Mechanisms of Age-Related Muscle Loss

• Young lean healthy inidivduals aged 18-35.
• Lean healthy older individuals aged 65-85.
• Obese inactive older individuals aged 65-85.

Inclusion Criteria:

1. Age: 65-85 years old for older individuals and 18-35 years for younger individuals
2. Sex: Men and women
3. BMI: 18-25 kg/m2 for healthy non-obese young and elderly control group and >30 kg/m2 for obese older participants.
4. Diagnosis / General Health: For healthy elderly, good general health (no known cardiovascular or metabolic disease), nonsmokers, accustomed to normal levels of activity as assessed by pedometer and accelerometer devices during baseline testing (>5000 steps per day). For obese elderly, general good health (no known cardiovascular or metabolic disease), nonsmokers, with low levels of physical activity as assessed by pedometer and accelerometer devices during baseline testing (<4000 steps per day). Fasting blood glucose must be <5.6 mmol/mL for healthy older adults and between 5.6 and 6.9 mmol/mL for obese older adults. Fasting concentrations of A1C should be <5.7% for healthy and between 5.7 and 6.4% for prediabetic older adults. These values are in line with the type 2 diabetes classification listed by The American Diabetes Association (DIABETES CARE, VOLUME 33, SUPPLEMENT 1, JANUARY 2010).
5. Compliance: understands and is willing, able and likely to comply with all study procedures and restrictions.
6. Consent: demonstrates understanding of the study and willingness to participate as evidenced by voluntary written informed consent.

Exclusion Criteria:

1. Health problems such as: heart disease, rheumatoid arthritis, diabetes, poor lung function, uncontrolled hypertension, or any health conditions that might put the participant at risk for this study.
2. Recent failure to obtain clearance for exercise participation from family physician/medical doctor.
3. Regular consumption of any analgesic or anti-inflammatory drug(s), prescription or nonprescription.
4. Taking any medications known to affect protein metabolism (i.e. b-blockers, corticosteroids, nonsteroidal anti-inflammatories, or prescription strength acne medications). Medications will be deemed inappropriate based on the Chief Investigators discretion
5. Individuals who complete fewer than 1000 steps per day (as assessed by pedometer prior to the study) or those who participate in regular structured exercise (running or strength training) more than 2 times per week.
6. Participants will be excluded if they fail to comply with the physical activity demands of the study. Exclusion will occur if the following are not met. Failure to meet the expected daily step count target on more than one occasion per week during the 21 day intervention will be deemed as failure to comply.
7. Participants who have previously (within 5 years of the present study) undergone infusion of an amino acid tracer and/or had 4 or more muscle biopsies obtained from the quadriceps region will be excluded.