Dose Response of Whey and Soy Protein Ingestion With and Without Resistance Exercise in Elderly Men (NDC)

• Muscle protein synthesis [ Time Frame: Acute within the day ] [ Designated as safety issue: No ]
• whole body amino acid oxidation [ Time Frame: acute within the day ] [ Designated as safety issue: No ]

• muscle protein breakdown [ Time Frame: Acute within the day ] [ Designated as safety issue: No ]
• serum insulin [ Time Frame: acute within the day ] [ Designated as safety issue: No ]
• plasma amino acid concentrations [ Time Frame: acute within the day ] [ Designated as safety issue: No ]

When we age, we lose muscle. It is not exactly clear why this happens, but we do know that this muscle loss can increase health risks and lead to health problems. Lifting weights (i.e. performing resistance exercise) and proper nutrition, in particular eating enough high quality protein, can help slow the loss of muscle mass or potentially even reverse it. Protein and resistance exercise are thought to do this by stimulating your muscle to make more proteins and/or potentially by slowing down the rate at which your body breaks proteins down. Whey protein is a high quality protein isolated from milk and is known to stimulate new protein synthesis for all proteins in your body. However, to date, the effect that whey protein has on muscle protein synthesis, particularly in the elderly has yet to be determined. Thus the purposes of this study are: 1) to determine if whey is an effective source of protein that will stimulate muscle protein synthesis in the elderly, similar to what we have previously seen in young persons; 2) to determine the smallest amount of whey protein to consume to maximally stimulate your muscle to make new proteins; 3) to see if performing resistance exercise will augment the increase in new muscle protein synthesis with whey consumption; and 4) to try and found out if whey is more effective than soy protein in stimulating new muscle protein synthesis and suppressing muscle protein breakdown in the elderly, similar to what we have previously seen in young persons

• Control group 0 g protein
  Control group in which a placebo drink containing no protein is given following unilateral knee extension exercise
  Intervention: Dietary Supplement: Whey or soy protein
• Experimental: 10g whey
  10g whey protein given following unilateral knee extension exercise
  Intervention: Dietary Supplement: Whey or soy protein
• Experimental: 20g whey
  20g whey protein given following unilateral knee extension exercise
  Intervention: Dietary Supplement: Whey or soy protein
• Experimental: 30g whey
  30g whey protein given following unilateral knee extension exercise
  Intervention: Dietary Supplement: Whey or soy protein
• Experimental: 40g whey
  40g whey protein given following unilateral knee extension exercise
  Intervention: Dietary Supplement: Whey or soy protein
• Experimental: 20g soy
  20g soy protein given following unilateral knee extension exercise
  Intervention: Dietary Supplement: Whey or soy protein
• Experimental: 40g soy
  40g soy protein given following unilateral knee extension exercise
  Intervention: Dietary Supplement: Whey or soy protein

Inclusion Criteria:

• Male
• Aged 60 to 80 years old
• Non-smoker
• Generally healthy and can tolerate the resistance exercise and protein drink

Exclusion Criteria:

• Allergies to whey, casein or soy
• Health problems such as: heart disease, rheumatoid arthritis of the knee joint, diabetes, poor lung function, uncontrolled hypertension, or any health conditions that might put participants at risks for this study
• Failed clearance for exercise participation by their medical doctor
• Failed an exercise stress test
• Taking metformin and/or other medications for the control of blood glucose even though one might not be classified as diabetic
• Taking prescribed blood thinners such as warfarin and heparin but excluding aspirin
• Taking medications for lung and kidney conditions but excluding medication for asthma that is under control