Nutrition and Exercise for Sarcopenia
Condition: Sarcopenia
MeSH terms: Sarcopenia
Study type: Interventional
Phase: Phase 1

Summary: 
      The investigators' general hypothesis is that nutritional factors, including protein/energy
      malnutrition and/or an impaired response of muscle to nutrition, and inactivity play
      significant roles in developing sarcopenia, the involuntary loss of muscle mass and function
      with age. Therefore, age-specific prolonged interventions including nutritional manipulations
      and/or exercise may help to reduce, stabilize, or even reverse sarcopenia.
    

Detailed description: 
      Our preliminary studies indicate that, in older adults, muscle protein anabolism is normally
      stimulated by amino acids alone, but impaired when nutritional stimuli contain carbohydrate
      due to a relative insulin resistance of muscle protein synthesis. We have also found that
      amino acids are the most efficient nutrients for the acute stimulation of muscle protein
      anabolism and our pilot data suggest that they can also increase muscle mass in healthy older
      adults.

      Inactivity is another likely contributor to sarcopenia. Exercise increases not only muscle
      protein synthesis,mass and strength, but also energy expenditure. Hence, exercise may improve
      the response of muscle to nutritional interventions in older subjects via increased energy
      requirements and food consumption, thereby allowing for achievement of true supplementation.

      We will test the following specific hypotheses in older, community indwelling, sedentary
      subjects:

      Using a factorial design we will address in older, community-indwelling, sedentary subjects
      the following hypotheses:

        1. Nutritional supplementation with amino acids will improve muscle mass, strength,
           function, quality, and protein synthesis.

        2. Progressive exercise training for 24 weeks will improve muscle mass strength,function,
           quality, perfusion, and protein metabolism.

        3. Combined treatment with nutritional supplementation and progressive exercise training
           for 24 weeks will improve muscle mass, strength, function, quality, perfusion, and
           protein metabolism more than either intervention alone.

      Our goal is to establish if specific interventions that can acutely increase muscle protein
      synthesis can also effectively translate into increased muscle mass and/or performance in
      older sedentary people, thus preventing frailty and promoting physical independence. To this
      end we will use stable isotope methodologies to measure muscle protein metabolism and
      contrast enhanced ultrasound to measure muscle perfusion, in order to determine if the
      treatments' acute effects can predict their chronic impact on muscle mass and function. We
      will also determine if chronic treatment leads to metabolic and/or vascular adaptations that
      may explain the measured changes in muscle mass and function.
    

Intervention name(s): Amino acids; Exercise
Intervention type(s): Dietary Supplement; Drug
Intervention description(s): mixed pure crystalline amino acids for human use (Ajinomoto), 15 g/d; progressive exercise training
Allocation: Randomized
Intervention model: Factorial Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Prevention
Keywords: Sarcopenia; nutrition; aging; metabolism; exercise