Investigating Fitness Interventions in the Elderly (INFINITE)
Condition: Obesity; Older Adults; Sedentary
MeSH terms: Obesity
Study type: Interventional

Summary: 
      Aging is associated with declines in aerobic capacity, exercise tolerance, and functional
      endurance that lead to physical disability and loss of independence. Furthermore, the
      existing high prevalence of obesity in the elderly is greatly exacerbating these
      aging-related declines in function. To date, regular exercise is the only known therapy to
      consistently improve aerobic function, and perhaps delay the onset of disability. Although
      aerobic exercise training does benefit both aerobic capacity and endurance even in obese
      persons, some data show that the maximal efficacy of exercise for improving aerobic function
      is blunted by obesity. In addition, our preliminary data show a potential dose-response
      benefit of concomitant fat loss on exercise-induced improvements in aerobic function. Thus,
      combining an exercise intervention with caloric restriction resulting in fat loss may be more
      efficacious for improving aerobic function than exercise alone in obese elderly, a population
      at high risk for disability. The purpose of this study is to determine whether the amount of
      fat loss (achieved through controlled underfeeding) affects the magnitude of improvement in
      aerobic function (maximal aerobic capacity and endurance) in response to a standardized
      exercise training stimulus that follows current recommendations for older persons.
    

Detailed description: 
      Design Overview:

      Phase 1 involves recruitment and screening followed by baseline research testing (Phase 2).
      Next, subjects will be randomly assigned to one of three 5-month treatments (Phase 3):
      exercise and high-caloric restriction diet, exercise and low-caloric restriction diet, or
      exercise only. Subjects will complete follow-up testing after their 5 month intervention.

      Interventions:

      Dietary interventions: All participants will be randomly assigned to an exercise intervention
      with either no dietary intervention (EX Only), or 1 of 2 hypocaloric controlled diets: 1)
      -250 kcal/day deficit for low fat loss (EX+LOW CR) or 2) -600 kcal/day deficit for high fat
      loss (EX+HIGH CR) for 20 weeks.

      All meals are prepared individually after participants choose from a hypocaloric menu
      designed by the RD to provide a balanced, healthy diet. The calorie level assigned for each
      person will provide him/her with an absolute daily caloric deficit consistent with their
      group assignment (-600 or -250 kcals/day). Individual calorie levels will be prescribed to
      provide calorie levels to the nearest 50 kcals (e.g., 1100 kcal, 1150 kcal, 1200 kcal, etc.).
      They are educated by the GCRC RDs and provided menus to guide their food purchasing and
      preparation of daily breakfast meals that are consistent with the prescribed calorie level.
      They are asked to consume only the food that is given to them or that is approved from the
      breakfast menu. All participants will pick up their food 3 times/wk during the intervention,
      and are asked to keep a log of everything they eat or drink.

      Exercise intervention: The exercise will take place in an exercise facility at the Geriatric
      Research Center on the campus of the Wake Forest University/Baptist Medical Center. Two study
      personnel, including at least one trained technician, will supervise all exercise sessions.
      Emergency equipment will be kept on site during exercise sessions. Blood pressure and heart
      rate (HR) will be measured before each exercise session and subjects will warm-up by walking
      for 3-5 min at a slow pace and will then walk at an intensity of 65-70% of heart rate reserve
      (HRR, assessed during the VO2max test). The duration of walking exercise will progress from
      15-20 mins at 50% HRR the 1st week to 30 mins at 65-70% HRR by the end of the 6th week and
      thereafter. Each walking session will end with a 3-5 min cool-down followed by 5 min of large
      muscle flexibility exercise.
    

Intervention name(s): Exercise Only; Exercise + Diet; Exercise + Diet
Intervention type(s): Behavioral; Behavioral; Behavioral
Intervention description(s): 4 d/wk of aerobic exercise; Exercise 4d/wk with moderate caloric restriction (-250 kcal/d deficit) designed for low fat loss (EX+Low CR; ~4.5 kg weight loss).; Exercise 4d/wk with intensive caloric restriction (-600 kcal/d deficit) designed for high fat loss (EX+High CR; ~10.9 kg weight loss)
Other intervention name(s): EX; EX+Low CR; EX+ High CR
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment
Keywords: obesity; exercise; intensity; weight loss; diet