RT) before and after intervention, on a mice treadmill (AVSprojects®) to determine maximal speed and maximal distance. RT initiated at 6m/min with a 2m/min increase every 2min (at 25°), until exhaustion. HIIT lasted for 8 wk, 5 days/wk. Each session lasted 45 min with 4-min high intensity bouts at 90% of the reached speed on first RT, followed by 3-min moderate intensity bouts at 70%. Animals were sacrificed after intervention and tissues were collected and weighed. One-way ANOVA (Tukey post hoc test) was used for comparison between groups, 5% level of significance. RESULTS: Baseline mean values of body weight before intervention were similar between groups (p=0.57). Hipercaloric diet groups gained more weight (IH: 26.6±3.1 g; CH: 23.9±3.2 g) than control group (CC: 15.1±4.6 g) after diet protocol/before intervention (p=0.001). After 8-wks intervention, CC (6.3±2.2 g) gained more weight than IH (3.7±0.9 g)(p=0.03). IH improved endurance performance (209.8±80.2 m), more than CH (54.8±30.3 m) and CC (118.2±28.5 m)(p=0.002) groups. Brown adipose tissue mass of IH (434.7±94.1 g) was higher than CC (214.5±65.6 g)(p=0.04). CONCLUSIONS: Eight-weeks HIIT improved endurance performance on diet-induced obese mice and attenuate the weight gain as compared with no exercise control diet group. The weight gain in non-exercising lean animals highlights the importance of being physically active to prevent obesity, with HIIT being a time-effective strategy. Brown adipose tissue is associated with more efficient thermogenesis and seems to mediate the effects of HIIT. Supported by CNPq/pro-centro-oeste grant 564658/2010-3