Inclusion Criteria:

• Age 70 to 85 years
• Summary score between 88 (80 for less than 8 years of education) and 95 on the Modified Mini-Mental Exam
• Sedentary lifestyle, i.e., not actively participating in a formal exercise program within the past 3 months (defined as 30 minutes or more of formal exercise at least once a week; brisk walks will be considered formal exercise, leisurely walks will not)
• Fluency in standard American English (to limit staffing and translation costs in this pilot)
• Willingness to be randomized to any of the four intervention conditions

Exclusion Criteria:

• Failure to provide the name of a personal physician
• Living in a nursing home; persons living in assisted or independent housing will not be excluded
• Unable to communicate because of severe hearing loss or speech disorder
• Severe visual impairment, which would preclude completion of the assessments and/or intervention
• Neurologic disease, e.g. Alzheimer's (or other types of dementia), stroke that required hospitalization, Parkinson's, multiple sclerosis, ALS, or prior diagnosis of MCI
• Abnormal functioning based on the modified Telephone Interview for Cognitive Status (less than 30)
• Positive screen for MCI or dementia
• Scores greater than or equal to 1.5 standard deviations below normal on memory and non-memory domain tests (speed of processing, and verbal fluency)
• Severe rheumatologic or orthopedic diseases, e.g., awaiting joint replacement, active inflammatory disease
• Terminal illness with life expectancy less than 8 months, as determined by a physician
• Severe pulmonary disease, e.g., on home oxygen or chronic steroids
• Severe cardiac disease, including NYHA Class III or IV congestive heart failure, clinically significant aortic stenosis, history of cardiac arrest which required resuscitation, use of a cardiac defibrillator, or uncontrolled angina
• Other significant co-morbid disease that would impair ability to participate in the exercise-based intervention, e.g. renal failure on hemodialysis, severe or acute psychiatric disorder (e.g. bipolar disorder or major depression, schizophrenia), excessive alcohol use (more than 14 drinks per wk); persons with managed depression (on stable dosage for at least 3 months) will not be excluded
• Baseline Geriatric Depression Scale score greater than 6
• Other significant factors that may affect the ability for cognitive training, including a history of head trauma resulting in a loss of consciousness, current use of benzodiazepines, hypnotic or anticholinergic agents, and current use of cognitive enhancing prescription or investigational medications (e.g., donepezil, selegiline, tacrine)
• Member of household is already enrolled
• Lives distant from the study site or is planning to move out of the area in next 3 years or leave the area for more than 3 months during the next year
• History of participation in a cognitive program in the last 2 years (includes research studies involving memory training)
• Myocardial infarction, CABG, or valve replacement within past 6 months
• Serious conduction disorder (e.g., 3rd degree heart block), uncontrolled arrhythmia
• Pulmonary embolism or deep venous thrombosis within past 6 months
• Stroke, hip fracture, hip or knee replacement, or spinal surgery within past 4 months
• Receiving physical therapy for gait, balance, or other lower extremity training
• Severe hypertension, e.g., systolic blood pressure over 160 mmHg, diastolic blood pressure over 110 mmHg
• Other temporary intervening events, such as sick spouse, bereavement, or recent move
• Participation in another intervention trial; participation in an observational study may be permitted
• Inability to commit to intervention schedule requirements