Changes in Intrahepatic Lipids With Exercise
Condition: Obese
Study type: Interventional

Summary: 
      Individuals with obesity and particular type 2 diabetes have abnormally high levels of fat in
      liver cells and are at increased risk for cardiovascular and liver-related mortality. Prior
      research has shown that caloric restriction, exercise, and behavior modification can help
      lower hepatic fat levels in these individuals. Additional research has also shown that
      exercise independent of weight loss can reduce hepatic fat content in obese humans. The
      current exercise guidelines do not specify what type or what intensity of exercise is
      required to induce such reductions in hepatic fat. Thus, the purpose for doing this study is
      to determine if there are differential effects on liver fat with 4 wk of high intensity
      intermittent exercise compared with continuous moderate exercise in obese individuals.
    

Detailed description: 
      Subjects will complete a liver spectroscopy scan to ensure that they have 5% body fat.
      Subjects passing screening will then have body composition measurement and aerobic capacity
      (VO2 peak) measured. Blood samples will also be taken and subjects will complete an oral
      glucose tolerance test. Upon completion of this testing subjects will be randomized into one
      of two groups: Continuous moderate exercise group or High-intensity interval exercise .

      Continuous moderate exercise group (CME): Subjects will perform a 5-10 minute warm-up at 50%
      VO2peak. Thereafter, the intensity of exercise will be increased to 70% VO2peak by increasing
      the speed and incline of the treadmill. Subjects will exercise at this intensity for 60
      minutes. A 5 minute cool-down (50% VO2peak).

      High-intensity interval exercise (HIIE): Subjects will perform 5-10 minute warm-up (50%
      VO2peak). Following the warm-up, the speed and incline of the treadmill will be increased so
      that subjects reach an exercise intensity that corresponds to 90% Heart Rate max. Subjects
      will exercise at this intensity for 4 minutes, after which the treadmill speed and incline
      will be reduced to an intensity between 55% and 70% Heart Rate max for 3 minutes. This
      procedure will be replicated three additional times for a total of four intervals/recovery
      periods. The total exercise commitment will be ~45 minutes.

      After 4 wk of exercise training all subjects will undergo all of the initial testing.
    

Intervention name(s): high intensity exercise; continuous moderate exercise
Intervention type(s): Other; Other
Intervention description(s): Subjects will perform 5-10 minute warm-up (50% VO2peak). Subjects will then exercise at an exercise intensity that corresponds to 90% HRmax, for 4 minutes. This will be followed by 3 min of exercise at 55% HRmax. Four of these exercise intervals/recovery periods will be completed. The total exercise commitment will be ~45 minutes; Subjects will perform a 5-10 minute warm-up at 50% VO2peak. Thereafter, the intensity of exercise will be increased to 70% VO2peak by increasing the speed and incline of the treadmill. Subjects will exercise at this intensity for 60 minutes.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Other
Keywords: NAFLD; obesity; ck18; blood lipids; high intensity exercise training; individuals; >5% liver fat