Time Course Adaptations Using Deuterated Creatine (D3Cr) Method

Inclusion Criteria: * men and women aged 70 or greater * at high risk for mobility disability based on lower extremity functional limitations measured by Short Physical Performance battery (SPPB) with a score ≤ 8 out of 12 * could safely participate in the resistance training intervention as determined by medical history and physical examination. * willing to give informed consent to be randomized to either the resistance training group or successful aging heath education comparison group and willing to follow the study protocol Exclusion Criteria: * Severe cardiac disease, including NYHA Class III or IV congestive heart failure, clinically significant aortic stenosis, history of cardiac arrest, use of a cardiac defibrillator, or uncontrolled angina * Myocardial infarction, major heart surgery, stroke, deep vein thrombosis, or pulmonary embolus in the past 6 months * Lung disease requiring either oral or injected steroids, or the use of supplemental oxygen * Short, portable mental status questionnaire with 3 or more errors * Severe arthritis (either osteoarthritis or rheumatoid arthritis) that severely limits mobility * Severe lower back or shoulder pain that can worsen with weight lifting exercises. * Cancer requiring treatment in the past 1 year (Melanomas excluded) * Any present or recent history of severe psychiatric illness including depression that might preclude providing informed consent, safe participation, or compliance (self-report and investigator judgement * Development of chest pain or severe shortness of breath on the 400 m self-paced walk test * Parkinson's disease or other serious neurological disorders; renal disease requiring dialysis; other illness of such severity that life expectancy is considered to be less than 12 months * Current diagnosis of schizophrenia, other psychotic disorders, or bipolar disorder * Current consumption of more than 14 alcoholic drinks per week * Uncontrolled hypertension (systolic blood pressure \> 200 mm Hg and/or diastolic blood pressure \>110 mm Hg) * Currently on testosterone, Dehydroepiandrosterone (DHEA), or anabolic steroids. * Undergoing physical therapy involving the lower extremities * Currently enrolled in another randomized trial involving a pharmaceutical or lifestyle intervention. Observational studies are permitted * Participation in progressive resistance exercise regimen ( ≥1 day/week) within the previous 6 months prior to screening. * Weight change (intentional or not) over the last 6 months of \> 5% of body or plan to lose or gain weight during the study * Any other cardiovascular, pulmonary, orthopedic, neurologic, or other conditions that in the opinion of the local clinician would preclude participation and successful completion of the protocol Temporary Exclusion Criteria: * Recent bacterial/viral infection (e.g. pneumonia) (\< 2 weeks); * Acute febrile illness in past 2 months; * Severe hypertension, e.g., SBP \> 200 mm Hg, DBP \> 110 mm Hg * Major surgery or fracture or hip/knee replacement (\< 6 months); * Hospitalization within the last 6 months ( Not ER visits)