This is a small pilot trial of a 5 month aerobic exercise intervention in participants with MCI (n=20) to begin to compare the effects of randomization to use an exercise buddy or to exercise without an assigned buddy. The investigators hypothesize that participants with MCI who exercise with a buddy will have higher adherence to the protocol and greater improvement in 400 meter walk time.

The overall objective of this pilot study is to determine feasibility and gather data that will inform the design of a larger, multicenter, randomized, controlled trial. Specifically, the investigators aim to:

2.1 Determine the feasibility of recruiting persons with MCI and a buddy for an exercise intervention.

- For MCI participants who do not identify a buddy, the investigators will determine the interest and feasibility of recruiting volunteers from the community to be an exercise buddy.

2.2 Determine the effects of having an exercise buddy on:

• adherence to the protocol
• 400 meter walk time, an objective measure of improved physical fitness
• retention and satisfaction for both participant with MCI and buddy

2.3 Establish a scientific partnership with a community based exercise facility.

Inclusion Criteria:

Participants:

• Age 60 and up
• Montreal Cognitive Assessment (MoCA) score 16-28
• CDR= 0.5 with memory box at least 0.5.
• Have a person (study partner) who can answer questions about their cognition for the CDR, FAQ and NPI-Q. This should be the same person who will come to all clinic visits whenever possible. This person can be called to answer these questions if unable to come into the clinic.
• Sedentary for past 3 months (< 45 min /wk of exercise, including walking)
• Able to walk 400 meters in < 15 min without assistance
• Willing to exercise 4 days a week at Body Check at CompRehab
• Physician approval for participation in the exercise intervention

Buddy:

• No report of memory problem
• MoCA score > 24 if > HS education; > 23 if 9-12 years; > 22 if ,< 9 years of education

Exclusion Criteria:

Due to Cognitive Confounders:

• Uncontrolled depression (PHQ-9 > 10)
• Schizophrenia or bipolar disorder
• Parkinson's disease
• Hachinski ischemic index > 4
• Daily use of highly anticholinergic medications (such as amitriptyline, diphenhydramine, scopolamine, etc) or benzodiazepines
• Use of stable dose of Cholinesterase inhibitors will be permitted. Must be on a stable dose for 4 weeks.
• Non-English speaking (as we are unable to administer the cognitive tests in languages other than English for this pilot)
• Vitamin B12 deficiency
• Uncontrolled hypothyroidism as measured by TSH blood test

Due to increased risk of or low likelihood of compliance with the exercise program:

• Active ischemic heart disease or angina
• symptomatic heart failure
• stroke
• screening blood pressure SBP > 170 or < 90; DBP > 100 or < 45
• Parkinson's disease or other neurologic disorder that might make exercise on a treadmill or bike unsafe
• Current or planned treatment for cancer
• peripheral artery disease that limits exercise capacity
• Severe respiratory-disease (e.g., COPD) that limits exercise capacity
• Severe arthritis that limits exercise capacity
• Serious conduction disorder, uncontrolled arrhythmia, or new Q waves or ST-segment depressions (> 3 mm) on ECG
• Severe anemia (Hgb < 8)
• Diagnosis of Diabetes and on medication
• Drinks more than 14 alcoholic drinks per week
• Dependent on a cane, walker or other device that would inhibit then from using a treadmill